Vendor dependencies for 0.3.0 release

vendor/prettyplease/src/algorithm.rs

@@ -0,0 +1,386 @@
+// Adapted from https://github.com/rust-lang/rust/blob/1.57.0/compiler/rustc_ast_pretty/src/pp.rs.
+// See "Algorithm notes" in the crate-level rustdoc.
+
+use crate::ring::RingBuffer;
+use crate::{MARGIN, MIN_SPACE};
+use std::borrow::Cow;
+use std::cmp;
+use std::collections::VecDeque;
+use std::iter;
+
+#[derive(Clone, Copy, PartialEq)]
+pub enum Breaks {
+    Consistent,
+    Inconsistent,
+}
+
+#[derive(Clone, Copy, Default)]
+pub struct BreakToken {
+    pub offset: isize,
+    pub blank_space: usize,
+    pub pre_break: Option<char>,
+    pub post_break: &'static str,
+    pub no_break: Option<char>,
+    pub if_nonempty: bool,
+    pub never_break: bool,
+}
+
+#[derive(Clone, Copy)]
+pub struct BeginToken {
+    pub offset: isize,
+    pub breaks: Breaks,
+}
+
+#[derive(Clone)]
+pub enum Token {
+    String(Cow<'static, str>),
+    Break(BreakToken),
+    Begin(BeginToken),
+    End,
+}
+
+#[derive(Copy, Clone)]
+enum PrintFrame {
+    Fits(Breaks),
+    Broken(usize, Breaks),
+}
+
+pub const SIZE_INFINITY: isize = 0xffff;
+
+pub struct Printer {
+    out: String,
+    // Number of spaces left on line
+    space: isize,
+    // Ring-buffer of tokens and calculated sizes
+    buf: RingBuffer<BufEntry>,
+    // Total size of tokens already printed
+    left_total: isize,
+    // Total size of tokens enqueued, including printed and not yet printed
+    right_total: isize,
+    // Holds the ring-buffer index of the Begin that started the current block,
+    // possibly with the most recent Break after that Begin (if there is any) on
+    // top of it. Values are pushed and popped on the back of the queue using it
+    // like stack, and elsewhere old values are popped from the front of the
+    // queue as they become irrelevant due to the primary ring-buffer advancing.
+    scan_stack: VecDeque<usize>,
+    // Stack of blocks-in-progress being flushed by print
+    print_stack: Vec<PrintFrame>,
+    // Level of indentation of current line
+    indent: usize,
+    // Buffered indentation to avoid writing trailing whitespace
+    pending_indentation: usize,
+}
+
+#[derive(Clone)]
+struct BufEntry {
+    token: Token,
+    size: isize,
+}
+
+impl Printer {
+    pub fn new() -> Self {
+        Printer {
+            out: String::new(),
+            space: MARGIN,
+            buf: RingBuffer::new(),
+            left_total: 0,
+            right_total: 0,
+            scan_stack: VecDeque::new(),
+            print_stack: Vec::new(),
+            indent: 0,
+            pending_indentation: 0,
+        }
+    }
+
+    pub fn eof(mut self) -> String {
+        if !self.scan_stack.is_empty() {
+            self.check_stack(0);
+            self.advance_left();
+        }
+        self.out
+    }
+
+    pub fn scan_begin(&mut self, token: BeginToken) {
+        if self.scan_stack.is_empty() {
+            self.left_total = 1;
+            self.right_total = 1;
+            self.buf.clear();
+        }
+        let right = self.buf.push(BufEntry {
+            token: Token::Begin(token),
+            size: -self.right_total,
+        });
+        self.scan_stack.push_back(right);
+    }
+
+    pub fn scan_end(&mut self) {
+        if self.scan_stack.is_empty() {
+            self.print_end();
+        } else {
+            if !self.buf.is_empty() {
+                if let Token::Break(break_token) = self.buf.last().token {
+                    if self.buf.len() >= 2 {
+                        if let Token::Begin(_) = self.buf.second_last().token {
+                            self.buf.pop_last();
+                            self.buf.pop_last();
+                            self.scan_stack.pop_back();
+                            self.scan_stack.pop_back();
+                            self.right_total -= break_token.blank_space as isize;
+                            return;
+                        }
+                    }
+                    if break_token.if_nonempty {
+                        self.buf.pop_last();
+                        self.scan_stack.pop_back();
+                        self.right_total -= break_token.blank_space as isize;
+                    }
+                }
+            }
+            let right = self.buf.push(BufEntry {
+                token: Token::End,
+                size: -1,
+            });
+            self.scan_stack.push_back(right);
+        }
+    }
+
+    pub fn scan_break(&mut self, token: BreakToken) {
+        if self.scan_stack.is_empty() {
+            self.left_total = 1;
+            self.right_total = 1;
+            self.buf.clear();
+        } else {
+            self.check_stack(0);
+        }
+        let right = self.buf.push(BufEntry {
+            token: Token::Break(token),
+            size: -self.right_total,
+        });
+        self.scan_stack.push_back(right);
+        self.right_total += token.blank_space as isize;
+    }
+
+    pub fn scan_string(&mut self, string: Cow<'static, str>) {
+        if self.scan_stack.is_empty() {
+            self.print_string(string);
+        } else {
+            let len = string.len() as isize;
+            self.buf.push(BufEntry {
+                token: Token::String(string),
+                size: len,
+            });
+            self.right_total += len;
+            self.check_stream();
+        }
+    }
+
+    #[track_caller]
+    pub fn offset(&mut self, offset: isize) {
+        match &mut self.buf.last_mut().token {
+            Token::Break(token) => token.offset += offset,
+            Token::Begin(_) => {}
+            Token::String(_) | Token::End => unreachable!(),
+        }
+    }
+
+    pub fn end_with_max_width(&mut self, max: isize) {
+        let mut depth = 1;
+        for &index in self.scan_stack.iter().rev() {
+            let entry = &self.buf[index];
+            match entry.token {
+                Token::Begin(_) => {
+                    depth -= 1;
+                    if depth == 0 {
+                        if entry.size < 0 {
+                            let actual_width = entry.size + self.right_total;
+                            if actual_width > max {
+                                self.buf.push(BufEntry {
+                                    token: Token::String(Cow::Borrowed("")),
+                                    size: SIZE_INFINITY,
+                                });
+                                self.right_total += SIZE_INFINITY;
+                            }
+                        }
+                        break;
+                    }
+                }
+                Token::End => depth += 1,
+                Token::Break(_) => {}
+                Token::String(_) => unreachable!(),
+            }
+        }
+        self.scan_end();
+    }
+
+    pub fn ends_with(&self, ch: char) -> bool {
+        for i in self.buf.index_range().rev() {
+            if let Token::String(token) = &self.buf[i].token {
+                return token.ends_with(ch);
+            }
+        }
+        self.out.ends_with(ch)
+    }
+
+    fn check_stream(&mut self) {
+        while self.right_total - self.left_total > self.space {
+            if *self.scan_stack.front().unwrap() == self.buf.index_range().start {
+                self.scan_stack.pop_front().unwrap();
+                self.buf.first_mut().size = SIZE_INFINITY;
+            }
+
+            self.advance_left();
+
+            if self.buf.is_empty() {
+                break;
+            }
+        }
+    }
+
+    fn advance_left(&mut self) {
+        while self.buf.first().size >= 0 {
+            let left = self.buf.pop_first();
+
+            match left.token {
+                Token::String(string) => {
+                    self.left_total += left.size;
+                    self.print_string(string);
+                }
+                Token::Break(token) => {
+                    self.left_total += token.blank_space as isize;
+                    self.print_break(token, left.size);
+                }
+                Token::Begin(token) => self.print_begin(token, left.size),
+                Token::End => self.print_end(),
+            }
+
+            if self.buf.is_empty() {
+                break;
+            }
+        }
+    }
+
+    fn check_stack(&mut self, mut depth: usize) {
+        while let Some(&index) = self.scan_stack.back() {
+            let entry = &mut self.buf[index];
+            match entry.token {
+                Token::Begin(_) => {
+                    if depth == 0 {
+                        break;
+                    }
+                    self.scan_stack.pop_back().unwrap();
+                    entry.size += self.right_total;
+                    depth -= 1;
+                }
+                Token::End => {
+                    self.scan_stack.pop_back().unwrap();
+                    entry.size = 1;
+                    depth += 1;
+                }
+                Token::Break(_) => {
+                    self.scan_stack.pop_back().unwrap();
+                    entry.size += self.right_total;
+                    if depth == 0 {
+                        break;
+                    }
+                }
+                Token::String(_) => unreachable!(),
+            }
+        }
+    }
+
+    fn get_top(&self) -> PrintFrame {
+        const OUTER: PrintFrame = PrintFrame::Broken(0, Breaks::Inconsistent);
+        self.print_stack.last().map_or(OUTER, PrintFrame::clone)
+    }
+
+    fn print_begin(&mut self, token: BeginToken, size: isize) {
+        if cfg!(prettyplease_debug) {
+            self.out.push(match token.breaks {
+                Breaks::Consistent => '«',
+                Breaks::Inconsistent => '‹',
+            });
+            if cfg!(prettyplease_debug_indent) {
+                self.out
+                    .extend(token.offset.to_string().chars().map(|ch| match ch {
+                        '0'..='9' => ['₀', '₁', '₂', '₃', '₄', '₅', '₆', '₇', '₈', '₉']
+                            [(ch as u8 - b'0') as usize],
+                        '-' => '₋',
+                        _ => unreachable!(),
+                    }));
+            }
+        }
+        if size > self.space {
+            self.print_stack
+                .push(PrintFrame::Broken(self.indent, token.breaks));
+            self.indent = usize::try_from(self.indent as isize + token.offset).unwrap();
+        } else {
+            self.print_stack.push(PrintFrame::Fits(token.breaks));
+        }
+    }
+
+    fn print_end(&mut self) {
+        let breaks = match self.print_stack.pop().unwrap() {
+            PrintFrame::Broken(indent, breaks) => {
+                self.indent = indent;
+                breaks
+            }
+            PrintFrame::Fits(breaks) => breaks,
+        };
+        if cfg!(prettyplease_debug) {
+            self.out.push(match breaks {
+                Breaks::Consistent => '»',
+                Breaks::Inconsistent => '›',
+            });
+        }
+    }
+
+    fn print_break(&mut self, token: BreakToken, size: isize) {
+        let fits = token.never_break
+            || match self.get_top() {
+                PrintFrame::Fits(..) => true,
+                PrintFrame::Broken(.., Breaks::Consistent) => false,
+                PrintFrame::Broken(.., Breaks::Inconsistent) => size <= self.space,
+            };
+        if fits {
+            self.pending_indentation += token.blank_space;
+            self.space -= token.blank_space as isize;
+            if let Some(no_break) = token.no_break {
+                self.out.push(no_break);
+                self.space -= no_break.len_utf8() as isize;
+            }
+            if cfg!(prettyplease_debug) {
+                self.out.push('·');
+            }
+        } else {
+            if let Some(pre_break) = token.pre_break {
+                self.print_indent();
+                self.out.push(pre_break);
+            }
+            if cfg!(prettyplease_debug) {
+                self.out.push('·');
+            }
+            self.out.push('\n');
+            let indent = self.indent as isize + token.offset;
+            self.pending_indentation = usize::try_from(indent).unwrap();
+            self.space = cmp::max(MARGIN - indent, MIN_SPACE);
+            if !token.post_break.is_empty() {
+                self.print_indent();
+                self.out.push_str(token.post_break);
+                self.space -= token.post_break.len() as isize;
+            }
+        }
+    }
+
+    fn print_string(&mut self, string: Cow<'static, str>) {
+        self.print_indent();
+        self.out.push_str(&string);
+        self.space -= string.len() as isize;
+    }
+
+    fn print_indent(&mut self) {
+        self.out.reserve(self.pending_indentation);
+        self.out
+            .extend(iter::repeat(' ').take(self.pending_indentation));
+        self.pending_indentation = 0;
+    }
+}

vendor/prettyplease/src/attr.rs

@@ -0,0 +1,288 @@
+use crate::algorithm::Printer;
+use crate::fixup::FixupContext;
+use crate::path::PathKind;
+use crate::INDENT;
+use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
+use syn::{AttrStyle, Attribute, Expr, Lit, MacroDelimiter, Meta, MetaList, MetaNameValue};
+
+impl Printer {
+    pub fn outer_attrs(&mut self, attrs: &[Attribute]) {
+        for attr in attrs {
+            if let AttrStyle::Outer = attr.style {
+                self.attr(attr);
+            }
+        }
+    }
+
+    pub fn inner_attrs(&mut self, attrs: &[Attribute]) {
+        for attr in attrs {
+            if let AttrStyle::Inner(_) = attr.style {
+                self.attr(attr);
+            }
+        }
+    }
+
+    fn attr(&mut self, attr: &Attribute) {
+        if let Some(mut doc) = value_of_attribute("doc", attr) {
+            if !doc.contains('\n')
+                && match attr.style {
+                    AttrStyle::Outer => !doc.starts_with('/'),
+                    AttrStyle::Inner(_) => true,
+                }
+            {
+                trim_trailing_spaces(&mut doc);
+                self.word(match attr.style {
+                    AttrStyle::Outer => "///",
+                    AttrStyle::Inner(_) => "//!",
+                });
+                self.word(doc);
+                self.hardbreak();
+                return;
+            } else if can_be_block_comment(&doc)
+                && match attr.style {
+                    AttrStyle::Outer => !doc.starts_with(&['*', '/'][..]),
+                    AttrStyle::Inner(_) => true,
+                }
+            {
+                trim_interior_trailing_spaces(&mut doc);
+                self.word(match attr.style {
+                    AttrStyle::Outer => "/**",
+                    AttrStyle::Inner(_) => "/*!",
+                });
+                self.word(doc);
+                self.word("*/");
+                self.hardbreak();
+                return;
+            }
+        } else if let Some(mut comment) = value_of_attribute("comment", attr) {
+            if !comment.contains('\n') {
+                trim_trailing_spaces(&mut comment);
+                self.word("//");
+                self.word(comment);
+                self.hardbreak();
+                return;
+            } else if can_be_block_comment(&comment) && !comment.starts_with(&['*', '!'][..]) {
+                trim_interior_trailing_spaces(&mut comment);
+                self.word("/*");
+                self.word(comment);
+                self.word("*/");
+                self.hardbreak();
+                return;
+            }
+        }
+
+        self.word(match attr.style {
+            AttrStyle::Outer => "#",
+            AttrStyle::Inner(_) => "#!",
+        });
+        self.word("[");
+        self.meta(&attr.meta);
+        self.word("]");
+        self.space();
+    }
+
+    fn meta(&mut self, meta: &Meta) {
+        match meta {
+            Meta::Path(path) => self.path(path, PathKind::Simple),
+            Meta::List(meta) => self.meta_list(meta),
+            Meta::NameValue(meta) => self.meta_name_value(meta),
+        }
+    }
+
+    fn meta_list(&mut self, meta: &MetaList) {
+        self.path(&meta.path, PathKind::Simple);
+        let delimiter = match meta.delimiter {
+            MacroDelimiter::Paren(_) => Delimiter::Parenthesis,
+            MacroDelimiter::Brace(_) => Delimiter::Brace,
+            MacroDelimiter::Bracket(_) => Delimiter::Bracket,
+        };
+        let group = Group::new(delimiter, meta.tokens.clone());
+        self.attr_tokens(TokenStream::from(TokenTree::Group(group)));
+    }
+
+    fn meta_name_value(&mut self, meta: &MetaNameValue) {
+        self.path(&meta.path, PathKind::Simple);
+        self.word(" = ");
+        self.expr(&meta.value, FixupContext::NONE);
+    }
+
+    fn attr_tokens(&mut self, tokens: TokenStream) {
+        let mut stack = Vec::new();
+        stack.push((tokens.into_iter().peekable(), Delimiter::None));
+        let mut space = Self::nbsp as fn(&mut Self);
+
+        #[derive(PartialEq)]
+        enum State {
+            Word,
+            Punct,
+            TrailingComma,
+        }
+
+        use State::*;
+        let mut state = Word;
+
+        while let Some((tokens, delimiter)) = stack.last_mut() {
+            match tokens.next() {
+                Some(TokenTree::Ident(ident)) => {
+                    if let Word = state {
+                        space(self);
+                    }
+                    self.ident(&ident);
+                    state = Word;
+                }
+                Some(TokenTree::Punct(punct)) => {
+                    let ch = punct.as_char();
+                    if let (Word, '=') = (state, ch) {
+                        self.nbsp();
+                    }
+                    if ch == ',' && tokens.peek().is_none() {
+                        self.trailing_comma(true);
+                        state = TrailingComma;
+                    } else {
+                        self.token_punct(ch);
+                        if ch == '=' {
+                            self.nbsp();
+                        } else if ch == ',' {
+                            space(self);
+                        }
+                        state = Punct;
+                    }
+                }
+                Some(TokenTree::Literal(literal)) => {
+                    if let Word = state {
+                        space(self);
+                    }
+                    self.token_literal(&literal);
+                    state = Word;
+                }
+                Some(TokenTree::Group(group)) => {
+                    let delimiter = group.delimiter();
+                    let stream = group.stream();
+                    match delimiter {
+                        Delimiter::Parenthesis => {
+                            self.word("(");
+                            self.cbox(INDENT);
+                            self.zerobreak();
+                            state = Punct;
+                        }
+                        Delimiter::Brace => {
+                            self.word("{");
+                            state = Punct;
+                        }
+                        Delimiter::Bracket => {
+                            self.word("[");
+                            state = Punct;
+                        }
+                        Delimiter::None => {}
+                    }
+                    stack.push((stream.into_iter().peekable(), delimiter));
+                    space = Self::space;
+                }
+                None => {
+                    match delimiter {
+                        Delimiter::Parenthesis => {
+                            if state != TrailingComma {
+                                self.zerobreak();
+                            }
+                            self.offset(-INDENT);
+                            self.end();
+                            self.word(")");
+                            state = Punct;
+                        }
+                        Delimiter::Brace => {
+                            self.word("}");
+                            state = Punct;
+                        }
+                        Delimiter::Bracket => {
+                            self.word("]");
+                            state = Punct;
+                        }
+                        Delimiter::None => {}
+                    }
+                    stack.pop();
+                    if stack.is_empty() {
+                        space = Self::nbsp;
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn value_of_attribute(requested: &str, attr: &Attribute) -> Option<String> {
+    let value = match &attr.meta {
+        Meta::NameValue(meta) if meta.path.is_ident(requested) => &meta.value,
+        _ => return None,
+    };
+    let lit = match value {
+        Expr::Lit(expr) if expr.attrs.is_empty() => &expr.lit,
+        _ => return None,
+    };
+    match lit {
+        Lit::Str(string) => Some(string.value()),
+        _ => None,
+    }
+}
+
+pub fn has_outer(attrs: &[Attribute]) -> bool {
+    for attr in attrs {
+        if let AttrStyle::Outer = attr.style {
+            return true;
+        }
+    }
+    false
+}
+
+pub fn has_inner(attrs: &[Attribute]) -> bool {
+    for attr in attrs {
+        if let AttrStyle::Inner(_) = attr.style {
+            return true;
+        }
+    }
+    false
+}
+
+fn trim_trailing_spaces(doc: &mut String) {
+    doc.truncate(doc.trim_end_matches(' ').len());
+}
+
+fn trim_interior_trailing_spaces(doc: &mut String) {
+    if !doc.contains(" \n") {
+        return;
+    }
+    let mut trimmed = String::with_capacity(doc.len());
+    let mut lines = doc.split('\n').peekable();
+    while let Some(line) = lines.next() {
+        if lines.peek().is_some() {
+            trimmed.push_str(line.trim_end_matches(' '));
+            trimmed.push('\n');
+        } else {
+            trimmed.push_str(line);
+        }
+    }
+    *doc = trimmed;
+}
+
+fn can_be_block_comment(value: &str) -> bool {
+    let mut depth = 0usize;
+    let bytes = value.as_bytes();
+    let mut i = 0usize;
+    let upper = bytes.len() - 1;
+
+    while i < upper {
+        if bytes[i] == b'/' && bytes[i + 1] == b'*' {
+            depth += 1;
+            i += 2;
+        } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
+            if depth == 0 {
+                return false;
+            }
+            depth -= 1;
+            i += 2;
+        } else {
+            i += 1;
+        }
+    }
+
+    depth == 0 && !value.ends_with('/')
+}

