diff options
Diffstat (limited to 'clang/lib/Sema/SemaOverload.cpp')
-rw-r--r-- | clang/lib/Sema/SemaOverload.cpp | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index 3db8e3d2e5c..80bd3562bc7 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -3765,6 +3765,34 @@ isBetterReferenceBindingKind(const StandardConversionSequence &SCS1, !SCS2.IsLvalueReference && SCS2.BindsToFunctionLvalue); } +enum class FixedEnumPromotion { + None, + ToUnderlyingType, + ToPromotedUnderlyingType +}; + +/// Returns kind of fixed enum promotion the \a SCS uses. +static FixedEnumPromotion +getFixedEnumPromtion(Sema &S, const StandardConversionSequence &SCS) { + + if (SCS.Second != ICK_Integral_Promotion) + return FixedEnumPromotion::None; + + QualType FromType = SCS.getFromType(); + if (!FromType->isEnumeralType()) + return FixedEnumPromotion::None; + + EnumDecl *Enum = FromType->getAs<EnumType>()->getDecl(); + if (!Enum->isFixed()) + return FixedEnumPromotion::None; + + QualType UnderlyingType = Enum->getIntegerType(); + if (S.Context.hasSameType(SCS.getToType(1), UnderlyingType)) + return FixedEnumPromotion::ToUnderlyingType; + + return FixedEnumPromotion::ToPromotedUnderlyingType; +} + /// CompareStandardConversionSequences - Compare two standard /// conversion sequences to determine whether one is better than the /// other or if they are indistinguishable (C++ 13.3.3.2p3). @@ -3806,6 +3834,20 @@ CompareStandardConversionSequences(Sema &S, SourceLocation Loc, ? ImplicitConversionSequence::Better : ImplicitConversionSequence::Worse; + // C++14 [over.ics.rank]p4b2: + // This is retroactively applied to C++11 by CWG 1601. + // + // A conversion that promotes an enumeration whose underlying type is fixed + // to its underlying type is better than one that promotes to the promoted + // underlying type, if the two are different. + FixedEnumPromotion FEP1 = getFixedEnumPromtion(S, SCS1); + FixedEnumPromotion FEP2 = getFixedEnumPromtion(S, SCS2); + if (FEP1 != FixedEnumPromotion::None && FEP2 != FixedEnumPromotion::None && + FEP1 != FEP2) + return FEP1 == FixedEnumPromotion::ToUnderlyingType + ? ImplicitConversionSequence::Better + : ImplicitConversionSequence::Worse; + // C++ [over.ics.rank]p4b2: // // If class B is derived directly or indirectly from class A, |