clippy_dev: Parsing revamp part 2/N (#15921)

Based on #15866

This adds a parsing context that can allocate from an arena. Ultimately
this will also store a source map for better error reporting, but a few
other changes are happening before that.

The arena itself is unlikely to be needed from a perf standpoint
(reading all the files should be the slow part), but having more things
be copyable is nice. For reference the perf impact of this change is
within the noise.

changelog: none

Author: samueltardieu

clippy_dev/src/deprecate_lint.rs

@@ -1,4 +1,4 @@
-use crate::parse::{DeprecatedLint, Lint, find_lint_decls, read_deprecated_lints};
+use crate::parse::{DeprecatedLint, Lint, ParseCx};
 use crate::update_lints::generate_lint_files;
 use crate::utils::{UpdateMode, Version};
 use std::ffi::OsStr;
@@ -14,17 +14,20 @@ use std::{fs, io};
 /// # Panics
 ///
 /// If a file path could not read from or written to
-pub fn deprecate(clippy_version: Version, name: &str, reason: &str) {
-    let mut lints = find_lint_decls();
-    let (mut deprecated_lints, renamed_lints) = read_deprecated_lints();
+pub fn deprecate<'cx>(cx: ParseCx<'cx>, clippy_version: Version, name: &'cx str, reason: &'cx str) {
+    let mut lints = cx.find_lint_decls();
+    let (mut deprecated_lints, renamed_lints) = cx.read_deprecated_lints();
 
     let Some(lint) = lints.iter().find(|l| l.name == name) else {
         eprintln!("error: failed to find lint `{name}`");
         return;
     };
 
-    let prefixed_name = String::from_iter(["clippy::", name]);
-    match deprecated_lints.binary_search_by(|x| x.name.cmp(&prefixed_name)) {
+    let prefixed_name = cx.str_buf.with(|buf| {
+        buf.extend(["clippy::", name]);
+        cx.arena.alloc_str(buf)
+    });
+    match deprecated_lints.binary_search_by(|x| x.name.cmp(prefixed_name)) {
         Ok(_) => {
             println!("`{name}` is already deprecated");
             return;
@@ -33,8 +36,8 @@ pub fn deprecate(clippy_version: Version, name: &str, reason: &str) {
             idx,
             DeprecatedLint {
                 name: prefixed_name,
-                reason: reason.into(),
-                version: clippy_version.rust_display().to_string(),
+                reason,
+                version: cx.str_buf.alloc_display(cx.arena, clippy_version.rust_display()),
             },
         ),
     }
@@ -58,8 +61,8 @@ pub fn deprecate(clippy_version: Version, name: &str, reason: &str) {
     }
 }
 
-fn remove_lint_declaration(name: &str, path: &Path, lints: &mut Vec<Lint>) -> io::Result<bool> {
-    fn remove_lint(name: &str, lints: &mut Vec<Lint>) {
+fn remove_lint_declaration(name: &str, path: &Path, lints: &mut Vec<Lint<'_>>) -> io::Result<bool> {
+    fn remove_lint(name: &str, lints: &mut Vec<Lint<'_>>) {
         lints.iter().position(|l| l.name == name).map(|pos| lints.remove(pos));
     }
 

clippy_dev/src/fmt.rs

@@ -268,7 +268,7 @@ fn run_rustfmt(update_mode: UpdateMode) {
     .expect("invalid rustfmt path");
     rustfmt_path.truncate(rustfmt_path.trim_end().len());
 
-    let args: Vec<_> = walk_dir_no_dot_or_target()
+    let args: Vec<_> = walk_dir_no_dot_or_target(".")
         .filter_map(|e| {
             let e = expect_action(e, ErrAction::Read, ".");
             e.path()

clippy_dev/src/lib.rs

@@ -5,6 +5,7 @@
     new_range_api,
     os_str_slice,
     os_string_truncate,
+    pattern,
     rustc_private,
     slice_split_once
 )]
@@ -17,6 +18,7 @@
 )]
 #![allow(clippy::missing_panics_doc)]
 
+extern crate rustc_arena;
 #[expect(unused_extern_crates, reason = "required to link to rustc crates")]
 extern crate rustc_driver;
 extern crate rustc_lexer;
@@ -34,7 +36,8 @@ pub mod setup;
 pub mod sync;
 pub mod update_lints;
 
+mod parse;
 mod utils;
-pub use utils::{ClippyInfo, UpdateMode};
 
-mod parse;
+pub use self::parse::{ParseCx, new_parse_cx};
+pub use self::utils::{ClippyInfo, UpdateMode};

clippy_dev/src/main.rs

@@ -4,8 +4,8 @@
 
 use clap::{Args, Parser, Subcommand};
 use clippy_dev::{
-    ClippyInfo, UpdateMode, deprecate_lint, dogfood, fmt, lint, new_lint, release, rename_lint, serve, setup, sync,
-    update_lints,
+    ClippyInfo, UpdateMode, deprecate_lint, dogfood, fmt, lint, new_lint, new_parse_cx, release, rename_lint, serve,
+    setup, sync, update_lints,
 };
 use std::env;
 
@@ -27,15 +27,15 @@ fn main() {
             allow_no_vcs,
         } => dogfood::dogfood(fix, allow_dirty, allow_staged, allow_no_vcs),
         DevCommand::Fmt { check } => fmt::run(UpdateMode::from_check(check)),
-        DevCommand::UpdateLints { check } => update_lints::update(UpdateMode::from_check(check)),
+        DevCommand::UpdateLints { check } => new_parse_cx(|cx| update_lints::update(cx, UpdateMode::from_check(check))),
         DevCommand::NewLint {
             pass,
             name,
             category,
             r#type,
             msrv,
         } => match new_lint::create(clippy.version, pass, &name, &category, r#type.as_deref(), msrv) {
-            Ok(()) => update_lints::update(UpdateMode::Change),
+            Ok(()) => new_parse_cx(|cx| update_lints::update(cx, UpdateMode::Change)),
             Err(e) => eprintln!("Unable to create lint: {e}"),
         },
         DevCommand::Setup(SetupCommand { subcommand }) => match subcommand {
@@ -78,13 +78,18 @@ fn main() {
             old_name,
             new_name,
             uplift,
-        } => rename_lint::rename(
-            clippy.version,
-            &old_name,
-            new_name.as_ref().unwrap_or(&old_name),
-            uplift,
-        ),
-        DevCommand::Deprecate { name, reason } => deprecate_lint::deprecate(clippy.version, &name, &reason),
+        } => new_parse_cx(|cx| {
+            rename_lint::rename(
+                cx,
+                clippy.version,
+                &old_name,
+                new_name.as_ref().unwrap_or(&old_name),
+                uplift,
+            );
+        }),
+        DevCommand::Deprecate { name, reason } => {
+            new_parse_cx(|cx| deprecate_lint::deprecate(cx, clippy.version, &name, &reason));
+        },
         DevCommand::Sync(SyncCommand { subcommand }) => match subcommand {
             SyncSubcommand::UpdateNightly => sync::update_nightly(),
         },