Vendor dependencies for 0.3.0 release

vendor/wasm-bindgen-backend/src/ast.rs

@@ -0,0 +1,607 @@
+//! A representation of the Abstract Syntax Tree of a Rust program,
+//! with all the added metadata necessary to generate Wasm bindings
+//! for it.
+
+use crate::{util::ShortHash, Diagnostic};
+use proc_macro2::{Ident, Span};
+use std::hash::{Hash, Hasher};
+use syn::Path;
+use wasm_bindgen_shared as shared;
+
+/// An abstract syntax tree representing a rust program. Contains
+/// extra information for joining up this rust code with javascript.
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct Program {
+    /// rust -> js interfaces
+    pub exports: Vec<Export>,
+    /// js -> rust interfaces
+    pub imports: Vec<Import>,
+    /// linked-to modules
+    pub linked_modules: Vec<ImportModule>,
+    /// rust enums
+    pub enums: Vec<Enum>,
+    /// rust structs
+    pub structs: Vec<Struct>,
+    /// custom typescript sections to be included in the definition file
+    pub typescript_custom_sections: Vec<LitOrExpr>,
+    /// Inline JS snippets
+    pub inline_js: Vec<String>,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+    /// Path to js_sys
+    pub js_sys: Path,
+    /// Path to wasm_bindgen_futures
+    pub wasm_bindgen_futures: Path,
+}
+
+impl Default for Program {
+    fn default() -> Self {
+        Self {
+            exports: Default::default(),
+            imports: Default::default(),
+            linked_modules: Default::default(),
+            enums: Default::default(),
+            structs: Default::default(),
+            typescript_custom_sections: Default::default(),
+            inline_js: Default::default(),
+            wasm_bindgen: syn::parse_quote! { wasm_bindgen },
+            js_sys: syn::parse_quote! { js_sys },
+            wasm_bindgen_futures: syn::parse_quote! { wasm_bindgen_futures },
+        }
+    }
+}
+
+impl Program {
+    /// Returns true if the Program is empty
+    pub fn is_empty(&self) -> bool {
+        self.exports.is_empty()
+            && self.imports.is_empty()
+            && self.enums.is_empty()
+            && self.structs.is_empty()
+            && self.typescript_custom_sections.is_empty()
+            && self.inline_js.is_empty()
+    }
+
+    /// Name of the link function for a specific linked module
+    pub fn link_function_name(&self, idx: usize) -> String {
+        let hash = match &self.linked_modules[idx] {
+            ImportModule::Inline(idx, _) => ShortHash((1, &self.inline_js[*idx])).to_string(),
+            other => ShortHash((0, other)).to_string(),
+        };
+        format!("__wbindgen_link_{}", hash)
+    }
+}
+
+/// An abstract syntax tree representing a link to a module in Rust.
+/// In contrast to Program, LinkToModule must expand to an expression.
+/// linked_modules of the inner Program must contain exactly one element
+/// whose link is produced by the expression.
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct LinkToModule(pub Program);
+
+/// A rust to js interface. Allows interaction with rust objects/functions
+/// from javascript.
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct Export {
+    /// Comments extracted from the rust source.
+    pub comments: Vec<String>,
+    /// The rust function
+    pub function: Function,
+    /// The class name in JS this is attached to
+    pub js_class: Option<String>,
+    /// The kind (static, named, regular)
+    pub method_kind: MethodKind,
+    /// The type of `self` (either `self`, `&self`, or `&mut self`)
+    pub method_self: Option<MethodSelf>,
+    /// The struct name, in Rust, this is attached to
+    pub rust_class: Option<Ident>,
+    /// The name of the rust function/method on the rust side.
+    pub rust_name: Ident,
+    /// Whether or not this function should be flagged as the Wasm start
+    /// function.
+    pub start: bool,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+    /// Path to wasm_bindgen_futures
+    pub wasm_bindgen_futures: Path,
+}
+
+/// The 3 types variations of `self`.
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Copy, Clone)]
+pub enum MethodSelf {
+    /// `self`
+    ByValue,
+    /// `&mut self`
+    RefMutable,
+    /// `&self`
+    RefShared,
+}
+
+/// Things imported from a JS module (in an `extern` block)
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct Import {
+    /// The type of module being imported from, if any
+    pub module: Option<ImportModule>,
+    /// The namespace to access the item through, if any
+    pub js_namespace: Option<Vec<String>>,
+    /// The type of item being imported
+    pub kind: ImportKind,
+}
+
+/// The possible types of module to import from
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub enum ImportModule {
+    /// Import from the named module, with relative paths interpreted
+    Named(String, Span),
+    /// Import from the named module, without interpreting paths
+    RawNamed(String, Span),
+    /// Import from an inline JS snippet
+    Inline(usize, Span),
+}
+
+impl Hash for ImportModule {
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        match self {
+            ImportModule::Named(name, _) => (1u8, name).hash(h),
+            ImportModule::Inline(idx, _) => (2u8, idx).hash(h),
+            ImportModule::RawNamed(name, _) => (3u8, name).hash(h),
+        }
+    }
+}
+
+/// The type of item being imported
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub enum ImportKind {
+    /// Importing a function
+    Function(ImportFunction),
+    /// Importing a static value
+    Static(ImportStatic),
+    /// Importing a static string
+    String(ImportString),
+    /// Importing a type/class
+    Type(ImportType),
+    /// Importing a JS enum
+    Enum(StringEnum),
+}
+
+/// A function being imported from JS
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct ImportFunction {
+    /// The full signature of the function
+    pub function: Function,
+    /// The name rust code will use
+    pub rust_name: Ident,
+    /// The type being returned
+    pub js_ret: Option<syn::Type>,
+    /// Whether to catch JS exceptions
+    pub catch: bool,
+    /// Whether the function is variadic on the JS side
+    pub variadic: bool,
+    /// Whether the function should use structural type checking
+    pub structural: bool,
+    /// Causes the Builder (See cli-support::js::binding::Builder) to error out if
+    /// it finds itself generating code for a function with this signature
+    pub assert_no_shim: bool,
+    /// The kind of function being imported
+    pub kind: ImportFunctionKind,
+    /// The shim name to use in the generated code. The 'shim' is a function that appears in
+    /// the generated JS as a wrapper around the actual function to import, performing any
+    /// necessary conversions (EG adding a try/catch to change a thrown error into a Result)
+    pub shim: Ident,
+    /// The doc comment on this import, if one is provided
+    pub doc_comment: String,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+    /// Path to wasm_bindgen_futures
+    pub wasm_bindgen_futures: Path,
+}
+
+/// The type of a function being imported
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub enum ImportFunctionKind {
+    /// A class method
+    Method {
+        /// The name of the class for this method, in JS
+        class: String,
+        /// The type of the class for this method, in Rust
+        ty: syn::Type,
+        /// The kind of method this is
+        kind: MethodKind,
+    },
+    /// A standard function
+    Normal,
+}
+
+/// The type of a method
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub enum MethodKind {
+    /// A class constructor
+    Constructor,
+    /// Any other kind of method
+    Operation(Operation),
+}
+
+/// The operation performed by a class method
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct Operation {
+    /// Whether this method is static
+    pub is_static: bool,
+    /// The internal kind of this Operation
+    pub kind: OperationKind,
+}
+
+/// The kind of operation performed by a method
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub enum OperationKind {
+    /// A standard method, nothing special
+    Regular,
+    /// A method for getting the value of the provided Ident or String
+    Getter(Option<String>),
+    /// A method for setting the value of the provided Ident or String
+    Setter(Option<String>),
+    /// A dynamically intercepted getter
+    IndexingGetter,
+    /// A dynamically intercepted setter
+    IndexingSetter,
+    /// A dynamically intercepted deleter
+    IndexingDeleter,
+}
+
+/// The type of a static being imported
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct ImportStatic {
+    /// The visibility of this static in Rust
+    pub vis: syn::Visibility,
+    /// The type of static being imported
+    pub ty: syn::Type,
+    /// The name of the shim function used to access this static
+    pub shim: Ident,
+    /// The name of this static on the Rust side
+    pub rust_name: Ident,
+    /// The name of this static on the JS side
+    pub js_name: String,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+    /// Version of `thread_local`, if any.
