Vendor dependencies for 0.3.0 release

vendor/codespan-reporting/src/term/config.rs

@@ -0,0 +1,321 @@
+use termcolor::{Color, ColorSpec};
+
+use crate::diagnostic::{LabelStyle, Severity};
+
+/// Configures how a diagnostic is rendered.
+#[derive(Clone, Debug)]
+pub struct Config {
+    /// The display style to use when rendering diagnostics.
+    /// Defaults to: [`DisplayStyle::Rich`].
+    ///
+    /// [`DisplayStyle::Rich`]: DisplayStyle::Rich
+    pub display_style: DisplayStyle,
+    /// Column width of tabs.
+    /// Defaults to: `4`.
+    pub tab_width: usize,
+    /// Styles to use when rendering the diagnostic.
+    pub styles: Styles,
+    /// Characters to use when rendering the diagnostic.
+    pub chars: Chars,
+    /// The minimum number of lines to be shown after the line on which a multiline [`Label`] begins.
+    ///
+    /// Defaults to: `3`.
+    ///
+    /// [`Label`]: crate::diagnostic::Label
+    pub start_context_lines: usize,
+    /// The minimum number of lines to be shown before the line on which a multiline [`Label`] ends.
+    ///
+    /// Defaults to: `1`.
+    ///
+    /// [`Label`]: crate::diagnostic::Label
+    pub end_context_lines: usize,
+}
+
+impl Default for Config {
+    fn default() -> Config {
+        Config {
+            display_style: DisplayStyle::Rich,
+            tab_width: 4,
+            styles: Styles::default(),
+            chars: Chars::default(),
+            start_context_lines: 3,
+            end_context_lines: 1,
+        }
+    }
+}
+
+/// The display style to use when rendering diagnostics.
+#[derive(Clone, Debug)]
+pub enum DisplayStyle {
+    /// Output a richly formatted diagnostic, with source code previews.
+    ///
+    /// ```text
+    /// error[E0001]: unexpected type in `+` application
+    ///   ┌─ test:2:9
+    ///   │
+    /// 2 │ (+ test "")
+    ///   │         ^^ expected `Int` but found `String`
+    ///   │
+    ///   = expected type `Int`
+    ///        found type `String`
+    ///
+    /// error[E0002]: Bad config found
+    ///
+    /// ```
+    Rich,
+    /// Output a condensed diagnostic, with a line number, severity, message and notes (if any).
+    ///
+    /// ```text
+    /// test:2:9: error[E0001]: unexpected type in `+` application
+    /// = expected type `Int`
+    ///      found type `String`
+    ///
+    /// error[E0002]: Bad config found
+    /// ```
+    Medium,
+    /// Output a short diagnostic, with a line number, severity, and message.
+    ///
+    /// ```text
+    /// test:2:9: error[E0001]: unexpected type in `+` application
+    /// error[E0002]: Bad config found
+    /// ```
+    Short,
+}
+
+/// Styles to use when rendering the diagnostic.
+#[derive(Clone, Debug)]
+pub struct Styles {
+    /// The style to use when rendering bug headers.
+    /// Defaults to `fg:red bold intense`.
+    pub header_bug: ColorSpec,
+    /// The style to use when rendering error headers.
+    /// Defaults to `fg:red bold intense`.
+    pub header_error: ColorSpec,
+    /// The style to use when rendering warning headers.
+    /// Defaults to `fg:yellow bold intense`.
+    pub header_warning: ColorSpec,
+    /// The style to use when rendering note headers.
+    /// Defaults to `fg:green bold intense`.
+    pub header_note: ColorSpec,
+    /// The style to use when rendering help headers.
+    /// Defaults to `fg:cyan bold intense`.
+    pub header_help: ColorSpec,
+    /// The style to use when the main diagnostic message.
+    /// Defaults to `bold intense`.
+    pub header_message: ColorSpec,
+
+    /// The style to use when rendering bug labels.
+    /// Defaults to `fg:red`.
+    pub primary_label_bug: ColorSpec,
+    /// The style to use when rendering error labels.
+    /// Defaults to `fg:red`.
