s3: reach the streaming download task through its raw pointer on both threads

.github/workflows/miri.yml

@@ -8,7 +8,7 @@ on:
   workflow_dispatch:
   pull_request:
     paths:
-      # The FFI-free crate set covered by MIRI_CRATES in scripts/rust-miri.ts
+      # The crate set covered by MIRI_CRATES in scripts/rust-miri.ts
       - "src/ast/**"
       - "src/base64/**"
       - "src/clap/**"
@@ -22,6 +22,7 @@ on:
       - "src/ptr/**"
       - "src/resolve_builtins/**"
       - "src/shell_parser/**"
+      - "src/threading/**"
       - "src/wyhash/**"
       - "scripts/rust-miri.ts"
       - "Cargo.toml"

scripts/rust-miri.ts

@@ -1,11 +1,12 @@
 #!/usr/bin/env bun
 /**
- * `cargo miri test` for the FFI-free crate set.
+ * `cargo miri test` for the crates Miri can interpret end to end.
  *
  * Miri interprets MIR and catches UB (use-after-free, out-of-bounds,
  * uninit reads, data races, aliasing violations) at runtime. It cannot call
- * foreign functions, so this only covers the pure-Rust corner of the
- * workspace — which is also where `unsafe` density is highest.
+ * foreign functions beyond the libc subset it ships shims for, so this only
+ * covers the (nearly) pure-Rust corner of the workspace — which is also where
+ * `unsafe` density is highest.
  *
  * Aliasing model: `-Zmiri-tree-borrows`, not the default Stacked Borrows.
  * Stacked Borrows invalidates every raw pointer derived from `&mut self` the
@@ -27,9 +28,11 @@ import { resolve } from "node:path";
 const repo = resolve(import.meta.dirname, "..");
 
 // Crates that pass `cargo miri test` under Tree Borrows. To add one it must
-// (a) have at least one `#[test]`, (b) compile under `--cfg test`, (c) not
-// call into `extern "C"` at test runtime — Miri reports
-// `unsupported operation: can't call foreign function` if it does.
+// (a) have at least one `#[test]`, (b) compile under `--cfg test`, (c) only
+// call `extern "C"` functions Miri ships shims for at test runtime (libc's
+// futex syscall and thread APIs, as bun_threading does, are fine; anything
+// vendored is not) — Miri reports
+// `unsupported operation: can't call foreign function` otherwise.
 const MIRI_CRATES = [
   "bun_ast",
   "bun_base64",
@@ -44,6 +47,7 @@ const MIRI_CRATES = [
   "bun_ptr",
   "bun_resolve_builtins",
   "bun_shell_parser",
+  "bun_threading",
   "bun_wyhash",
 ];
 

src/bundler/LinkerContext.rs

@@ -1366,9 +1366,17 @@ impl SourceMapDataTask {
         // pointee outlives every task (joined via `line_offset_wait_group`).
         let ctx = task.ctx.expect("SourceMapDataTask.ctx");
         scopeguard::defer! {
-            // Both `&self` methods (atomic ops) — safe via `ParentRef::Deref`.
             ctx.mark_pending_task_done();
-            ctx.source_maps.line_offset_wait_group.finish();
+            // SAFETY: the linker is blocked in `line_offset_wait_group.wait()`
+            // (or will be) until this finish, so the group is live; it frees the
+            // tasks as soon as `wait()` returns (`generate_chunks_in_parallel`),
+            // which is why this goes through `finish_raw` and is the last
+            // statement to touch `ctx`.
+            unsafe {
+                WaitGroup::finish_raw(
+                    &raw const (*ctx.as_const_ptr()).source_maps.line_offset_wait_group,
+                )
+            };
         }
 
         // SAFETY: ctx is BundleV2.linker; container_of recovers the parent. We
@@ -1403,9 +1411,13 @@ impl SourceMapDataTask {
         // pointee outlives every task (joined via `quoted_contents_wait_group`).
         let ctx = task.ctx.expect("SourceMapDataTask.ctx");
         scopeguard::defer! {
-            // Both `&self` methods (atomic ops) — safe via `ParentRef::Deref`.
             ctx.mark_pending_task_done();
-            ctx.source_maps.quoted_contents_wait_group.finish();
+            // SAFETY: as in `run_line_offset`, for `quoted_contents_wait_group`.
+            unsafe {
+                WaitGroup::finish_raw(
+                    &raw const (*ctx.as_const_ptr()).source_maps.quoted_contents_wait_group,
+                )
+            };
         }
 
         // SAFETY: see `run_line_offset` — raw-ptr container_of, no `&mut`