+    pub thread_local: Option<ThreadLocal>,
+}
+
+/// Which version of the `thread_local` attribute is enabled.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum ThreadLocal {
+    /// V1.
+    V1,
+    /// V2.
+    V2,
+}
+
+/// The type of a static string being imported
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct ImportString {
+    /// The visibility of this static string in Rust
+    pub vis: syn::Visibility,
+    /// The type specified by the user, which we only use to show an error if the wrong type is used.
+    pub ty: syn::Type,
+    /// The name of the shim function used to access this static
+    pub shim: Ident,
+    /// The name of this static on the Rust side
+    pub rust_name: Ident,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+    /// Path to js_sys
+    pub js_sys: Path,
+    /// The string to export.
+    pub string: String,
+    /// Version of `thread_local`.
+    pub thread_local: ThreadLocal,
+}
+
+/// The metadata for a type being imported
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct ImportType {
+    /// The visibility of this type in Rust
+    pub vis: syn::Visibility,
+    /// The name of this type on the Rust side
+    pub rust_name: Ident,
+    /// The name of this type on the JS side
+    pub js_name: String,
+    /// The custom attributes to apply to this type
+    pub attrs: Vec<syn::Attribute>,
+    /// The TS definition to generate for this type
+    pub typescript_type: Option<String>,
+    /// The doc comment applied to this type, if one exists
+    pub doc_comment: Option<String>,
+    /// The name of the shim to check instanceof for this type
+    pub instanceof_shim: String,
+    /// The name of the remote function to use for the generated is_type_of
+    pub is_type_of: Option<syn::Expr>,
+    /// The list of classes this extends, if any
+    pub extends: Vec<syn::Path>,
+    /// A custom prefix to add and attempt to fall back to, if the type isn't found
+    pub vendor_prefixes: Vec<Ident>,
+    /// If present, don't generate a `Deref` impl
+    pub no_deref: bool,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+}
+
+/// The metadata for a String Enum
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct StringEnum {
+    /// The Rust enum's visibility
+    pub vis: syn::Visibility,
+    /// The Rust enum's identifiers
+    pub name: Ident,
+    /// The name of this string enum in JS/TS code
+    pub js_name: String,
+    /// The Rust identifiers for the variants
+    pub variants: Vec<Ident>,
+    /// The JS string values of the variants
+    pub variant_values: Vec<String>,
+    /// The doc comments on this enum, if any
+    pub comments: Vec<String>,
+    /// Attributes to apply to the Rust enum
+    pub rust_attrs: Vec<syn::Attribute>,
+    /// Whether to generate a typescript definition for this enum
+    pub generate_typescript: bool,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+}
+
+/// Information about a function being imported or exported
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct Function {
+    /// The name of the function
+    pub name: String,
+    /// The span of the function's name in Rust code
+    pub name_span: Span,
+    /// Whether the function has a js_name attribute
+    pub renamed_via_js_name: bool,
+    /// The arguments to the function
+    pub arguments: Vec<FunctionArgumentData>,
+    /// The data of return type of the function
+    pub ret: Option<FunctionReturnData>,
+    /// Any custom attributes being applied to the function
+    pub rust_attrs: Vec<syn::Attribute>,
+    /// The visibility of this function in Rust
+    pub rust_vis: syn::Visibility,
+    /// Whether this is an `unsafe` function
+    pub r#unsafe: bool,
+    /// Whether this is an `async` function
+    pub r#async: bool,
+    /// Whether to generate a typescript definition for this function
+    pub generate_typescript: bool,
+    /// Whether to generate jsdoc documentation for this function
+    pub generate_jsdoc: bool,
+    /// Whether this is a function with a variadict parameter
+    pub variadic: bool,
+}
+
+/// Information about a function's return
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct FunctionReturnData {
+    /// Specifies the type of the function's return
+    pub r#type: syn::Type,
+    /// Specifies the JS return type override
+    pub js_type: Option<String>,
+    /// Specifies the return description
+    pub desc: Option<String>,
+}
+
+/// Information about a function's argument
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct FunctionArgumentData {
+    /// Specifies the type of the function's argument
+    pub pat_type: syn::PatType,
+    /// Specifies the JS argument name override
+    pub js_name: Option<String>,
+    /// Specifies the JS function argument type override
+    pub js_type: Option<String>,
+    /// Specifies the argument description
+    pub desc: Option<String>,
+}
+
+/// Information about a Struct being exported
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct Struct {
+    /// The name of the struct in Rust code
+    pub rust_name: Ident,
+    /// The name of the struct in JS code
+    pub js_name: String,
+    /// All the fields of this struct to export
+    pub fields: Vec<StructField>,
+    /// The doc comments on this struct, if provided
+    pub comments: Vec<String>,
+    /// Whether this struct is inspectable (provides toJSON/toString properties to JS)
+    pub is_inspectable: bool,
+    /// Whether to generate a typescript definition for this struct
+    pub generate_typescript: bool,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+}
+
+/// The field of a struct
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub struct StructField {
+    /// The name of the field in Rust code
+    pub rust_name: syn::Member,
+    /// The name of the field in JS code
+    pub js_name: String,
+    /// The name of the struct this field is part of
+    pub struct_name: Ident,
+    /// Whether this value is read-only to JS
+    pub readonly: bool,
+    /// The type of this field
+    pub ty: syn::Type,
+    /// The name of the getter shim for this field
+    pub getter: Ident,
+    /// The name of the setter shim for this field
+    pub setter: Ident,
+    /// The doc comments on this field, if any
+    pub comments: Vec<String>,
+    /// Whether to generate a typescript definition for this field
+    pub generate_typescript: bool,
+    /// Whether to generate jsdoc documentation for this field
+    pub generate_jsdoc: bool,
+    /// The span of the `#[wasm_bindgen(getter_with_clone)]` attribute applied
+    /// to this field, if any.