vendor/prettyplease/src/classify.rs

@@ -0,0 +1,324 @@
+use proc_macro2::{Delimiter, TokenStream, TokenTree};
+use std::ops::ControlFlow;
+use syn::punctuated::Punctuated;
+use syn::{Expr, MacroDelimiter, Path, PathArguments, ReturnType, Token, Type, TypeParamBound};
+
+pub(crate) fn requires_semi_to_be_stmt(expr: &Expr) -> bool {
+    match expr {
+        Expr::Macro(expr) => !matches!(expr.mac.delimiter, MacroDelimiter::Brace(_)),
+        _ => requires_comma_to_be_match_arm(expr),
+    }
+}
+
+pub(crate) fn requires_comma_to_be_match_arm(mut expr: &Expr) -> bool {
+    loop {
+        match expr {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Expr::If(_)
+            | Expr::Match(_)
+            | Expr::Block(_) | Expr::Unsafe(_) // both under ExprKind::Block in rustc
+            | Expr::While(_)
+            | Expr::Loop(_)
+            | Expr::ForLoop(_)
+            | Expr::TryBlock(_)
+            | Expr::Const(_) => return false,
+
+            Expr::Array(_)
+            | Expr::Assign(_)
+            | Expr::Async(_)
+            | Expr::Await(_)
+            | Expr::Binary(_)
+            | Expr::Break(_)
+            | Expr::Call(_)
+            | Expr::Cast(_)
+            | Expr::Closure(_)
+            | Expr::Continue(_)
+            | Expr::Field(_)
+            | Expr::Index(_)
+            | Expr::Infer(_)
+            | Expr::Let(_)
+            | Expr::Lit(_)
+            | Expr::Macro(_)
+            | Expr::MethodCall(_)
+            | Expr::Paren(_)
+            | Expr::Path(_)
+            | Expr::Range(_)
+            | Expr::RawAddr(_)
+            | Expr::Reference(_)
+            | Expr::Repeat(_)
+            | Expr::Return(_)
+            | Expr::Struct(_)
+            | Expr::Try(_)
+            | Expr::Tuple(_)
+            | Expr::Unary(_)
+            | Expr::Yield(_)
+            | Expr::Verbatim(_) => return true,
+
+            Expr::Group(group) => expr = &group.expr,
+
+            _ => return true,
+        }
+    }
+}
+
+pub(crate) fn trailing_unparameterized_path(mut ty: &Type) -> bool {
+    loop {
+        match ty {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Type::BareFn(t) => match &t.output {
+                ReturnType::Default => return false,
+                ReturnType::Type(_, ret) => ty = ret,
+            },
+            Type::ImplTrait(t) => match last_type_in_bounds(&t.bounds) {
+                ControlFlow::Break(trailing_path) => return trailing_path,
+                ControlFlow::Continue(t) => ty = t,
+            },
+            Type::Path(t) => match last_type_in_path(&t.path) {
+                ControlFlow::Break(trailing_path) => return trailing_path,
+                ControlFlow::Continue(t) => ty = t,
+            },
+            Type::Ptr(t) => ty = &t.elem,
+            Type::Reference(t) => ty = &t.elem,
+            Type::TraitObject(t) => match last_type_in_bounds(&t.bounds) {
+                ControlFlow::Break(trailing_path) => return trailing_path,
+                ControlFlow::Continue(t) => ty = t,
+            },
+
+            Type::Array(_)
+            | Type::Group(_)
+            | Type::Infer(_)
+            | Type::Macro(_)
+            | Type::Never(_)
+            | Type::Paren(_)
+            | Type::Slice(_)
+            | Type::Tuple(_)
+            | Type::Verbatim(_) => return false,
+
+            _ => return false,
+        }
+    }
+
+    fn last_type_in_path(path: &Path) -> ControlFlow<bool, &Type> {
+        match &path.segments.last().unwrap().arguments {
+            PathArguments::None => ControlFlow::Break(true),
+            PathArguments::AngleBracketed(_) => ControlFlow::Break(false),
+            PathArguments::Parenthesized(arg) => match &arg.output {
+                ReturnType::Default => ControlFlow::Break(false),
+                ReturnType::Type(_, ret) => ControlFlow::Continue(ret),
+            },
+        }
+    }
+
+    fn last_type_in_bounds(
+        bounds: &Punctuated<TypeParamBound, Token![+]>,
+    ) -> ControlFlow<bool, &Type> {
+        match bounds.last().unwrap() {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            TypeParamBound::Trait(t) => last_type_in_path(&t.path),
+            TypeParamBound::Lifetime(_)
+            | TypeParamBound::PreciseCapture(_)
+            | TypeParamBound::Verbatim(_) => ControlFlow::Break(false),
+            _ => ControlFlow::Break(false),
+        }
+    }
+}
+
+/// Whether the expression's first token is the label of a loop/block.
+pub(crate) fn expr_leading_label(mut expr: &Expr) -> bool {
+    loop {
+        match expr {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Expr::Block(e) => return e.label.is_some(),
+            Expr::ForLoop(e) => return e.label.is_some(),
+            Expr::Loop(e) => return e.label.is_some(),
+            Expr::While(e) => return e.label.is_some(),
+
+            Expr::Assign(e) => expr = &e.left,
+            Expr::Await(e) => expr = &e.base,
+            Expr::Binary(e) => expr = &e.left,
+            Expr::Call(e) => expr = &e.func,
+            Expr::Cast(e) => expr = &e.expr,
+            Expr::Field(e) => expr = &e.base,
+            Expr::Index(e) => expr = &e.expr,
+            Expr::MethodCall(e) => expr = &e.receiver,
+            Expr::Range(e) => match &e.start {
+                Some(start) => expr = start,
+                None => return false,
+            },
+            Expr::Try(e) => expr = &e.expr,
+
+            Expr::Array(_)
+            | Expr::Async(_)
+            | Expr::Break(_)
+            | Expr::Closure(_)
+            | Expr::Const(_)
+            | Expr::Continue(_)
+            | Expr::If(_)
+            | Expr::Infer(_)
+            | Expr::Let(_)
+            | Expr::Lit(_)
+            | Expr::Macro(_)
+            | Expr::Match(_)
+            | Expr::Paren(_)
+            | Expr::Path(_)
+            | Expr::RawAddr(_)
+            | Expr::Reference(_)
+            | Expr::Repeat(_)
+            | Expr::Return(_)
+            | Expr::Struct(_)
+            | Expr::TryBlock(_)
+            | Expr::Tuple(_)
+            | Expr::Unary(_)
+            | Expr::Unsafe(_)
+            | Expr::Verbatim(_)
+            | Expr::Yield(_) => return false,
+
+            Expr::Group(e) => {
+                if !e.attrs.is_empty() {
+                    return false;
+                }
+                expr = &e.expr;
+            }
+
+            _ => return false,
+        }
+    }
+}
+
+/// Whether the expression's last token is `}`.
+pub(crate) fn expr_trailing_brace(mut expr: &Expr) -> bool {
+    loop {
+        match expr {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Expr::Async(_)
+            | Expr::Block(_)
+            | Expr::Const(_)
+            | Expr::ForLoop(_)
+            | Expr::If(_)
+            | Expr::Loop(_)
+            | Expr::Match(_)
+            | Expr::Struct(_)
+            | Expr::TryBlock(_)
+            | Expr::Unsafe(_)
+            | Expr::While(_) => return true,
+
+            Expr::Assign(e) => expr = &e.right,
+            Expr::Binary(e) => expr = &e.right,
+            Expr::Break(e) => match &e.expr {
+                Some(e) => expr = e,
+                None => return false,
+            },
+            Expr::Cast(e) => return type_trailing_brace(&e.ty),
+            Expr::Closure(e) => expr = &e.body,
+            Expr::Group(e) => expr = &e.expr,
+            Expr::Let(e) => expr = &e.expr,
+            Expr::Macro(e) => return matches!(e.mac.delimiter, MacroDelimiter::Brace(_)),
+            Expr::Range(e) => match &e.end {
+                Some(end) => expr = end,
+                None => return false,
+            },
+            Expr::RawAddr(e) => expr = &e.expr,
+            Expr::Reference(e) => expr = &e.expr,
+            Expr::Return(e) => match &e.expr {
+                Some(e) => expr = e,
+                None => return false,
+            },
+            Expr::Unary(e) => expr = &e.expr,
+            Expr::Verbatim(e) => return tokens_trailing_brace(e),
+            Expr::Yield(e) => match &e.expr {
+                Some(e) => expr = e,
+                None => return false,
+            },
+
+            Expr::Array(_)
+            | Expr::Await(_)
+            | Expr::Call(_)
+            | Expr::Continue(_)
+            | Expr::Field(_)
+            | Expr::Index(_)
+            | Expr::Infer(_)
+            | Expr::Lit(_)
+            | Expr::MethodCall(_)
+            | Expr::Paren(_)
+            | Expr::Path(_)
+            | Expr::Repeat(_)
+            | Expr::Try(_)
+            | Expr::Tuple(_) => return false,
+
+            _ => return false,
+        }
+    }
+
+    fn type_trailing_brace(mut ty: &Type) -> bool {
+        loop {
+            match ty {
+                #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+                Type::BareFn(t) => match &t.output {
+                    ReturnType::Default => return false,
+                    ReturnType::Type(_, ret) => ty = ret,
+                },
+                Type::ImplTrait(t) => match last_type_in_bounds(&t.bounds) {
+                    ControlFlow::Break(trailing_brace) => return trailing_brace,
+                    ControlFlow::Continue(t) => ty = t,
+                },
+                Type::Macro(t) => return matches!(t.mac.delimiter, MacroDelimiter::Brace(_)),
+                Type::Path(t) => match last_type_in_path(&t.path) {
+                    Some(t) => ty = t,
+                    None => return false,
+                },
+                Type::Ptr(t) => ty = &t.elem,
+                Type::Reference(t) => ty = &t.elem,
+                Type::TraitObject(t) => match last_type_in_bounds(&t.bounds) {
+                    ControlFlow::Break(trailing_brace) => return trailing_brace,
+                    ControlFlow::Continue(t) => ty = t,
+                },
+                Type::Verbatim(t) => return tokens_trailing_brace(t),
+
+                Type::Array(_)
+                | Type::Group(_)
+                | Type::Infer(_)
+                | Type::Never(_)
+                | Type::Paren(_)
+                | Type::Slice(_)
+                | Type::Tuple(_) => return false,
+
+                _ => return false,
+            }
+        }
+    }
+
+    fn last_type_in_path(path: &Path) -> Option<&Type> {
+        match &path.segments.last().unwrap().arguments {
+            PathArguments::None | PathArguments::AngleBracketed(_) => None,
+            PathArguments::Parenthesized(arg) => match &arg.output {
+                ReturnType::Default => None,
+                ReturnType::Type(_, ret) => Some(ret),
+            },
+        }
+    }
+
+    fn last_type_in_bounds(
+        bounds: &Punctuated<TypeParamBound, Token![+]>,
+    ) -> ControlFlow<bool, &Type> {
+        match bounds.last().unwrap() {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            TypeParamBound::Trait(t) => match last_type_in_path(&t.path) {
+                Some(t) => ControlFlow::Continue(t),
+                None => ControlFlow::Break(false),
+            },
+            TypeParamBound::Lifetime(_) | TypeParamBound::PreciseCapture(_) => {
+                ControlFlow::Break(false)
+            }
+            TypeParamBound::Verbatim(t) => ControlFlow::Break(tokens_trailing_brace(t)),
+            _ => ControlFlow::Break(false),
+        }
+    }
+
+    fn tokens_trailing_brace(tokens: &TokenStream) -> bool {
+        if let Some(TokenTree::Group(last)) = tokens.clone().into_iter().last() {
+            last.delimiter() == Delimiter::Brace
+        } else {
+            false
+        }
+    }
+}

vendor/prettyplease/src/convenience.rs

@@ -0,0 +1,98 @@
+use crate::algorithm::{self, BeginToken, BreakToken, Breaks, Printer};
+use std::borrow::Cow;
+
+impl Printer {
+    pub fn ibox(&mut self, indent: isize) {
+        self.scan_begin(BeginToken {
+            offset: indent,
+            breaks: Breaks::Inconsistent,
+        });
+    }
+
+    pub fn cbox(&mut self, indent: isize) {
+        self.scan_begin(BeginToken {
+            offset: indent,
+            breaks: Breaks::Consistent,
+        });
+    }
+
+    pub fn end(&mut self) {
+        self.scan_end();
+    }
+
+    pub fn word<S: Into<Cow<'static, str>>>(&mut self, wrd: S) {
+        let s = wrd.into();
+        self.scan_string(s);
+    }
+
+    fn spaces(&mut self, n: usize) {
+        self.scan_break(BreakToken {
+            blank_space: n,
+            ..BreakToken::default()
+        });
+    }
+
+    pub fn zerobreak(&mut self) {
+        self.spaces(0);
+    }
+
+    pub fn space(&mut self) {
+        self.spaces(1);
+    }
+
+    pub fn nbsp(&mut self) {
+        self.word(" ");
+    }
+
+    pub fn hardbreak(&mut self) {
+        self.spaces(algorithm::SIZE_INFINITY as usize);
+    }
+
+    pub fn space_if_nonempty(&mut self) {
+        self.scan_break(BreakToken {
+            blank_space: 1,
+            if_nonempty: true,
+            ..BreakToken::default()
+        });
+    }
+
+    pub fn hardbreak_if_nonempty(&mut self) {
+        self.scan_break(BreakToken {
+            blank_space: algorithm::SIZE_INFINITY as usize,
+            if_nonempty: true,
+            ..BreakToken::default()
+        });
+    }
+
+    pub fn trailing_comma(&mut self, is_last: bool) {
+        if is_last {
+            self.scan_break(BreakToken {
+                pre_break: Some(','),
+                ..BreakToken::default()
+            });
+        } else {
+            self.word(",");
+            self.space();
+        }
+    }
+
+    pub fn trailing_comma_or_space(&mut self, is_last: bool) {
+        if is_last {
+            self.scan_break(BreakToken {
+                blank_space: 1,
+                pre_break: Some(','),
+                ..BreakToken::default()
+            });
+        } else {
+            self.word(",");
+            self.space();
+        }
+    }
+
+    pub fn neverbreak(&mut self) {
+        self.scan_break(BreakToken {
+            never_break: true,
+            ..BreakToken::default()
+        });
+    }
+}

vendor/prettyplease/src/data.rs

@@ -0,0 +1,79 @@
+use crate::algorithm::Printer;
+use crate::fixup::FixupContext;
+use crate::iter::IterDelimited;
+use crate::path::PathKind;
+use crate::INDENT;
+use syn::{Field, Fields, FieldsUnnamed, Variant, VisRestricted, Visibility};
+
+impl Printer {
+    pub fn variant(&mut self, variant: &Variant) {
+        self.outer_attrs(&variant.attrs);
+        self.ident(&variant.ident);
+        match &variant.fields {
+            Fields::Named(fields) => {
+                self.nbsp();
+                self.word("{");
+                self.cbox(INDENT);
+                self.space();
+                for field in fields.named.iter().delimited() {
+                    self.field(&field);
+                    self.trailing_comma_or_space(field.is_last);
+                }
+                self.offset(-INDENT);
+                self.end();
+                self.word("}");
+            }
+            Fields::Unnamed(fields) => {
+                self.cbox(INDENT);
+                self.fields_unnamed(fields);
+                self.end();
+            }
+            Fields::Unit => {}
+        }
+        if let Some((_eq_token, discriminant)) = &variant.discriminant {
+            self.word(" = ");
+            self.expr(discriminant, FixupContext::NONE);
+        }
+    }
+
+    pub fn fields_unnamed(&mut self, fields: &FieldsUnnamed) {
+        self.word("(");
+        self.zerobreak();
+        for field in fields.unnamed.iter().delimited() {
+            self.field(&field);
+            self.trailing_comma(field.is_last);
+        }
+        self.offset(-INDENT);
+        self.word(")");
+    }
+
+    pub fn field(&mut self, field: &Field) {
+        self.outer_attrs(&field.attrs);
+        self.visibility(&field.vis);
+        if let Some(ident) = &field.ident {
+            self.ident(ident);
+            self.word(": ");
+        }
+        self.ty(&field.ty);
+    }
+
+    pub fn visibility(&mut self, vis: &Visibility) {
+        match vis {
+            Visibility::Public(_) => self.word("pub "),
+            Visibility::Restricted(vis) => self.vis_restricted(vis),
+            Visibility::Inherited => {}
+        }
+    }
+
+    fn vis_restricted(&mut self, vis: &VisRestricted) {
+        self.word("pub(");
+        let omit_in = vis.path.get_ident().map_or(false, |ident| {
+            matches!(ident.to_string().as_str(), "self" | "super" | "crate")
+        });
+        if !omit_in {
+            self.word("in ");
+        }
+        self.path(&vis.path, PathKind::Simple);
+        self.word(") ");
+    }
+}

vendor/prettyplease/src/file.rs

@@ -0,0 +1,17 @@
+use crate::algorithm::Printer;
+use syn::File;
+
+impl Printer {
+    pub fn file(&mut self, file: &File) {
+        self.cbox(0);
+        if let Some(shebang) = &file.shebang {
+            self.word(shebang.clone());
+            self.hardbreak();
+        }
+        self.inner_attrs(&file.attrs);
+        for item in &file.items {
+            self.item(item);
+        }
+        self.end();
+    }
+}

