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gerrit-public.fairphone.software / platform / external / clang / d570a9282fd1793cbf21c090d80cb0b6b4b89982 / . / lib / Sema / SemaTemplateDeduction.cpp
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//===------- SemaTemplateDeduction.cpp - Template Argument Deduction ------===/
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//===----------------------------------------------------------------------===/
//
// This file implements C++ template argument deduction.
//
//===----------------------------------------------------------------------===/
#include "clang/Sema/TemplateDeduction.h"
#include "TreeTransform.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Sema.h"
#include "clang/Sema/Template.h"
#include "llvm/ADT/SmallBitVector.h"
#include <algorithm>
namespace clang {
using namespace sema;
/// \brief Various flags that control template argument deduction.
///
/// These flags can be bitwise-OR'd together.
enum TemplateDeductionFlags {
/// \brief No template argument deduction flags, which indicates the
/// strictest results for template argument deduction (as used for, e.g.,
/// matching class template partial specializations).
TDF_None = 0,
/// \brief Within template argument deduction from a function call, we are
/// matching with a parameter type for which the original parameter was
/// a reference.
TDF_ParamWithReferenceType = 0x1,
/// \brief Within template argument deduction from a function call, we
/// are matching in a case where we ignore cv-qualifiers.
TDF_IgnoreQualifiers = 0x02,
/// \brief Within template argument deduction from a function call,
/// we are matching in a case where we can perform template argument
/// deduction from a template-id of a derived class of the argument type.
TDF_DerivedClass = 0x04,
/// \brief Allow non-dependent types to differ, e.g., when performing
/// template argument deduction from a function call where conversions
/// may apply.
TDF_SkipNonDependent = 0x08,
/// \brief Whether we are performing template argument deduction for
/// parameters and arguments in a top-level template argument
TDF_TopLevelParameterTypeList = 0x10,
/// \brief Within template argument deduction from overload resolution per
/// C++ [over.over] allow matching function types that are compatible in
/// terms of noreturn and default calling convention adjustments.
TDF_InOverloadResolution = 0x20
};
}
using namespace clang;
/// \brief Compare two APSInts, extending and switching the sign as
/// necessary to compare their values regardless of underlying type.
static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
if (Y.getBitWidth() > X.getBitWidth())
X = X.extend(Y.getBitWidth());
else if (Y.getBitWidth() < X.getBitWidth())
Y = Y.extend(X.getBitWidth());
// If there is a signedness mismatch, correct it.
if (X.isSigned() != Y.isSigned()) {
// If the signed value is negative, then the values cannot be the same.
if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
return false;
Y.setIsSigned(true);
X.setIsSigned(true);
}
return X == Y;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
TemplateArgument Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced);
/// \brief Whether template argument deduction for two reference parameters
/// resulted in the argument type, parameter type, or neither type being more
/// qualified than the other.
enum DeductionQualifierComparison {
NeitherMoreQualified = 0,
ParamMoreQualified,
ArgMoreQualified
};
/// \brief Stores the result of comparing two reference parameters while
/// performing template argument deduction for partial ordering of function
/// templates.
struct RefParamPartialOrderingComparison {
/// \brief Whether the parameter type is an rvalue reference type.
bool ParamIsRvalueRef;
/// \brief Whether the argument type is an rvalue reference type.
bool ArgIsRvalueRef;
/// \brief Whether the parameter or argument (or neither) is more qualified.
DeductionQualifierComparison Qualifiers;
};
static Sema::TemplateDeductionResult
DeduceTemplateArgumentsByTypeMatch(Sema &S,
TemplateParameterList *TemplateParams,
QualType Param,
QualType Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &
Deduced,
unsigned TDF,
bool PartialOrdering = false,
SmallVectorImpl<RefParamPartialOrderingComparison> *
RefParamComparisons = 0);
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument *Params, unsigned NumParams,
const TemplateArgument *Args, unsigned NumArgs,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced);
/// \brief If the given expression is of a form that permits the deduction
/// of a non-type template parameter, return the declaration of that
/// non-type template parameter.
static NonTypeTemplateParmDecl *getDeducedParameterFromExpr(Expr *E) {
// If we are within an alias template, the expression may have undergone
// any number of parameter substitutions already.
while (1) {
if (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
E = IC->getSubExpr();
else if (SubstNonTypeTemplateParmExpr *Subst =
dyn_cast<SubstNonTypeTemplateParmExpr>(E))
E = Subst->getReplacement();
else
break;
}
if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
return dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
return 0;
}
/// \brief Determine whether two declaration pointers refer to the same
/// declaration.
static bool isSameDeclaration(Decl *X, Decl *Y) {
if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
X = NX->getUnderlyingDecl();
if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
Y = NY->getUnderlyingDecl();
return X->getCanonicalDecl() == Y->getCanonicalDecl();
}
/// \brief Verify that the given, deduced template arguments are compatible.