+    ///
+    /// If this is `Some`, the auto-generated getter for this field must clone
+    /// the field instead of copying it.
+    pub getter_with_clone: Option<Span>,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+}
+
+/// The metadata for an Enum
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct Enum {
+    /// The name of this enum in Rust code
+    pub rust_name: Ident,
+    /// The name of this enum in JS code
+    pub js_name: String,
+    /// Whether the variant values and hole are signed, meaning that they
+    /// represent the bits of a `i32` value.
+    pub signed: bool,
+    /// The variants provided by this enum
+    pub variants: Vec<Variant>,
+    /// The doc comments on this enum, if any
+    pub comments: Vec<String>,
+    /// The value to use for a `none` variant of the enum
+    pub hole: u32,
+    /// Whether to generate a typescript definition for this enum
+    pub generate_typescript: bool,
+    /// Path to wasm_bindgen
+    pub wasm_bindgen: Path,
+}
+
+/// The variant of an enum
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+#[derive(Clone)]
+pub struct Variant {
+    /// The name of this variant
+    pub name: Ident,
+    /// The backing value of this variant
+    pub value: u32,
+    /// The doc comments on this variant, if any
+    pub comments: Vec<String>,
+}
+
+/// Unused, the type of an argument to / return from a function
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum TypeKind {
+    /// A by-reference arg, EG `&T`
+    ByRef,
+    /// A by-mutable-reference arg, EG `&mut T`
+    ByMutRef,
+    /// A by-value arg, EG `T`
+    ByValue,
+}
+
+/// Unused, the location of a type for a function argument (import/export, argument/ret)
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum TypeLocation {
+    /// An imported argument (JS side type)
+    ImportArgument,
+    /// An imported return
+    ImportRet,
+    /// An exported argument (Rust side type)
+    ExportArgument,
+    /// An exported return
+    ExportRet,
+}
+
+/// An enum representing either a literal value (`Lit`) or an expression (`syn::Expr`).
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+#[derive(Clone)]
+pub enum LitOrExpr {
+    /// Represents an expression that needs to be evaluated before it can be encoded
+    Expr(syn::Expr),
+    /// Represents a literal string that can be directly encoded.
+    Lit(String),
+}
+
+impl Export {
+    /// Mangles a rust -> javascript export, so that the created Ident will be unique over function
+    /// name and class name, if the function belongs to a javascript class.
+    pub(crate) fn rust_symbol(&self) -> Ident {
+        let mut generated_name = String::from("__wasm_bindgen_generated");
+        if let Some(class) = &self.js_class {
+            generated_name.push('_');
+            generated_name.push_str(class);
+        }
+        generated_name.push('_');
+        generated_name.push_str(&self.function.name.to_string());
+        Ident::new(&generated_name, Span::call_site())
+    }
+
+    /// This is the name of the shim function that gets exported and takes the raw
+    /// ABI form of its arguments and converts them back into their normal,
+    /// "high level" form before calling the actual function.
+    pub(crate) fn export_name(&self) -> String {
+        let fn_name = self.function.name.to_string();
+        match &self.js_class {
+            Some(class) => shared::struct_function_export_name(class, &fn_name),
+            None => shared::free_function_export_name(&fn_name),
+        }
+    }
+}
+
+impl ImportKind {
+    /// Whether this type can be inside an `impl` block.
+    pub fn fits_on_impl(&self) -> bool {
+        match *self {
+            ImportKind::Function(_) => true,
+            ImportKind::Static(_) => false,
+            ImportKind::String(_) => false,
+            ImportKind::Type(_) => false,
+            ImportKind::Enum(_) => false,
+        }
+    }
+}
+
+impl Function {
+    /// If the rust object has a `fn xxx(&self) -> MyType` method, get the name for a getter in
+    /// javascript (in this case `xxx`, so you can write `val = obj.xxx`)
+    pub fn infer_getter_property(&self) -> &str {
+        &self.name
+    }
+
+    /// If the rust object has a `fn set_xxx(&mut self, MyType)` style method, get the name
+    /// for a setter in javascript (in this case `xxx`, so you can write `obj.xxx = val`)
+    pub fn infer_setter_property(&self) -> Result<String, Diagnostic> {
+        let name = self.name.to_string();
+
+        // Otherwise we infer names based on the Rust function name.