+    pub primary_label_error: ColorSpec,
+    /// The style to use when rendering warning labels.
+    /// Defaults to `fg:yellow`.
+    pub primary_label_warning: ColorSpec,
+    /// The style to use when rendering note labels.
+    /// Defaults to `fg:green`.
+    pub primary_label_note: ColorSpec,
+    /// The style to use when rendering help labels.
+    /// Defaults to `fg:cyan`.
+    pub primary_label_help: ColorSpec,
+    /// The style to use when rendering secondary labels.
+    /// Defaults `fg:blue` (or `fg:cyan` on windows).
+    pub secondary_label: ColorSpec,
+
+    /// The style to use when rendering the line numbers.
+    /// Defaults `fg:blue` (or `fg:cyan` on windows).
+    pub line_number: ColorSpec,
+    /// The style to use when rendering the source code borders.
+    /// Defaults `fg:blue` (or `fg:cyan` on windows).
+    pub source_border: ColorSpec,
+    /// The style to use when rendering the note bullets.
+    /// Defaults `fg:blue` (or `fg:cyan` on windows).
+    pub note_bullet: ColorSpec,
+}
+
+impl Styles {
+    /// The style used to mark a header at a given severity.
+    pub fn header(&self, severity: Severity) -> &ColorSpec {
+        match severity {
+            Severity::Bug => &self.header_bug,
+            Severity::Error => &self.header_error,
+            Severity::Warning => &self.header_warning,
+            Severity::Note => &self.header_note,
+            Severity::Help => &self.header_help,
+        }
+    }
+
+    /// The style used to mark a primary or secondary label at a given severity.
+    pub fn label(&self, severity: Severity, label_style: LabelStyle) -> &ColorSpec {
+        match (label_style, severity) {
+            (LabelStyle::Primary, Severity::Bug) => &self.primary_label_bug,
+            (LabelStyle::Primary, Severity::Error) => &self.primary_label_error,
+            (LabelStyle::Primary, Severity::Warning) => &self.primary_label_warning,
+            (LabelStyle::Primary, Severity::Note) => &self.primary_label_note,
+            (LabelStyle::Primary, Severity::Help) => &self.primary_label_help,
+            (LabelStyle::Secondary, _) => &self.secondary_label,
+        }
+    }
+
+    #[doc(hidden)]
+    pub fn with_blue(blue: Color) -> Styles {
+        let header = ColorSpec::new().set_bold(true).set_intense(true).clone();
+
+        Styles {
+            header_bug: header.clone().set_fg(Some(Color::Red)).clone(),
+            header_error: header.clone().set_fg(Some(Color::Red)).clone(),
+            header_warning: header.clone().set_fg(Some(Color::Yellow)).clone(),
+            header_note: header.clone().set_fg(Some(Color::Green)).clone(),
+            header_help: header.clone().set_fg(Some(Color::Cyan)).clone(),
+            header_message: header,
+
+            primary_label_bug: ColorSpec::new().set_fg(Some(Color::Red)).clone(),
+            primary_label_error: ColorSpec::new().set_fg(Some(Color::Red)).clone(),
+            primary_label_warning: ColorSpec::new().set_fg(Some(Color::Yellow)).clone(),
+            primary_label_note: ColorSpec::new().set_fg(Some(Color::Green)).clone(),
+            primary_label_help: ColorSpec::new().set_fg(Some(Color::Cyan)).clone(),
+            secondary_label: ColorSpec::new().set_fg(Some(blue)).clone(),
+
+            line_number: ColorSpec::new().set_fg(Some(blue)).clone(),
+            source_border: ColorSpec::new().set_fg(Some(blue)).clone(),
+            note_bullet: ColorSpec::new().set_fg(Some(blue)).clone(),
+        }
+    }
+}
+
+impl Default for Styles {
+    fn default() -> Styles {
+        // Blue is really difficult to see on the standard windows command line
+        #[cfg(windows)]
+        const BLUE: Color = Color::Cyan;
+        #[cfg(not(windows))]
+        const BLUE: Color = Color::Blue;
+
+        Self::with_blue(BLUE)
+    }
+}
+
+/// Characters to use when rendering the diagnostic.
