Improve compile time a tiny bit

xtask/src/codegen.rs

@@ -77,12 +77,12 @@ fn update(path: &Path, contents: &str, mode: Mode) -> Result<()> {
 
 const PREAMBLE: &str = "Generated file, do not edit by hand, see `xtask/src/codegen`";
 
-fn reformat(text: impl std::fmt::Display) -> Result<String> {
+fn reformat(text: &str) -> Result<String> {
     let _e = pushenv("RUSTUP_TOOLCHAIN", "stable");
     ensure_rustfmt()?;
     let stdout = run!(
         "rustfmt --config-path {} --config fn_single_line=true", project_root().join("rustfmt.toml").display();
-        <text.to_string().as_bytes()
+        <text.as_bytes()
     )?;
     Ok(format!("//! {}\n\n{}\n", PREAMBLE, stdout))
 }

xtask/src/codegen/gen_assists_docs.rs

@@ -134,7 +134,7 @@ r#####"
 
         buf.push_str(&test)
     }
-    let buf = reformat(buf)?;
+    let buf = reformat(&buf.to_string())?;
     codegen::update(&project_root().join("crates/assists/src/tests/generated.rs"), &buf, mode)
 }
 

xtask/src/codegen/gen_features.rs

@@ -46,5 +46,5 @@ fn generate_descriptor(src_dir: PathBuf) -> Result<String> {
             #(#definitions),*
         ];
     };
-    reformat(ts)
+    reformat(&ts.to_string())
 }

xtask/src/codegen/gen_syntax.rs

@@ -61,10 +61,13 @@ fn generate_tokens(grammar: &AstSrc) -> Result<String> {
         }
     });
 
-    let pretty = reformat(quote! {
+    let pretty = reformat(
+        &quote! {
             use crate::{SyntaxKind::{self, *}, SyntaxToken, ast::AstToken};
             #(#tokens)*
-    })?
+        }
+        .to_string(),
+    )?
     .replace("#[derive", "\n#[derive");
     Ok(pretty)
 }
@@ -261,7 +264,7 @@ fn generate_nodes(kinds: KindsSrc<'_>, grammar: &AstSrc) -> Result<String> {
         }
     }
 
-    let pretty = reformat(res)?;
+    let pretty = reformat(&res)?;
     Ok(pretty)
 }
 
@@ -383,7 +386,7 @@ fn generate_syntax_kinds(grammar: KindsSrc<'_>) -> Result<String> {
         }
     };
 
-    reformat(ast)
+    reformat(&ast.to_string())
 }
 
 fn to_upper_snake_case(s: &str) -> String {