This flag is used to make the execution order around `+=` operators
pessimistic. Failure to save/restore the flag was causing independent
async blocks to effect one another, leading to strange ICEs and failed
assumptions.
let outer_ec = mem::replace(&mut self.expr_and_pat_count, 0);
let outer_cx = self.cx;
let outer_ts = mem::take(&mut self.terminating_scopes);
+ let outer_pessimistic_yield = mem::replace(&mut self.pessimistic_yield, false);
self.terminating_scopes.insert(body.value.hir_id.local_id);
if let Some(root_id) = self.cx.root_id {
self.expr_and_pat_count = outer_ec;
self.cx = outer_cx;
self.terminating_scopes = outer_ts;
+ self.pessimistic_yield = outer_pessimistic_yield;
}
fn visit_arm(&mut self, a: &'tcx Arm<'tcx>) {
--- /dev/null
+// Regression test for #69307
+//
+// Having a `async { .. foo.await .. }` block appear inside of a `+=`
+// expression was causing an ICE due to a failure to save/restore
+// state in the AST numbering pass when entering a nested body.
+//
+// check-pass
+// edition:2018
+
+fn block_on<F>(_: F) -> usize {
+ 0
+}
+
+fn main() {}
+
+async fn bar() {
+ let mut sum = 0;
+ sum += block_on(async {
+ baz().await;
+ });
+}
+
+async fn baz() {}