forked from OSchip/llvm-project
PR22435: Correctly implement tiebreaker for reference ordering in function
template partial ordering rules. This rule applies per pair of types being compared, not per pair of function templates being compared. llvm-svn: 229965
This commit is contained in:
Richard Smith
parent
4041f2217b
commit
ed563c27fe
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@ -91,30 +91,6 @@ DeduceTemplateArguments(Sema &S,
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TemplateDeductionInfo &Info,
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SmallVectorImpl<DeducedTemplateArgument> &Deduced);
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/// \brief Whether template argument deduction for two reference parameters
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/// resulted in the argument type, parameter type, or neither type being more
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/// qualified than the other.
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enum DeductionQualifierComparison {
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NeitherMoreQualified = 0,
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ParamMoreQualified,
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ArgMoreQualified
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};
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/// \brief Stores the result of comparing two reference parameters while
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/// performing template argument deduction for partial ordering of function
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/// templates.
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struct RefParamPartialOrderingComparison {
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/// \brief Whether the parameter type is an rvalue reference type.
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bool ParamIsRvalueRef;
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/// \brief Whether the argument type is an rvalue reference type.
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bool ArgIsRvalueRef;
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/// \brief Whether the parameter or argument (or neither) is more qualified.
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DeductionQualifierComparison Qualifiers;
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};
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static Sema::TemplateDeductionResult
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DeduceTemplateArgumentsByTypeMatch(Sema &S,
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TemplateParameterList *TemplateParams,
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@ -124,9 +100,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
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SmallVectorImpl<DeducedTemplateArgument> &
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Deduced,
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unsigned TDF,
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bool PartialOrdering = false,
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SmallVectorImpl<RefParamPartialOrderingComparison> *
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RefParamComparisons = nullptr);
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bool PartialOrdering = false);
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static Sema::TemplateDeductionResult
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DeduceTemplateArguments(Sema &S,
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@ -784,9 +758,6 @@ private:
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/// deduction for during partial ordering for a call
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/// (C++0x [temp.deduct.partial]).
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///
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/// \param RefParamComparisons If we're performing template argument deduction
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/// in the context of partial ordering, the set of qualifier comparisons.
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///
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/// \returns the result of template argument deduction so far. Note that a
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/// "success" result means that template argument deduction has not yet failed,
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/// but it may still fail, later, for other reasons.
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@ -798,9 +769,7 @@ DeduceTemplateArguments(Sema &S,
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TemplateDeductionInfo &Info,
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SmallVectorImpl<DeducedTemplateArgument> &Deduced,
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unsigned TDF,
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bool PartialOrdering = false,
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SmallVectorImpl<RefParamPartialOrderingComparison> *
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RefParamComparisons = nullptr) {
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bool PartialOrdering = false) {
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// Fast-path check to see if we have too many/too few arguments.
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if (NumParams != NumArgs &&
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!(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
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@ -836,8 +805,7 @@ DeduceTemplateArguments(Sema &S,
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= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
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Params[ParamIdx], Args[ArgIdx],
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Info, Deduced, TDF,
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PartialOrdering,
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RefParamComparisons))
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PartialOrdering))
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return Result;
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++ArgIdx;
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@ -869,8 +837,7 @@ DeduceTemplateArguments(Sema &S,
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if (Sema::TemplateDeductionResult Result
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= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
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Args[ArgIdx], Info, Deduced,
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TDF, PartialOrdering,
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RefParamComparisons))
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TDF, PartialOrdering))
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return Result;
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PackScope.nextPackElement();
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@ -967,9 +934,6 @@ bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
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/// \param PartialOrdering Whether we're performing template argument deduction
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/// in the context of partial ordering (C++0x [temp.deduct.partial]).
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///
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/// \param RefParamComparisons If we're performing template argument deduction
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/// in the context of partial ordering, the set of qualifier comparisons.
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///
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/// \returns the result of template argument deduction so far. Note that a
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/// "success" result means that template argument deduction has not yet failed,
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/// but it may still fail, later, for other reasons.