///
/// \returns The deduced template argument, or a NULL template argument if
/// the deduced template arguments were incompatible.
static DeducedTemplateArgument
checkDeducedTemplateArguments(ASTContext &Context,
const DeducedTemplateArgument &X,
const DeducedTemplateArgument &Y) {
// We have no deduction for one or both of the arguments; they're compatible.
if (X.isNull())
return Y;
if (Y.isNull())
return X;
switch (X.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Non-deduced template arguments handled above");
case TemplateArgument::Type:
// If two template type arguments have the same type, they're compatible.
if (Y.getKind() == TemplateArgument::Type &&
Context.hasSameType(X.getAsType(), Y.getAsType()))
return X;
return DeducedTemplateArgument();
case TemplateArgument::Integral:
// If we deduced a constant in one case and either a dependent expression or
// declaration in another case, keep the integral constant.
// If both are integral constants with the same value, keep that value.
if (Y.getKind() == TemplateArgument::Expression ||
Y.getKind() == TemplateArgument::Declaration ||
(Y.getKind() == TemplateArgument::Integral &&
hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
return DeducedTemplateArgument(X,
X.wasDeducedFromArrayBound() &&
Y.wasDeducedFromArrayBound());
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Template:
if (Y.getKind() == TemplateArgument::Template &&
Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::TemplateExpansion:
if (Y.getKind() == TemplateArgument::TemplateExpansion &&
Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
Y.getAsTemplateOrTemplatePattern()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Expression:
// If we deduced a dependent expression in one case and either an integral
// constant or a declaration in another case, keep the integral constant
// or declaration.
if (Y.getKind() == TemplateArgument::Integral ||
Y.getKind() == TemplateArgument::Declaration)
return DeducedTemplateArgument(Y, X.wasDeducedFromArrayBound() &&
Y.wasDeducedFromArrayBound());
if (Y.getKind() == TemplateArgument::Expression) {
// Compare the expressions for equality
llvm::FoldingSetNodeID ID1, ID2;
X.getAsExpr()->Profile(ID1, Context, true);
Y.getAsExpr()->Profile(ID2, Context, true);
if (ID1 == ID2)
return X;
}
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Declaration:
// If we deduced a declaration and a dependent expression, keep the
// declaration.
if (Y.getKind() == TemplateArgument::Expression)
return X;
// If we deduced a declaration and an integral constant, keep the
// integral constant.
if (Y.getKind() == TemplateArgument::Integral)
return Y;
// If we deduced two declarations, make sure they they refer to the
// same declaration.
if (Y.getKind() == TemplateArgument::Declaration &&
isSameDeclaration(X.getAsDecl(), Y.getAsDecl()) &&
X.isDeclForReferenceParam() == Y.isDeclForReferenceParam())
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::NullPtr:
// If we deduced a null pointer and a dependent expression, keep the
// null pointer.
if (Y.getKind() == TemplateArgument::Expression)
return X;
// If we deduced a null pointer and an integral constant, keep the
// integral constant.
if (Y.getKind() == TemplateArgument::Integral)
return Y;
// If we deduced two null pointers, make sure they have the same type.
if (Y.getKind() == TemplateArgument::NullPtr &&
Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Pack:
if (Y.getKind() != TemplateArgument::Pack ||
X.pack_size() != Y.pack_size())
return DeducedTemplateArgument();
for (TemplateArgument::pack_iterator XA = X.pack_begin(),
XAEnd = X.pack_end(),
YA = Y.pack_begin();
XA != XAEnd; ++XA, ++YA) {
if (checkDeducedTemplateArguments(Context,
DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()))
.isNull())
return DeducedTemplateArgument();
}
return X;
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// \brief Deduce the value of the given non-type template parameter
/// from the given constant.
