[test] Test ext_vector_type operators with implicit conversions

[porglezomp]

Summary

An extra test for implicit conversion issues discovered while testing D151060.

[porglezomp]

Add significantly more variations in this test case. I discovered multiple
inconsistencies while expanding this list out. Filed an issue on GitHub here:
https://github.com/llvm/llvm-project/issues/62949

[aaron.ballman]

LGTM! Thank you for the extra test coverage.

clang/test/SemaCXX/vector.cpp

 
 void test_scoped_enum_vector(EnumClass ea, v2u v2ua) {
   // Scoped enumerations are only compatible with exactly matching types. They shouldn't integral promote.
   (void)(v2ua + ea); // expected-error{{cannot convert between vector and non-scalar values}}
   (void)(ea + v2ua); // expected-error{{cannot convert between vector and non-scalar values}}
 }
 #endif
 }
+
+namespace {
+// Test ext_vector_type builtin operators in the presence of implicit conversions
+
+typedef int __attribute__((ext_vector_type(4))) vec4i;
+
+struct simd4i {
+    vec4i x;
+
+    simd4i(const vec4i& val): x(val) {}
+    operator vec4i() const { return x; }
+};
+
+simd4i operator| (const simd4i& lhs, const simd4i& rhs) { return vec4i(lhs) | vec4i(rhs); }
+simd4i& operator|= (simd4i& lhs, const simd4i& rhs) { return lhs = lhs | rhs; }
+
+simd4i test1(simd4i a, vec4i b) {
+    return a |= b;
+}
+
+simd4i test2(simd4i a, vec4i b) {
+    return a | b;
+}
+}