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@ -980,9 +944,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
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TemplateDeductionInfo &Info,
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SmallVectorImpl<DeducedTemplateArgument> &Deduced,
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unsigned TDF,
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bool PartialOrdering,
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SmallVectorImpl<RefParamPartialOrderingComparison> *
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RefParamComparisons) {
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bool PartialOrdering) {
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// We only want to look at the canonical types, since typedefs and
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// sugar are not part of template argument deduction.
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QualType Param = S.Context.getCanonicalType(ParamIn);
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@ -995,7 +957,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
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Arg = ArgExpansion->getPattern();
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if (PartialOrdering) {
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// C++0x [temp.deduct.partial]p5:
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// C++11 [temp.deduct.partial]p5:
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// Before the partial ordering is done, certain transformations are
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// performed on the types used for partial ordering:
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// - If P is a reference type, P is replaced by the type referred to.
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@ -1008,42 +970,42 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
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if (ArgRef)
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Arg = ArgRef->getPointeeType();
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if (RefParamComparisons && ParamRef && ArgRef) {
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// C++0x [temp.deduct.partial]p6:
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// If both P and A were reference types (before being replaced with the
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// type referred to above), determine which of the two types (if any) is
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// more cv-qualified than the other; otherwise the types are considered
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// to be equally cv-qualified for partial ordering purposes. The result
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// of this determination will be used below.
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if (ParamRef && ArgRef && S.Context.hasSameUnqualifiedType(Param, Arg)) {
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// C++11 [temp.deduct.partial]p9:
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// If, for a given type, deduction succeeds in both directions (i.e.,
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// the types are identical after the transformations above) and both
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// P and A were reference types [...]:
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// - if [one type] was an lvalue reference and [the other type] was
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// not, [the other type] is not considered to be at least as
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// specialized as [the first type]
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// - if [one type] is more cv-qualified than [the other type],
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// [the other type] is not considered to be at least as specialized
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// as [the first type]
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// Objective-C ARC adds:
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// - [one type] has non-trivial lifetime, [the other type] has
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// __unsafe_unretained lifetime, and the types are otherwise
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// identical
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//
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// We save this information for later, using it only when deduction
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// succeeds in both directions.
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RefParamPartialOrderingComparison Comparison;
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Comparison.ParamIsRvalueRef = ParamRef->getAs<RValueReferenceType>();
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Comparison.ArgIsRvalueRef = ArgRef->getAs<RValueReferenceType>();
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Comparison.Qualifiers = NeitherMoreQualified;
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// A is "considered to be at least as specialized" as P iff deduction
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// succeeds, so we model this as a deduction failure. Note that
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// [the first type] is P and [the other type] is A here; the standard
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// gets this backwards.
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Qualifiers ParamQuals = Param.getQualifiers();
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Qualifiers ArgQuals = Arg.getQualifiers();
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if (ParamQuals.isStrictSupersetOf(ArgQuals))
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Comparison.Qualifiers = ParamMoreQualified;
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else if (ArgQuals.isStrictSupersetOf(ParamQuals))
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Comparison.Qualifiers = ArgMoreQualified;
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else if (ArgQuals.getObjCLifetime() != ParamQuals.getObjCLifetime() &&
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ArgQuals.withoutObjCLifetime()
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== ParamQuals.withoutObjCLifetime()) {
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// Prefer binding to non-__unsafe_autoretained parameters.
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if (ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
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ParamQuals.getObjCLifetime())
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Comparison.Qualifiers = ParamMoreQualified;
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else if (ParamQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
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ArgQuals.getObjCLifetime())
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Comparison.Qualifiers = ArgMoreQualified;
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if ((ParamRef->isLValueReferenceType() &&
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!ArgRef->isLValueReferenceType()) ||
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ParamQuals.isStrictSupersetOf(ArgQuals) ||
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(ParamQuals.hasNonTrivialObjCLifetime() &&
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ArgQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
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ParamQuals.withoutObjCLifetime() ==
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ArgQuals.withoutObjCLifetime())) {
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Info.FirstArg = TemplateArgument(ParamIn);
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Info.SecondArg = TemplateArgument(ArgIn);
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return Sema::TDK_NonDeducedMismatch;
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}
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RefParamComparisons->push_back(Comparison);
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}
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// C++0x [temp.deduct.partial]p7:
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// C++11 [temp.deduct.partial]p7:
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// Remove any top-level cv-qualifiers:
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// - If P is a cv-qualified type, P is replaced by the cv-unqualified
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// version of P.