vendor/prettyplease/src/fixup.rs

@@ -0,0 +1,676 @@
+use crate::classify;
+use crate::precedence::Precedence;
+use syn::{
+    Expr, ExprBreak, ExprRange, ExprRawAddr, ExprReference, ExprReturn, ExprUnary, ExprYield,
+};
+
+#[derive(Copy, Clone)]
+pub struct FixupContext {
+    previous_operator: Precedence,
+    next_operator: Precedence,
+
+    // Print expression such that it can be parsed back as a statement
+    // consisting of the original expression.
+    //
+    // The effect of this is for binary operators in statement position to set
+    // `leftmost_subexpression_in_stmt` when printing their left-hand operand.
+    //
+    //     (match x {}) - 1;  // match needs parens when LHS of binary operator
+    //
+    //     match x {};  // not when its own statement
+    //
+    stmt: bool,
+
+    // This is the difference between:
+    //
+    //     (match x {}) - 1;  // subexpression needs parens
+    //
+    //     let _ = match x {} - 1;  // no parens
+    //
+    // There are 3 distinguishable contexts in which `print_expr` might be
+    // called with the expression `$match` as its argument, where `$match`
+    // represents an expression of kind `ExprKind::Match`:
+    //
+    //   - stmt=false leftmost_subexpression_in_stmt=false
+    //
+    //     Example: `let _ = $match - 1;`
+    //
+    //     No parentheses required.
+    //
+    //   - stmt=false leftmost_subexpression_in_stmt=true
+    //
+    //     Example: `$match - 1;`
+    //
+    //     Must parenthesize `($match)`, otherwise parsing back the output as a
+    //     statement would terminate the statement after the closing brace of
+    //     the match, parsing `-1;` as a separate statement.
+    //
+    //   - stmt=true leftmost_subexpression_in_stmt=false
+    //
+    //     Example: `$match;`
+    //
+    //     No parentheses required.
+    leftmost_subexpression_in_stmt: bool,
+
+    // Print expression such that it can be parsed as a match arm.
+    //
+    // This is almost equivalent to `stmt`, but the grammar diverges a tiny bit
+    // between statements and match arms when it comes to braced macro calls.
+    // Macro calls with brace delimiter terminate a statement without a
+    // semicolon, but do not terminate a match-arm without comma.
+    //
+    //     m! {} - 1;  // two statements: a macro call followed by -1 literal
+    //
+    //     match () {
+    //         _ => m! {} - 1,  // binary subtraction operator
+    //     }
+    //
+    match_arm: bool,
+
+    // This is almost equivalent to `leftmost_subexpression_in_stmt`, other than
+    // for braced macro calls.
+    //
+    // If we have `m! {} - 1` as an expression, the leftmost subexpression
+    // `m! {}` will need to be parenthesized in the statement case but not the
+    // match-arm case.
+    //
+    //     (m! {}) - 1;  // subexpression needs parens
+    //
+    //     match () {
+    //         _ => m! {} - 1,  // no parens
+    //     }
+    //
+    leftmost_subexpression_in_match_arm: bool,
+
+    // This is the difference between:
+    //
+    //     if let _ = (Struct {}) {}  // needs parens
+    //
+    //     match () {
+    //         () if let _ = Struct {} => {}  // no parens
+    //     }
+    //
+    condition: bool,
+
+    // This is the difference between:
+    //
+    //     if break Struct {} == (break) {}  // needs parens
+    //
+    //     if break break == Struct {} {}  // no parens
+    //
+    rightmost_subexpression_in_condition: bool,
+
+    // This is the difference between:
+    //
+    //     if break ({ x }).field + 1 {}  needs parens
+    //
+    //     if break 1 + { x }.field {}  // no parens
+    //
+    leftmost_subexpression_in_optional_operand: bool,
+
+    // This is the difference between:
+    //
+    //     let _ = (return) - 1;  // without paren, this would return -1
+    //
+    //     let _ = return + 1;  // no paren because '+' cannot begin expr
+    //
+    next_operator_can_begin_expr: bool,
+
+    // This is the difference between:
+    //
+    //     let _ = 1 + return 1;  // no parens if rightmost subexpression
+    //
+    //     let _ = 1 + (return 1) + 1;  // needs parens
+    //
+    next_operator_can_continue_expr: bool,
+
+    // This is the difference between:
+    //
+    //     let _ = x as u8 + T;
+    //
+    //     let _ = (x as u8) < T;
+    //
+    // Without parens, the latter would want to parse `u8<T...` as a type.
+    next_operator_can_begin_generics: bool,
+}
+
+impl FixupContext {
+    /// The default amount of fixing is minimal fixing. Fixups should be turned
+    /// on in a targeted fashion where needed.
+    pub const NONE: Self = FixupContext {
+        previous_operator: Precedence::MIN,
+        next_operator: Precedence::MIN,
+        stmt: false,
+        leftmost_subexpression_in_stmt: false,
+        match_arm: false,
+        leftmost_subexpression_in_match_arm: false,
+        condition: false,
+        rightmost_subexpression_in_condition: false,
+        leftmost_subexpression_in_optional_operand: false,
+        next_operator_can_begin_expr: false,
+        next_operator_can_continue_expr: false,
+        next_operator_can_begin_generics: false,
+    };
+
+    /// Create the initial fixup for printing an expression in statement
+    /// position.
+    pub fn new_stmt() -> Self {
+        FixupContext {
+            stmt: true,
+            ..FixupContext::NONE
+        }
+    }
+
+    /// Create the initial fixup for printing an expression as the right-hand
+    /// side of a match arm.
+    pub fn new_match_arm() -> Self {
+        FixupContext {
+            match_arm: true,
+            ..FixupContext::NONE
+        }
+    }
+
+    /// Create the initial fixup for printing an expression as the "condition"
+    /// of an `if` or `while`. There are a few other positions which are
+    /// grammatically equivalent and also use this, such as the iterator
+    /// expression in `for` and the scrutinee in `match`.
+    pub fn new_condition() -> Self {
+        FixupContext {
+            condition: true,
+            rightmost_subexpression_in_condition: true,
+            ..FixupContext::NONE
+        }
+    }
+
+    /// Transform this fixup into the one that should apply when printing the
+    /// leftmost subexpression of the current expression.
+    ///
+    /// The leftmost subexpression is any subexpression that has the same first
+    /// token as the current expression, but has a different last token.
+    ///
+    /// For example in `$a + $b` and `$a.method()`, the subexpression `$a` is a
+    /// leftmost subexpression.
+    ///
+    /// Not every expression has a leftmost subexpression. For example neither
+    /// `-$a` nor `[$a]` have one.
+    pub fn leftmost_subexpression_with_operator(
+        self,
+        expr: &Expr,
+        next_operator_can_begin_expr: bool,
+        next_operator_can_begin_generics: bool,
+        precedence: Precedence,
+    ) -> (Precedence, Self) {
+        let fixup = FixupContext {
+            next_operator: precedence,
+            stmt: false,
+            leftmost_subexpression_in_stmt: self.stmt || self.leftmost_subexpression_in_stmt,
+            match_arm: false,
+            leftmost_subexpression_in_match_arm: self.match_arm
+                || self.leftmost_subexpression_in_match_arm,
+            rightmost_subexpression_in_condition: false,
+            next_operator_can_begin_expr,
+            next_operator_can_continue_expr: true,
+            next_operator_can_begin_generics,
+            ..self
+        };
+
+        (fixup.leftmost_subexpression_precedence(expr), fixup)
+    }
+
+    /// Transform this fixup into the one that should apply when printing a
+    /// leftmost subexpression followed by a `.` or `?` token, which confer
+    /// different statement boundary rules compared to other leftmost
+    /// subexpressions.
+    pub fn leftmost_subexpression_with_dot(self, expr: &Expr) -> (Precedence, Self) {
+        let fixup = FixupContext {
+            next_operator: Precedence::Unambiguous,
+            stmt: self.stmt || self.leftmost_subexpression_in_stmt,
+            leftmost_subexpression_in_stmt: false,
+            match_arm: self.match_arm || self.leftmost_subexpression_in_match_arm,
+            leftmost_subexpression_in_match_arm: false,
+            rightmost_subexpression_in_condition: false,
+            next_operator_can_begin_expr: false,
+            next_operator_can_continue_expr: true,
+            next_operator_can_begin_generics: false,
+            ..self
+        };
+
+        (fixup.leftmost_subexpression_precedence(expr), fixup)
+    }
+
+    fn leftmost_subexpression_precedence(self, expr: &Expr) -> Precedence {
+        if !self.next_operator_can_begin_expr || self.next_operator == Precedence::Range {
+            if let Scan::Bailout = scan_right(expr, self, Precedence::MIN, 0, 0) {
+                if scan_left(expr, self) {
+                    return Precedence::Unambiguous;
+                }
+            }
+        }
+
+        self.precedence(expr)
+    }
+
+    /// Transform this fixup into the one that should apply when printing the
+    /// rightmost subexpression of the current expression.
+    ///
+    /// The rightmost subexpression is any subexpression that has a different
+    /// first token than the current expression, but has the same last token.
+    ///
+    /// For example in `$a + $b` and `-$b`, the subexpression `$b` is a
+    /// rightmost subexpression.
+    ///
+    /// Not every expression has a rightmost subexpression. For example neither
+    /// `[$b]` nor `$a.f($b)` have one.
+    pub fn rightmost_subexpression(
+        self,
+        expr: &Expr,
+        precedence: Precedence,
+    ) -> (Precedence, Self) {
+        let fixup = self.rightmost_subexpression_fixup(false, false, precedence);
+        (fixup.rightmost_subexpression_precedence(expr), fixup)
+    }
+
+    pub fn rightmost_subexpression_fixup(
+        self,
+        reset_allow_struct: bool,
+        optional_operand: bool,
+        precedence: Precedence,
+    ) -> Self {
+        FixupContext {
+            previous_operator: precedence,
+            stmt: false,
+            leftmost_subexpression_in_stmt: false,
+            match_arm: false,
+            leftmost_subexpression_in_match_arm: false,
+            condition: self.condition && !reset_allow_struct,
+            leftmost_subexpression_in_optional_operand: self.condition && optional_operand,
+            ..self
+        }
+    }
+
+    pub fn rightmost_subexpression_precedence(self, expr: &Expr) -> Precedence {
+        let default_prec = self.precedence(expr);
+
+        if match self.previous_operator {
+            Precedence::Assign | Precedence::Let | Precedence::Prefix => {
+                default_prec < self.previous_operator
+            }
+            _ => default_prec <= self.previous_operator,
+        } && match self.next_operator {
+            Precedence::Range | Precedence::Or | Precedence::And => true,
+            _ => !self.next_operator_can_begin_expr,
+        } {
+            if let Scan::Bailout | Scan::Fail = scan_right(expr, self, self.previous_operator, 1, 0)
+            {
+                if scan_left(expr, self) {
+                    return Precedence::Prefix;
+                }
+            }
+        }
+
+        default_prec
+    }
+
+    /// Determine whether parentheses are needed around the given expression to
+    /// head off the early termination of a statement or condition.
+    pub fn parenthesize(self, expr: &Expr) -> bool {
+        (self.leftmost_subexpression_in_stmt && !classify::requires_semi_to_be_stmt(expr))
+            || ((self.stmt || self.leftmost_subexpression_in_stmt) && matches!(expr, Expr::Let(_)))
+            || (self.leftmost_subexpression_in_match_arm
+                && !classify::requires_comma_to_be_match_arm(expr))
+            || (self.condition && matches!(expr, Expr::Struct(_)))
+            || (self.rightmost_subexpression_in_condition
+                && matches!(
+                    expr,
+                    Expr::Return(ExprReturn { expr: None, .. })
+                        | Expr::Yield(ExprYield { expr: None, .. })
+                ))
+            || (self.rightmost_subexpression_in_condition
+                && !self.condition
+                && matches!(
+                    expr,
+                    Expr::Break(ExprBreak { expr: None, .. })
+                        | Expr::Path(_)
+                        | Expr::Range(ExprRange { end: None, .. })
+                ))
+            || (self.leftmost_subexpression_in_optional_operand
+                && matches!(expr, Expr::Block(expr) if expr.attrs.is_empty() && expr.label.is_none()))
+    }
+
+    /// Determines the effective precedence of a subexpression. Some expressions
+    /// have higher or lower precedence when adjacent to particular operators.
+    fn precedence(self, expr: &Expr) -> Precedence {
+        if self.next_operator_can_begin_expr {
+            // Decrease precedence of value-less jumps when followed by an
+            // operator that would otherwise get interpreted as beginning a
+            // value for the jump.
+            if let Expr::Break(ExprBreak { expr: None, .. })
+            | Expr::Return(ExprReturn { expr: None, .. })
+            | Expr::Yield(ExprYield { expr: None, .. }) = expr
+            {
+                return Precedence::Jump;
+            }
+        }
+
+        if !self.next_operator_can_continue_expr {
+            match expr {
+                // Increase precedence of expressions that extend to the end of
+                // current statement or group.
+                Expr::Break(_)
+                | Expr::Closure(_)
+                | Expr::Let(_)
+                | Expr::Return(_)
+                | Expr::Yield(_) => {
+                    return Precedence::Prefix;
+                }
+                Expr::Range(e) if e.start.is_none() => return Precedence::Prefix,
+                _ => {}
+            }
+        }
+
+        if self.next_operator_can_begin_generics {
+            if let Expr::Cast(cast) = expr {
+                if classify::trailing_unparameterized_path(&cast.ty) {
+                    return Precedence::MIN;
+                }
+            }
+        }
+
+        Precedence::of(expr)
+    }
+}
+
+#[derive(Copy, Clone, PartialEq)]
+enum Scan {
+    Fail,
+    Bailout,
+    Consume,
+}
+
+fn scan_left(expr: &Expr, fixup: FixupContext) -> bool {
+    match expr {
+        Expr::Assign(_) => fixup.previous_operator <= Precedence::Assign,
+        Expr::Binary(e) => match Precedence::of_binop(&e.op) {
+            Precedence::Assign => fixup.previous_operator <= Precedence::Assign,
+            binop_prec => fixup.previous_operator < binop_prec,
+        },
+        Expr::Cast(_) => fixup.previous_operator < Precedence::Cast,
+        Expr::Range(e) => e.start.is_none() || fixup.previous_operator < Precedence::Assign,
+        _ => true,
+    }
+}
+
+fn scan_right(
+    expr: &Expr,
+    fixup: FixupContext,
+    precedence: Precedence,
+    fail_offset: u8,
+    bailout_offset: u8,
+) -> Scan {
+    let consume_by_precedence = if match precedence {
+        Precedence::Assign | Precedence::Compare => precedence <= fixup.next_operator,
+        _ => precedence < fixup.next_operator,
+    } || fixup.next_operator == Precedence::MIN
+    {
+        Scan::Consume
+    } else {
+        Scan::Bailout
+    };
+    if fixup.parenthesize(expr) {
+        return consume_by_precedence;
+    }
+    match expr {
+        #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+        Expr::Assign(e) if e.attrs.is_empty() => {
+            if match fixup.next_operator {
+                Precedence::Unambiguous => fail_offset >= 2,
+                _ => bailout_offset >= 1,
+            } {
+                return Scan::Consume;
+            }
+            let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Assign);
+            let scan = scan_right(
+                &e.right,
+                right_fixup,
+                Precedence::Assign,
+                match fixup.next_operator {
+                    Precedence::Unambiguous => fail_offset,
+                    _ => 1,
+                },
+                1,
+            );
+            if let Scan::Bailout | Scan::Consume = scan {
+                Scan::Consume
+            } else if let Precedence::Unambiguous = fixup.next_operator {
+                Scan::Fail
+            } else {
+                Scan::Bailout
+            }
+        }
+        Expr::Binary(e) if e.attrs.is_empty() => {
+            if match fixup.next_operator {
+                Precedence::Unambiguous => {
+                    fail_offset >= 2
+                        && (consume_by_precedence == Scan::Consume || bailout_offset >= 1)
+                }
+                _ => bailout_offset >= 1,
+            } {
+                return Scan::Consume;
+            }
+            let binop_prec = Precedence::of_binop(&e.op);
+            if binop_prec == Precedence::Compare && fixup.next_operator == Precedence::Compare {
+                return Scan::Consume;
+            }
+            let right_fixup = fixup.rightmost_subexpression_fixup(false, false, binop_prec);
+            let scan = scan_right(
+                &e.right,
+                right_fixup,
+                binop_prec,
+                match fixup.next_operator {
+                    Precedence::Unambiguous => fail_offset,
+                    _ => 1,
+                },
+                consume_by_precedence as u8 - Scan::Bailout as u8,
+            );
+            match scan {
+                Scan::Fail => {}
+                Scan::Bailout => return consume_by_precedence,
+                Scan::Consume => return Scan::Consume,
+            }
+            let right_needs_group = binop_prec != Precedence::Assign
+                && right_fixup.rightmost_subexpression_precedence(&e.right) <= binop_prec;
+            if right_needs_group {
+                consume_by_precedence
+            } else if let (Scan::Fail, Precedence::Unambiguous) = (scan, fixup.next_operator) {
+                Scan::Fail
+            } else {
+                Scan::Bailout
+            }
+        }
+        Expr::RawAddr(ExprRawAddr { expr, .. })
+        | Expr::Reference(ExprReference { expr, .. })
+        | Expr::Unary(ExprUnary { expr, .. }) => {
+            if match fixup.next_operator {
+                Precedence::Unambiguous => {
+                    fail_offset >= 2
+                        && (consume_by_precedence == Scan::Consume || bailout_offset >= 1)
+                }
+                _ => bailout_offset >= 1,
+            } {
+                return Scan::Consume;
+            }
+            let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Prefix);
+            let scan = scan_right(
+                expr,
+                right_fixup,
+                precedence,
+                match fixup.next_operator {
+                    Precedence::Unambiguous => fail_offset,
+                    _ => 1,
+                },
+                consume_by_precedence as u8 - Scan::Bailout as u8,
+            );
+            match scan {
+                Scan::Fail => {}
+                Scan::Bailout => return consume_by_precedence,
+                Scan::Consume => return Scan::Consume,
+            }
+            if right_fixup.rightmost_subexpression_precedence(expr) < Precedence::Prefix {
+                consume_by_precedence
+            } else if let (Scan::Fail, Precedence::Unambiguous) = (scan, fixup.next_operator) {
+                Scan::Fail
+            } else {
+                Scan::Bailout
+            }
+        }
+        Expr::Range(e) if e.attrs.is_empty() => match &e.end {
+            Some(end) => {
+                if fail_offset >= 2 {
+                    return Scan::Consume;
+                }
+                let right_fixup =
+                    fixup.rightmost_subexpression_fixup(false, true, Precedence::Range);
+                let scan = scan_right(
+                    end,
+                    right_fixup,
+                    Precedence::Range,
+                    fail_offset,
+                    match fixup.next_operator {
+                        Precedence::Assign | Precedence::Range => 0,
+                        _ => 1,
+                    },
+                );
+                if match (scan, fixup.next_operator) {
+                    (Scan::Fail, _) => false,
+                    (Scan::Bailout, Precedence::Assign | Precedence::Range) => false,
+                    (Scan::Bailout | Scan::Consume, _) => true,
+                } {
+                    return Scan::Consume;
+                }
+                if right_fixup.rightmost_subexpression_precedence(end) <= Precedence::Range {
+                    Scan::Consume
+                } else {
+                    Scan::Fail
+                }
+            }
+            None => {
+                if fixup.next_operator_can_begin_expr {
+                    Scan::Consume
+                } else {
+                    Scan::Fail
+                }
+            }
+        },
+        Expr::Break(e) => match &e.expr {
+            Some(value) => {
+                if bailout_offset >= 1 || e.label.is_none() && classify::expr_leading_label(value) {
+                    return Scan::Consume;
+                }
+                let right_fixup = fixup.rightmost_subexpression_fixup(true, true, Precedence::Jump);
+                match scan_right(value, right_fixup, Precedence::Jump, 1, 1) {
+                    Scan::Fail => Scan::Bailout,
+                    Scan::Bailout | Scan::Consume => Scan::Consume,
+                }
+            }
+            None => match fixup.next_operator {
+                Precedence::Assign if precedence > Precedence::Assign => Scan::Fail,
+                _ => Scan::Consume,
+            },
+        },
+        Expr::Return(ExprReturn { expr, .. }) | Expr::Yield(ExprYield { expr, .. }) => match expr {
+            Some(e) => {
+                if bailout_offset >= 1 {
+                    return Scan::Consume;
+                }
+                let right_fixup =
+                    fixup.rightmost_subexpression_fixup(true, false, Precedence::Jump);
+                match scan_right(e, right_fixup, Precedence::Jump, 1, 1) {
+                    Scan::Fail => Scan::Bailout,
+                    Scan::Bailout | Scan::Consume => Scan::Consume,
+                }
+            }
+            None => match fixup.next_operator {
+                Precedence::Assign if precedence > Precedence::Assign => Scan::Fail,
+                _ => Scan::Consume,
+            },
+        },
+        Expr::Closure(_) => Scan::Consume,
+        Expr::Let(e) => {
+            if bailout_offset >= 1 {
+                return Scan::Consume;
+            }
+            let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Let);
+            let scan = scan_right(
+                &e.expr,
+                right_fixup,
+                Precedence::Let,
+                1,
+                if fixup.next_operator < Precedence::Let {
+                    0
+                } else {
+                    1
+                },
+            );
+            match scan {
+                Scan::Fail | Scan::Bailout if fixup.next_operator < Precedence::Let => {
+                    return Scan::Bailout;
+                }
+                Scan::Consume => return Scan::Consume,
+                _ => {}
+            }
+            if right_fixup.rightmost_subexpression_precedence(&e.expr) < Precedence::Let {
+                Scan::Consume
+            } else if let Scan::Fail = scan {
+                Scan::Bailout
+            } else {
+                Scan::Consume
+            }
+        }
+        Expr::Group(e) => scan_right(&e.expr, fixup, precedence, fail_offset, bailout_offset),
+        Expr::Array(_)
+        | Expr::Assign(_)
+        | Expr::Async(_)
+        | Expr::Await(_)
+        | Expr::Binary(_)
+        | Expr::Block(_)
+        | Expr::Call(_)
+        | Expr::Cast(_)
+        | Expr::Const(_)
+        | Expr::Continue(_)
+        | Expr::Field(_)
+        | Expr::ForLoop(_)
+        | Expr::If(_)
+        | Expr::Index(_)
+        | Expr::Infer(_)
+        | Expr::Lit(_)
+        | Expr::Loop(_)
+        | Expr::Macro(_)
+        | Expr::Match(_)
+        | Expr::MethodCall(_)
+        | Expr::Paren(_)
+        | Expr::Path(_)
+        | Expr::Range(_)
+        | Expr::Repeat(_)
+        | Expr::Struct(_)
+        | Expr::Try(_)
+        | Expr::TryBlock(_)
+        | Expr::Tuple(_)
+        | Expr::Unsafe(_)
+        | Expr::Verbatim(_)
+        | Expr::While(_) => match fixup.next_operator {
+            Precedence::Assign | Precedence::Range if precedence == Precedence::Range => Scan::Fail,
+            _ if precedence == Precedence::Let && fixup.next_operator < Precedence::Let => {
+                Scan::Fail
+            }
+            _ => consume_by_precedence,
+        },
+
+        _ => match fixup.next_operator {
+            Precedence::Assign | Precedence::Range if precedence == Precedence::Range => Scan::Fail,
+            _ if precedence == Precedence::Let && fixup.next_operator < Precedence::Let => {
+                Scan::Fail
+            }
+            _ => consume_by_precedence,
+        },
+    }
+}