+///
+/// By using [`Chars::ascii()`] you can switch to an ASCII-only format suitable
+/// for rendering on terminals that do not support box drawing characters.
+#[derive(Clone, Debug)]
+pub struct Chars {
+    /// The characters to use for the top-left border of the snippet.
+    /// Defaults to: `"┌─"` or `"-->"` with [`Chars::ascii()`].
+    pub snippet_start: String,
+    /// The character to use for the left border of the source.
+    /// Defaults to: `'│'` or `'|'` with [`Chars::ascii()`].
+    pub source_border_left: char,
+    /// The character to use for the left border break of the source.
+    /// Defaults to: `'·'` or `'.'` with [`Chars::ascii()`].
+    pub source_border_left_break: char,
+
+    /// The character to use for the note bullet.
+    /// Defaults to: `'='`.
+    pub note_bullet: char,
+
+    /// The character to use for marking a single-line primary label.
+    /// Defaults to: `'^'`.
+    pub single_primary_caret: char,
+    /// The character to use for marking a single-line secondary label.
+    /// Defaults to: `'-'`.
+    pub single_secondary_caret: char,
+
+    /// The character to use for marking the start of a multi-line primary label.
+    /// Defaults to: `'^'`.
+    pub multi_primary_caret_start: char,
+    /// The character to use for marking the end of a multi-line primary label.
+    /// Defaults to: `'^'`.
+    pub multi_primary_caret_end: char,
+    /// The character to use for marking the start of a multi-line secondary label.
+    /// Defaults to: `'\''`.
+    pub multi_secondary_caret_start: char,
+    /// The character to use for marking the end of a multi-line secondary label.
+    /// Defaults to: `'\''`.
+    pub multi_secondary_caret_end: char,
+    /// The character to use for the top-left corner of a multi-line label.
+    /// Defaults to: `'╭'` or `'/'` with [`Chars::ascii()`].
+    pub multi_top_left: char,
+    /// The character to use for the top of a multi-line label.
+    /// Defaults to: `'─'` or `'-'` with [`Chars::ascii()`].
+    pub multi_top: char,
+    /// The character to use for the bottom-left corner of a multi-line label.
+    /// Defaults to: `'╰'` or `'\'` with [`Chars::ascii()`].
+    pub multi_bottom_left: char,
+    /// The character to use when marking the bottom of a multi-line label.
+    /// Defaults to: `'─'` or `'-'` with [`Chars::ascii()`].
+    pub multi_bottom: char,
+    /// The character to use for the left of a multi-line label.
+    /// Defaults to: `'│'` or `'|'` with [`Chars::ascii()`].
+    pub multi_left: char,
+
+    /// The character to use for the left of a pointer underneath a caret.
+    /// Defaults to: `'│'` or `'|'` with [`Chars::ascii()`].
+    pub pointer_left: char,
+}
+
+impl Default for Chars {
+    fn default() -> Chars {
+        Chars::box_drawing()
+    }
+}
+
+impl Chars {
+    /// A character set that uses Unicode box drawing characters.
+    pub fn box_drawing() -> Chars {
+        Chars {
+            snippet_start: "┌─".into(),
+            source_border_left: '│',
+            source_border_left_break: '·',
+
+            note_bullet: '=',
+
+            single_primary_caret: '^',
+            single_secondary_caret: '-',
+
+            multi_primary_caret_start: '^',
+            multi_primary_caret_end: '^',
+            multi_secondary_caret_start: '\'',
+            multi_secondary_caret_end: '\'',
+            multi_top_left: '╭',
+            multi_top: '─',
+            multi_bottom_left: '╰',
+            multi_bottom: '─',
+            multi_left: '│',
+
+            pointer_left: '│',
+        }
+    }
+
+    /// A character set that only uses ASCII characters.
+    ///
+    /// This is useful if your terminal's font does not support box drawing
+    /// characters well and results in output that looks similar to rustc's
+    /// diagnostic output.
