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

[via cfe-commits]

================
@@ -3747,6 +3747,16 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
         Diag(ReturnLoc, diag::err_acc_branch_in_out_compute_construct)
         << /*return*/ 1 << /*out of */ 0);
 
+  // using plain return in a coroutine is not allowed.
+  FunctionScopeInfo *FSI = getCurFunction();
+  if (getLangOpts().Coroutines && FSI->isCoroutine()) {
----------------
ivanaivanovska wrote:

Done.

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