vendor/prettyplease/src/generics.rs

@@ -0,0 +1,426 @@
+use crate::algorithm::Printer;
+use crate::iter::IterDelimited;
+use crate::path::PathKind;
+use crate::INDENT;
+use proc_macro2::TokenStream;
+use std::ptr;
+use syn::{
+    BoundLifetimes, CapturedParam, ConstParam, Expr, GenericParam, Generics, LifetimeParam,
+    PreciseCapture, PredicateLifetime, PredicateType, TraitBound, TraitBoundModifier, TypeParam,
+    TypeParamBound, WhereClause, WherePredicate,
+};
+
+impl Printer {
+    pub fn generics(&mut self, generics: &Generics) {
+        if generics.params.is_empty() {
+            return;
+        }
+
+        self.word("<");
+        self.cbox(0);
+        self.zerobreak();
+
+        // Print lifetimes before types and consts, regardless of their
+        // order in self.params.
+        #[derive(Ord, PartialOrd, Eq, PartialEq)]
+        enum Group {
+            First,
+            Second,
+        }
+        fn group(param: &GenericParam) -> Group {
+            match param {
+                GenericParam::Lifetime(_) => Group::First,
+                GenericParam::Type(_) | GenericParam::Const(_) => Group::Second,
+            }
+        }
+        let last = generics.params.iter().max_by_key(|param| group(param));
+        for current_group in [Group::First, Group::Second] {
+            for param in &generics.params {
+                if group(param) == current_group {
+                    self.generic_param(param);
+                    self.trailing_comma(ptr::eq(param, last.unwrap()));
+                }
+            }
+        }
+
+        self.offset(-INDENT);
+        self.end();
+        self.word(">");
+    }
+
+    fn generic_param(&mut self, generic_param: &GenericParam) {
+        match generic_param {
+            GenericParam::Type(type_param) => self.type_param(type_param),
+            GenericParam::Lifetime(lifetime_param) => self.lifetime_param(lifetime_param),
+            GenericParam::Const(const_param) => self.const_param(const_param),
+        }
+    }
+
+    pub fn bound_lifetimes(&mut self, bound_lifetimes: &BoundLifetimes) {
+        self.word("for<");
+        for param in bound_lifetimes.lifetimes.iter().delimited() {
+            self.generic_param(&param);
+            if !param.is_last {
+                self.word(", ");
+            }
+        }
+        self.word("> ");
+    }
+
+    fn lifetime_param(&mut self, lifetime_param: &LifetimeParam) {
+        self.outer_attrs(&lifetime_param.attrs);
+        self.lifetime(&lifetime_param.lifetime);
+        for lifetime in lifetime_param.bounds.iter().delimited() {
+            if lifetime.is_first {
+                self.word(": ");
+            } else {
+                self.word(" + ");
+            }
+            self.lifetime(&lifetime);
+        }
+    }
+
+    fn type_param(&mut self, type_param: &TypeParam) {
+        self.outer_attrs(&type_param.attrs);
+        self.ident(&type_param.ident);
+        self.ibox(INDENT);
+        for type_param_bound in type_param.bounds.iter().delimited() {
+            if type_param_bound.is_first {
+                self.word(": ");
+            } else {
+                self.space();
+                self.word("+ ");
+            }
+            self.type_param_bound(&type_param_bound);
+        }
+        if let Some(default) = &type_param.default {
+            self.space();
+            self.word("= ");
+            self.ty(default);
+        }
+        self.end();
+    }
+
+    pub fn type_param_bound(&mut self, type_param_bound: &TypeParamBound) {
+        match type_param_bound {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            TypeParamBound::Trait(trait_bound) => {
+                self.trait_bound(trait_bound, TraitBoundConst::None);
+            }
+            TypeParamBound::Lifetime(lifetime) => self.lifetime(lifetime),
+            TypeParamBound::PreciseCapture(precise_capture) => {
+                self.precise_capture(precise_capture);
+            }
+            TypeParamBound::Verbatim(bound) => self.type_param_bound_verbatim(bound),
+            _ => unimplemented!("unknown TypeParamBound"),
+        }
+    }
+
+    fn trait_bound(&mut self, trait_bound: &TraitBound, constness: TraitBoundConst) {
+        if trait_bound.paren_token.is_some() {
+            self.word("(");
+        }
+        if let Some(bound_lifetimes) = &trait_bound.lifetimes {
+            self.bound_lifetimes(bound_lifetimes);
+        }
+        match constness {
+            TraitBoundConst::None => {}
+            #[cfg(feature = "verbatim")]
+            TraitBoundConst::Conditional => self.word("[const] "),
+            #[cfg(feature = "verbatim")]
+            TraitBoundConst::Unconditional => self.word("const "),
+        }
+        self.trait_bound_modifier(&trait_bound.modifier);
+        for segment in trait_bound.path.segments.iter().delimited() {
+            if !segment.is_first || trait_bound.path.leading_colon.is_some() {
+                self.word("::");
+            }
+            self.path_segment(&segment, PathKind::Type);
+        }
+        if trait_bound.paren_token.is_some() {
+            self.word(")");
+        }
+    }
+
+    fn trait_bound_modifier(&mut self, trait_bound_modifier: &TraitBoundModifier) {
+        match trait_bound_modifier {
+            TraitBoundModifier::None => {}
+            TraitBoundModifier::Maybe(_question_mark) => self.word("?"),
+        }
+    }
+
+    #[cfg(not(feature = "verbatim"))]
+    fn type_param_bound_verbatim(&mut self, bound: &TokenStream) {
+        unimplemented!("TypeParamBound::Verbatim `{}`", bound);
+    }
+
+    #[cfg(feature = "verbatim")]
+    fn type_param_bound_verbatim(&mut self, tokens: &TokenStream) {
+        use syn::parse::{Parse, ParseStream, Result};
+        use syn::{
+            bracketed, parenthesized, token, ParenthesizedGenericArguments, Path, PathArguments,
+            Token,
+        };
+
+        enum TypeParamBoundVerbatim {
+            Ellipsis,
+            Const(TraitBound, TraitBoundConst),
+        }
+
+        impl Parse for TypeParamBoundVerbatim {
+            fn parse(input: ParseStream) -> Result<Self> {
+                if input.peek(Token![...]) {
+                    input.parse::<Token![...]>()?;
+                    return Ok(TypeParamBoundVerbatim::Ellipsis);
+                }
+
+                let content;
+                let content = if input.peek(token::Paren) {
+                    parenthesized!(content in input);
+                    &content
+                } else {
+                    input
+                };
+
+                let lifetimes: Option<BoundLifetimes> = content.parse()?;
+
+                let constness = if content.peek(token::Bracket) {
+                    let conditionally_const;
+                    bracketed!(conditionally_const in content);
+                    conditionally_const.parse::<Token![const]>()?;
+                    TraitBoundConst::Conditional
+                } else if content.peek(Token![const]) {
+                    content.parse::<Token![const]>()?;
+                    TraitBoundConst::Unconditional
+                } else {
+                    TraitBoundConst::None
+                };
+
+                let modifier: TraitBoundModifier = content.parse()?;
+
+                let mut path: Path = content.parse()?;
+                if path.segments.last().unwrap().arguments.is_empty()
+                    && (content.peek(token::Paren)
+                        || content.peek(Token![::]) && content.peek3(token::Paren))
+                {
+                    content.parse::<Option<Token![::]>>()?;
+                    let args: ParenthesizedGenericArguments = content.parse()?;
+                    let parenthesized = PathArguments::Parenthesized(args);
+                    path.segments.last_mut().unwrap().arguments = parenthesized;
+                }
+
+                Ok(TypeParamBoundVerbatim::Const(
+                    TraitBound {
+                        paren_token: None,
+                        modifier,
+                        lifetimes,
+                        path,
+                    },
+                    constness,
+                ))
+            }
+        }
+
+        let bound: TypeParamBoundVerbatim = match syn::parse2(tokens.clone()) {
+            Ok(bound) => bound,
+            Err(_) => unimplemented!("TypeParamBound::Verbatim `{}`", tokens),
+        };
+
+        match bound {
+            TypeParamBoundVerbatim::Ellipsis => {
+                self.word("...");
+            }
+            TypeParamBoundVerbatim::Const(trait_bound, constness) => {
+                self.trait_bound(&trait_bound, constness);
+            }
+        }
+    }
+
+    fn const_param(&mut self, const_param: &ConstParam) {
+        self.outer_attrs(&const_param.attrs);
+        self.word("const ");
+        self.ident(&const_param.ident);
+        self.word(": ");
+        self.ty(&const_param.ty);
+        if let Some(default) = &const_param.default {
+            self.word(" = ");
+            self.const_argument(default);
+        }
+    }
+
+    pub fn where_clause_for_body(&mut self, where_clause: &Option<WhereClause>) {
+        let hardbreaks = true;
+        let semi = false;
+        self.where_clause_impl(where_clause, hardbreaks, semi);
+    }
+
+    pub fn where_clause_semi(&mut self, where_clause: &Option<WhereClause>) {
+        let hardbreaks = true;
+        let semi = true;
+        self.where_clause_impl(where_clause, hardbreaks, semi);
+    }
+
+    pub fn where_clause_oneline(&mut self, where_clause: &Option<WhereClause>) {
+        let hardbreaks = false;
+        let semi = false;
+        self.where_clause_impl(where_clause, hardbreaks, semi);
+    }
+
+    pub fn where_clause_oneline_semi(&mut self, where_clause: &Option<WhereClause>) {
+        let hardbreaks = false;
+        let semi = true;
+        self.where_clause_impl(where_clause, hardbreaks, semi);
+    }
+
+    fn where_clause_impl(
+        &mut self,
+        where_clause: &Option<WhereClause>,
+        hardbreaks: bool,
+        semi: bool,
+    ) {
+        let where_clause = match where_clause {
+            Some(where_clause) if !where_clause.predicates.is_empty() => where_clause,
+            _ => {
+                if semi {
+                    self.word(";");
+                } else {
+                    self.nbsp();
+                }
+                return;
+            }
+        };
+        if hardbreaks {
+            self.hardbreak();
+            self.offset(-INDENT);
+            self.word("where");
+            self.hardbreak();
+            for predicate in where_clause.predicates.iter().delimited() {
+                self.where_predicate(&predicate);
+                if predicate.is_last && semi {
+                    self.word(";");
+                } else {
+                    self.word(",");
+                    self.hardbreak();
+                }
+            }
+            if !semi {
+                self.offset(-INDENT);
+            }
+        } else {
+            self.space();
+            self.offset(-INDENT);
+            self.word("where");
+            self.space();
+            for predicate in where_clause.predicates.iter().delimited() {
+                self.where_predicate(&predicate);
+                if predicate.is_last && semi {
+                    self.word(";");
+                } else {
+                    self.trailing_comma_or_space(predicate.is_last);
+                }
+            }
+            if !semi {
+                self.offset(-INDENT);
+            }
+        }
+    }
+
+    fn where_predicate(&mut self, predicate: &WherePredicate) {
+        match predicate {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            WherePredicate::Type(predicate) => self.predicate_type(predicate),
+            WherePredicate::Lifetime(predicate) => self.predicate_lifetime(predicate),
+            _ => unimplemented!("unknown WherePredicate"),
+        }
+    }
+
+    fn predicate_type(&mut self, predicate: &PredicateType) {
+        if let Some(bound_lifetimes) = &predicate.lifetimes {
+            self.bound_lifetimes(bound_lifetimes);
+        }
+        self.ty(&predicate.bounded_ty);
+        self.word(":");
+        if predicate.bounds.len() == 1 {
+            self.ibox(0);
+        } else {
+            self.ibox(INDENT);
+        }
+        for type_param_bound in predicate.bounds.iter().delimited() {
+            if type_param_bound.is_first {
+                self.nbsp();
+            } else {
+                self.space();
+                self.word("+ ");
+            }
+            self.type_param_bound(&type_param_bound);
+        }
+        self.end();
+    }
+
+    fn predicate_lifetime(&mut self, predicate: &PredicateLifetime) {
+        self.lifetime(&predicate.lifetime);
+        self.word(":");
+        self.ibox(INDENT);
+        for lifetime in predicate.bounds.iter().delimited() {
+            if lifetime.is_first {
+                self.nbsp();
+            } else {
+                self.space();
+                self.word("+ ");
+            }
+            self.lifetime(&lifetime);
+        }
+        self.end();
+    }
+
+    fn precise_capture(&mut self, precise_capture: &PreciseCapture) {
+        self.word("use<");
+        for capture in precise_capture.params.iter().delimited() {
+            self.captured_param(&capture);
+            if !capture.is_last {
+                self.word(", ");
+            }
+        }
+        self.word(">");
+    }
+
+    fn captured_param(&mut self, capture: &CapturedParam) {
+        match capture {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            CapturedParam::Lifetime(lifetime) => self.lifetime(lifetime),
+            CapturedParam::Ident(ident) => self.ident(ident),
+            _ => unimplemented!("unknown CapturedParam"),
+        }
+    }
+
+    pub fn const_argument(&mut self, expr: &Expr) {
+        match expr {
+            #![cfg_attr(all(test, exhaustive), allow(non_exhaustive_omitted_patterns))]
+            Expr::Lit(expr) => self.expr_lit(expr),
+
+            Expr::Path(expr)
+                if expr.attrs.is_empty()
+                    && expr.qself.is_none()
+                    && expr.path.get_ident().is_some() =>
+            {
+                self.expr_path(expr);
+            }
+
+            Expr::Block(expr) => self.expr_block(expr),
+
+            _ => {
+                self.cbox(INDENT);
+                self.expr_as_small_block(expr, 0);
+                self.end();
+            }
+        }
+    }
+}
+
+enum TraitBoundConst {
+    None,
+    #[cfg(feature = "verbatim")]
+    Conditional,
+    #[cfg(feature = "verbatim")]
+    Unconditional,
+}

vendor/prettyplease/src/iter.rs

@@ -0,0 +1,46 @@
+use std::iter::Peekable;
+use std::ops::Deref;
+
+pub struct Delimited<I: Iterator> {
+    is_first: bool,
+    iter: Peekable<I>,
+}
+
+pub trait IterDelimited: Iterator + Sized {
+    fn delimited(self) -> Delimited<Self> {
+        Delimited {
+            is_first: true,
+            iter: self.peekable(),
+        }
+    }
+}
+
+impl<I: Iterator> IterDelimited for I {}
+
+pub struct IteratorItem<T> {
+    value: T,
+    pub is_first: bool,
+    pub is_last: bool,
+}
+
+impl<I: Iterator> Iterator for Delimited<I> {
+    type Item = IteratorItem<I::Item>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let item = IteratorItem {
+            value: self.iter.next()?,
+            is_first: self.is_first,
+            is_last: self.iter.peek().is_none(),
+        };
+        self.is_first = false;
+        Some(item)
+    }
+}
+
+impl<T> Deref for IteratorItem<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}