static Sema::TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S,
NonTypeTemplateParmDecl *NTTP,
llvm::APSInt Value, QualType ValueType,
bool DeducedFromArrayBound,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument with depth > 0");
DeducedTemplateArgument NewDeduced(S.Context, Value, ValueType,
DeducedFromArrayBound);
DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
Deduced[NTTP->getIndex()],
NewDeduced);
if (Result.isNull()) {
Info.Param = NTTP;
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = NewDeduced;
return Sema::TDK_Inconsistent;
}
Deduced[NTTP->getIndex()] = Result;
return Sema::TDK_Success;
}
/// \brief Deduce the value of the given non-type template parameter
/// from the given type- or value-dependent expression.
///
/// \returns true if deduction succeeded, false otherwise.
static Sema::TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S,
NonTypeTemplateParmDecl *NTTP,
Expr *Value,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument with depth > 0");
assert((Value->isTypeDependent() || Value->isValueDependent()) &&
"Expression template argument must be type- or value-dependent.");
DeducedTemplateArgument NewDeduced(Value);
DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
Deduced[NTTP->getIndex()],
NewDeduced);
if (Result.isNull()) {
Info.Param = NTTP;
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = NewDeduced;
return Sema::TDK_Inconsistent;
}
Deduced[NTTP->getIndex()] = Result;
return Sema::TDK_Success;
}
/// \brief Deduce the value of the given non-type template parameter
/// from the given declaration.
///
/// \returns true if deduction succeeded, false otherwise.
static Sema::TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S,
NonTypeTemplateParmDecl *NTTP,
ValueDecl *D,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument with depth > 0");
D = D ? cast<ValueDecl>(D->getCanonicalDecl()) : 0;
TemplateArgument New(D, NTTP->getType()->isReferenceType());
DeducedTemplateArgument NewDeduced(New);
DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
Deduced[NTTP->getIndex()],
NewDeduced);
if (Result.isNull()) {
Info.Param = NTTP;
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = NewDeduced;
return Sema::TDK_Inconsistent;
}
Deduced[NTTP->getIndex()] = Result;
return Sema::TDK_Success;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
TemplateName Param,
TemplateName Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
if (!ParamDecl) {
// The parameter type is dependent and is not a template template parameter,
// so there is nothing that we can deduce.
return Sema::TDK_Success;
}
if (TemplateTemplateParmDecl *TempParam
= dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
DeducedTemplateArgument NewDeduced(S.Context.getCanonicalTemplateName(Arg));
DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
Deduced[TempParam->getIndex()],
NewDeduced);
if (Result.isNull()) {
Info.Param = TempParam;
Info.FirstArg = Deduced[TempParam->getIndex()];
Info.SecondArg = NewDeduced;
return Sema::TDK_Inconsistent;
}
Deduced[TempParam->getIndex()] = Result;
return Sema::TDK_Success;
}
// Verify that the two template names are equivalent.
if (S.Context.hasSameTemplateName(Param, Arg))
return Sema::TDK_Success;
// Mismatch of non-dependent template parameter to argument.
Info.FirstArg = TemplateArgument(Param);
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_NonDeducedMismatch;
}
/// \brief Deduce the template arguments by comparing the template parameter
/// type (which is a template-id) with the template argument type.
///
/// \param S the Sema
///
/// \param TemplateParams the template parameters that we are deducing
///
/// \param Param the parameter type
///
/// \param Arg the argument type
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateSpecializationType *Param,
QualType Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
assert(Arg.isCanonical() && "Argument type must be canonical");
// Check whether the template argument is a dependent template-id.
if (const TemplateSpecializationType *SpecArg
= dyn_cast<TemplateSpecializationType>(Arg)) {
// Perform template argument deduction for the template name.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S, TemplateParams,
Param->getTemplateName(),
SpecArg->getTemplateName(),
Info, Deduced))
return Result;
// Perform template argument deduction on each template
// argument. Ignore any missing/extra arguments, since they could be
// filled in by default arguments.
return DeduceTemplateArguments(S, TemplateParams,
Param->getArgs(), Param->getNumArgs(),
SpecArg->getArgs(), SpecArg->getNumArgs(),
Info, Deduced);
}
// If the argument type is a class template specialization, we
// perform template argument deduction using its template
// arguments.