+    pub fn ascii() -> Chars {
+        Chars {
+            snippet_start: "-->".into(),
+            source_border_left: '|',
+            source_border_left_break: '.',
+
+            note_bullet: '=',
+
+            single_primary_caret: '^',
+            single_secondary_caret: '-',
+
+            multi_primary_caret_start: '^',
+            multi_primary_caret_end: '^',
+            multi_secondary_caret_start: '\'',
+            multi_secondary_caret_end: '\'',
+            multi_top_left: '/',
+            multi_top: '-',
+            multi_bottom_left: '\\',
+            multi_bottom: '-',
+            multi_left: '|',
+
+            pointer_left: '|',
+        }
+    }
+}

vendor/codespan-reporting/src/term/views.rs

@@ -0,0 +1,478 @@
+use std::ops::Range;
+
+use crate::diagnostic::{Diagnostic, LabelStyle};
+use crate::files::{Error, Files, Location};
+use crate::term::renderer::{Locus, MultiLabel, Renderer, SingleLabel};
+use crate::term::Config;
+
+/// Count the number of decimal digits in `n`.
+fn count_digits(mut n: usize) -> usize {
+    let mut count = 0;
+    while n != 0 {
+        count += 1;
+        n /= 10; // remove last digit
+    }
+    count
+}
+
+/// Output a richly formatted diagnostic, with source code previews.
+pub struct RichDiagnostic<'diagnostic, 'config, FileId> {
+    diagnostic: &'diagnostic Diagnostic<FileId>,
+    config: &'config Config,
+}
+
+impl<'diagnostic, 'config, FileId> RichDiagnostic<'diagnostic, 'config, FileId>
+where
+    FileId: Copy + PartialEq,
+{
+    pub fn new(
+        diagnostic: &'diagnostic Diagnostic<FileId>,
+        config: &'config Config,
+    ) -> RichDiagnostic<'diagnostic, 'config, FileId> {
+        RichDiagnostic { diagnostic, config }
+    }
+
+    pub fn render<'files>(
+        &self,
+        files: &'files impl Files<'files, FileId = FileId>,
+        renderer: &mut Renderer<'_, '_>,
+    ) -> Result<(), Error>
+    where
+        FileId: 'files,
+    {
+        use std::collections::BTreeMap;
+
+        struct LabeledFile<'diagnostic, FileId> {
+            file_id: FileId,
+            start: usize,
+            name: String,
+            location: Location,
+            num_multi_labels: usize,
+            lines: BTreeMap<usize, Line<'diagnostic>>,
+            max_label_style: LabelStyle,
+        }
+
+        impl<'diagnostic, FileId> LabeledFile<'diagnostic, FileId> {
+            fn get_or_insert_line(
+                &mut self,
+                line_index: usize,
+                line_range: Range<usize>,
+                line_number: usize,
+            ) -> &mut Line<'diagnostic> {
+                self.lines.entry(line_index).or_insert_with(|| Line {
+                    range: line_range,
+                    number: line_number,
+                    single_labels: vec![],
+                    multi_labels: vec![],
+                    // This has to be false by default so we know if it must be rendered by another condition already.
+                    must_render: false,
+                })
+            }
+        }
+
+        struct Line<'diagnostic> {
+            number: usize,
+            range: std::ops::Range<usize>,
+            // TODO: How do we reuse these allocations?
+            single_labels: Vec<SingleLabel<'diagnostic>>,
+            multi_labels: Vec<(usize, LabelStyle, MultiLabel<'diagnostic>)>,
+            must_render: bool,
+        }
+
+        // TODO: Make this data structure external, to allow for allocation reuse
+        let mut labeled_files = Vec::<LabeledFile<'_, _>>::new();
+        // Keep track of the outer padding to use when rendering the
+        // snippets of source code.
+        let mut outer_padding = 0;
+
+        // Group labels by file
+        for label in &self.diagnostic.labels {
+            let start_line_index = files.line_index(label.file_id, label.range.start)?;
+            let start_line_number = files.line_number(label.file_id, start_line_index)?;
+            let start_line_range = files.line_range(label.file_id, start_line_index)?;
+            let end_line_index = files.line_index(label.file_id, label.range.end)?;
+            let end_line_number = files.line_number(label.file_id, end_line_index)?;
+            let end_line_range = files.line_range(label.file_id, end_line_index)?;
+
+            outer_padding = std::cmp::max(outer_padding, count_digits(start_line_number));
+            outer_padding = std::cmp::max(outer_padding, count_digits(end_line_number));
+
+            // NOTE: This could be made more efficient by using an associative
+            // data structure like a hashmap or B-tree,  but we use a vector to
+            // preserve the order that unique files appear in the list of labels.
