[clang] Fobbid co_await and co_yield in invalid expr context (PR #130455)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-coroutines

Author: None (NewSigma)

<details>
<summary>Changes</summary>

Fix #<!-- -->78426 

C++26 introduced braced initializer lists as template arguments. However, such contexts should be considered invalid for co_await and co_yield. This commit explicitly rules out the possibility of using these exprs in template arguments.

---
Full diff: https://github.com/llvm/llvm-project/pull/130455.diff


1 Files Affected:

- (modified) clang/lib/Sema/SemaCoroutine.cpp (+5-2) 


``````````diff
diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index 0e4f3b20c78cd..53536b0d14037 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -788,7 +788,11 @@ static bool checkSuspensionContext(Sema &S, SourceLocation Loc,
   // First emphasis of [expr.await]p2: must be a potentially evaluated context.
   // That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
   // \c sizeof.
-  if (S.isUnevaluatedContext()) {
+  const auto ExprContext = S.currentEvaluationContext().ExprContext;
+  const bool BadContext =
+      S.isUnevaluatedContext() ||
+      ExprContext != Sema::ExpressionEvaluationContextRecord::EK_Other;
+  if (BadContext) {
     S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
     return false;
   }
@@ -798,7 +802,6 @@ static bool checkSuspensionContext(Sema &S, SourceLocation Loc,
     S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
     return false;
   }
-
   return true;
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/130455