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@ -4146,8 +4108,7 @@ static bool isAtLeastAsSpecializedAs(Sema &S,
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FunctionTemplateDecl *FT1,
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FunctionTemplateDecl *FT2,
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TemplatePartialOrderingContext TPOC,
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unsigned NumCallArguments1,
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SmallVectorImpl<RefParamPartialOrderingComparison> *RefParamComparisons) {
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unsigned NumCallArguments1) {
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FunctionDecl *FD1 = FT1->getTemplatedDecl();
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FunctionDecl *FD2 = FT2->getTemplatedDecl();
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const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
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@ -4212,8 +4173,7 @@ static bool isAtLeastAsSpecializedAs(Sema &S,
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Args2.resize(NumComparedArguments);
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if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
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Args1.data(), Args1.size(), Info, Deduced,
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TDF_None, /*PartialOrdering=*/true,
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RefParamComparisons))
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TDF_None, /*PartialOrdering=*/true))
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return false;
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break;
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@ -4225,7 +4185,7 @@ static bool isAtLeastAsSpecializedAs(Sema &S,
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if (DeduceTemplateArgumentsByTypeMatch(
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S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
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Info, Deduced, TDF_None,
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/*PartialOrdering=*/true, RefParamComparisons))
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/*PartialOrdering=*/true))
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return false;
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break;
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@ -4235,8 +4195,7 @@ static bool isAtLeastAsSpecializedAs(Sema &S,
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if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
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FD2->getType(), FD1->getType(),
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Info, Deduced, TDF_None,
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/*PartialOrdering=*/true,
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RefParamComparisons))
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/*PartialOrdering=*/true))
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return false;
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break;
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}
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@ -4335,83 +4294,17 @@ Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
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TemplatePartialOrderingContext TPOC,
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unsigned NumCallArguments1,
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unsigned NumCallArguments2) {
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SmallVector<RefParamPartialOrderingComparison, 4> RefParamComparisons;
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bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
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NumCallArguments1, nullptr);
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NumCallArguments1);
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bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
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NumCallArguments2,
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&RefParamComparisons);
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NumCallArguments2);
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if (Better1 != Better2) // We have a clear winner
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return Better1? FT1 : FT2;
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return Better1 ? FT1 : FT2;
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if (!Better1 && !Better2) // Neither is better than the other
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return nullptr;
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// C++0x [temp.deduct.partial]p10:
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// If for each type being considered a given template is at least as
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// specialized for all types and more specialized for some set of types and
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// the other template is not more specialized for any types or is not at
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// least as specialized for any types, then the given template is more
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// specialized than the other template. Otherwise, neither template is more
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// specialized than the other.
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Better1 = false;
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Better2 = false;
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for (unsigned I = 0, N = RefParamComparisons.size(); I != N; ++I) {
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// C++0x [temp.deduct.partial]p9:
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// If, for a given type, deduction succeeds in both directions (i.e., the
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// types are identical after the transformations above) and both P and A
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// were reference types (before being replaced with the type referred to
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// above):
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// -- if the type from the argument template was an lvalue reference
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// and the type from the parameter template was not, the argument
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// type is considered to be more specialized than the other;
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// otherwise,
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if (!RefParamComparisons[I].ArgIsRvalueRef &&
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RefParamComparisons[I].ParamIsRvalueRef) {
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Better2 = true;
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if (Better1)
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return nullptr;
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continue;
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} else if (!RefParamComparisons[I].ParamIsRvalueRef &&
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RefParamComparisons[I].ArgIsRvalueRef) {
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Better1 = true;
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if (Better2)
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return nullptr;
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continue;
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}
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// -- if the type from the argument template is more cv-qualified than
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// the type from the parameter template (as described above), the
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// argument type is considered to be more specialized than the
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// other; otherwise,
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switch (RefParamComparisons[I].Qualifiers) {
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case NeitherMoreQualified:
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break;
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case ParamMoreQualified:
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Better1 = true;
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if (Better2)
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return nullptr;
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continue;
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case ArgMoreQualified:
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Better2 = true;
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if (Better1)
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return nullptr;
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continue;
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}
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// -- neither type is more specialized than the other.