vendor/prettyplease/src/lib.rs

@@ -0,0 +1,385 @@
+//! [![github]](https://github.com/dtolnay/prettyplease) [![crates-io]](https://crates.io/crates/prettyplease) [![docs-rs]](https://docs.rs/prettyplease)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
+//!
+//! <br>
+//!
+//! **prettyplease::unparse** &mdash; a minimal `syn` syntax tree pretty-printer
+//!
+//! <br>
+//!
+//! # Overview
+//!
+//! This is a pretty-printer to turn a `syn` syntax tree into a `String` of
+//! well-formatted source code. In contrast to rustfmt, this library is intended
+//! to be suitable for arbitrary generated code.
+//!
+//! Rustfmt prioritizes high-quality output that is impeccable enough that you'd
+//! be comfortable spending your career staring at its output &mdash; but that
+//! means some heavyweight algorithms, and it has a tendency to bail out on code
+//! that is hard to format (for example [rustfmt#3697], and there are dozens
+//! more issues like it). That's not necessarily a big deal for human-generated
+//! code because when code gets highly nested, the human will naturally be
+//! inclined to refactor into more easily formattable code. But for generated
+//! code, having the formatter just give up leaves it totally unreadable.
+//!
+//! [rustfmt#3697]: https://github.com/rust-lang/rustfmt/issues/3697
+//!
+//! This library is designed using the simplest possible algorithm and data
+//! structures that can deliver about 95% of the quality of rustfmt-formatted
+//! output. In my experience testing real-world code, approximately 97-98% of
+//! output lines come out identical between rustfmt's formatting and this
+//! crate's. The rest have slightly different linebreak decisions, but still
+//! clearly follow the dominant modern Rust style.
+//!
+//! The tradeoffs made by this crate are a good fit for generated code that you
+//! will *not* spend your career staring at. For example, the output of
+//! `bindgen`, or the output of `cargo-expand`. In those cases it's more
+//! important that the whole thing be formattable without the formatter giving
+//! up, than that it be flawless.
+//!
+//! <br>
+//!
+//! # Feature matrix
+//!
+//! Here are a few superficial comparisons of this crate against the AST
+//! pretty-printer built into rustc, and rustfmt. The sections below go into
+//! more detail comparing the output of each of these libraries.
+//!
+//! | | prettyplease | rustc | rustfmt |
+//! |:---|:---:|:---:|:---:|
+//! | non-pathological behavior on big or generated code | 💚 | ❌ | ❌ |
+//! | idiomatic modern formatting ("locally indistinguishable from rustfmt") | 💚 | ❌ | 💚 |
+//! | throughput | 60 MB/s | 39 MB/s | 2.8 MB/s |
+//! | number of dependencies | 3 | 72 | 66 |
+//! | compile time including dependencies | 2.4 sec | 23.1 sec | 29.8 sec |
+//! | buildable using a stable Rust compiler | 💚 | ❌ | ❌ |
+//! | published to crates.io | 💚 | ❌ | ❌ |
+//! | extensively configurable output | ❌ | ❌ | 💚 |
+//! | intended to accommodate hand-maintained source code | ❌ | ❌ | 💚 |
+//!
+//! <br>
+//!
+//! # Comparison to rustfmt
+//!
+//! - [input.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/input.rs)
+//! - [output.prettyplease.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/output.prettyplease.rs)
+//! - [output.rustfmt.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/output.rustfmt.rs)
+//!
+//! If you weren't told which output file is which, it would be practically
+//! impossible to tell &mdash; **except** for line 435 in the rustfmt output,
+//! which is more than 1000 characters long because rustfmt just gave up
+//! formatting that part of the file:
+//!
+//! ```
+//! # const _: &str = stringify! {{{
+//!             match segments[5] {
+//!                 0 => write!(f, "::{}", ipv4),
+//!                 0xffff => write!(f, "::ffff:{}", ipv4),
+//!                 _ => unreachable!(),
+//!             }
+//!         } else { # [derive (Copy , Clone , Default)] struct Span { start : usize , len : usize , } let zeroes = { let mut longest = Span :: default () ; let mut current = Span :: default () ; for (i , & segment) in segments . iter () . enumerate () { if segment == 0 { if current . len == 0 { current . start = i ; } current . len += 1 ; if current . len > longest . len { longest = current ; } } else { current = Span :: default () ; } } longest } ; # [doc = " Write a colon-separated part of the address"] # [inline] fn fmt_subslice (f : & mut fmt :: Formatter < '_ > , chunk : & [u16]) -> fmt :: Result { if let Some ((first , tail)) = chunk . split_first () { write ! (f , "{:x}" , first) ? ; for segment in tail { f . write_char (':') ? ; write ! (f , "{:x}" , segment) ? ; } } Ok (()) } if zeroes . len > 1 { fmt_subslice (f , & segments [.. zeroes . start]) ? ; f . write_str ("::") ? ; fmt_subslice (f , & segments [zeroes . start + zeroes . len ..]) } else { fmt_subslice (f , & segments) } }
+//!     } else {
+//!         const IPV6_BUF_LEN: usize = (4 * 8) + 7;
+//!         let mut buf = [0u8; IPV6_BUF_LEN];
+//!         let mut buf_slice = &mut buf[..];
+//! # }};
+//! ```
+//!
+//! This is a pretty typical manifestation of rustfmt bailing out in generated
+//! code &mdash; a chunk of the input ends up on one line. The other
+//! manifestation is that you're working on some code, running rustfmt on save
+//! like a conscientious developer, but after a while notice it isn't doing
+//! anything. You introduce an intentional formatting issue, like a stray indent
+//! or semicolon, and run rustfmt to check your suspicion. Nope, it doesn't get
+//! cleaned up &mdash; rustfmt is just not formatting the part of the file you
+//! are working on.
+//!
+//! The prettyplease library is designed to have no pathological cases that
+//! force a bail out; the entire input you give it will get formatted in some
+//! "good enough" form.
+//!
+//! Separately, rustfmt can be problematic to integrate into projects. It's
+//! written using rustc's internal syntax tree, so it can't be built by a stable
+//! compiler. Its releases are not regularly published to crates.io, so in Cargo
+//! builds you'd need to depend on it as a git dependency, which precludes
+//! publishing your crate to crates.io also. You can shell out to a `rustfmt`
+//! binary, but that'll be whatever rustfmt version is installed on each
+//! developer's system (if any), which can lead to spurious diffs in checked-in
+//! generated code formatted by different versions. In contrast prettyplease is
+//! designed to be easy to pull in as a library, and compiles fast.
+//!
+//! <br>
+//!
+//! # Comparison to rustc_ast_pretty
+//!
+//! - [input.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/input.rs)
+//! - [output.prettyplease.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/output.prettyplease.rs)
+//! - [output.rustc.rs](https://github.com/dtolnay/prettyplease/blob/0.1.0/examples/output.rustc.rs)
+//!
+//! This is the pretty-printer that gets used when rustc prints source code,
+//! such as `rustc -Zunpretty=expanded`. It's used also by the standard
+//! library's `stringify!` when stringifying an interpolated macro_rules AST
+//! fragment, like an $:expr, and transitively by `dbg!` and many macros in the
+//! ecosystem.
+//!
+//! Rustc's formatting is mostly okay, but does not hew closely to the dominant
+//! contemporary style of Rust formatting. Some things wouldn't ever be written
+//! on one line, like this `match` expression, and certainly not with a comma in
+//! front of the closing brace:
+//!
+//! ```
+//! # const _: &str = stringify! {
+//! fn eq(&self, other: &IpAddr) -> bool {
+//!     match other { IpAddr::V4(v4) => self == v4, IpAddr::V6(_) => false, }
+//! }
+//! # };
+//! ```
+//!
+//! Some places use non-multiple-of-4 indentation, which is definitely not the
+//! norm:
+//!
+//! ```
+//! # const _: &str = stringify! {
+//! pub const fn to_ipv6_mapped(&self) -> Ipv6Addr {
+//!     let [a, b, c, d] = self.octets();
+//!     Ipv6Addr{inner:
+//!                  c::in6_addr{s6_addr:
+//!                                  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF,
+//!                                   0xFF, a, b, c, d],},}
+//! }
+//! # };
+//! ```
+//!
+//! And although there isn't an egregious example of it in the link because the
+//! input code is pretty tame, in general rustc_ast_pretty has pathological
+//! behavior on generated code. It has a tendency to use excessive horizontal
+//! indentation and rapidly run out of width:
+//!
+//! ```
+//! # const _: &str = stringify! {
+//! ::std::io::_print(::core::fmt::Arguments::new_v1(&[""],
+//!                                                  &match (&msg,) {
+//!                                                       _args =>
+//!                                                       [::core::fmt::ArgumentV1::new(_args.0,
+//!                                                                                     ::core::fmt::Display::fmt)],
+//!                                                   }));
+//! # };
+//! ```
+//!
+//! The snippets above are clearly different from modern rustfmt style. In
+//! contrast, prettyplease is designed to have output that is practically
+//! indistinguishable from rustfmt-formatted code.
+//!
+//! <br>
+//!
+//! # Example
+//!
+//! ```
+//! // [dependencies]
+//! // prettyplease = "0.2"
+//! // syn = { version = "2", default-features = false, features = ["full", "parsing"] }
+//!
+//! const INPUT: &str = stringify! {
+//!     use crate::{
+//!           lazy::{Lazy, SyncLazy, SyncOnceCell}, panic,
+//!         sync::{ atomic::{AtomicUsize, Ordering::SeqCst},
+//!             mpsc::channel, Mutex, },
+//!       thread,
+//!     };
+//!     impl<T, U> Into<U> for T where U: From<T> {
+//!         fn into(self) -> U { U::from(self) }
+//!     }
+//! };
+//!
+//! fn main() {
+//!     let syntax_tree = syn::parse_file(INPUT).unwrap();
+//!     let formatted = prettyplease::unparse(&syntax_tree);
+//!     print!("{}", formatted);
+//! }
+//! ```
+//!
+//! <br>
+//!
+//! # Algorithm notes
+//!
+//! The approach and terminology used in the implementation are derived from
+//! [*Derek C. Oppen, "Pretty Printing" (1979)*][paper], on which
+//! rustc_ast_pretty is also based, and from rustc_ast_pretty's implementation
+//! written by Graydon Hoare in 2011 (and modernized over the years by dozens of
+//! volunteer maintainers).
+//!
+//! [paper]: http://i.stanford.edu/pub/cstr/reports/cs/tr/79/770/CS-TR-79-770.pdf
+//!
+//! The paper describes two language-agnostic interacting procedures `Scan()`
+//! and `Print()`. Language-specific code decomposes an input data structure
+//! into a stream of `string` and `break` tokens, and `begin` and `end` tokens
+//! for grouping. Each `begin`&ndash;`end` range may be identified as either
+//! "consistent breaking" or "inconsistent breaking". If a group is consistently
+//! breaking, then if the whole contents do not fit on the line, *every* `break`
+//! token in the group will receive a linebreak. This is appropriate, for
+//! example, for Rust struct literals, or arguments of a function call. If a
+//! group is inconsistently breaking, then the `string` tokens in the group are
+//! greedily placed on the line until out of space, and linebroken only at those
+//! `break` tokens for which the next string would not fit. For example, this is
+//! appropriate for the contents of a braced `use` statement in Rust.
+//!
+//! Scan's job is to efficiently accumulate sizing information about groups and
+//! breaks. For every `begin` token we compute the distance to the matched `end`
+//! token, and for every `break` we compute the distance to the next `break`.
+//! The algorithm uses a ringbuffer to hold tokens whose size is not yet
+//! ascertained. The maximum size of the ringbuffer is bounded by the target
+//! line length and does not grow indefinitely, regardless of deep nesting in
+//! the input stream. That's because once a group is sufficiently big, the
+//! precise size can no longer make a difference to linebreak decisions and we
+//! can effectively treat it as "infinity".
+//!
+//! Print's job is to use the sizing information to efficiently assign a
+//! "broken" or "not broken" status to every `begin` token. At that point the
+//! output is easily constructed by concatenating `string` tokens and breaking
+//! at `break` tokens contained within a broken group.
+//!
+//! Leveraging these primitives (i.e. cleverly placing the all-or-nothing
+//! consistent breaks and greedy inconsistent breaks) to yield
+//! rustfmt-compatible formatting for all of Rust's syntax tree nodes is a fun
+//! challenge.
+//!
+//! Here is a visualization of some Rust tokens fed into the pretty printing
+//! algorithm. Consistently breaking `begin`&mdash;`end` pairs are represented
+//! by `«`&#8288;`»`, inconsistently breaking by `‹`&#8288;`›`, `break` by `·`,
+//! and the rest of the non-whitespace are `string`.
+//!
+//! ```text
+//! use crate::«{·
+//! ‹    lazy::«{·‹Lazy,· SyncLazy,· SyncOnceCell›·}»,·
+//!     panic,·
+//!     sync::«{·
+//! ‹        atomic::«{·‹AtomicUsize,· Ordering::SeqCst›·}»,·
+//!         mpsc::channel,· Mutex›,·
+//!     }»,·
+//!     thread›,·
+//! }»;·
+//! «‹«impl<«·T‹›,· U‹›·»>» Into<«·U·»>· for T›·
+//! where·
+//!     U:‹ From<«·T·»>›,·
+//! {·
+//! «    fn into(·«·self·») -> U {·
+//! ‹        U::from(«·self·»)›·
+//! »    }·
+//! »}·
+//! ```
+//!
+//! The algorithm described in the paper is not quite sufficient for producing
+//! well-formatted Rust code that is locally indistinguishable from rustfmt's
+//! style. The reason is that in the paper, the complete non-whitespace contents
+//! are assumed to be independent of linebreak decisions, with Scan and Print
+//! being only in control of the whitespace (spaces and line breaks). In Rust as
+//! idiomatically formatted by rustfmt, that is not the case. Trailing commas
+//! are one example; the punctuation is only known *after* the broken vs
+//! non-broken status of the surrounding group is known:
+//!
+//! ```
+//! # struct Struct { x: u64, y: bool }
+//! # let xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx = 0;
+//! # let yyyyyyyyyyyyyyyyyyyyyyyyyyyyyy = true;
+//! #
+//! let _ = Struct { x: 0, y: true };
+//!
+//! let _ = Struct {
+//!     x: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,
+//!     y: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,   //<- trailing comma if the expression wrapped
+//! };
+//! ```
+//!
+//! The formatting of `match` expressions is another case; we want small arms on
+//! the same line as the pattern, and big arms wrapped in a brace. The presence
+//! of the brace punctuation, comma, and semicolon are all dependent on whether
+//! the arm fits on the line:
+//!
+//! ```
+//! # struct Entry { nanos: u32 }
+//! # let total_nanos = 0u64;
+//! # let mut total_secs = 0u64;
+//! # let tmp;
+//! # let entry = Entry { nanos: 0 };
+//! # const NANOS_PER_SEC: u32 = 1_000_000_000;
+//! #
+//! match total_nanos.checked_add(entry.nanos as u64) {
+//!     Some(n) => tmp = n,   //<- small arm, inline with comma
+//!     None => {
+//!         total_secs = total_secs
+//!             .checked_add(total_nanos / NANOS_PER_SEC as u64)
+//!             .expect("overflow in iter::sum over durations");
+//!     }   //<- big arm, needs brace added, and also semicolon^
+//! }
+//! ```
+//!
+//! The printing algorithm implementation in this crate accommodates all of
+//! these situations with conditional punctuation tokens whose selection can be
+//! deferred and populated after it's known that the group is or is not broken.
+
+#![doc(html_root_url = "https://docs.rs/prettyplease/0.2.37")]
+#![allow(
+    clippy::bool_to_int_with_if,
+    clippy::cast_possible_wrap,
+    clippy::cast_sign_loss,
+    clippy::derive_partial_eq_without_eq,
+    clippy::doc_markdown,
+    clippy::enum_glob_use,
+    clippy::items_after_statements,
+    clippy::let_underscore_untyped,
+    clippy::match_like_matches_macro,
+    clippy::match_same_arms,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::needless_pass_by_value,
+    clippy::ref_option,
+    clippy::similar_names,
+    clippy::struct_excessive_bools,
+    clippy::too_many_lines,
+    clippy::unused_self,
+    clippy::vec_init_then_push
+)]
+#![cfg_attr(all(test, exhaustive), feature(non_exhaustive_omitted_patterns_lint))]
+
+mod algorithm;
+mod attr;
+mod classify;
+mod convenience;
+mod data;
+mod expr;
+mod file;
+mod fixup;
+mod generics;
+mod item;
+mod iter;
+mod lifetime;
+mod lit;
+mod mac;
+mod pat;
+mod path;
+mod precedence;
+mod ring;
+mod stmt;
+mod token;
+mod ty;
+
+use crate::algorithm::Printer;
+use syn::File;
+
+// Target line width.
+const MARGIN: isize = 89;
+
+// Number of spaces increment at each level of block indentation.
+const INDENT: isize = 4;
+
+// Every line is allowed at least this much space, even if highly indented.
+const MIN_SPACE: isize = 60;
+
+pub fn unparse(file: &File) -> String {
+    let mut p = Printer::new();
+    p.file(file);
+    p.eof()
+}

vendor/prettyplease/src/lifetime.rs

@@ -0,0 +1,9 @@
+use crate::algorithm::Printer;
+use syn::Lifetime;
+
+impl Printer {
+    pub fn lifetime(&mut self, lifetime: &Lifetime) {
+        self.word("'");
+        self.ident(&lifetime.ident);
+    }
+}

vendor/prettyplease/src/lit.rs

@@ -0,0 +1,57 @@
+use crate::algorithm::Printer;
+use proc_macro2::Literal;
+use syn::{Lit, LitBool, LitByte, LitByteStr, LitCStr, LitChar, LitFloat, LitInt, LitStr};
+
+impl Printer {
+    pub fn lit(&mut self, lit: &Lit) {
+        match lit {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Lit::Str(lit) => self.lit_str(lit),
+            Lit::ByteStr(lit) => self.lit_byte_str(lit),
+            Lit::CStr(lit) => self.lit_c_str(lit),
+            Lit::Byte(lit) => self.lit_byte(lit),
+            Lit::Char(lit) => self.lit_char(lit),
+            Lit::Int(lit) => self.lit_int(lit),
+            Lit::Float(lit) => self.lit_float(lit),
+            Lit::Bool(lit) => self.lit_bool(lit),
+            Lit::Verbatim(lit) => self.lit_verbatim(lit),
+            _ => unimplemented!("unknown Lit"),
+        }
+    }
+
+    pub fn lit_str(&mut self, lit: &LitStr) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_byte_str(&mut self, lit: &LitByteStr) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_c_str(&mut self, lit: &LitCStr) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_byte(&mut self, lit: &LitByte) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_char(&mut self, lit: &LitChar) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_int(&mut self, lit: &LitInt) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_float(&mut self, lit: &LitFloat) {
+        self.word(lit.token().to_string());
+    }
+
+    fn lit_bool(&mut self, lit: &LitBool) {
+        self.word(if lit.value { "true" } else { "false" });
+    }
+
+    fn lit_verbatim(&mut self, token: &Literal) {
+        self.word(token.to_string());
+    }
+}

