perf(diagnostics): use fixed ANSI styles (#26130)

Replace dynamic diagnostic styles with fixed ANSI prefixes, reducing `oxfmt` and `oxlint` release text size.

AI assistance: Codex was used. The contributor remains responsible for this change.

Cargo.lock

@@ -1992,7 +1992,6 @@ dependencies = [
  "cow-utils",
  "itoa",
  "memchr",
- "owo-colors",
  "oxc_span",
  "percent-encoding",
  "smallvec",

Cargo.toml

@@ -243,7 +243,6 @@ oxc-css-parser = "0.0.11" # CSS/SCSS/Less parser (raffia 0.12.3 fork: adds `temp
 oxc-graphql-parser = "0.0.9" # GraphQL parser (direct AST; apollo-parser 0.8.6 fork aligned with graphql-js 17 syntax)
 oxc-toml = "0.14.5" # TOML formatter
 oxc-yaml-parser = "0.0.5" # YAML 1.2 parser (comment-preserving typed AST, node naming from `yaml-unist-parser`)
-owo-colors = "4.3.0" # Terminal colors
 papaya = "0.2.4" # Concurrent hash map
 percent-encoding = "2.3.2" # URL encoding
 petgraph = { version = "0.8.3", default-features = false } # Graph data structures

apps/oxfmt/src/cli/walk_runner.rs

@@ -223,16 +223,16 @@ impl WalkRunner {
             // Color support is detected the same way as `GraphicalReportHandler` used by `DefaultReporter`,
             // and when colors are disabled, every style is empty and renders nothing.
             // `ListDifferent` mode output is meant for piping, keep it style-free.
-            let warning_style = matches!(format_mode, OutputMode::Check)
-                .then(|| GraphicalTheme::default().warning_style());
+            let warning_theme =
+                matches!(format_mode, OutputMode::Check).then(GraphicalTheme::default);
             let mut output = String::new();
             for (idx, (path, elapsed)) in changed_paths.into_iter().enumerate() {
                 if idx != 0 {
                     output.push('\n');
                 }
-                match warning_style {
+                match &warning_theme {
                     // Style per line, some log viewers reset ANSI state on line breaks
-                    Some(style) => write!(output, "{}", style.style(&path)).unwrap(),
+                    Some(theme) => theme.write_warning(&mut output, &path).unwrap(),
                     None => output.push_str(&path),
                 }
                 if let Some(elapsed) = elapsed {

crates/oxc_diagnostics/Cargo.toml

@@ -23,7 +23,6 @@ bytecount = { workspace = true }
 cow-utils = { workspace = true }
 itoa = { workspace = true }
 memchr = { workspace = true }
-owo-colors = { workspace = true }
 percent-encoding = { workspace = true }
 smallvec = { workspace = true }
 textwrap = { workspace = true }

crates/oxc_diagnostics/src/handlers/graphical/gutter.rs

@@ -8,14 +8,13 @@
 
 use std::fmt::{self, Write};
 
-use owo_colors::OwoColorize;
-
 use super::{
     handler::GraphicalReportHandler,
     label::write_repeated_char,
     line::Line,
     span::{FancySpan, LabelRenderMode},
 };
+use crate::handlers::theme::DiagnosticColorize;
 
 impl GraphicalReportHandler {
     pub(super) fn write_linum(

crates/oxc_diagnostics/src/handlers/graphical/label.rs

@@ -9,7 +9,6 @@
 
 use std::{cmp::max, fmt};
 
-use owo_colors::{OwoColorize, Style};
 use smallvec::SmallVec;
 
 use super::{
@@ -17,7 +16,7 @@ use super::{
     line::Line,
     span::{FancySpan, LabelRenderMode},
 };
-use crate::handlers::theme::ThemeCharacters;
+use crate::handlers::theme::{DiagnosticColorize, Style, ThemeCharacters};
 
 struct Underline {
     padding: usize,
@@ -351,7 +350,7 @@ mod tests {
             let label = LabelText {
                 chars: &theme.characters,
                 label: "plain label",
-                style: Style::new(),
+                style: Style::Plain,
                 render_mode,
             };
             output.clear();

crates/oxc_diagnostics/src/handlers/graphical/report.rs

@@ -9,11 +9,10 @@
 
 use std::fmt::{self, Write as _};
 
-use owo_colors::OwoColorize;
 use smallvec::SmallVec;
 
 use super::handler::{GraphicalReportHandler, LinkStyle};
-use crate::{Diagnostic, Severity, source_impls::SpanScanner};
+use crate::{Diagnostic, Severity, handlers::theme::DiagnosticColorize, source_impls::SpanScanner};
 
 struct TitleBuffer(SmallVec<[u8; 128]>);
 

crates/oxc_diagnostics/src/handlers/graphical/snippet.rs

@@ -10,7 +10,6 @@
 
 use std::{borrow::Cow, cmp::max, fmt};
 
-use owo_colors::OwoColorize;
 use smallvec::SmallVec;
 
 use super::{
@@ -20,6 +19,7 @@ use super::{
 };
 use crate::{
     Diagnostic, LabeledSpan,
+    handlers::theme::DiagnosticColorize,
     source_impls::{SpanContents, SpanScanner},
 };
 

crates/oxc_diagnostics/src/handlers/graphical/span.rs

@@ -4,10 +4,10 @@
 //! it will be drawn in. Label text stays borrowed and is split into display
 //! lines only when it is drawn.
 