+        if !name.starts_with("set_") {
+            bail_span!(
+                syn::token::Pub(self.name_span),
+                "setters must start with `set_`, found: {}",
+                name,
+            );
+        }
+        Ok(name[4..].to_string())
+    }
+}

vendor/wasm-bindgen-backend/src/encode.rs

@@ -0,0 +1,626 @@
+use crate::util::ShortHash;
+use proc_macro2::{Ident, Span};
+use std::cell::{Cell, RefCell};
+use std::collections::HashMap;
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+use syn::ext::IdentExt;
+
+use crate::ast;
+use crate::Diagnostic;
+
+#[derive(Clone)]
+pub enum EncodeChunk {
+    EncodedBuf(Vec<u8>),
+    StrExpr(syn::Expr),
+    // TODO: support more expr type;
+}
+
+pub struct EncodeResult {
+    pub custom_section: Vec<EncodeChunk>,
+    pub included_files: Vec<PathBuf>,
+}
+
+pub fn encode(program: &ast::Program) -> Result<EncodeResult, Diagnostic> {
+    let mut e = Encoder::new();
+    let i = Interner::new();
+    shared_program(program, &i)?.encode(&mut e);
+    let custom_section = e.finish();
+    let included_files = i
+        .files
+        .borrow()
+        .values()
+        .map(|p| &p.path)
+        .cloned()
+        .collect();
+    Ok(EncodeResult {
+        custom_section,
+        included_files,
+    })
+}
+
+struct Interner {
+    bump: bumpalo::Bump,
+    files: RefCell<HashMap<String, LocalFile>>,
+    root: PathBuf,
+    crate_name: String,
+    has_package_json: Cell<bool>,
+}
+
+struct LocalFile {
+    path: PathBuf,
+    definition: Span,
+    new_identifier: String,
+    linked_module: bool,
+}
+
+impl Interner {
+    fn new() -> Interner {
+        let root = env::var_os("CARGO_MANIFEST_DIR")
+            .expect("should have CARGO_MANIFEST_DIR env var")
+            .into();
+        let crate_name = env::var("CARGO_PKG_NAME").expect("should have CARGO_PKG_NAME env var");
+        Interner {
+            bump: bumpalo::Bump::new(),
+            files: RefCell::new(HashMap::new()),
+            root,
+            crate_name,
+            has_package_json: Cell::new(false),
+        }
+    }
+
+    fn intern(&self, s: &Ident) -> &str {
+        self.intern_str(&s.to_string())
+    }
+
+    fn intern_str(&self, s: &str) -> &str {
+        // NB: eventually this could be used to intern `s` to only allocate one
+        // copy, but for now let's just "transmute" `s` to have the same
+        // lifetime as this struct itself (which is our main goal here)
+        self.bump.alloc_str(s)
+    }
+
+    /// Given an import to a local module `id` this generates a unique module id
+    /// to assign to the contents of `id`.
+    ///
+    /// Note that repeated invocations of this function will be memoized, so the
+    /// same `id` will always return the same resulting unique `id`.
+    fn resolve_import_module(
+        &self,
+        id: &str,
+        span: Span,
+        linked_module: bool,
+    ) -> Result<ImportModule<'_>, Diagnostic> {
+        let mut files = self.files.borrow_mut();
+        if let Some(file) = files.get(id) {
+            return Ok(ImportModule::Named(self.intern_str(&file.new_identifier)));
+        }
+        self.check_for_package_json();
+        let path = if let Some(id) = id.strip_prefix('/') {
+            self.root.join(id)
+        } else if id.starts_with("./") || id.starts_with("../") {
+            let msg = "relative module paths aren't supported yet";
+            return Err(Diagnostic::span_error(span, msg));
+        } else {
+            return Ok(ImportModule::RawNamed(self.intern_str(id)));
+        };
+
+        // Generate a unique ID which is somewhat readable as well, so mix in
+        // the crate name, hash to make it unique, and then the original path.
+        let new_identifier = format!("{}{}", self.unique_crate_identifier(), id);
+        let file = LocalFile {
+            path,
+            definition: span,
+            new_identifier,
+            linked_module,
+        };
+        files.insert(id.to_string(), file);
+        drop(files);
+        self.resolve_import_module(id, span, linked_module)
+    }
+
+    fn unique_crate_identifier(&self) -> String {
+        format!("{}-{}", self.crate_name, ShortHash(0))
+    }
+
+    fn check_for_package_json(&self) {
+        if self.has_package_json.get() {
+            return;
+        }
+        let path = self.root.join("package.json");
+        if path.exists() {
+            self.has_package_json.set(true);
+        }
+    }
+}
+
+fn shared_program<'a>(
+    prog: &'a ast::Program,
+    intern: &'a Interner,
+) -> Result<Program<'a>, Diagnostic> {
+    Ok(Program {
+        exports: prog
+            .exports
+            .iter()
+            .map(|a| shared_export(a, intern))
+            .collect::<Result<Vec<_>, _>>()?,
+        structs: prog
+            .structs
+            .iter()
+            .map(|a| shared_struct(a, intern))
+            .collect(),
+        enums: prog.enums.iter().map(|a| shared_enum(a, intern)).collect(),
+        imports: prog
+            .imports
+            .iter()
+            .map(|a| shared_import(a, intern))
+            .collect::<Result<Vec<_>, _>>()?,
+        typescript_custom_sections: prog
+            .typescript_custom_sections
+            .iter()
+            .map(|x| shared_lit_or_expr(x, intern))
+            .collect(),
+        linked_modules: prog
+            .linked_modules
+            .iter()
+            .enumerate()
+            .map(|(i, a)| shared_linked_module(&prog.link_function_name(i), a, intern))
+            .collect::<Result<Vec<_>, _>>()?,
+        local_modules: intern
+            .files
+            .borrow()
+            .values()
+            .map(|file| {
+                fs::read_to_string(&file.path)
+                    .map(|s| LocalModule {
+                        identifier: intern.intern_str(&file.new_identifier),
+                        contents: intern.intern_str(&s),
+                        linked_module: file.linked_module,
+                    })
+                    .map_err(|e| {
+                        let msg = format!("failed to read file `{}`: {}", file.path.display(), e);
+                        Diagnostic::span_error(file.definition, msg)
+                    })
+            })
+            .collect::<Result<Vec<_>, _>>()?,
+        inline_js: prog
+            .inline_js
+            .iter()
+            .map(|js| intern.intern_str(js))
+            .collect(),
+        unique_crate_identifier: intern.intern_str(&intern.unique_crate_identifier()),
+        package_json: if intern.has_package_json.get() {
+            Some(intern.intern_str(intern.root.join("package.json").to_str().unwrap()))
+        } else {
+            None
+        },
+    })
+}
+
+fn shared_export<'a>(
