perf(cfg, diagnostics, lexer, syntax, tasks): remove write! macro where unnecessary (#10236)

Same as #10230, for small changes to various crates.

Replace usages of `write!` macro with either `fmt.write_str(...)` for static strings or `Display::fmt` / `Debug::fmt` for other values, where it's not being used to concatenate multiple values.

`Formatter::write_str` is more performant, as it avoids various checks. `Display::fmt` / `Debug::fmt` may also perform a little better in some cases, and will be equivalent in others. But in all cases it should be better for compile times, due to avoiding macro expansion and trait resolution.

crates/oxc_cfg/src/dot.rs

@@ -1,4 +1,7 @@
-use std::{borrow::Cow, fmt};
+use std::{
+    borrow::Cow,
+    fmt::{self, Debug, Display},
+};
 
 use itertools::Itertools as _;
 use petgraph::{
@@ -104,12 +107,12 @@ impl<'a> Attr<'a> {
     }
 }
 
-impl fmt::Debug for Attr<'_> {
+impl Debug for Attr<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Int(i) => write!(f, "{i}"),
-            Self::String(s) => write!(f, "{s:?}"),
-            Self::Identifier(ident) => write!(f, "{ident}"), // display instead of debug
+            Self::Int(i) => Display::fmt(i, f),
+            Self::String(s) => Debug::fmt(s, f),
+            Self::Identifier(ident) => Display::fmt(ident, f), // Display instead of Debug
         }
     }
 }
@@ -167,17 +170,17 @@ where
     }
 }
 
-impl fmt::Debug for Attrs<'_> {
+impl Debug for Attrs<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if self.0.is_empty() {
             return Ok(());
         }
 
-        let l = self.0.len();
         for (i, (k, v)) in self.0.iter().enumerate() {
-            write!(f, "{k}={v:?}")?;
-            if i < l - 1 {
-                write!(f, ", ")?;
+            if i == 0 {
+                write!(f, "{k}={v:?}")?;
+            } else {
+                write!(f, ", {k}={v:?}")?;
             }
         }
 

crates/oxc_diagnostics/src/lib.rs

@@ -105,7 +105,7 @@ impl OxcCode {
     }
 }
 
-impl fmt::Display for OxcCode {
+impl Display for OxcCode {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match (&self.scope, &self.number) {
             (Some(scope), Some(number)) => write!(f, "{scope}({number})"),
@@ -126,9 +126,9 @@ pub struct OxcDiagnosticInner {
     pub url: Option<Cow<'static, str>>,
 }
 
-impl fmt::Display for OxcDiagnostic {
+impl Display for OxcDiagnostic {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", &self.message)
+        self.message.fmt(f)
     }
 }
 

crates/oxc_parser/src/lexer/kind.rs

@@ -1,6 +1,6 @@
 //! ECMAScript Token Kinds
 
-use std::fmt;
+use std::fmt::{self, Display};
 
 /// Lexer token kind
 ///
@@ -693,8 +693,8 @@ impl Kind {
     }
 }
 
-impl fmt::Display for Kind {
+impl Display for Kind {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.to_str())
+        self.to_str().fmt(f)
     }
 }

crates/oxc_syntax/src/es_target.rs

@@ -63,6 +63,6 @@ impl fmt::Display for ESTarget {
             Self::ES2025 => "es2025",
             Self::ESNext => "esnext",
         };
-        write!(f, "{s}",)
+        f.write_str(s)
     }
 }

tasks/rulegen/src/main.rs

@@ -621,22 +621,23 @@ impl RuleKind {
 
 impl Display for RuleKind {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        match self {
-            Self::ESLint => write!(f, "eslint"),
-            Self::Typescript => write!(f, "typescript-eslint"),
-            Self::Jest => write!(f, "eslint-plugin-jest"),
-            Self::Unicorn => write!(f, "eslint-plugin-unicorn"),
-            Self::Import => write!(f, "eslint-plugin-import"),
-            Self::React => write!(f, "eslint-plugin-react"),
-            Self::ReactPerf => write!(f, "eslint-plugin-react-perf"),
-            Self::JSXA11y => write!(f, "eslint-plugin-jsx-a11y"),
-            Self::Oxc => write!(f, "oxc"),
-            Self::NextJS => write!(f, "eslint-plugin-next"),
-            Self::JSDoc => write!(f, "eslint-plugin-jsdoc"),
-            Self::Node => write!(f, "eslint-plugin-n"),
-            Self::Promise => write!(f, "eslint-plugin-promise"),
-            Self::Vitest => write!(f, "eslint-plugin-vitest"),
-        }
+        let kind_name = match self {
+            Self::ESLint => "eslint",
+            Self::Typescript => "typescript-eslint",
+            Self::Jest => "eslint-plugin-jest",
+            Self::Unicorn => "eslint-plugin-unicorn",
+            Self::Import => "eslint-plugin-import",
+            Self::React => "eslint-plugin-react",
+            Self::ReactPerf => "eslint-plugin-react-perf",
+            Self::JSXA11y => "eslint-plugin-jsx-a11y",
+            Self::Oxc => "oxc",
+            Self::NextJS => "eslint-plugin-next",
+            Self::JSDoc => "eslint-plugin-jsdoc",
+            Self::Node => "eslint-plugin-n",
+            Self::Promise => "eslint-plugin-promise",
+            Self::Vitest => "eslint-plugin-vitest",
+        };
+        f.write_str(kind_name)
     }
 }
 

tasks/website/src/linter/rules/html.rs

@@ -81,7 +81,7 @@ impl HtmlWriter {
         // Write the opening tag
         write!(s, "<{tag}")?;
         if attrs.is_empty() {
-            writeln!(s, ">")?;
+            s.write_str(">\n")?;
         } else {
             writeln!(s, " {attrs}>")?;
         }