vendor/prettyplease/src/mac.rs

@@ -0,0 +1,706 @@
+use crate::algorithm::Printer;
+use crate::path::PathKind;
+use crate::token::Token;
+use crate::INDENT;
+use proc_macro2::{Delimiter, Spacing, TokenStream};
+use syn::{Ident, Macro, MacroDelimiter};
+
+impl Printer {
+    pub fn mac(&mut self, mac: &Macro, ident: Option<&Ident>, semicolon: bool) {
+        if mac.path.is_ident("macro_rules") {
+            if let Some(ident) = ident {
+                self.macro_rules(ident, &mac.tokens);
+                return;
+            }
+        }
+        #[cfg(feature = "verbatim")]
+        if ident.is_none() && self.standard_library_macro(mac, semicolon) {
+            return;
+        }
+        self.path(&mac.path, PathKind::Simple);
+        self.word("!");
+        if let Some(ident) = ident {
+            self.nbsp();
+            self.ident(ident);
+        }
+        let (open, close, delimiter_break) = match mac.delimiter {
+            MacroDelimiter::Paren(_) => ("(", ")", Self::zerobreak as fn(&mut Self)),
+            MacroDelimiter::Brace(_) => (" {", "}", Self::hardbreak as fn(&mut Self)),
+            MacroDelimiter::Bracket(_) => ("[", "]", Self::zerobreak as fn(&mut Self)),
+        };
+        self.word(open);
+        if !mac.tokens.is_empty() {
+            self.cbox(INDENT);
+            delimiter_break(self);
+            self.ibox(0);
+            self.macro_rules_tokens(mac.tokens.clone(), false);
+            self.end();
+            delimiter_break(self);
+            self.offset(-INDENT);
+            self.end();
+        }
+        self.word(close);
+        if semicolon {
+            self.word(";");
+        }
+    }
+
+    fn macro_rules(&mut self, name: &Ident, rules: &TokenStream) {
+        enum State {
+            Start,
+            Matcher,
+            Equal,
+            Greater,
+            Expander,
+        }
+
+        use State::*;
+
+        self.word("macro_rules! ");
+        self.ident(name);
+        self.word(" {");
+        self.cbox(INDENT);
+        self.hardbreak_if_nonempty();
+        let mut state = State::Start;
+        for tt in rules.clone() {
+            let token = Token::from(tt);
+            match (state, token) {
+                (Start, Token::Group(delimiter, stream)) => {
+                    self.delimiter_open(delimiter);
+                    if !stream.is_empty() {
+                        self.cbox(INDENT);
+                        self.zerobreak();
+                        self.ibox(0);
+                        self.macro_rules_tokens(stream, true);
+                        self.end();
+                        self.zerobreak();
+                        self.offset(-INDENT);
+                        self.end();
+                    }
+                    self.delimiter_close(delimiter);
+                    state = Matcher;
+                }
+                (Matcher, Token::Punct('=', Spacing::Joint)) => {
+                    self.word(" =");
+                    state = Equal;
+                }
+                (Equal, Token::Punct('>', Spacing::Alone)) => {
+                    self.word(">");
+                    state = Greater;
+                }
+                (Greater, Token::Group(_delimiter, stream)) => {
+                    self.word(" {");
+                    self.neverbreak();
+                    if !stream.is_empty() {
+                        self.cbox(INDENT);
+                        self.hardbreak();
+                        self.ibox(0);
+                        self.macro_rules_tokens(stream, false);
+                        self.end();
+                        self.hardbreak();
+                        self.offset(-INDENT);
+                        self.end();
+                    }
+                    self.word("}");
+                    state = Expander;
+                }
+                (Expander, Token::Punct(';', Spacing::Alone)) => {
+                    self.word(";");
+                    self.hardbreak();
+                    state = Start;
+                }
+                _ => unimplemented!("bad macro_rules syntax"),
+            }
+        }
+        match state {
+            Start => {}
+            Expander => {
+                self.word(";");
+                self.hardbreak();
+            }
+            _ => self.hardbreak(),
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word("}");
+    }
+
+    pub fn macro_rules_tokens(&mut self, stream: TokenStream, matcher: bool) {
+        #[derive(PartialEq)]
+        enum State {
+            Start,
+            Dollar,
+            DollarCrate,
+            DollarIdent,
+            DollarIdentColon,
+            DollarParen,
+            DollarParenSep,
+            Pound,
+            PoundBang,
+            Dot,
+            Colon,
+            Colon2,
+            Ident,
+            IdentBang,
+            Delim,
+            Other,
+        }
+
+        use State::*;
+
+        let mut state = Start;
+        let mut previous_is_joint = true;
+        for tt in stream {
+            let token = Token::from(tt);
+            let (needs_space, next_state) = match (&state, &token) {
+                (Dollar, Token::Ident(_)) if matcher => (false, DollarIdent),
+                (Dollar, Token::Ident(ident)) if ident == "crate" => (false, DollarCrate),
+                (Dollar, Token::Ident(_)) => (false, Other),
+                (DollarIdent, Token::Punct(':', Spacing::Alone)) => (false, DollarIdentColon),
+                (DollarIdentColon, Token::Ident(_)) => (false, Other),
+                (DollarParen, Token::Punct('+' | '*' | '?', Spacing::Alone)) => (false, Other),
+                (DollarParen, Token::Ident(_) | Token::Literal(_)) => (false, DollarParenSep),
+                (DollarParen, Token::Punct(_, Spacing::Joint)) => (false, DollarParen),
+                (DollarParen, Token::Punct(_, Spacing::Alone)) => (false, DollarParenSep),
+                (DollarParenSep, Token::Punct('+' | '*', _)) => (false, Other),
+                (Pound, Token::Punct('!', _)) => (false, PoundBang),
+                (Dollar, Token::Group(Delimiter::Parenthesis, _)) => (false, DollarParen),
+                (Pound | PoundBang, Token::Group(Delimiter::Bracket, _)) => (false, Other),
+                (Ident, Token::Group(Delimiter::Parenthesis | Delimiter::Bracket, _)) => {
+                    (false, Delim)
+                }
+                (Ident, Token::Punct('!', Spacing::Alone)) => (false, IdentBang),
+                (IdentBang, Token::Group(Delimiter::Parenthesis | Delimiter::Bracket, _)) => {
+                    (false, Other)
+                }
+                (Colon, Token::Punct(':', _)) => (false, Colon2),
+                (_, Token::Group(Delimiter::Parenthesis | Delimiter::Bracket, _)) => (true, Delim),
+                (_, Token::Group(Delimiter::Brace | Delimiter::None, _)) => (true, Other),
+                (_, Token::Ident(ident)) if !is_keyword(ident) => {
+                    (state != Dot && state != Colon2, Ident)
+                }
+                (_, Token::Literal(lit)) if lit.to_string().ends_with('.') => (state != Dot, Other),
+                (_, Token::Literal(_)) => (state != Dot, Ident),
+                (_, Token::Punct(',' | ';', _)) => (false, Other),
+                (_, Token::Punct('.', _)) if !matcher => (state != Ident && state != Delim, Dot),
+                (_, Token::Punct(':', Spacing::Joint)) => {
+                    (state != Ident && state != DollarCrate, Colon)
+                }
+                (_, Token::Punct('$', _)) => (true, Dollar),
+                (_, Token::Punct('#', _)) => (true, Pound),
+                (_, _) => (true, Other),
+            };
+            if !previous_is_joint {
+                if needs_space {
+                    self.space();
+                } else if let Token::Punct('.', _) = token {
+                    self.zerobreak();
+                }
+            }
+            previous_is_joint = match token {
+                Token::Punct(_, Spacing::Joint) | Token::Punct('$', _) => true,
+                _ => false,
+            };
+            self.single_token(
+                token,
+                if matcher {
+                    |printer, stream| printer.macro_rules_tokens(stream, true)
+                } else {
+                    |printer, stream| printer.macro_rules_tokens(stream, false)
+                },
+            );
+            state = next_state;
+        }
+    }
+}
+
+pub(crate) fn requires_semi(delimiter: &MacroDelimiter) -> bool {
+    match delimiter {
+        MacroDelimiter::Paren(_) | MacroDelimiter::Bracket(_) => true,
+        MacroDelimiter::Brace(_) => false,
+    }
+}
+
+fn is_keyword(ident: &Ident) -> bool {
+    match ident.to_string().as_str() {
+        "as" | "async" | "await" | "box" | "break" | "const" | "continue" | "crate" | "dyn"
+        | "else" | "enum" | "extern" | "fn" | "for" | "if" | "impl" | "in" | "let" | "loop"
+        | "macro" | "match" | "mod" | "move" | "mut" | "pub" | "ref" | "return" | "static"
+        | "struct" | "trait" | "type" | "unsafe" | "use" | "where" | "while" | "yield" => true,
+        _ => false,
+    }
+}
+
+#[cfg(feature = "verbatim")]
+mod standard_library {
+    use crate::algorithm::Printer;
+    use crate::expr;
+    use crate::fixup::FixupContext;
+    use crate::iter::IterDelimited;
+    use crate::path::PathKind;
+    use crate::INDENT;
+    use syn::ext::IdentExt;
+    use syn::parse::{Parse, ParseStream, Parser, Result};
+    use syn::punctuated::Punctuated;
+    use syn::{
+        parenthesized, token, Attribute, Expr, ExprAssign, ExprPath, Ident, Lit, Macro, Pat, Path,
+        Token, Type, Visibility,
+    };
+
+    enum KnownMacro {
+        Expr(Expr),
+        Exprs(Vec<Expr>),
+        Cfg(Cfg),
+        Matches(Matches),
+        ThreadLocal(Vec<ThreadLocal>),
+        VecArray(Punctuated<Expr, Token![,]>),
+        VecRepeat { elem: Expr, n: Expr },
+    }
+
+    enum Cfg {
+        Eq(Ident, Option<Lit>),
+        Call(Ident, Vec<Cfg>),
+    }
+
+    struct Matches {
+        expression: Expr,
+        pattern: Pat,
+        guard: Option<Expr>,
+    }
+
+    struct ThreadLocal {
+        attrs: Vec<Attribute>,
+        vis: Visibility,
+        name: Ident,
+        ty: Type,
+        init: Expr,
+    }
+
+    struct FormatArgs {
+        format_string: Expr,
+        args: Vec<Expr>,
+    }
+
+    impl Parse for FormatArgs {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let format_string: Expr = input.parse()?;
+
+            let mut args = Vec::new();
+            while !input.is_empty() {
+                input.parse::<Token![,]>()?;
+                if input.is_empty() {
+                    break;
+                }
+                let arg = if input.peek(Ident::peek_any)
+                    && input.peek2(Token![=])
+                    && !input.peek2(Token![==])
+                {
+                    let key = input.call(Ident::parse_any)?;
+                    let eq_token: Token![=] = input.parse()?;
+                    let value: Expr = input.parse()?;
+                    Expr::Assign(ExprAssign {
+                        attrs: Vec::new(),
+                        left: Box::new(Expr::Path(ExprPath {
+                            attrs: Vec::new(),
+                            qself: None,
+                            path: Path::from(key),
+                        })),
+                        eq_token,
+                        right: Box::new(value),
+                    })
+                } else {
+                    input.parse()?
+                };
+                args.push(arg);
+            }
+
+            Ok(FormatArgs {
+                format_string,
+                args,
+            })
+        }
+    }
+
+    impl KnownMacro {
+        fn parse_expr(input: ParseStream) -> Result<Self> {
+            let expr: Expr = input.parse()?;
+            Ok(KnownMacro::Expr(expr))
+        }
+
+        fn parse_expr_comma(input: ParseStream) -> Result<Self> {
+            let expr: Expr = input.parse()?;
+            input.parse::<Option<Token![,]>>()?;
+            Ok(KnownMacro::Exprs(vec![expr]))
+        }
+
+        fn parse_exprs(input: ParseStream) -> Result<Self> {
+            let exprs = input.parse_terminated(Expr::parse, Token![,])?;
+            Ok(KnownMacro::Exprs(Vec::from_iter(exprs)))
+        }
+
+        fn parse_assert(input: ParseStream) -> Result<Self> {
+            let mut exprs = Vec::new();
+            let cond: Expr = input.parse()?;
+            exprs.push(cond);
+            if input.parse::<Option<Token![,]>>()?.is_some() && !input.is_empty() {
+                let format_args: FormatArgs = input.parse()?;
+                exprs.push(format_args.format_string);
+                exprs.extend(format_args.args);
+            }
+            Ok(KnownMacro::Exprs(exprs))
+        }
+
+        fn parse_assert_cmp(input: ParseStream) -> Result<Self> {
+            let mut exprs = Vec::new();
+            let left: Expr = input.parse()?;
+            exprs.push(left);
+            input.parse::<Token![,]>()?;
+            let right: Expr = input.parse()?;
+            exprs.push(right);
+            if input.parse::<Option<Token![,]>>()?.is_some() && !input.is_empty() {
+                let format_args: FormatArgs = input.parse()?;
+                exprs.push(format_args.format_string);
+                exprs.extend(format_args.args);
+            }
+            Ok(KnownMacro::Exprs(exprs))
+        }
+
+        fn parse_cfg(input: ParseStream) -> Result<Self> {
+            fn parse_single(input: ParseStream) -> Result<Cfg> {
+                let ident: Ident = input.parse()?;
+                if input.peek(token::Paren) && (ident == "all" || ident == "any") {
+                    let content;
+                    parenthesized!(content in input);
+                    let list = content.call(parse_multiple)?;
+                    Ok(Cfg::Call(ident, list))
+                } else if input.peek(token::Paren) && ident == "not" {
+                    let content;
+                    parenthesized!(content in input);
+                    let cfg = content.call(parse_single)?;
+                    content.parse::<Option<Token![,]>>()?;
+                    Ok(Cfg::Call(ident, vec![cfg]))
+                } else if input.peek(Token![=]) {
+                    input.parse::<Token![=]>()?;
+                    let string: Lit = input.parse()?;
+                    Ok(Cfg::Eq(ident, Some(string)))
+                } else {
+                    Ok(Cfg::Eq(ident, None))
+                }
+            }
+
+            fn parse_multiple(input: ParseStream) -> Result<Vec<Cfg>> {
+                let mut vec = Vec::new();
+                while !input.is_empty() {
+                    let cfg = input.call(parse_single)?;
+                    vec.push(cfg);
+                    if input.is_empty() {
+                        break;
+                    }
+                    input.parse::<Token![,]>()?;
+                }
+                Ok(vec)
+            }
+
+            let cfg = input.call(parse_single)?;
+            input.parse::<Option<Token![,]>>()?;
+            Ok(KnownMacro::Cfg(cfg))
+        }
+
+        fn parse_env(input: ParseStream) -> Result<Self> {
+            let mut exprs = Vec::new();
+            let name: Expr = input.parse()?;
+            exprs.push(name);
+            if input.parse::<Option<Token![,]>>()?.is_some() && !input.is_empty() {
+                let error_msg: Expr = input.parse()?;
+                exprs.push(error_msg);
+                input.parse::<Option<Token![,]>>()?;
+            }
+            Ok(KnownMacro::Exprs(exprs))
+        }
+
+        fn parse_format_args(input: ParseStream) -> Result<Self> {
+            let format_args: FormatArgs = input.parse()?;
+            let mut exprs = format_args.args;
+            exprs.insert(0, format_args.format_string);
+            Ok(KnownMacro::Exprs(exprs))
+        }
+
+        fn parse_matches(input: ParseStream) -> Result<Self> {
+            let expression: Expr = input.parse()?;
+            input.parse::<Token![,]>()?;
+            let pattern = input.call(Pat::parse_multi_with_leading_vert)?;
+            let guard = if input.parse::<Option<Token![if]>>()?.is_some() {
+                Some(input.parse()?)
+            } else {
+                None
+            };
+            input.parse::<Option<Token![,]>>()?;
+            Ok(KnownMacro::Matches(Matches {
+                expression,
+                pattern,
+                guard,
+            }))
+        }
+
+        fn parse_thread_local(input: ParseStream) -> Result<Self> {
+            let mut items = Vec::new();
+            while !input.is_empty() {
+                let attrs = input.call(Attribute::parse_outer)?;
+                let vis: Visibility = input.parse()?;
+                input.parse::<Token![static]>()?;
+                let name: Ident = input.parse()?;
+                input.parse::<Token![:]>()?;
+                let ty: Type = input.parse()?;
+                input.parse::<Token![=]>()?;
+                let init: Expr = input.parse()?;
+                if input.is_empty() {
+                    break;
+                }
+                input.parse::<Token![;]>()?;
+                items.push(ThreadLocal {
+                    attrs,
+                    vis,
+                    name,
+                    ty,
+                    init,
+                });
+            }
+            Ok(KnownMacro::ThreadLocal(items))
+        }
+
+        fn parse_vec(input: ParseStream) -> Result<Self> {
+            if input.is_empty() {
+                return Ok(KnownMacro::VecArray(Punctuated::new()));
+            }
+            let first: Expr = input.parse()?;
+            if input.parse::<Option<Token![;]>>()?.is_some() {
+                let len: Expr = input.parse()?;
+                Ok(KnownMacro::VecRepeat {
+                    elem: first,
+                    n: len,
+                })
+            } else {
+                let mut vec = Punctuated::new();
+                vec.push_value(first);
+                while !input.is_empty() {
+                    let comma: Token![,] = input.parse()?;
+                    vec.push_punct(comma);
+                    if input.is_empty() {
+                        break;
+                    }
+                    let next: Expr = input.parse()?;
+                    vec.push_value(next);
+                }
+                Ok(KnownMacro::VecArray(vec))
+            }
+        }
+
+        fn parse_write(input: ParseStream) -> Result<Self> {
+            let mut exprs = Vec::new();
+            let dst: Expr = input.parse()?;
+            exprs.push(dst);
+            input.parse::<Token![,]>()?;
+            let format_args: FormatArgs = input.parse()?;
+            exprs.push(format_args.format_string);
+            exprs.extend(format_args.args);
+            Ok(KnownMacro::Exprs(exprs))
+        }
+
+        fn parse_writeln(input: ParseStream) -> Result<Self> {
+            let mut exprs = Vec::new();
+            let dst: Expr = input.parse()?;
+            exprs.push(dst);
+            if input.parse::<Option<Token![,]>>()?.is_some() && !input.is_empty() {
+                let format_args: FormatArgs = input.parse()?;
+                exprs.push(format_args.format_string);
+                exprs.extend(format_args.args);
+            }
+            Ok(KnownMacro::Exprs(exprs))
+        }
+    }
+
+    impl Printer {
+        pub fn standard_library_macro(&mut self, mac: &Macro, mut semicolon: bool) -> bool {
+            let name = mac.path.segments.last().unwrap().ident.to_string();
+            let parser = match name.as_str() {
+                "addr_of" | "addr_of_mut" => KnownMacro::parse_expr,
+                "assert" | "debug_assert" => KnownMacro::parse_assert,
+                "assert_eq" | "assert_ne" | "debug_assert_eq" | "debug_assert_ne" => {
+                    KnownMacro::parse_assert_cmp
+                }
+                "cfg" => KnownMacro::parse_cfg,
+                "compile_error" | "include" | "include_bytes" | "include_str" | "option_env" => {
+                    KnownMacro::parse_expr_comma
+                }
+                "concat" | "concat_bytes" | "dbg" => KnownMacro::parse_exprs,
+                "const_format_args" | "eprint" | "eprintln" | "format" | "format_args"
+                | "format_args_nl" | "panic" | "print" | "println" | "todo" | "unimplemented"
+                | "unreachable" => KnownMacro::parse_format_args,
+                "env" => KnownMacro::parse_env,
+                "matches" => KnownMacro::parse_matches,
+                "thread_local" => KnownMacro::parse_thread_local,
+                "vec" => KnownMacro::parse_vec,
+                "write" => KnownMacro::parse_write,
+                "writeln" => KnownMacro::parse_writeln,
+                _ => return false,
+            };
+
+            let known_macro = match parser.parse2(mac.tokens.clone()) {
+                Ok(known_macro) => known_macro,
+                Err(_) => return false,
+            };
+
+            self.path(&mac.path, PathKind::Simple);
+            self.word("!");
+
+            match &known_macro {
+                KnownMacro::Expr(expr) => {
+                    self.word("(");
+                    self.cbox(INDENT);
+                    self.zerobreak();
+                    self.expr(expr, FixupContext::NONE);
+                    self.zerobreak();
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word(")");
+                }
+                KnownMacro::Exprs(exprs) => {
+                    self.word("(");
+                    self.cbox(INDENT);
+                    self.zerobreak();
+                    for elem in exprs.iter().delimited() {
+                        self.expr(&elem, FixupContext::NONE);
+                        self.trailing_comma(elem.is_last);
+                    }
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word(")");
+                }
+                KnownMacro::Cfg(cfg) => {
+                    self.word("(");
+                    self.cfg(cfg);
+                    self.word(")");
+                }
+                KnownMacro::Matches(matches) => {
+                    self.word("(");
+                    self.cbox(INDENT);
+                    self.zerobreak();
+                    self.expr(&matches.expression, FixupContext::NONE);
+                    self.word(",");
+                    self.space();
+                    self.pat(&matches.pattern);
+                    if let Some(guard) = &matches.guard {
+                        self.space();
+                        self.word("if ");
+                        self.expr(guard, FixupContext::NONE);
+                    }
+                    self.zerobreak();
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word(")");
+                }
+                KnownMacro::ThreadLocal(items) => {
+                    self.word(" {");
+                    self.cbox(INDENT);
+                    self.hardbreak_if_nonempty();
+                    for item in items {
+                        self.outer_attrs(&item.attrs);
+                        self.cbox(0);
+                        self.visibility(&item.vis);
+                        self.word("static ");
+                        self.ident(&item.name);
+                        self.word(": ");
+                        self.ty(&item.ty);
+                        self.word(" = ");
+                        self.neverbreak();
+                        self.expr(&item.init, FixupContext::NONE);
+                        self.word(";");
+                        self.end();
+                        self.hardbreak();
+                    }
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word("}");
+                    semicolon = false;
+                }
+                KnownMacro::VecArray(vec) => {
+                    if vec.is_empty() {
+                        self.word("[]");
+                    } else if expr::simple_array(vec) {
+                        self.cbox(INDENT);
+                        self.word("[");
+                        self.zerobreak();
+                        self.ibox(0);
+                        for elem in vec.iter().delimited() {
+                            self.expr(&elem, FixupContext::NONE);
+                            if !elem.is_last {
+                                self.word(",");
+                                self.space();
+                            }
+                        }
+                        self.end();
+                        self.trailing_comma(true);
+                        self.offset(-INDENT);
+                        self.word("]");
+                        self.end();
+                    } else {
+                        self.word("[");
+                        self.cbox(INDENT);
+                        self.zerobreak();
+                        for elem in vec.iter().delimited() {
+                            self.expr(&elem, FixupContext::NONE);
+                            self.trailing_comma(elem.is_last);
+                        }
+                        self.offset(-INDENT);
+                        self.end();
+                        self.word("]");
+                    }
+                }
+                KnownMacro::VecRepeat { elem, n } => {
+                    self.word("[");
+                    self.cbox(INDENT);
+                    self.zerobreak();
+                    self.expr(elem, FixupContext::NONE);
+                    self.word(";");
+                    self.space();
+                    self.expr(n, FixupContext::NONE);
+                    self.zerobreak();
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word("]");
+                }
+            }
+
+            if semicolon {
+                self.word(";");
+            }
+
+            true
+        }
+
+        fn cfg(&mut self, cfg: &Cfg) {
+            match cfg {
+                Cfg::Eq(ident, value) => {
+                    self.ident(ident);
+                    if let Some(value) = value {
+                        self.word(" = ");
+                        self.lit(value);
+                    }
+                }
+                Cfg::Call(ident, args) => {
+                    self.ident(ident);
+                    self.word("(");
+                    self.cbox(INDENT);
+                    self.zerobreak();
+                    for arg in args.iter().delimited() {
+                        self.cfg(&arg);
+                        self.trailing_comma(arg.is_last);
+                    }
+                    self.offset(-INDENT);
+                    self.end();
+                    self.word(")");
+                }
+            }
+        }
+    }
+}