+    export: &'a ast::Export,
+    intern: &'a Interner,
+) -> Result<Export<'a>, Diagnostic> {
+    let consumed = matches!(export.method_self, Some(ast::MethodSelf::ByValue));
+    let method_kind = from_ast_method_kind(&export.function, intern, &export.method_kind)?;
+    Ok(Export {
+        class: export.js_class.as_deref(),
+        comments: export.comments.iter().map(|s| &**s).collect(),
+        consumed,
+        function: shared_function(&export.function, intern),
+        method_kind,
+        start: export.start,
+    })
+}
+
+fn shared_function<'a>(func: &'a ast::Function, _intern: &'a Interner) -> Function<'a> {
+    let args =
+        func.arguments
+            .iter()
+            .enumerate()
+            .map(|(idx, arg)| FunctionArgumentData {
+                // use argument's "js_name" if it was provided via attributes
+                // if not use the original Rust argument ident
+                name: arg.js_name.clone().unwrap_or(
+                    if let syn::Pat::Ident(x) = &*arg.pat_type.pat {
+                        x.ident.unraw().to_string()
+                    } else {
+                        format!("arg{}", idx)
+                    },
+                ),
+                ty_override: arg.js_type.as_deref(),
+                desc: arg.desc.as_deref(),
+            })
+            .collect::<Vec<_>>();
+
+    Function {
+        args,
+        asyncness: func.r#async,
+        name: &func.name,
+        generate_typescript: func.generate_typescript,
+        generate_jsdoc: func.generate_jsdoc,
+        variadic: func.variadic,
+        ret_ty_override: func.ret.as_ref().and_then(|v| v.js_type.as_deref()),
+        ret_desc: func.ret.as_ref().and_then(|v| v.desc.as_deref()),
+    }
+}
+
+fn shared_enum<'a>(e: &'a ast::Enum, intern: &'a Interner) -> Enum<'a> {
+    Enum {
+        name: &e.js_name,
+        signed: e.signed,
+        variants: e
+            .variants
+            .iter()
+            .map(|v| shared_variant(v, intern))
+            .collect(),
+        comments: e.comments.iter().map(|s| &**s).collect(),
+        generate_typescript: e.generate_typescript,
+    }
+}
+
+fn shared_variant<'a>(v: &'a ast::Variant, intern: &'a Interner) -> EnumVariant<'a> {
+    EnumVariant {
+        name: intern.intern(&v.name),
+        value: v.value,
+        comments: v.comments.iter().map(|s| &**s).collect(),
+    }
+}
+
+fn shared_import<'a>(i: &'a ast::Import, intern: &'a Interner) -> Result<Import<'a>, Diagnostic> {
+    Ok(Import {
+        module: i
+            .module
+            .as_ref()
+            .map(|m| shared_module(m, intern, false))
+            .transpose()?,
+        js_namespace: i.js_namespace.clone(),
+        kind: shared_import_kind(&i.kind, intern)?,
+    })
+}
+
+fn shared_lit_or_expr<'a>(i: &'a ast::LitOrExpr, _intern: &'a Interner) -> LitOrExpr<'a> {
+    match i {
+        ast::LitOrExpr::Lit(lit) => LitOrExpr::Lit(lit),
+        ast::LitOrExpr::Expr(expr) => LitOrExpr::Expr(expr),
+    }
+}
+
+fn shared_linked_module<'a>(
+    name: &str,
+    i: &'a ast::ImportModule,
+    intern: &'a Interner,
+) -> Result<LinkedModule<'a>, Diagnostic> {
+    Ok(LinkedModule {
+        module: shared_module(i, intern, true)?,
+        link_function_name: intern.intern_str(name),
+    })
+}
+
+fn shared_module<'a>(
+    m: &'a ast::ImportModule,
+    intern: &'a Interner,
+    linked_module: bool,
+) -> Result<ImportModule<'a>, Diagnostic> {
+    Ok(match m {
+        ast::ImportModule::Named(m, span) => {
+            intern.resolve_import_module(m, *span, linked_module)?
+        }
+        ast::ImportModule::RawNamed(m, _span) => ImportModule::RawNamed(intern.intern_str(m)),
+        ast::ImportModule::Inline(idx, _) => ImportModule::Inline(*idx as u32),
+    })
+}
+
+fn shared_import_kind<'a>(
+    i: &'a ast::ImportKind,
+    intern: &'a Interner,
+) -> Result<ImportKind<'a>, Diagnostic> {
+    Ok(match i {
+        ast::ImportKind::Function(f) => ImportKind::Function(shared_import_function(f, intern)?),
+        ast::ImportKind::Static(f) => ImportKind::Static(shared_import_static(f, intern)),
+        ast::ImportKind::String(f) => ImportKind::String(shared_import_string(f, intern)),
+        ast::ImportKind::Type(f) => ImportKind::Type(shared_import_type(f, intern)),
+        ast::ImportKind::Enum(f) => ImportKind::Enum(shared_import_enum(f, intern)),
+    })
+}
+
+fn shared_import_function<'a>(
+    i: &'a ast::ImportFunction,
+    intern: &'a Interner,
+) -> Result<ImportFunction<'a>, Diagnostic> {
+    let method = match &i.kind {
+        ast::ImportFunctionKind::Method { class, kind, .. } => {
+            let kind = from_ast_method_kind(&i.function, intern, kind)?;
+            Some(MethodData { class, kind })
+        }
+        ast::ImportFunctionKind::Normal => None,
+    };
+
+    Ok(ImportFunction {
+        shim: intern.intern(&i.shim),
+        catch: i.catch,
+        method,
+        assert_no_shim: i.assert_no_shim,
+        structural: i.structural,
+        function: shared_function(&i.function, intern),
+        variadic: i.variadic,
+    })
+}
+
+fn shared_import_static<'a>(i: &'a ast::ImportStatic, intern: &'a Interner) -> ImportStatic<'a> {
+    ImportStatic {
+        name: &i.js_name,
+        shim: intern.intern(&i.shim),
+    }
+}
+
+fn shared_import_string<'a>(i: &'a ast::ImportString, intern: &'a Interner) -> ImportString<'a> {
+    ImportString {
+        shim: intern.intern(&i.shim),
+        string: &i.string,
+    }
+}
+
+fn shared_import_type<'a>(i: &'a ast::ImportType, intern: &'a Interner) -> ImportType<'a> {
+    ImportType {
+        name: &i.js_name,
+        instanceof_shim: &i.instanceof_shim,
+        vendor_prefixes: i.vendor_prefixes.iter().map(|x| intern.intern(x)).collect(),
+    }
+}
+
+fn shared_import_enum<'a>(i: &'a ast::StringEnum, _intern: &'a Interner) -> StringEnum<'a> {
+    StringEnum {
+        name: &i.js_name,
+        generate_typescript: i.generate_typescript,
+        variant_values: i.variant_values.iter().map(|x| &**x).collect(),
+        comments: i.comments.iter().map(|s| &**s).collect(),
+    }
+}
+
+fn shared_struct<'a>(s: &'a ast::Struct, intern: &'a Interner) -> Struct<'a> {
+    Struct {
+        name: &s.js_name,
+        fields: s
+            .fields
+            .iter()
+            .map(|s| shared_struct_field(s, intern))
+            .collect(),
+        comments: s.comments.iter().map(|s| &**s).collect(),
+        is_inspectable: s.is_inspectable,
+        generate_typescript: s.generate_typescript,
+    }
+}
+
+fn shared_struct_field<'a>(s: &'a ast::StructField, _intern: &'a Interner) -> StructField<'a> {
+    StructField {
+        name: &s.js_name,
+        readonly: s.readonly,
+        comments: s.comments.iter().map(|s| &**s).collect(),
