Fix for Bug 33471: Preventing operator auto from resolving to a template operator.
As the bug report says,
struct A
{
template<typename T> operator T();
};
void foo()
{
A().operator auto();
}
causes: "undeduced type in IR-generation
UNREACHABLE executed at llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp:208!"
The problem is that in this case, "T" is being deduced as "auto",
which I believe is incorrect.
The 'operator auto' implementation in Clang is standards compliant, however
there is a defect report against core (1670).
Differential Revision: https://reviews.llvm.org/D34370
llvm-svn: 305812
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 1fb25f4..9f657a4 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -862,6 +862,16 @@
if (!Record->isCompleteDefinition())
return Found;
+ // For conversion operators, 'operator auto' should only match
+ // 'operator auto'. Since 'auto' is not a type, it shouldn't be considered
+ // as a candidate for template substitution.
+ auto *ContainedDeducedType =
+ R.getLookupName().getCXXNameType()->getContainedDeducedType();
+ if (R.getLookupName().getNameKind() ==
+ DeclarationName::CXXConversionFunctionName &&
+ ContainedDeducedType && ContainedDeducedType->isUndeducedType())
+ return Found;
+
for (CXXRecordDecl::conversion_iterator U = Record->conversion_begin(),
UEnd = Record->conversion_end(); U != UEnd; ++U) {
FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(*U);