vendor/prettyplease/src/pat.rs

@@ -0,0 +1,254 @@
+use crate::algorithm::Printer;
+use crate::fixup::FixupContext;
+use crate::iter::IterDelimited;
+use crate::path::PathKind;
+use crate::INDENT;
+use proc_macro2::TokenStream;
+use syn::{
+    FieldPat, Pat, PatIdent, PatOr, PatParen, PatReference, PatRest, PatSlice, PatStruct, PatTuple,
+    PatTupleStruct, PatType, PatWild,
+};
+
+impl Printer {
+    pub fn pat(&mut self, pat: &Pat) {
+        match pat {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Pat::Const(pat) => self.expr_const(pat),
+            Pat::Ident(pat) => self.pat_ident(pat),
+            Pat::Lit(pat) => self.expr_lit(pat),
+            Pat::Macro(pat) => self.expr_macro(pat),
+            Pat::Or(pat) => self.pat_or(pat),
+            Pat::Paren(pat) => self.pat_paren(pat),
+            Pat::Path(pat) => self.expr_path(pat),
+            Pat::Range(pat) => self.expr_range(pat, FixupContext::NONE),
+            Pat::Reference(pat) => self.pat_reference(pat),
+            Pat::Rest(pat) => self.pat_rest(pat),
+            Pat::Slice(pat) => self.pat_slice(pat),
+            Pat::Struct(pat) => self.pat_struct(pat),
+            Pat::Tuple(pat) => self.pat_tuple(pat),
+            Pat::TupleStruct(pat) => self.pat_tuple_struct(pat),
+            Pat::Type(pat) => self.pat_type(pat),
+            Pat::Verbatim(pat) => self.pat_verbatim(pat),
+            Pat::Wild(pat) => self.pat_wild(pat),
+            _ => unimplemented!("unknown Pat"),
+        }
+    }
+
+    fn pat_ident(&mut self, pat: &PatIdent) {
+        self.outer_attrs(&pat.attrs);
+        if pat.by_ref.is_some() {
+            self.word("ref ");
+        }
+        if pat.mutability.is_some() {
+            self.word("mut ");
+        }
+        self.ident(&pat.ident);
+        if let Some((_at_token, subpat)) = &pat.subpat {
+            self.word(" @ ");
+            self.pat(subpat);
+        }
+    }
+
+    fn pat_or(&mut self, pat: &PatOr) {
+        self.outer_attrs(&pat.attrs);
+        let mut consistent_break = false;
+        for case in &pat.cases {
+            match case {
+                Pat::Lit(_) | Pat::Wild(_) => {}
+                _ => {
+                    consistent_break = true;
+                    break;
+                }
+            }
+        }
+        if consistent_break {
+            self.cbox(0);
+        } else {
+            self.ibox(0);
+        }
+        for case in pat.cases.iter().delimited() {
+            if !case.is_first {
+                self.space();
+                self.word("| ");
+            }
+            self.pat(&case);
+        }
+        self.end();
+    }
+
+    fn pat_paren(&mut self, pat: &PatParen) {
+        self.outer_attrs(&pat.attrs);
+        self.word("(");
+        self.pat(&pat.pat);
+        self.word(")");
+    }
+
+    fn pat_reference(&mut self, pat: &PatReference) {
+        self.outer_attrs(&pat.attrs);
+        self.word("&");
+        if pat.mutability.is_some() {
+            self.word("mut ");
+        }
+        self.pat(&pat.pat);
+    }
+
+    fn pat_rest(&mut self, pat: &PatRest) {
+        self.outer_attrs(&pat.attrs);
+        self.word("..");
+    }
+
+    fn pat_slice(&mut self, pat: &PatSlice) {
+        self.outer_attrs(&pat.attrs);
+        self.word("[");
+        for elem in pat.elems.iter().delimited() {
+            self.pat(&elem);
+            self.trailing_comma(elem.is_last);
+        }
+        self.word("]");
+    }
+
+    fn pat_struct(&mut self, pat: &PatStruct) {
+        self.outer_attrs(&pat.attrs);
+        self.cbox(INDENT);
+        self.path(&pat.path, PathKind::Expr);
+        self.word(" {");
+        self.space_if_nonempty();
+        for field in pat.fields.iter().delimited() {
+            self.field_pat(&field);
+            self.trailing_comma_or_space(field.is_last && pat.rest.is_none());
+        }
+        if let Some(rest) = &pat.rest {
+            self.pat_rest(rest);
+            self.space();
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word("}");
+    }
+
+    fn pat_tuple(&mut self, pat: &PatTuple) {
+        self.outer_attrs(&pat.attrs);
+        self.word("(");
+        self.cbox(INDENT);
+        self.zerobreak();
+        for elem in pat.elems.iter().delimited() {
+            self.pat(&elem);
+            if pat.elems.len() == 1 {
+                if pat.elems.trailing_punct() {
+                    self.word(",");
+                }
+                self.zerobreak();
+            } else {
+                self.trailing_comma(elem.is_last);
+            }
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word(")");
+    }
+
+    fn pat_tuple_struct(&mut self, pat: &PatTupleStruct) {
+        self.outer_attrs(&pat.attrs);
+        self.path(&pat.path, PathKind::Expr);
+        self.word("(");
+        self.cbox(INDENT);
+        self.zerobreak();
+        for elem in pat.elems.iter().delimited() {
+            self.pat(&elem);
+            self.trailing_comma(elem.is_last);
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word(")");
+    }
+
+    pub fn pat_type(&mut self, pat: &PatType) {
+        self.outer_attrs(&pat.attrs);
+        self.pat(&pat.pat);
+        self.word(": ");
+        self.ty(&pat.ty);
+    }
+
+    #[cfg(not(feature = "verbatim"))]
+    fn pat_verbatim(&mut self, pat: &TokenStream) {
+        unimplemented!("Pat::Verbatim `{}`", pat);
+    }
+
+    #[cfg(feature = "verbatim")]
+    fn pat_verbatim(&mut self, tokens: &TokenStream) {
+        use syn::parse::{Parse, ParseStream, Result};
+        use syn::{braced, Attribute, Block, Token};
+
+        enum PatVerbatim {
+            Ellipsis,
+            Box(Pat),
+            Const(PatConst),
+        }
+
+        struct PatConst {
+            attrs: Vec<Attribute>,
+            block: Block,
+        }
+
+        impl Parse for PatVerbatim {
+            fn parse(input: ParseStream) -> Result<Self> {
+                let lookahead = input.lookahead1();
+                if lookahead.peek(Token![box]) {
+                    input.parse::<Token![box]>()?;
+                    let inner = Pat::parse_single(input)?;
+                    Ok(PatVerbatim::Box(inner))
+                } else if lookahead.peek(Token![const]) {
+                    input.parse::<Token![const]>()?;
+                    let content;
+                    let brace_token = braced!(content in input);
+                    let attrs = content.call(Attribute::parse_inner)?;
+                    let stmts = content.call(Block::parse_within)?;
+                    Ok(PatVerbatim::Const(PatConst {
+                        attrs,
+                        block: Block { brace_token, stmts },
+                    }))
+                } else if lookahead.peek(Token![...]) {
+                    input.parse::<Token![...]>()?;
+                    Ok(PatVerbatim::Ellipsis)
+                } else {
+                    Err(lookahead.error())
+                }
+            }
+        }
+
+        let pat: PatVerbatim = match syn::parse2(tokens.clone()) {
+            Ok(pat) => pat,
+            Err(_) => unimplemented!("Pat::Verbatim `{}`", tokens),
+        };
+
+        match pat {
+            PatVerbatim::Ellipsis => {
+                self.word("...");
+            }
+            PatVerbatim::Box(pat) => {
+                self.word("box ");
+                self.pat(&pat);
+            }
+            PatVerbatim::Const(pat) => {
+                self.word("const ");
+                self.cbox(INDENT);
+                self.small_block(&pat.block, &pat.attrs);
+                self.end();
+            }
+        }
+    }
+
+    fn pat_wild(&mut self, pat: &PatWild) {
+        self.outer_attrs(&pat.attrs);
+        self.word("_");
+    }
+
+    fn field_pat(&mut self, field_pat: &FieldPat) {
+        self.outer_attrs(&field_pat.attrs);
+        if field_pat.colon_token.is_some() {
+            self.member(&field_pat.member);
+            self.word(": ");
+        }
+        self.pat(&field_pat.pat);
+    }
+}

vendor/prettyplease/src/path.rs

@@ -0,0 +1,194 @@
+use crate::algorithm::Printer;
+use crate::iter::IterDelimited;
+use crate::INDENT;
+use std::ptr;
+use syn::{
+    AngleBracketedGenericArguments, AssocConst, AssocType, Constraint, GenericArgument,
+    ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
+};
+
+#[derive(Copy, Clone, PartialEq)]
+pub enum PathKind {
+    // a::B
+    Simple,
+    // a::B<T>
+    Type,
+    // a::B::<T>
+    Expr,
+}
+
+impl Printer {
+    pub fn path(&mut self, path: &Path, kind: PathKind) {
+        assert!(!path.segments.is_empty());
+        for segment in path.segments.iter().delimited() {
+            if !segment.is_first || path.leading_colon.is_some() {
+                self.word("::");
+            }
+            self.path_segment(&segment, kind);
+        }
+    }
+
+    pub fn path_segment(&mut self, segment: &PathSegment, kind: PathKind) {
+        self.ident(&segment.ident);
+        self.path_arguments(&segment.arguments, kind);
+    }
+
+    fn path_arguments(&mut self, arguments: &PathArguments, kind: PathKind) {
+        match arguments {
+            PathArguments::None => {}
+            PathArguments::AngleBracketed(arguments) => {
+                self.angle_bracketed_generic_arguments(arguments, kind);
+            }
+            PathArguments::Parenthesized(arguments) => {
+                self.parenthesized_generic_arguments(arguments);
+            }
+        }
+    }
+
+    fn generic_argument(&mut self, arg: &GenericArgument) {
+        match arg {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            GenericArgument::Lifetime(lifetime) => self.lifetime(lifetime),
+            GenericArgument::Type(ty) => self.ty(ty),
+            GenericArgument::Const(expr) => self.const_argument(expr),
+            GenericArgument::AssocType(assoc) => self.assoc_type(assoc),
+            GenericArgument::AssocConst(assoc) => self.assoc_const(assoc),
+            GenericArgument::Constraint(constraint) => self.constraint(constraint),
+            _ => unimplemented!("unknown GenericArgument"),
+        }
+    }
+
+    pub fn angle_bracketed_generic_arguments(
+        &mut self,
+        generic: &AngleBracketedGenericArguments,
+        path_kind: PathKind,
+    ) {
+        if generic.args.is_empty() || path_kind == PathKind::Simple {
+            return;
+        }
+
+        if path_kind == PathKind::Expr {
+            self.word("::");
+        }
+        self.word("<");
+        self.cbox(INDENT);
+        self.zerobreak();
+
+        // Print lifetimes before types/consts/bindings, regardless of their
+        // order in self.args.
+        #[derive(Ord, PartialOrd, Eq, PartialEq)]
+        enum Group {
+            First,
+            Second,
+        }
+        fn group(arg: &GenericArgument) -> Group {
+            match arg {
+                #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+                GenericArgument::Lifetime(_) => Group::First,
+                GenericArgument::Type(_)
+                | GenericArgument::Const(_)
+                | GenericArgument::AssocType(_)
+                | GenericArgument::AssocConst(_)
+                | GenericArgument::Constraint(_) => Group::Second,
+                _ => Group::Second,
+            }
+        }
+        let last = generic.args.iter().max_by_key(|param| group(param));
+        for current_group in [Group::First, Group::Second] {
+            for arg in &generic.args {
+                if group(arg) == current_group {
+                    self.generic_argument(arg);
+                    self.trailing_comma(ptr::eq(arg, last.unwrap()));
+                }
+            }
+        }
+
+        self.offset(-INDENT);
+        self.end();
+        self.word(">");
+    }
+
+    fn assoc_type(&mut self, assoc: &AssocType) {
+        self.ident(&assoc.ident);
+        if let Some(generics) = &assoc.generics {
+            self.angle_bracketed_generic_arguments(generics, PathKind::Type);
+        }
+        self.word(" = ");
+        self.ty(&assoc.ty);
+    }
+
+    fn assoc_const(&mut self, assoc: &AssocConst) {
+        self.ident(&assoc.ident);
+        if let Some(generics) = &assoc.generics {
+            self.angle_bracketed_generic_arguments(generics, PathKind::Type);
+        }
+        self.word(" = ");
+        self.const_argument(&assoc.value);
+    }
+
+    fn constraint(&mut self, constraint: &Constraint) {
+        self.ident(&constraint.ident);
+        if let Some(generics) = &constraint.generics {
+            self.angle_bracketed_generic_arguments(generics, PathKind::Type);
+        }
+        self.ibox(INDENT);
+        for bound in constraint.bounds.iter().delimited() {
+            if bound.is_first {
+                self.word(": ");
+            } else {
+                self.space();
+                self.word("+ ");
+            }
+            self.type_param_bound(&bound);
+        }
+        self.end();
+    }
+
+    fn parenthesized_generic_arguments(&mut self, arguments: &ParenthesizedGenericArguments) {
+        self.cbox(INDENT);
+        self.word("(");
+        self.zerobreak();
+        for ty in arguments.inputs.iter().delimited() {
+            self.ty(&ty);
+            self.trailing_comma(ty.is_last);
+        }
+        self.offset(-INDENT);
+        self.word(")");
+        self.return_type(&arguments.output);
+        self.end();
+    }
+
+    pub fn qpath(&mut self, qself: &Option<QSelf>, path: &Path, kind: PathKind) {
+        let qself = if let Some(qself) = qself {
+            qself
+        } else {
+            self.path(path, kind);
+            return;
+        };
+
+        assert!(qself.position < path.segments.len());
+
+        self.word("<");
+        self.ty(&qself.ty);
+
+        let mut segments = path.segments.iter();
+        if qself.position > 0 {
+            self.word(" as ");
+            for segment in segments.by_ref().take(qself.position).delimited() {
+                if !segment.is_first || path.leading_colon.is_some() {
+                    self.word("::");
+                }
+                self.path_segment(&segment, PathKind::Type);
+                if segment.is_last {
+                    self.word(">");
+                }
+            }
+        } else {
+            self.word(">");
+        }
+        for segment in segments {
+            self.word("::");
+            self.path_segment(segment, kind);
+        }
+    }
+}

vendor/prettyplease/src/precedence.rs

@@ -0,0 +1,148 @@
+use syn::{
+    AttrStyle, Attribute, BinOp, Expr, ExprArray, ExprAsync, ExprAwait, ExprBlock, ExprBreak,
+    ExprCall, ExprConst, ExprContinue, ExprField, ExprForLoop, ExprIf, ExprIndex, ExprInfer,
+    ExprLit, ExprLoop, ExprMacro, ExprMatch, ExprMethodCall, ExprParen, ExprPath, ExprRepeat,
+    ExprReturn, ExprStruct, ExprTry, ExprTryBlock, ExprTuple, ExprUnsafe, ExprWhile, ExprYield,
+    ReturnType,
+};
+
+// Reference: https://doc.rust-lang.org/reference/expressions.html#expression-precedence
+#[derive(Copy, Clone, PartialEq, PartialOrd)]
+pub enum Precedence {
+    // return, break, closures
+    Jump,
+    // = += -= *= /= %= &= |= ^= <<= >>=
+    Assign,
+    // .. ..=
+    Range,
+    // ||
+    Or,
+    // &&
+    And,
+    // let
+    Let,
+    // == != < > <= >=
+    Compare,
+    // |
+    BitOr,
+    // ^
+    BitXor,
+    // &
+    BitAnd,
+    // << >>
+    Shift,
+    // + -
+    Sum,
+    // * / %
+    Product,
+    // as
+    Cast,
+    // unary - * ! & &mut
+    Prefix,
+    // paths, loops, function calls, array indexing, field expressions, method calls
+    Unambiguous,
+}
+
+impl Precedence {
+    pub(crate) const MIN: Self = Precedence::Jump;
+
+    pub(crate) fn of_binop(op: &BinOp) -> Self {
+        match op {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            BinOp::Add(_) | BinOp::Sub(_) => Precedence::Sum,
+            BinOp::Mul(_) | BinOp::Div(_) | BinOp::Rem(_) => Precedence::Product,
+            BinOp::And(_) => Precedence::And,
+            BinOp::Or(_) => Precedence::Or,
+            BinOp::BitXor(_) => Precedence::BitXor,
+            BinOp::BitAnd(_) => Precedence::BitAnd,
+            BinOp::BitOr(_) => Precedence::BitOr,
+            BinOp::Shl(_) | BinOp::Shr(_) => Precedence::Shift,
+
+            BinOp::Eq(_)
+            | BinOp::Lt(_)
+            | BinOp::Le(_)
+            | BinOp::Ne(_)
+            | BinOp::Ge(_)
+            | BinOp::Gt(_) => Precedence::Compare,
+
+            BinOp::AddAssign(_)
+            | BinOp::SubAssign(_)
+            | BinOp::MulAssign(_)
+            | BinOp::DivAssign(_)
+            | BinOp::RemAssign(_)
+            | BinOp::BitXorAssign(_)
+            | BinOp::BitAndAssign(_)
+            | BinOp::BitOrAssign(_)
+            | BinOp::ShlAssign(_)
+            | BinOp::ShrAssign(_) => Precedence::Assign,
+
+            _ => Precedence::MIN,
+        }
+    }
+
+    pub(crate) fn of(e: &Expr) -> Self {
+        fn prefix_attrs(attrs: &[Attribute]) -> Precedence {
+            for attr in attrs {
+                if let AttrStyle::Outer = attr.style {
+                    return Precedence::Prefix;
+                }
+            }
+            Precedence::Unambiguous
+        }
+
+        match e {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Expr::Closure(e) => match e.output {
+                ReturnType::Default => Precedence::Jump,
+                ReturnType::Type(..) => prefix_attrs(&e.attrs),
+            },
+
+            Expr::Break(ExprBreak { expr, .. })
+            | Expr::Return(ExprReturn { expr, .. })
+            | Expr::Yield(ExprYield { expr, .. }) => match expr {
+                Some(_) => Precedence::Jump,
+                None => Precedence::Unambiguous,
+            },
+
+            Expr::Assign(_) => Precedence::Assign,
+            Expr::Range(_) => Precedence::Range,
+            Expr::Binary(e) => Precedence::of_binop(&e.op),
+            Expr::Let(_) => Precedence::Let,
+            Expr::Cast(_) => Precedence::Cast,
+            Expr::RawAddr(_) | Expr::Reference(_) | Expr::Unary(_) => Precedence::Prefix,
+
+            Expr::Array(ExprArray { attrs, .. })
+            | Expr::Async(ExprAsync { attrs, .. })
+            | Expr::Await(ExprAwait { attrs, .. })
+            | Expr::Block(ExprBlock { attrs, .. })
+            | Expr::Call(ExprCall { attrs, .. })
+            | Expr::Const(ExprConst { attrs, .. })
+            | Expr::Continue(ExprContinue { attrs, .. })
+            | Expr::Field(ExprField { attrs, .. })
+            | Expr::ForLoop(ExprForLoop { attrs, .. })
+            | Expr::If(ExprIf { attrs, .. })
+            | Expr::Index(ExprIndex { attrs, .. })
+            | Expr::Infer(ExprInfer { attrs, .. })
+            | Expr::Lit(ExprLit { attrs, .. })
+            | Expr::Loop(ExprLoop { attrs, .. })
+            | Expr::Macro(ExprMacro { attrs, .. })
+            | Expr::Match(ExprMatch { attrs, .. })
+            | Expr::MethodCall(ExprMethodCall { attrs, .. })
+            | Expr::Paren(ExprParen { attrs, .. })
+            | Expr::Path(ExprPath { attrs, .. })
+            | Expr::Repeat(ExprRepeat { attrs, .. })
+            | Expr::Struct(ExprStruct { attrs, .. })
+            | Expr::Try(ExprTry { attrs, .. })
+            | Expr::TryBlock(ExprTryBlock { attrs, .. })
+            | Expr::Tuple(ExprTuple { attrs, .. })
+            | Expr::Unsafe(ExprUnsafe { attrs, .. })
+            | Expr::While(ExprWhile { attrs, .. }) => prefix_attrs(attrs),
+
+            Expr::Group(e) => Precedence::of(&e.expr),
+
+            Expr::Verbatim(_) => Precedence::Unambiguous,
+
+            _ => Precedence::Unambiguous,
+        }
+    }
+}

vendor/prettyplease/src/ring.rs

@@ -0,0 +1,81 @@
+use std::collections::VecDeque;
+use std::ops::{Index, IndexMut, Range};
+
+pub struct RingBuffer<T> {
+    data: VecDeque<T>,
+    // Abstract index of data[0] in infinitely sized queue
+    offset: usize,
+}
+
+impl<T> RingBuffer<T> {
+    pub fn new() -> Self {
+        RingBuffer {
+            data: VecDeque::new(),
+            offset: 0,
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.data.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.data.len()
+    }
+
+    pub fn push(&mut self, value: T) -> usize {
+        let index = self.offset + self.data.len();
+        self.data.push_back(value);
+        index
+    }
+
+    pub fn clear(&mut self) {
+        self.data.clear();
+    }
+
+    pub fn index_range(&self) -> Range<usize> {
+        self.offset..self.offset + self.data.len()
+    }
+
+    pub fn first(&self) -> &T {
+        &self.data[0]
+    }
+
+    pub fn first_mut(&mut self) -> &mut T {
+        &mut self.data[0]
+    }
+
+    pub fn pop_first(&mut self) -> T {
+        self.offset += 1;
+        self.data.pop_front().unwrap()
+    }
+
+    pub fn last(&self) -> &T {
+        self.data.back().unwrap()
+    }
+
+    pub fn last_mut(&mut self) -> &mut T {
+        self.data.back_mut().unwrap()
+    }
+
+    pub fn second_last(&self) -> &T {
+        &self.data[self.data.len() - 2]
+    }
+
+    pub fn pop_last(&mut self) {
+        self.data.pop_back().unwrap();
+    }
+}
+
+impl<T> Index<usize> for RingBuffer<T> {
+    type Output = T;
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.data[index.checked_sub(self.offset).unwrap()]
+    }
+}
+
+impl<T> IndexMut<usize> for RingBuffer<T> {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        &mut self.data[index.checked_sub(self.offset).unwrap()]
+    }
+}