+        generate_typescript: s.generate_typescript,
+        generate_jsdoc: s.generate_jsdoc,
+    }
+}
+
+trait Encode {
+    fn encode(&self, dst: &mut Encoder);
+}
+
+struct Encoder {
+    dst: Vec<EncodeChunk>,
+}
+
+enum LitOrExpr<'a> {
+    Expr(&'a syn::Expr),
+    Lit(&'a str),
+}
+
+impl Encode for LitOrExpr<'_> {
+    fn encode(&self, dst: &mut Encoder) {
+        match self {
+            LitOrExpr::Expr(expr) => {
+                dst.dst.push(EncodeChunk::StrExpr((*expr).clone()));
+            }
+            LitOrExpr::Lit(s) => s.encode(dst),
+        }
+    }
+}
+
+impl Encoder {
+    fn new() -> Encoder {
+        Encoder { dst: vec![] }
+    }
+
+    fn finish(self) -> Vec<EncodeChunk> {
+        self.dst
+    }
+
+    fn byte(&mut self, byte: u8) {
+        if let Some(EncodeChunk::EncodedBuf(buf)) = self.dst.last_mut() {
+            buf.push(byte);
+        } else {
+            self.dst.push(EncodeChunk::EncodedBuf(vec![byte]));
+        }
+    }
+
+    fn extend_from_slice(&mut self, slice: &[u8]) {
+        if let Some(EncodeChunk::EncodedBuf(buf)) = self.dst.last_mut() {
+            buf.extend_from_slice(slice);
+        } else {
+            self.dst.push(EncodeChunk::EncodedBuf(slice.to_owned()));
+        }
+    }
+}
+
+impl Encode for bool {
+    fn encode(&self, dst: &mut Encoder) {
+        dst.byte(*self as u8);
+    }
+}
+
+impl Encode for u32 {
+    fn encode(&self, dst: &mut Encoder) {
+        let mut val = *self;
+        while (val >> 7) != 0 {
+            dst.byte((val as u8) | 0x80);
+            val >>= 7;
+        }
+        assert_eq!(val >> 7, 0);
+        dst.byte(val as u8);
+    }
+}
+
+impl Encode for usize {
+    fn encode(&self, dst: &mut Encoder) {
+        assert!(*self <= u32::MAX as usize);
+        (*self as u32).encode(dst);
+    }
+}
+
+impl Encode for &[u8] {
+    fn encode(&self, dst: &mut Encoder) {
+        self.len().encode(dst);
+        dst.extend_from_slice(self);
+    }
+}
+
+impl Encode for &str {
+    fn encode(&self, dst: &mut Encoder) {
+        self.as_bytes().encode(dst);
+    }
+}
+
+impl Encode for String {
+    fn encode(&self, dst: &mut Encoder) {
+        self.as_bytes().encode(dst);
+    }
+}
+
+impl<T: Encode> Encode for Vec<T> {
+    fn encode(&self, dst: &mut Encoder) {
+        self.len().encode(dst);
+        for item in self {
+            item.encode(dst);
+        }
+    }
+}
+
+impl<T: Encode> Encode for Option<T> {
+    fn encode(&self, dst: &mut Encoder) {
+        match self {
+            None => dst.byte(0),
+            Some(val) => {
+                dst.byte(1);
+                val.encode(dst)
+            }
+        }
+    }
+}
+
+macro_rules! encode_struct {
+    ($name:ident ($($lt:tt)*) $($field:ident: $ty:ty,)*) => {
+        struct $name $($lt)* {
+            $($field: $ty,)*
+        }
+
+        impl $($lt)* Encode for $name $($lt)* {
+            fn encode(&self, _dst: &mut Encoder) {
+                $(self.$field.encode(_dst);)*
+            }
+        }
+    }
+}
+
+macro_rules! encode_enum {
+    ($name:ident ($($lt:tt)*) $($fields:tt)*) => (
+        enum $name $($lt)* { $($fields)* }
+
+        impl$($lt)* Encode for $name $($lt)* {
+            fn encode(&self, dst: &mut Encoder) {
+                use self::$name::*;
+                encode_enum!(@arms self dst (0) () $($fields)*)
+            }
+        }
+    );
+
+    (@arms $me:ident $dst:ident ($cnt:expr) ($($arms:tt)*)) => (
+        encode_enum!(@expr match $me { $($arms)* })
+    );
+
+    (@arms $me:ident $dst:ident ($cnt:expr) ($($arms:tt)*) $name:ident, $($rest:tt)*) => (
+        encode_enum!(
+            @arms
+            $me
+            $dst
+            ($cnt+1)
+            ($($arms)* $name => $dst.byte($cnt),)
+            $($rest)*
+        )
+    );
+
+    (@arms $me:ident $dst:ident ($cnt:expr) ($($arms:tt)*) $name:ident($t:ty), $($rest:tt)*) => (
+        encode_enum!(
+            @arms
+            $me
+            $dst
+            ($cnt+1)
+            ($($arms)* $name(val) => { $dst.byte($cnt); val.encode($dst) })
+            $($rest)*
+        )
+    );
+
+    (@expr $e:expr) => ($e);
+}
+
+macro_rules! encode_api {
+    () => ();
+    (struct $name:ident<'a> { $($fields:tt)* } $($rest:tt)*) => (
+        encode_struct!($name (<'a>) $($fields)*);
+        encode_api!($($rest)*);
+    );
+    (struct $name:ident { $($fields:tt)* } $($rest:tt)*) => (
+        encode_struct!($name () $($fields)*);
+        encode_api!($($rest)*);
+    );
+    (enum $name:ident<'a> { $($variants:tt)* } $($rest:tt)*) => (
+        encode_enum!($name (<'a>) $($variants)*);
+        encode_api!($($rest)*);
+    );
+    (enum $name:ident { $($variants:tt)* } $($rest:tt)*) => (
+        encode_enum!($name () $($variants)*);
+        encode_api!($($rest)*);
+    );
+}
+wasm_bindgen_shared::shared_api!(encode_api);
+
+fn from_ast_method_kind<'a>(
+    function: &'a ast::Function,
+    intern: &'a Interner,
+    method_kind: &'a ast::MethodKind,
+) -> Result<MethodKind<'a>, Diagnostic> {
+    Ok(match method_kind {
+        ast::MethodKind::Constructor => MethodKind::Constructor,
+        ast::MethodKind::Operation(ast::Operation { is_static, kind }) => {
+            let is_static = *is_static;
+            let kind = match kind {
+                ast::OperationKind::Getter(g) => {
+                    let g = g.as_ref().map(|g| intern.intern_str(g));
+                    OperationKind::Getter(g.unwrap_or_else(|| function.infer_getter_property()))
+                }
+                ast::OperationKind::Regular => OperationKind::Regular,
+                ast::OperationKind::Setter(s) => {
+                    let s = s.as_ref().map(|s| intern.intern_str(s));
+                    OperationKind::Setter(match s {
+                        Some(s) => s,
+                        None => intern.intern_str(&function.infer_setter_property()?),
+                    })
+                }
+                ast::OperationKind::IndexingGetter => OperationKind::IndexingGetter,
+                ast::OperationKind::IndexingSetter => OperationKind::IndexingSetter,
+                ast::OperationKind::IndexingDeleter => OperationKind::IndexingDeleter,
+            };
+            MethodKind::Operation(Operation { is_static, kind })
+        }
+    })
+}

vendor/wasm-bindgen-backend/src/error.rs

@@ -0,0 +1,134 @@
+use proc_macro2::*;
+use quote::{ToTokens, TokenStreamExt};
+use syn::parse::Error;
+
+/// Provide a Diagnostic with the given span and message
+#[macro_export]
+macro_rules! err_span {
+    ($span:expr, $($msg:tt)*) => (
+        $crate::Diagnostic::spanned_error(&$span, format!($($msg)*))
+    )
+}
+
+/// Immediately fail and return an Err, with the arguments passed to err_span!
