[coroutines] Remove assert on CoroutineParameterMoves in Sema::buildCoroutineParameterMoves

Summary:
The assertion of CoroutineParameterMoves happens when build coroutine function with arguments  multiple time while fails to build promise type.

Fix: use return false instead.

Test Plan: check-clang

Reviewers: modocache, GorNishanov, rjmccall

Reviewed By: modocache

Subscribers: rjmccall, EricWF, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69022

Patch by junparser (JunMa)!

2 files changed, 7 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index 7c125e999d0..271c4a10f3e 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -1527,8 +1527,8 @@ bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
   auto *FD = cast<FunctionDecl>(CurContext);
 
   auto *ScopeInfo = getCurFunction();
-  assert(ScopeInfo->CoroutineParameterMoves.empty() &&
-         "Should not build parameter moves twice");
+  if (!ScopeInfo->CoroutineParameterMoves.empty())
+    return false;
 
   for (auto *PD : FD->parameters()) {
     if (PD->getType()->isDependentType())
diff --git a/clang/test/SemaCXX/coroutines.cpp b/clang/test/SemaCXX/coroutines.cpp
index c8de7b01785..677c6e6ff8d 100644
--- a/clang/test/SemaCXX/coroutines.cpp
+++ b/clang/test/SemaCXX/coroutines.cpp
@@ -87,6 +87,11 @@ int no_promise_type() { // expected-error {{this function cannot be a coroutine:
   co_await a;
 }
 
+int no_promise_type_multiple_awaits(int) { // expected-error {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<int, int>' has no member named 'promise_type'}}
+  co_await a;
+  co_await a;
+}
+
 template <>
 struct std::experimental::coroutine_traits<double, double> { typedef int promise_type; };
 double bad_promise_type(double) { // expected-error {{this function cannot be a coroutine: 'experimental::coroutine_traits<double, double>::promise_type' (aka 'int') is not a class}}