[CUDA][HIP] Fix typo in `BestViableFunction`

Summary:
- Should consider viable ones only when checking SameSide candidates.
- Replace erasing with clearing viable flag to reduce data
  moving/copying.
- Add one and revise another one as the diagnostic message are more
  relevant compared to previous one.

Reviewers: tra

Subscribers: cfe-commits, yaxunl

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67730

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@372318 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 0 deletions

diff --git a/test/SemaCUDA/function-overload.cu b/test/SemaCUDA/function-overload.cu
index 1d78636a70..b9efd1c09e 100644
--- a/test/SemaCUDA/function-overload.cu
+++ b/test/SemaCUDA/function-overload.cu
@@ -402,3 +402,20 @@ __host__ void test_host_template_overload() {
 __device__ void test_device_template_overload() {
   template_overload(1); // OK. Attribute-based overloading picks __device__ variant.
 }
+
+// Two classes with `operator-` defined. One of them is device only.
+struct C1;
+struct C2;
+__device__
+int operator-(const C1 &x, const C1 &y);
+int operator-(const C2 &x, const C2 &y);
+
+template <typename T>
+__host__ __device__ int constexpr_overload(const T &x, const T &y) {
+  return x - y;
+}
+
+// Verify that function overloading doesn't prune candidate wrongly.
+int test_constexpr_overload(C2 &x, C2 &y) {
+  return constexpr_overload(x, y);
+}