+#[macro_export]
+macro_rules! bail_span {
+    ($($t:tt)*) => (
+        return Err(err_span!($($t)*).into())
+    )
+}
+
+/// A struct representing a diagnostic to emit to the end-user as an error.
+#[derive(Debug)]
+pub struct Diagnostic {
+    inner: Repr,
+}
+
+#[derive(Debug)]
+enum Repr {
+    Single {
+        text: String,
+        span: Option<(Span, Span)>,
+    },
+    SynError(Error),
+    Multi {
+        diagnostics: Vec<Diagnostic>,
+    },
+}
+
+impl Diagnostic {
+    /// Generate a `Diagnostic` from an informational message with no Span
+    pub fn error<T: Into<String>>(text: T) -> Diagnostic {
+        Diagnostic {
+            inner: Repr::Single {
+                text: text.into(),
+                span: None,
+            },
+        }
+    }
+
+    /// Generate a `Diagnostic` from a Span and an informational message
+    pub fn span_error<T: Into<String>>(span: Span, text: T) -> Diagnostic {
+        Diagnostic {
+            inner: Repr::Single {
+                text: text.into(),
+                span: Some((span, span)),
+            },
+        }
+    }
+
+    /// Generate a `Diagnostic` from the span of any tokenizable object and a message
+    pub fn spanned_error<T: Into<String>>(node: &dyn ToTokens, text: T) -> Diagnostic {
+        Diagnostic {
+            inner: Repr::Single {
+                text: text.into(),
+                span: extract_spans(node),
+            },
+        }
+    }
+
+    /// Attempt to generate a `Diagnostic` from a vector of other `Diagnostic` instances.
+    /// If the `Vec` is empty, returns `Ok(())`, otherwise returns the new `Diagnostic`
+    pub fn from_vec(diagnostics: Vec<Diagnostic>) -> Result<(), Diagnostic> {
+        if diagnostics.is_empty() {
+            Ok(())
+        } else {
+            Err(Diagnostic {
+                inner: Repr::Multi { diagnostics },
+            })
+        }
+    }
+
+    /// Immediately trigger a panic from this `Diagnostic`
+    #[allow(unconditional_recursion)]
+    pub fn panic(&self) -> ! {
+        match &self.inner {
+            Repr::Single { text, .. } => panic!("{}", text),
+            Repr::SynError(error) => panic!("{}", error),
+            Repr::Multi { diagnostics } => diagnostics[0].panic(),
+        }
+    }
+}
+
+impl From<Error> for Diagnostic {
+    fn from(err: Error) -> Diagnostic {
+        Diagnostic {
+            inner: Repr::SynError(err),
+        }
+    }
+}
+
+fn extract_spans(node: &dyn ToTokens) -> Option<(Span, Span)> {
+    let mut t = TokenStream::new();
+    node.to_tokens(&mut t);
+    let mut tokens = t.into_iter();
+    let start = tokens.next().map(|t| t.span());
+    let end = tokens.last().map(|t| t.span());
+    start.map(|start| (start, end.unwrap_or(start)))
+}
+
+impl ToTokens for Diagnostic {
+    fn to_tokens(&self, dst: &mut TokenStream) {
+        match &self.inner {
+            Repr::Single { text, span } => {
+                let cs2 = (Span::call_site(), Span::call_site());
+                let (start, end) = span.unwrap_or(cs2);
+                dst.append(Ident::new("compile_error", start));
+                dst.append(Punct::new('!', Spacing::Alone));
+                let mut message = TokenStream::new();
+                message.append(Literal::string(text));
+                let mut group = Group::new(Delimiter::Brace, message);
+                group.set_span(end);
+                dst.append(group);
+            }
+            Repr::Multi { diagnostics } => {
+                for diagnostic in diagnostics {
+                    diagnostic.to_tokens(dst);
+                }
+            }
+            Repr::SynError(err) => {
+                err.to_compile_error().to_tokens(dst);
+            }
+        }
+    }
+}

vendor/wasm-bindgen-backend/src/lib.rs

@@ -0,0 +1,40 @@
+//! A common backend for bindgen crates.
+//!
+//! This (internal) crate provides functionality common to multiple bindgen
+//! dependency crates. There are 4 main things exported from this crate:
+//!
+//! 1. [**`TryToTokens`**](./trait.TryToTokens.html)
+//!
+//!    Provides the ability to attempt conversion from an AST struct
+//!    into a TokenStream
+//!
+//! 2. [**`Diagnostic`**](./struct.Diagnostic.html)
+//!
+//!    A struct used to provide diagnostic responses for failures of said
+//!    tokenization
+//!
+//! 3. [**`ast`**](./ast/index.html)
+//!
