Add codegen tidy check enforcing FIXME over TODO

Author: reddevilmidzy

src/tools/tidy/src/codegen.rs

@@ -0,0 +1,60 @@
+//! Tidy check for codegen backend TODO policy.
+
+use std::ffi::OsStr;
+use std::path::Path;
+
+use crate::diagnostics::{CheckId, TidyCtx};
+use crate::walk::walk;
+
+fn is_codegen_repo_path(path: &Path) -> bool {
+    const CODEGEN_REPO_PATHS: &[&str] =
+        &["compiler/rustc_codegen_cranelift", "compiler/rustc_codegen_gcc"];
+
+    CODEGEN_REPO_PATHS.iter().any(|repo| path.ancestors().any(|p| p.ends_with(Path::new(repo))))
+}
+
+fn has_supported_extension(path: &Path) -> bool {
+    const EXTENSIONS: &[&str] =
+        &["rs", "py", "js", "sh", "c", "cpp", "h", "md", "css", "ftl", "toml", "yml", "yaml"];
+    path.extension().is_some_and(|ext| EXTENSIONS.iter().any(|e| ext == OsStr::new(e)))
+}
+
+pub fn check(path: &Path, tidy_ctx: TidyCtx) {
+    let mut check = tidy_ctx.start_check(CheckId::new("codegen").path(path));
+
+    fn skip(path: &Path, is_dir: bool) -> bool {
+        if path.file_name().is_some_and(|name| name.to_string_lossy().starts_with(".#")) {
+            // Editor temp file.
+            return true;
+        }
+
+        if is_dir {
+            return false;
+        }
+
+        // Scan only selected text file types.
+        !has_supported_extension(path)
+    }
+
+    walk(path, skip, &mut |entry, contents| {
+        let file = entry.path();
+
+        if !is_codegen_repo_path(file) {
+            return;
+        }
+
+        for (i, line) in contents.split('\n').enumerate() {
+            let trimmed = line.trim();
+
+            // TODO policy for codegen-only trees.
+            if trimmed.contains("TODO") && !trimmed.contains("ignore-tidy-todo") {
+                check.error(format!(
+                    "{}:{}: TODO is used for tasks that should be done before merging a PR; \
+                     if you want to leave a message in the codebase use FIXME",
+                    file.display(),
+                    i + 1
+                ));
+            }
+        }
+    });
+}

src/tools/tidy/src/lib.rs

@@ -104,6 +104,7 @@ pub fn files_modified(
 pub mod alphabetical;
 pub mod arg_parser;
 pub mod bins;
+pub mod codegen;
 pub mod debug_artifacts;
 pub mod deps;
 pub mod diagnostics;

src/tools/tidy/src/main.rs

@@ -109,6 +109,7 @@ fn main() {
         check!(error_codes, &root_path, &[&compiler_path, &librustdoc_path]);
         check!(target_policy, &root_path);
         check!(gcc_submodule, &root_path, &compiler_path);
+        check!(codegen, &compiler_path);
 
         // Checks that only make sense for the std libs.
         check!(pal, &library_path);

src/tools/tidy/src/style.rs

@@ -378,11 +378,16 @@ pub fn check(path: &Path, tidy_ctx: TidyCtx) {
     // In some cases, a style check would be triggered by its own implementation
     // or comments. A simple workaround is to just allowlist this file.
     let this_file = Path::new(file!());
+    let codegen_file = Path::new("src/tools/tidy/src/codegen.rs");
 
     walk(path, skip, &mut |entry, contents| {
         let file = entry.path();
         let path_str = file.to_string_lossy();
         let filename = file.file_name().unwrap().to_string_lossy();
+        let is_codegen_tidy_file = file.ends_with(codegen_file);
+        if is_codegen_tidy_file {
+            return;
+        }
 
         let is_css_file = filename.ends_with(".css");
         let under_rustfmt = filename.ends_with(".rs") &&