-use owo_colors::Style;
-
 use oxc_span::Span;
 
+use crate::handlers::theme::Style;
+
 /// How a label is being drawn on the current output line.
 ///
 /// A label can be a single trailing line, or a block that spans several output

crates/oxc_diagnostics/src/handlers/theme.rs

@@ -1,10 +1,8 @@
 use std::{
-    env,
+    env, fmt,
     io::{self, IsTerminal},
 };
 
-use owo_colors::Style;
-
 /// Theme used by [`GraphicalReportHandler`](crate::GraphicalReportHandler).
 ///
 /// Use one of the predefined constructors below.
@@ -66,13 +64,82 @@ impl GraphicalTheme {
         Self { characters: ThemeCharacters::ascii(), styles: ThemeStyles::none() }
     }
 
-    /// Style used for warning text.
-    #[must_use]
-    pub const fn warning_style(&self) -> Style {
-        self.styles.warning
+    /// Write text using the theme's warning style.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error when writing the text fails.
+    pub fn write_warning(&self, f: &mut impl fmt::Write, value: impl fmt::Display) -> fmt::Result {
+        self.styles.warning.write(f, value)
     }
 }
 
+const ANSI_RESET: &str = "\x1b[0m";
+const ANSI_PREFIXES: [&str; 9] = [
+    "",
+    "\x1b[38;2;225;80;80;1m",
+    "\x1b[38;2;244;191;117;1m",
+    "\x1b[38;2;106;159;181m",
+    "\x1b[38;2;92;157;255;1m",
+    "\x1b[2m",
+    "\x1b[38;2;246;87;248m",
+    "\x1b[38;2;30;201;212m",
+    "\x1b[38;2;145;246;111m",
+];
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+#[repr(u8)]
+pub(super) enum Style {
+    Plain,
+    Error,
+    Warning,
+    Info,
+    Link,
+    LineNumber,
+    Highlight1,
+    Highlight2,
+    Highlight3,
+}
+
+impl Style {
+    const fn prefix(self) -> &'static str {
+        ANSI_PREFIXES[self as usize]
+    }
+
+    pub(super) const fn is_plain(self) -> bool {
+        matches!(self, Self::Plain)
+    }
+
+    fn write(self, f: &mut impl fmt::Write, value: impl fmt::Display) -> fmt::Result {
+        let prefix = self.prefix();
+        f.write_str(prefix)?;
+        write!(f, "{value}")?;
+        if self.is_plain() { Ok(()) } else { f.write_str(ANSI_RESET) }
+    }
+}
+
+pub(super) struct Styled<T> {
+    target: T,
+    style: Style,
+}
+
+impl<T: fmt::Display> fmt::Display for Styled<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let prefix = self.style.prefix();
+        f.write_str(prefix)?;
+        self.target.fmt(f)?;
+        if self.style.is_plain() { Ok(()) } else { f.write_str(ANSI_RESET) }
+    }
+}
+
+pub(super) trait DiagnosticColorize: Sized {
+    fn style(self, style: Style) -> Styled<Self> {
+        Styled { target: self, style }
+    }
+}
+
+impl<T> DiagnosticColorize for T {}
+
 #[derive(Debug, Clone)]
 pub(super) struct ThemeStyles {
     pub(super) error: Style,
@@ -85,38 +152,30 @@ pub(super) struct ThemeStyles {
     pub(super) highlights: [Style; 3],
 }
 
-fn style() -> Style {
-    Style::new()
-}
-
 impl ThemeStyles {
     fn rgb() -> Self {
         Self {
-            error: style().fg_rgb::<225, 80, 80>().bold(),
-            warning: style().fg_rgb::<244, 191, 117>().bold(),
-            advice: style().fg_rgb::<106, 159, 181>(),
-            help: style().fg_rgb::<106, 159, 181>(),
-            note: style().fg_rgb::<106, 159, 181>(),
-            link: style().fg_rgb::<92, 157, 255>().bold(),
-            linum: style().dimmed(),
-            highlights: [
-                style().fg_rgb::<246, 87, 248>(),
-                style().fg_rgb::<30, 201, 212>(),
-                style().fg_rgb::<145, 246, 111>(),
-            ],
+            error: Style::Error,
+            warning: Style::Warning,
+            advice: Style::Info,
+            help: Style::Info,
+            note: Style::Info,
+            link: Style::Link,
+            linum: Style::LineNumber,
+            highlights: [Style::Highlight1, Style::Highlight2, Style::Highlight3],
         }
     }
 
     fn none() -> Self {
         Self {
-            error: style(),
-            warning: style(),
-            advice: style(),
-            help: style(),
-            note: style(),
-            link: style(),
-            linum: style(),
-            highlights: [style(); 3],
+            error: Style::Plain,
+            warning: Style::Plain,
+            advice: Style::Plain,
+            help: Style::Plain,
+            note: Style::Plain,
+            link: Style::Plain,
+            linum: Style::Plain,
+            highlights: [Style::Plain; 3],
         }
     }
 }