bun_core: fix clippy on the Windows and FreeBSD targets and lint them in CI

.github/workflows/clippy.yml

@@ -13,6 +13,8 @@ on:
       - "src/codegen/**"
       - "scripts/build/**"
       - "scripts/build.ts"
+      - "scripts/rust-clippy-cross.ts"
+      - "scripts/rust-clippy-cross-budgets.json"
       - "Cargo.toml"
       - "Cargo.lock"
       - "clippy.toml"
@@ -26,8 +28,9 @@ env:
   BUN_VERSION: "1.3.14"
   LLVM_VERSION_MAJOR: "21"
   # Pin the toolchain explicitly so rustup ignores rust-toolchain.toml's
-  # `targets` list (11 cross triples ≈ 450 MB of prebuilt std we don't need
-  # to lint the host). Keep in sync with `channel` in rust-toolchain.toml.
+  # `targets` list (11 cross triples ≈ 450 MB of prebuilt std); the Setup Rust
+  # step adds the std of just the triples `rust:clippy-cross` lints. Keep in
+  # sync with `channel` in rust-toolchain.toml.
   RUSTUP_TOOLCHAIN: nightly-2026-07-20
 
 jobs:
@@ -59,12 +62,16 @@ jobs:
 
       - name: Setup Rust
         run: |
-          rustup toolchain install "$RUSTUP_TOOLCHAIN" --profile minimal --component clippy
+          # The budget file's keys are the triples the cross step lints; clippy
+          # needs their rust-std and nothing else.
+          cross_targets=$(bun -e 'console.log(Object.keys(await Bun.file("scripts/rust-clippy-cross-budgets.json").json()).join(","))')
+          rustup toolchain install "$RUSTUP_TOOLCHAIN" --profile minimal --component clippy --target "$cross_targets"
           rustup override set "$RUSTUP_TOOLCHAIN"
           # rustc/clippy diagnostics → inline PR annotations
           echo "::add-matcher::.github/rust-matcher.json"
 
       - name: Generate codegen
+        id: codegen
         # bun_runtime/bun_jsc/bun_core `include!()` files under
         # build/debug/codegen/; clippy can't lint those crates without them.
         # `clone-lolhtml` fetches the vendored Rust path-dep
@@ -78,3 +85,13 @@ jobs:
         env:
           BUN_CODEGEN_DIR: ${{ github.workspace }}/build/debug/codegen
         run: bun run rust:clippy
+
+      - name: cargo clippy (cross targets)
+        # Code gated on another OS / arch / libc is invisible to the host run
+        # above; this lints it per target against the per-file budgets in
+        # scripts/rust-clippy-cross-budgets.json. Runs even when the host run
+        # failed so a PR gets both sets of diagnostics at once.
+        if: ${{ !cancelled() && steps.codegen.outcome == 'success' }}
+        env:
+          BUN_CODEGEN_DIR: ${{ github.workspace }}/build/debug/codegen
+        run: bun run rust:clippy-cross

CLAUDE.md

@@ -198,7 +198,7 @@ Several situational sections live in `.claude/docs/landing-prs.md` — read the
 6. **Use absolute paths** - Always use absolute paths in file operations
 7. **Avoid shell commands** - Don't use `find` or `grep` in tests; use Bun's Glob and built-in tools
 8. **Memory management** - Prefer RAII (`Drop`) over manual cleanup. Arena edge case: values allocated in an arena (`Arena<T>`/`bumpalo`) do **not** run `Drop` on arena reset — types owning a heap allocation or refcount must be freed/deref'd explicitly first, mirroring the original Zig `deinit()` order.
-9. **Cross-platform** - Run `bun run rust:check-all` to compile across all targets (linux/macos/windows × x64/aarch64) when making platform-specific changes. `#[cfg(...)]`-gated code is not type-checked unless the matching target is built.
+9. **Cross-platform** - Run `bun run rust:check-all` to compile across all targets (linux/macos/windows × x64/aarch64) when making platform-specific changes. `#[cfg(...)]`-gated code is not type-checked unless the matching target is built. Same for clippy: CI lints the Linux host plus the targets in `scripts/rust-clippy-cross-budgets.json` (per-file budgets of the remaining hits), so also run `bun run rust:clippy-cross` when touching `cfg(windows)` / `cfg(target_os = ...)` code.
 10. **Debug builds** - Use `BUN_DEBUG_QUIET_LOGS=1` to disable debug logging, or `BUN_DEBUG_<SCOPE>=1` to enable a specific `bun_core::output` scoped logger
 11. **Be humble & honest** - NEVER overstate what you got done or what actually works in commits, PRs or in messages to the user.
 12. **Branch names must start with `claude/`** - This is a requirement for the CI to work.

package.json

@@ -71,6 +71,7 @@
     "rust:check": "cargo check --workspace --keep-going",
     "rust:check-all": "bun scripts/rust-check-all.ts",
     "rust:clippy": "cargo clippy --workspace --no-deps --keep-going",
+    "rust:clippy-cross": "bun scripts/rust-clippy-cross.ts",
     "rust:miri": "bun scripts/rust-miri.ts",
     "rust:timings": "bun scripts/rust-timings.ts",
     "codegen:string-maps": "for f in src/**/*.string-map.ts; do bun src/codegen/generate-string-map.ts \"$f\" \"${f%.string-map.ts}.generated.rs\"; done",