vendor/prettyplease/src/stmt.rs

@@ -0,0 +1,221 @@
+use crate::algorithm::Printer;
+use crate::classify;
+use crate::expr;
+use crate::fixup::FixupContext;
+use crate::mac;
+use crate::INDENT;
+use syn::{BinOp, Expr, Stmt};
+
+impl Printer {
+    pub fn stmt(&mut self, stmt: &Stmt, is_last: bool) {
+        match stmt {
+            Stmt::Local(local) => {
+                self.outer_attrs(&local.attrs);
+                self.ibox(0);
+                self.word("let ");
+                self.pat(&local.pat);
+                if let Some(local_init) = &local.init {
+                    self.word(" = ");
+                    self.neverbreak();
+                    self.subexpr(
+                        &local_init.expr,
+                        local_init.diverge.is_some()
+                            && classify::expr_trailing_brace(&local_init.expr),
+                        FixupContext::NONE,
+                    );
+                    if let Some((_else, diverge)) = &local_init.diverge {
+                        self.space();
+                        self.word("else ");
+                        self.end();
+                        self.neverbreak();
+                        self.cbox(INDENT);
+                        if let Some(expr) = expr::simple_block(diverge) {
+                            self.small_block(&expr.block, &[]);
+                        } else {
+                            self.expr_as_small_block(diverge, INDENT);
+                        }
+                    }
+                }
+                self.end();
+                self.word(";");
+                self.hardbreak();
+            }
+            Stmt::Item(item) => self.item(item),
+            Stmt::Expr(expr, None) => {
+                if break_after(expr) {
+                    self.ibox(0);
+                    self.expr_beginning_of_line(expr, false, true, FixupContext::new_stmt());
+                    if add_semi(expr) {
+                        self.word(";");
+                    }
+                    self.end();
+                    self.hardbreak();
+                } else {
+                    self.expr_beginning_of_line(expr, false, true, FixupContext::new_stmt());
+                }
+            }
+            Stmt::Expr(expr, Some(_semi)) => {
+                if let Expr::Verbatim(tokens) = expr {
+                    if tokens.is_empty() {
+                        return;
+                    }
+                }
+                self.ibox(0);
+                self.expr_beginning_of_line(expr, false, true, FixupContext::new_stmt());
+                if !remove_semi(expr) {
+                    self.word(";");
+                }
+                self.end();
+                self.hardbreak();
+            }
+            Stmt::Macro(stmt) => {
+                self.outer_attrs(&stmt.attrs);
+                let semicolon = stmt.semi_token.is_some()
+                    || !is_last && mac::requires_semi(&stmt.mac.delimiter);
+                self.mac(&stmt.mac, None, semicolon);
+                self.hardbreak();
+            }
+        }
+    }
+}
+
+pub fn add_semi(expr: &Expr) -> bool {
+    match expr {
+        #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+        Expr::Assign(_) | Expr::Break(_) | Expr::Continue(_) | Expr::Return(_) | Expr::Yield(_) => {
+            true
+        }
+        Expr::Binary(expr) =>
+        {
+            match expr.op {
+                #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+                BinOp::AddAssign(_)
+                | BinOp::SubAssign(_)
+                | BinOp::MulAssign(_)
+                | BinOp::DivAssign(_)
+                | BinOp::RemAssign(_)
+                | BinOp::BitXorAssign(_)
+                | BinOp::BitAndAssign(_)
+                | BinOp::BitOrAssign(_)
+                | BinOp::ShlAssign(_)
+                | BinOp::ShrAssign(_) => true,
+                BinOp::Add(_)
+                | BinOp::Sub(_)
+                | BinOp::Mul(_)
+                | BinOp::Div(_)
+                | BinOp::Rem(_)
+                | BinOp::And(_)
+                | BinOp::Or(_)
+                | BinOp::BitXor(_)
+                | BinOp::BitAnd(_)
+                | BinOp::BitOr(_)
+                | BinOp::Shl(_)
+                | BinOp::Shr(_)
+                | BinOp::Eq(_)
+                | BinOp::Lt(_)
+                | BinOp::Le(_)
+                | BinOp::Ne(_)
+                | BinOp::Ge(_)
+                | BinOp::Gt(_) => false,
+                _ => unimplemented!("unknown BinOp"),
+            }
+        }
+        Expr::Group(group) => add_semi(&group.expr),
+
+        Expr::Array(_)
+        | Expr::Async(_)
+        | Expr::Await(_)
+        | Expr::Block(_)
+        | Expr::Call(_)
+        | Expr::Cast(_)
+        | Expr::Closure(_)
+        | Expr::Const(_)
+        | Expr::Field(_)
+        | Expr::ForLoop(_)
+        | Expr::If(_)
+        | Expr::Index(_)
+        | Expr::Infer(_)
+        | Expr::Let(_)
+        | Expr::Lit(_)
+        | Expr::Loop(_)
+        | Expr::Macro(_)
+        | Expr::Match(_)
+        | Expr::MethodCall(_)
+        | Expr::Paren(_)
+        | Expr::Path(_)
+        | Expr::Range(_)
+        | Expr::RawAddr(_)
+        | Expr::Reference(_)
+        | Expr::Repeat(_)
+        | Expr::Struct(_)
+        | Expr::Try(_)
+        | Expr::TryBlock(_)
+        | Expr::Tuple(_)
+        | Expr::Unary(_)
+        | Expr::Unsafe(_)
+        | Expr::Verbatim(_)
+        | Expr::While(_) => false,
+
+        _ => false,
+    }
+}
+
+pub fn break_after(expr: &Expr) -> bool {
+    if let Expr::Group(group) = expr {
+        if let Expr::Verbatim(verbatim) = group.expr.as_ref() {
+            return !verbatim.is_empty();
+        }
+    }
+    true
+}
+
+fn remove_semi(expr: &Expr) -> bool {
+    match expr {
+        #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+        Expr::ForLoop(_) | Expr::While(_) => true,
+        Expr::Group(group) => remove_semi(&group.expr),
+        Expr::If(expr) => match &expr.else_branch {
+            Some((_else_token, else_branch)) => remove_semi(else_branch),
+            None => true,
+        },
+
+        Expr::Array(_)
+        | Expr::Assign(_)
+        | Expr::Async(_)
+        | Expr::Await(_)
+        | Expr::Binary(_)
+        | Expr::Block(_)
+        | Expr::Break(_)
+        | Expr::Call(_)
+        | Expr::Cast(_)
+        | Expr::Closure(_)
+        | Expr::Continue(_)
+        | Expr::Const(_)
+        | Expr::Field(_)
+        | Expr::Index(_)
+        | Expr::Infer(_)
+        | Expr::Let(_)
+        | Expr::Lit(_)
+        | Expr::Loop(_)
+        | Expr::Macro(_)
+        | Expr::Match(_)
+        | Expr::MethodCall(_)
+        | Expr::Paren(_)
+        | Expr::Path(_)
+        | Expr::Range(_)
+        | Expr::RawAddr(_)
+        | Expr::Reference(_)
+        | Expr::Repeat(_)
+        | Expr::Return(_)
+        | Expr::Struct(_)
+        | Expr::Try(_)
+        | Expr::TryBlock(_)
+        | Expr::Tuple(_)
+        | Expr::Unary(_)
+        | Expr::Unsafe(_)
+        | Expr::Verbatim(_)
+        | Expr::Yield(_) => false,
+
+        _ => false,
+    }
+}

vendor/prettyplease/src/token.rs

@@ -0,0 +1,80 @@
+use crate::algorithm::Printer;
+use proc_macro2::{Delimiter, Ident, Literal, Spacing, TokenStream, TokenTree};
+
+impl Printer {
+    pub fn single_token(&mut self, token: Token, group_contents: fn(&mut Self, TokenStream)) {
+        match token {
+            Token::Group(delimiter, stream) => self.token_group(delimiter, stream, group_contents),
+            Token::Ident(ident) => self.ident(&ident),
+            Token::Punct(ch, _spacing) => self.token_punct(ch),
+            Token::Literal(literal) => self.token_literal(&literal),
+        }
+    }
+
+    fn token_group(
+        &mut self,
+        delimiter: Delimiter,
+        stream: TokenStream,
+        group_contents: fn(&mut Self, TokenStream),
+    ) {
+        self.delimiter_open(delimiter);
+        if !stream.is_empty() {
+            if delimiter == Delimiter::Brace {
+                self.space();
+            }
+            group_contents(self, stream);
+            if delimiter == Delimiter::Brace {
+                self.space();
+            }
+        }
+        self.delimiter_close(delimiter);
+    }
+
+    pub fn ident(&mut self, ident: &Ident) {
+        self.word(ident.to_string());
+    }
+
+    pub fn token_punct(&mut self, ch: char) {
+        self.word(ch.to_string());
+    }
+
+    pub fn token_literal(&mut self, literal: &Literal) {
+        self.word(literal.to_string());
+    }
+
+    pub fn delimiter_open(&mut self, delimiter: Delimiter) {
+        self.word(match delimiter {
+            Delimiter::Parenthesis => "(",
+            Delimiter::Brace => "{",
+            Delimiter::Bracket => "[",
+            Delimiter::None => return,
+        });
+    }
+
+    pub fn delimiter_close(&mut self, delimiter: Delimiter) {
+        self.word(match delimiter {
+            Delimiter::Parenthesis => ")",
+            Delimiter::Brace => "}",
+            Delimiter::Bracket => "]",
+            Delimiter::None => return,
+        });
+    }
+}
+
+pub enum Token {
+    Group(Delimiter, TokenStream),
+    Ident(Ident),
+    Punct(char, Spacing),
+    Literal(Literal),
+}
+
+impl From<TokenTree> for Token {
+    fn from(tt: TokenTree) -> Self {
+        match tt {
+            TokenTree::Group(group) => Token::Group(group.delimiter(), group.stream()),
+            TokenTree::Ident(ident) => Token::Ident(ident),
+            TokenTree::Punct(punct) => Token::Punct(punct.as_char(), punct.spacing()),
+            TokenTree::Literal(literal) => Token::Literal(literal),
+        }
+    }
+}

vendor/prettyplease/src/ty.rs

@@ -0,0 +1,326 @@
+use crate::algorithm::Printer;
+use crate::fixup::FixupContext;
+use crate::iter::IterDelimited;
+use crate::path::PathKind;
+use crate::INDENT;
+use proc_macro2::TokenStream;
+use syn::{
+    Abi, BareFnArg, BareVariadic, ReturnType, Type, TypeArray, TypeBareFn, TypeGroup,
+    TypeImplTrait, TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr, TypeReference,
+    TypeSlice, TypeTraitObject, TypeTuple,
+};
+
+impl Printer {
+    pub fn ty(&mut self, ty: &Type) {
+        match ty {
+            #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
+            Type::Array(ty) => self.type_array(ty),
+            Type::BareFn(ty) => self.type_bare_fn(ty),
+            Type::Group(ty) => self.type_group(ty),
+            Type::ImplTrait(ty) => self.type_impl_trait(ty),
+            Type::Infer(ty) => self.type_infer(ty),
+            Type::Macro(ty) => self.type_macro(ty),
+            Type::Never(ty) => self.type_never(ty),
+            Type::Paren(ty) => self.type_paren(ty),
+            Type::Path(ty) => self.type_path(ty),
+            Type::Ptr(ty) => self.type_ptr(ty),
+            Type::Reference(ty) => self.type_reference(ty),
+            Type::Slice(ty) => self.type_slice(ty),
+            Type::TraitObject(ty) => self.type_trait_object(ty),
+            Type::Tuple(ty) => self.type_tuple(ty),
+            Type::Verbatim(ty) => self.type_verbatim(ty),
+            _ => unimplemented!("unknown Type"),
+        }
+    }
+
+    fn type_array(&mut self, ty: &TypeArray) {
+        self.word("[");
+        self.ty(&ty.elem);
+        self.word("; ");
+        self.expr(&ty.len, FixupContext::NONE);
+        self.word("]");
+    }
+
+    fn type_bare_fn(&mut self, ty: &TypeBareFn) {
+        if let Some(bound_lifetimes) = &ty.lifetimes {
+            self.bound_lifetimes(bound_lifetimes);
+        }
+        if ty.unsafety.is_some() {
+            self.word("unsafe ");
+        }
+        if let Some(abi) = &ty.abi {
+            self.abi(abi);
+        }
+        self.word("fn(");
+        self.cbox(INDENT);
+        self.zerobreak();
+        for bare_fn_arg in ty.inputs.iter().delimited() {
+            self.bare_fn_arg(&bare_fn_arg);
+            self.trailing_comma(bare_fn_arg.is_last && ty.variadic.is_none());
+        }
+        if let Some(variadic) = &ty.variadic {
+            self.bare_variadic(variadic);
+            self.zerobreak();
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word(")");
+        self.return_type(&ty.output);
+    }
+
+    fn type_group(&mut self, ty: &TypeGroup) {
+        self.ty(&ty.elem);
+    }
+
+    fn type_impl_trait(&mut self, ty: &TypeImplTrait) {
+        self.word("impl ");
+        for type_param_bound in ty.bounds.iter().delimited() {
+            if !type_param_bound.is_first {
+                self.word(" + ");
+            }
+            self.type_param_bound(&type_param_bound);
+        }
+    }
+
+    fn type_infer(&mut self, ty: &TypeInfer) {
+        let _ = ty;
+        self.word("_");
+    }
+
+    fn type_macro(&mut self, ty: &TypeMacro) {
+        let semicolon = false;
+        self.mac(&ty.mac, None, semicolon);
+    }
+
+    fn type_never(&mut self, ty: &TypeNever) {
+        let _ = ty;
+        self.word("!");
+    }
+
+    fn type_paren(&mut self, ty: &TypeParen) {
+        self.word("(");
+        self.ty(&ty.elem);
+        self.word(")");
+    }
+
+    fn type_path(&mut self, ty: &TypePath) {
+        self.qpath(&ty.qself, &ty.path, PathKind::Type);
+    }
+
+    fn type_ptr(&mut self, ty: &TypePtr) {
+        self.word("*");
+        if ty.mutability.is_some() {
+            self.word("mut ");
+        } else {
+            self.word("const ");
+        }
+        self.ty(&ty.elem);
+    }
+
+    fn type_reference(&mut self, ty: &TypeReference) {
+        self.word("&");
+        if let Some(lifetime) = &ty.lifetime {
+            self.lifetime(lifetime);
+            self.nbsp();
+        }
+        if ty.mutability.is_some() {
+            self.word("mut ");
+        }
+        self.ty(&ty.elem);
+    }
+
+    fn type_slice(&mut self, ty: &TypeSlice) {
+        self.word("[");
+        self.ty(&ty.elem);
+        self.word("]");
+    }
+
+    fn type_trait_object(&mut self, ty: &TypeTraitObject) {
+        self.word("dyn ");
+        for type_param_bound in ty.bounds.iter().delimited() {
+            if !type_param_bound.is_first {
+                self.word(" + ");
+            }
+            self.type_param_bound(&type_param_bound);
+        }
+    }
+
+    fn type_tuple(&mut self, ty: &TypeTuple) {
+        self.word("(");
+        self.cbox(INDENT);
+        self.zerobreak();
+        for elem in ty.elems.iter().delimited() {
+            self.ty(&elem);
+            if ty.elems.len() == 1 {
+                self.word(",");
+                self.zerobreak();
+            } else {
+                self.trailing_comma(elem.is_last);
+            }
+        }
+        self.offset(-INDENT);
+        self.end();
+        self.word(")");
+    }
+
+    #[cfg(not(feature = "verbatim"))]
+    fn type_verbatim(&mut self, ty: &TokenStream) {
+        unimplemented!("Type::Verbatim `{}`", ty);
+    }
+
+    #[cfg(feature = "verbatim")]
+    fn type_verbatim(&mut self, tokens: &TokenStream) {
+        use syn::parse::{Parse, ParseStream, Result};
+        use syn::punctuated::Punctuated;
+        use syn::{token, FieldsNamed, Token, TypeParamBound};
+
+        enum TypeVerbatim {
+            Ellipsis,
+            AnonStruct(AnonStruct),
+            AnonUnion(AnonUnion),
+            DynStar(DynStar),
+            MutSelf(MutSelf),
+        }
+
+        struct AnonStruct {
+            fields: FieldsNamed,
+        }
+
+        struct AnonUnion {
+            fields: FieldsNamed,
+        }
+
+        struct DynStar {
+            bounds: Punctuated<TypeParamBound, Token![+]>,
+        }
+
+        struct MutSelf {
+            ty: Option<Type>,
+        }
+
+        impl Parse for TypeVerbatim {
+            fn parse(input: ParseStream) -> Result<Self> {
+                let lookahead = input.lookahead1();
+                if lookahead.peek(Token![struct]) {
+                    input.parse::<Token![struct]>()?;
+                    let fields: FieldsNamed = input.parse()?;
+                    Ok(TypeVerbatim::AnonStruct(AnonStruct { fields }))
+                } else if lookahead.peek(Token![union]) && input.peek2(token::Brace) {
+                    input.parse::<Token![union]>()?;
+                    let fields: FieldsNamed = input.parse()?;
+                    Ok(TypeVerbatim::AnonUnion(AnonUnion { fields }))
+                } else if lookahead.peek(Token![dyn]) {
+                    input.parse::<Token![dyn]>()?;
+                    input.parse::<Token![*]>()?;
+                    let bounds = input.parse_terminated(TypeParamBound::parse, Token![+])?;
+                    Ok(TypeVerbatim::DynStar(DynStar { bounds }))
+                } else if lookahead.peek(Token![mut]) {
+                    input.parse::<Token![mut]>()?;
+                    input.parse::<Token![self]>()?;
+                    let ty = if input.is_empty() {
+                        None
+                    } else {
+                        input.parse::<Token![:]>()?;
+                        let ty: Type = input.parse()?;
+                        Some(ty)
+                    };
+                    Ok(TypeVerbatim::MutSelf(MutSelf { ty }))
+                } else if lookahead.peek(Token![...]) {
+                    input.parse::<Token![...]>()?;
+                    Ok(TypeVerbatim::Ellipsis)
+                } else {
+                    Err(lookahead.error())
+                }
+            }
+        }
+
+        let ty: TypeVerbatim = match syn::parse2(tokens.clone()) {
+            Ok(ty) => ty,
+            Err(_) => unimplemented!("Type::Verbatim `{}`", tokens),
+        };
+
+        match ty {
+            TypeVerbatim::Ellipsis => {
+                self.word("...");
+            }
+            TypeVerbatim::AnonStruct(ty) => {
+                self.cbox(INDENT);
+                self.word("struct {");
+                self.hardbreak_if_nonempty();
+                for field in &ty.fields.named {
+                    self.field(field);
+                    self.word(",");
+                    self.hardbreak();
+                }
+                self.offset(-INDENT);
+                self.end();
+                self.word("}");
+            }
+            TypeVerbatim::AnonUnion(ty) => {
+                self.cbox(INDENT);
+                self.word("union {");
+                self.hardbreak_if_nonempty();
+                for field in &ty.fields.named {
+                    self.field(field);
+                    self.word(",");
+                    self.hardbreak();
+                }
+                self.offset(-INDENT);
+                self.end();
+                self.word("}");
+            }
+            TypeVerbatim::DynStar(ty) => {
+                self.word("dyn* ");
+                for type_param_bound in ty.bounds.iter().delimited() {
+                    if !type_param_bound.is_first {
+                        self.word(" + ");
+                    }
+                    self.type_param_bound(&type_param_bound);
+                }
+            }
+            TypeVerbatim::MutSelf(bare_fn_arg) => {
+                self.word("mut self");
+                if let Some(ty) = &bare_fn_arg.ty {
+                    self.word(": ");
+                    self.ty(ty);
+                }
+            }
+        }
+    }
+
+    pub fn return_type(&mut self, ty: &ReturnType) {
+        match ty {
+            ReturnType::Default => {}
+            ReturnType::Type(_arrow, ty) => {
+                self.word(" -> ");
+                self.ty(ty);
+            }
+        }
+    }
+
+    fn bare_fn_arg(&mut self, bare_fn_arg: &BareFnArg) {
+        self.outer_attrs(&bare_fn_arg.attrs);
+        if let Some((name, _colon)) = &bare_fn_arg.name {
+            self.ident(name);
+            self.word(": ");
+        }
+        self.ty(&bare_fn_arg.ty);
+    }
+
+    fn bare_variadic(&mut self, variadic: &BareVariadic) {
+        self.outer_attrs(&variadic.attrs);
+        if let Some((name, _colon)) = &variadic.name {
+            self.ident(name);
+            self.word(": ");
+        }
+        self.word("...");
+    }
+
+    pub fn abi(&mut self, abi: &Abi) {
+        self.word("extern ");
+        if let Some(name) = &abi.name {
+            self.lit_str(name);
+            self.nbsp();
+        }
+    }
+}