Address code review: checked arithmetic, threading feature deps, Send gate

youknowone · youknowone · commit 3af0cf862962 · 2026-03-04T20:02:28.000+09:00
- Use checked arithmetic for nlocalsplus in Frame::new
- Add "std" to threading feature dependencies in rustpython-common
- Gate GcState Send impl with #[cfg(feature = "threading")]
diff --git a/crates/common/Cargo.toml b/crates/common/Cargo.toml
@@ -11,7 +11,7 @@ license.workspace = true
 [features]
 default = ["std"]
 std = []
-threading = ["parking_lot"]
+threading = ["parking_lot", "std"]
 wasm_js = ["getrandom/wasm_js"]
 
 [dependencies]
diff --git a/crates/vm/src/frame.rs b/crates/vm/src/frame.rs
@@ -672,7 +672,10 @@ impl Frame {
                 .collect();
 
         // Create unified localsplus: varnames + cellvars + freevars + stack
-        let nlocalsplus = nlocals + num_cells + nfrees;
+        let nlocalsplus = nlocals
+            .checked_add(num_cells)
+            .and_then(|v| v.checked_add(nfrees))
+            .expect("Frame::new: nlocalsplus overflow");
         let max_stackdepth = code.max_stackdepth as usize;
         let mut localsplus = if use_datastack {
             LocalsPlus::new_on_datastack(nlocalsplus, max_stackdepth, vm)
diff --git a/crates/vm/src/gc_state.rs b/crates/vm/src/gc_state.rs
@@ -136,7 +136,9 @@ pub struct GcState {
 
 // SAFETY: GcObjectPtr wraps NonNull which is !Send/!Sync, but we only use it as an opaque
 // hash key. PyObjectRef is Send. In threading mode, PyRwLock/PyMutex are parking_lot based
-// and genuinely Sync. In non-threading mode, gc_state() is thread-local so Sync is not needed.
+// and genuinely Sync. In non-threading mode, gc_state() is thread-local so neither Send
+// nor Sync is needed.
+#[cfg(feature = "threading")]
 unsafe impl Send for GcState {}
 #[cfg(feature = "threading")]
 unsafe impl Sync for GcState {}