+            let labeled_file = match labeled_files
+                .iter_mut()
+                .find(|labeled_file| label.file_id == labeled_file.file_id)
+            {
+                Some(labeled_file) => {
+                    // another diagnostic also referenced this file
+                    if labeled_file.max_label_style > label.style
+                        || (labeled_file.max_label_style == label.style
+                            && labeled_file.start > label.range.start)
+                    {
+                        // this label has a higher style or has the same style but starts earlier
+                        labeled_file.start = label.range.start;
+                        labeled_file.location = files.location(label.file_id, label.range.start)?;
+                        labeled_file.max_label_style = label.style;
+                    }
+                    labeled_file
+                }
+                None => {
+                    // no other diagnostic referenced this file yet
+                    labeled_files.push(LabeledFile {
+                        file_id: label.file_id,
+                        start: label.range.start,
+                        name: files.name(label.file_id)?.to_string(),
+                        location: files.location(label.file_id, label.range.start)?,
+                        num_multi_labels: 0,
+                        lines: BTreeMap::new(),
+                        max_label_style: label.style,
+                    });
+                    // this unwrap should never fail because we just pushed an element
+                    labeled_files
+                        .last_mut()
+                        .expect("just pushed an element that disappeared")
+                }
+            };
+
+            if start_line_index == end_line_index {
+                // Single line
+                //
+                // ```text
+                // 2 │ (+ test "")
+                //   │         ^^ expected `Int` but found `String`
+                // ```
+                let label_start = label.range.start - start_line_range.start;
+                // Ensure that we print at least one caret, even when we
+                // have a zero-length source range.
+                let label_end =
+                    usize::max(label.range.end - start_line_range.start, label_start + 1);
+
+                let line = labeled_file.get_or_insert_line(
+                    start_line_index,
+                    start_line_range,
+                    start_line_number,
+                );
+
+                // Ensure that the single line labels are lexicographically
+                // sorted by the range of source code that they cover.
+                let index = match line.single_labels.binary_search_by(|(_, range, _)| {
+                    // `Range<usize>` doesn't implement `Ord`, so convert to `(usize, usize)`
+                    // to piggyback off its lexicographic comparison implementation.
+                    (range.start, range.end).cmp(&(label_start, label_end))
+                }) {
+                    // If the ranges are the same, order the labels in reverse
+                    // to how they were originally specified in the diagnostic.
+                    // This helps with printing in the renderer.
+                    Ok(index) | Err(index) => index,
+                };
+
+                line.single_labels
+                    .insert(index, (label.style, label_start..label_end, &label.message));
+
+                // If this line is not rendered, the SingleLabel is not visible.
+                line.must_render = true;
+            } else {
+                // Multiple lines
+                //
+                // ```text
+                // 4 │   fizz₁ num = case (mod num 5) (mod num 3) of
+                //   │ ╭─────────────^
+                // 5 │ │     0 0 => "FizzBuzz"
+                // 6 │ │     0 _ => "Fizz"
+                // 7 │ │     _ 0 => "Buzz"
+                // 8 │ │     _ _ => num
+                //   │ ╰──────────────^ `case` clauses have incompatible types
+                // ```
+
+                let label_index = labeled_file.num_multi_labels;
+                labeled_file.num_multi_labels += 1;
+
+                // First labeled line
+                let label_start = label.range.start - start_line_range.start;
+
+                let start_line = labeled_file.get_or_insert_line(
+                    start_line_index,
+                    start_line_range.clone(),
+                    start_line_number,
+                );
+
+                start_line.multi_labels.push((
+                    label_index,
+                    label.style,
+                    MultiLabel::Top(label_start),
+                ));
+
+                // The first line has to be rendered so the start of the label is visible.