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}
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assert(!(Better1 && Better2) && "Should have broken out in the loop above");
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if (Better1)
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return FT1;
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else if (Better2)
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return FT2;
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// FIXME: This mimics what GCC implements, but doesn't match up with the
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// proposed resolution for core issue 692. This area needs to be sorted out,
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// but for now we attempt to maintain compatibility.
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@ -4584,8 +4477,7 @@ Sema::getMoreSpecializedPartialSpecialization(
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bool Better1 = !DeduceTemplateArgumentsByTypeMatch(*this,
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PS2->getTemplateParameters(),
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PT2, PT1, Info, Deduced, TDF_None,
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/*PartialOrdering=*/true,
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/*RefParamComparisons=*/nullptr);
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/*PartialOrdering=*/true);
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if (Better1) {
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SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
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InstantiatingTemplate Inst(*this, Loc, PS2, DeducedArgs, Info);
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@ -4598,8 +4490,7 @@ Sema::getMoreSpecializedPartialSpecialization(
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Deduced.resize(PS1->getTemplateParameters()->size());
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bool Better2 = !DeduceTemplateArgumentsByTypeMatch(
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*this, PS1->getTemplateParameters(), PT1, PT2, Info, Deduced, TDF_None,
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/*PartialOrdering=*/true,
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/*RefParamComparisons=*/nullptr);
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/*PartialOrdering=*/true);
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if (Better2) {
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SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
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Deduced.end());
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@ -4642,8 +4533,7 @@ Sema::getMoreSpecializedPartialSpecialization(
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Deduced.resize(PS2->getTemplateParameters()->size());
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bool Better1 = !DeduceTemplateArgumentsByTypeMatch(
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*this, PS2->getTemplateParameters(), PT2, PT1, Info, Deduced, TDF_None,
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/*PartialOrdering=*/true,
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/*RefParamComparisons=*/nullptr);
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/*PartialOrdering=*/true);
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if (Better1) {
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SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
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Deduced.end());
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@ -4659,8 +4549,7 @@ Sema::getMoreSpecializedPartialSpecialization(
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bool Better2 = !DeduceTemplateArgumentsByTypeMatch(*this,
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PS1->getTemplateParameters(),
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PT1, PT2, Info, Deduced, TDF_None,
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/*PartialOrdering=*/true,
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/*RefParamComparisons=*/nullptr);
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/*PartialOrdering=*/true);
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if (Better2) {
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SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
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InstantiatingTemplate Inst(*this, Loc, PS1, DeducedArgs, Info);
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@ -1,4 +1,5 @@
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// RUN: %clang_cc1 -fsyntax-only -verify %s
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// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
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// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
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template<class T> struct A { A(); };
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template<class T> int &f(T);
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@ -21,3 +22,23 @@ void m() {
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const A<int> z2;
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int &ir1 = h(z2);
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}
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namespace core_26909 {
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template<typename T> struct A {};
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template<typename T, typename U> void f(T&, U); // expected-note {{candidate}}
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template<typename T, typename U> void f(T&&, A<U>); // expected-note {{candidate}} expected-warning 0-1{{extension}}
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template<typename T, typename U> void g(const T&, U); // expected-note {{candidate}}
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template<typename T, typename U> void g(T&, A<U>); // expected-note {{candidate}}
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void h(int a, const char b, A<int> c) {
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f(a, c); // expected-error{{ambiguous}}
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g(b, c); // expected-error{{ambiguous}}
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}
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}
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namespace PR22435 {
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template<typename T, typename U> void foo(void (*)(T), const U &); // expected-note {{candidate}}
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template<typename T, typename U> bool foo(void (*)(T &), U &); // expected-note {{candidate}}
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void bar(const int x) { bool b = foo<char>(0, x); } // expected-error {{ambiguous}}
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}
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