[clang] Surface error for plain return statement in coroutine earlier (PR #100985)

[Ilya Biryukov via cfe-commits]

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@@ -684,6 +684,19 @@ bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
   return ThrowingDecls.empty();
 }
 
+// [stmt.return.coroutine]p1:
+//   A coroutine shall not enclose a return statement ([stmt.return]).
+static void checkReturnStmtInCoroutine(Sema &S, FunctionScopeInfo *FSI) {
+  assert (!FSI && "FunctionScopeInfo is null");
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ilya-biryukov wrote:

This should be `assert(FSI)`, it should fail with the current version.

BTW, are you building with `LLVM_ENABLE_ASSERTIONS=On`? It's definitely recommended for the day-to-day development.

https://github.com/llvm/llvm-project/pull/100985