+                start_line.must_render = true;
+
+                // Marked lines
+                //
+                // ```text
+                // 5 │ │     0 0 => "FizzBuzz"
+                // 6 │ │     0 _ => "Fizz"
+                // 7 │ │     _ 0 => "Buzz"
+                // ```
+                for line_index in (start_line_index + 1)..end_line_index {
+                    let line_range = files.line_range(label.file_id, line_index)?;
+                    let line_number = files.line_number(label.file_id, line_index)?;
+
+                    outer_padding = std::cmp::max(outer_padding, count_digits(line_number));
+
+                    let line = labeled_file.get_or_insert_line(line_index, line_range, line_number);
+
+                    line.multi_labels
+                        .push((label_index, label.style, MultiLabel::Left));
+
+                    // The line should be rendered to match the configuration of how much context to show.
+                    line.must_render |=
+                        // Is this line part of the context after the start of the label?
+                        line_index - start_line_index <= self.config.start_context_lines
+                        ||
+                        // Is this line part of the context before the end of the label?
+                        end_line_index - line_index <= self.config.end_context_lines;
+                }
+
+                // Last labeled line
+                //
+                // ```text
+                // 8 │ │     _ _ => num
+                //   │ ╰──────────────^ `case` clauses have incompatible types
+                // ```
+                let label_end = label.range.end - end_line_range.start;
+
+                let end_line = labeled_file.get_or_insert_line(
+                    end_line_index,
+                    end_line_range,
+                    end_line_number,
+                );
+
+                end_line.multi_labels.push((
+                    label_index,
+                    label.style,
+                    MultiLabel::Bottom(label_end, &label.message),
+                ));
+
+                // The last line has to be rendered so the end of the label is visible.
+                end_line.must_render = true;
+            }
+        }
+
+        // Header and message
+        //
+        // ```text
+        // error[E0001]: unexpected type in `+` application
+        // ```
+        renderer.render_header(
+            None,
+            self.diagnostic.severity,
+            self.diagnostic.code.as_deref(),
+            self.diagnostic.message.as_str(),
+        )?;
+
+        // Source snippets
+        //
+        // ```text
+        //   ┌─ test:2:9
+        //   │
+        // 2 │ (+ test "")
+        //   │         ^^ expected `Int` but found `String`
+        //   │
+        // ```
+        let mut labeled_files = labeled_files.into_iter().peekable();
+        while let Some(labeled_file) = labeled_files.next() {
+            let source = files.source(labeled_file.file_id)?;
+            let source = source.as_ref();
+
+            // Top left border and locus.
+            //
+            // ```text
+            // ┌─ test:2:9
+            // ```
+            if !labeled_file.lines.is_empty() {
+                renderer.render_snippet_start(
+                    outer_padding,
+                    &Locus {
+                        name: labeled_file.name,
+                        location: labeled_file.location,
+                    },
+                )?;
+                renderer.render_snippet_empty(
+                    outer_padding,
+                    self.diagnostic.severity,
+                    labeled_file.num_multi_labels,
+                    &[],
+                )?;
+            }
+
+            let mut lines = labeled_file
+                .lines
+                .iter()
+                .filter(|(_, line)| line.must_render)
+                .peekable();
+
+            while let Some((line_index, line)) = lines.next() {
+                renderer.render_snippet_source(
+                    outer_padding,
+                    line.number,
+                    &source[line.range.clone()],
+                    self.diagnostic.severity,
+                    &line.single_labels,
+                    labeled_file.num_multi_labels,
+                    &line.multi_labels,
+                )?;
+
+                // Check to see if we need to render any intermediate stuff
+                // before rendering the next line.
+                if let Some((next_line_index, _)) = lines.peek() {
+                    match next_line_index.checked_sub(*line_index) {
+                        // Consecutive lines
+                        Some(1) => {}
+                        // One line between the current line and the next line
+                        Some(2) => {
+                            // Write a source line
+                            let file_id = labeled_file.file_id;
+
+                            // This line was not intended to be rendered initially.
+                            // To render the line right, we have to get back the original labels.
