PR17295: Do not allow explicit conversion functions to be used in cases where
an additional conversion (other than a qualification conversion) would be
required after the explicit conversion.
Conversely, do allow explicit conversion functions to be used when initializing
a temporary for a reference binding in direct-list-initialization.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191150 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 800f983..df18752 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -5829,6 +5829,17 @@
ConvType = Conversion->getConversionType().getNonReferenceType();
}
+ // Per C++ [over.match.conv]p1, [over.match.ref]p1, an explicit conversion
+ // operator is only a candidate if its return type is the target type or
+ // can be converted to the target type with a qualification conversion.
+ bool ObjCLifetimeConversion;
+ QualType ToNonRefType = ToType.getNonReferenceType();
+ if (Conversion->isExplicit() &&
+ !Context.hasSameUnqualifiedType(ConvType, ToNonRefType) &&
+ !IsQualificationConversion(ConvType, ToNonRefType, /*CStyle*/false,
+ ObjCLifetimeConversion))
+ return;
+
// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);