+//!    Abstract Syntax Tree types used to represent a Rust program, with
+//!    the necessary metadata to generate bindings for it
+//!
+//! 4. [**`util`**](./util/index.html)
+//!
+//!    Common utilities for manipulating parsed types from syn
+//!
+
+#![recursion_limit = "256"]
+#![cfg_attr(feature = "extra-traits", deny(missing_debug_implementations))]
+#![deny(missing_docs)]
+#![doc(html_root_url = "https://docs.rs/wasm-bindgen-backend/0.2")]
+
+pub use crate::codegen::TryToTokens;
+pub use crate::error::Diagnostic;
+
+#[macro_use]
+mod error;
+
+pub mod ast;
+mod codegen;
+mod encode;
+pub mod util;

vendor/wasm-bindgen-backend/src/util.rs

@@ -0,0 +1,161 @@
+//! Common utility function for manipulating syn types and
+//! handling parsed values
+
+use std::collections::hash_map::DefaultHasher;
+use std::env;
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::iter::FromIterator;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering::SeqCst;
+
+use crate::ast;
+use proc_macro2::{self, Ident};
+
+/// Check whether a given `&str` is a Rust keyword
+#[rustfmt::skip]
+fn is_rust_keyword(name: &str) -> bool {
+    matches!(name,
+        "abstract" | "alignof" | "as" | "become" | "box" | "break" | "const" | "continue"
+        | "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" | "for" | "if"
+        | "impl" | "in" | "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut"
+        | "offsetof" | "override" | "priv" | "proc" | "pub" | "pure" | "ref" | "return"
+        | "Self" | "self" | "sizeof" | "static" | "struct" | "super" | "trait" | "true"
+        | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" | "while"
+        | "yield" | "bool" | "_"
+    )
+}
+
+/// Create an `Ident`, possibly mangling it if it conflicts with a Rust keyword.
+pub fn rust_ident(name: &str) -> Ident {
+    if name.is_empty() {
+        panic!("tried to create empty Ident (from \"\")");
+    } else if is_rust_keyword(name) {
+        Ident::new(&format!("{}_", name), proc_macro2::Span::call_site())
+
+    // we didn't historically have `async` in the `is_rust_keyword` list above,
+    // so for backwards compatibility reasons we need to generate an `async`
+    // identifier as well, but we'll be sure to use a raw identifier to ease
+    // compatibility with the 2018 edition.
+    //
+    // Note, though, that `proc-macro` doesn't support a normal way to create a
+    // raw identifier. To get around that we do some wonky parsing to
+    // roundaboutly create one.
+    } else if name == "async" {
+        let ident = "r#async"
+            .parse::<proc_macro2::TokenStream>()
+            .unwrap()
+            .into_iter()
+            .next()
+            .unwrap();
+        match ident {
+            proc_macro2::TokenTree::Ident(i) => i,
+            _ => unreachable!(),
+        }
+    } else if name.chars().next().unwrap().is_ascii_digit() {
+        Ident::new(&format!("N{}", name), proc_macro2::Span::call_site())
+    } else {
+        raw_ident(name)
+    }
+}
+
+/// Create an `Ident` without checking to see if it conflicts with a Rust
+/// keyword.
+pub fn raw_ident(name: &str) -> Ident {
+    Ident::new(name, proc_macro2::Span::call_site())
+}
+
+/// Create a path type from the given segments. For example an iterator yielding
+/// the idents `[foo, bar, baz]` will result in the path type `foo::bar::baz`.
+pub fn simple_path_ty<I>(segments: I) -> syn::Type
+where
+    I: IntoIterator<Item = Ident>,
+{
+    path_ty(false, segments)
+}
+
+/// Create a global path type from the given segments. For example an iterator
+/// yielding the idents `[foo, bar, baz]` will result in the path type
+/// `::foo::bar::baz`.
+pub fn leading_colon_path_ty<I>(segments: I) -> syn::Type
+where
+    I: IntoIterator<Item = Ident>,
+{
+    path_ty(true, segments)
+}
+
+fn path_ty<I>(leading_colon: bool, segments: I) -> syn::Type
+where
+    I: IntoIterator<Item = Ident>,
+{
+    let segments: Vec<_> = segments
+        .into_iter()
+        .map(|i| syn::PathSegment {
+            ident: i,
+            arguments: syn::PathArguments::None,
+        })
+        .collect();
+
+    syn::TypePath {
+        qself: None,
+        path: syn::Path {
+            leading_colon: if leading_colon {
+                Some(Default::default())
+            } else {
+                None
+            },
+            segments: syn::punctuated::Punctuated::from_iter(segments),
+        },
+    }
+    .into()
+}
+
+/// Create a path type with a single segment from a given Identifier
+pub fn ident_ty(ident: Ident) -> syn::Type {
+    simple_path_ty(Some(ident))
+}
+
+/// Convert an ImportFunction into the more generic Import type, wrapping the provided function
+pub fn wrap_import_function(function: ast::ImportFunction) -> ast::Import {
+    ast::Import {
+        module: None,
+        js_namespace: None,
+        kind: ast::ImportKind::Function(function),
+    }
+}
+
+/// Small utility used when generating symbol names.
+///
+/// Hashes the public field here along with a few cargo-set env vars to
+/// distinguish between runs of the procedural macro.
+#[derive(Debug)]
+pub struct ShortHash<T>(pub T);
+
+impl<T: Hash> fmt::Display for ShortHash<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        static HASHED: AtomicBool = AtomicBool::new(false);
+        static HASH: AtomicUsize = AtomicUsize::new(0);
+
+        // Try to amortize the cost of loading env vars a lot as we're gonna be
+        // hashing for a lot of symbols.
+        if !HASHED.load(SeqCst) {
+            let mut h = DefaultHasher::new();
+            env::var("CARGO_PKG_NAME")
+                .expect("should have CARGO_PKG_NAME env var")
+                .hash(&mut h);
+            env::var("CARGO_PKG_VERSION")
+                .expect("should have CARGO_PKG_VERSION env var")
+                .hash(&mut h);
+            // This may chop off 32 bits on 32-bit platforms, but that's ok, we
+            // just want something to mix in below anyway.
+            HASH.store(h.finish() as usize, SeqCst);
+            HASHED.store(true, SeqCst);
+        }
+
+        let mut h = DefaultHasher::new();
+        HASH.load(SeqCst).hash(&mut h);
+        self.0.hash(&mut h);
+        write!(f, "{:016x}", h.finish())
+    }
+}