+                            let labels = labeled_file
+                                .lines
+                                .get(&(line_index + 1))
+                                .map_or(&[][..], |line| &line.multi_labels[..]);
+
+                            renderer.render_snippet_source(
+                                outer_padding,
+                                files.line_number(file_id, line_index + 1)?,
+                                &source[files.line_range(file_id, line_index + 1)?],
+                                self.diagnostic.severity,
+                                &[],
+                                labeled_file.num_multi_labels,
+                                labels,
+                            )?;
+                        }
+                        // More than one line between the current line and the next line.
+                        Some(_) | None => {
+                            // Source break
+                            //
+                            // ```text
+                            // ·
+                            // ```
+                            renderer.render_snippet_break(
+                                outer_padding,
+                                self.diagnostic.severity,
+                                labeled_file.num_multi_labels,
+                                &line.multi_labels,
+                            )?;
+                        }
+                    }
+                }
+            }
+
+            // Check to see if we should render a trailing border after the
+            // final line of the snippet.
+            if labeled_files.peek().is_none() && self.diagnostic.notes.is_empty() {
+                // We don't render a border if we are at the final newline
+                // without trailing notes, because it would end up looking too
+                // spaced-out in combination with the final new line.
+            } else {
+                // Render the trailing snippet border.
+                renderer.render_snippet_empty(
+                    outer_padding,
+                    self.diagnostic.severity,
+                    labeled_file.num_multi_labels,
+                    &[],
+                )?;
+            }
+        }
+
+        // Additional notes
+        //
+        // ```text
+        // = expected type `Int`
+        //      found type `String`
+        // ```
+        for note in &self.diagnostic.notes {
+            renderer.render_snippet_note(outer_padding, note)?;
+        }
+        renderer.render_empty()
+    }
+}
+
+/// Output a short diagnostic, with a line number, severity, and message.
+pub struct ShortDiagnostic<'diagnostic, FileId> {
+    diagnostic: &'diagnostic Diagnostic<FileId>,
+    show_notes: bool,
+}
+
+impl<'diagnostic, FileId> ShortDiagnostic<'diagnostic, FileId>
+where
+    FileId: Copy + PartialEq,
+{
+    pub fn new(
+        diagnostic: &'diagnostic Diagnostic<FileId>,
+        show_notes: bool,
+    ) -> ShortDiagnostic<'diagnostic, FileId> {
+        ShortDiagnostic {
+            diagnostic,
+            show_notes,
+        }
+    }
+
+    pub fn render<'files>(
+        &self,
+        files: &'files impl Files<'files, FileId = FileId>,
+        renderer: &mut Renderer<'_, '_>,
+    ) -> Result<(), Error>
+    where
+        FileId: 'files,
+    {
+        // Located headers
+        //
+        // ```text
+        // test:2:9: error[E0001]: unexpected type in `+` application
+        // ```
+        let mut primary_labels_encountered = 0;
+        let labels = self.diagnostic.labels.iter();
+        for label in labels.filter(|label| label.style == LabelStyle::Primary) {
+            primary_labels_encountered += 1;
+
+            renderer.render_header(
+                Some(&Locus {
+                    name: files.name(label.file_id)?.to_string(),
+                    location: files.location(label.file_id, label.range.start)?,
+                }),
+                self.diagnostic.severity,
+                self.diagnostic.code.as_deref(),
+                self.diagnostic.message.as_str(),
+            )?;
+        }
+
+        // Fallback to printing a non-located header if no primary labels were encountered
+        //
+        // ```text
+        // error[E0002]: Bad config found
+        // ```
+        if primary_labels_encountered == 0 {
+            renderer.render_header(
+                None,
+                self.diagnostic.severity,
+                self.diagnostic.code.as_deref(),
+                self.diagnostic.message.as_str(),
+            )?;
+        }
+
+        if self.show_notes {
+            // Additional notes
+            //
+            // ```text
+            // = expected type `Int`
+            //      found type `String`
+            // ```
+            for note in &self.diagnostic.notes {
+                renderer.render_snippet_note(0, note)?;
+            }
+        }
+
+        Ok(())
+    }
+}