const RecordType *RecordArg = dyn_cast<RecordType>(Arg);
if (!RecordArg) {
Info.FirstArg = TemplateArgument(QualType(Param, 0));
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_NonDeducedMismatch;
}
ClassTemplateSpecializationDecl *SpecArg
= dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
if (!SpecArg) {
Info.FirstArg = TemplateArgument(QualType(Param, 0));
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_NonDeducedMismatch;
}
// Perform template argument deduction for the template name.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S,
TemplateParams,
Param->getTemplateName(),
TemplateName(SpecArg->getSpecializedTemplate()),
Info, Deduced))
return Result;
// Perform template argument deduction for the template arguments.
return DeduceTemplateArguments(S, TemplateParams,
Param->getArgs(), Param->getNumArgs(),
SpecArg->getTemplateArgs().data(),
SpecArg->getTemplateArgs().size(),
Info, Deduced);
}
/// \brief Determines whether the given type is an opaque type that
/// might be more qualified when instantiated.
static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
switch (T->getTypeClass()) {
case Type::TypeOfExpr:
case Type::TypeOf:
case Type::DependentName:
case Type::Decltype:
case Type::UnresolvedUsing:
case Type::TemplateTypeParm:
return true;
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::VariableArray:
case Type::DependentSizedArray:
return IsPossiblyOpaquelyQualifiedType(
cast<ArrayType>(T)->getElementType());
default:
return false;
}
}
/// \brief Retrieve the depth and index of a template parameter.
static std::pair<unsigned, unsigned>
getDepthAndIndex(NamedDecl *ND) {
if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ND))
return std::make_pair(TTP->getDepth(), TTP->getIndex());
if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(ND))
return std::make_pair(NTTP->getDepth(), NTTP->getIndex());
TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(ND);
return std::make_pair(TTP->getDepth(), TTP->getIndex());
}
/// \brief Retrieve the depth and index of an unexpanded parameter pack.
static std::pair<unsigned, unsigned>
getDepthAndIndex(UnexpandedParameterPack UPP) {
if (const TemplateTypeParmType *TTP
= UPP.first.dyn_cast<const TemplateTypeParmType *>())
return std::make_pair(TTP->getDepth(), TTP->getIndex());
return getDepthAndIndex(UPP.first.get<NamedDecl *>());
}
/// \brief Helper function to build a TemplateParameter when we don't
/// know its type statically.
static TemplateParameter makeTemplateParameter(Decl *D) {
if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
return TemplateParameter(TTP);
else if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
return TemplateParameter(NTTP);
return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
}
/// \brief Prepare to perform template argument deduction for all of the
/// arguments in a set of argument packs.
static void PrepareArgumentPackDeduction(Sema &S,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
ArrayRef<unsigned> PackIndices,
SmallVectorImpl<DeducedTemplateArgument> &SavedPacks,
SmallVectorImpl<
SmallVector<DeducedTemplateArgument, 4> > &NewlyDeducedPacks) {
// Save the deduced template arguments for each parameter pack expanded
// by this pack expansion, then clear out the deduction.
for (unsigned I = 0, N = PackIndices.size(); I != N; ++I) {
// Save the previously-deduced argument pack, then clear it out so that we
// can deduce a new argument pack.
SavedPacks[I] = Deduced[PackIndices[I]];
Deduced[PackIndices[I]] = TemplateArgument();
if (!S.CurrentInstantiationScope)
continue;
// If the template argument pack was explicitly specified, add that to
// the set of deduced arguments.
const TemplateArgument *ExplicitArgs;
unsigned NumExplicitArgs;
if (NamedDecl *PartiallySubstitutedPack
= S.CurrentInstantiationScope->getPartiallySubstitutedPack(
&ExplicitArgs,
&NumExplicitArgs)) {
if (getDepthAndIndex(PartiallySubstitutedPack).second == PackIndices[I])
NewlyDeducedPacks[I].append(ExplicitArgs,
ExplicitArgs + NumExplicitArgs);
}
}
}
/// \brief Finish template argument deduction for a set of argument packs,
/// producing the argument packs and checking for consistency with prior
/// deductions.
static Sema::TemplateDeductionResult
FinishArgumentPackDeduction(Sema &S,
TemplateParameterList *TemplateParams,
bool HasAnyArguments,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
ArrayRef<unsigned> PackIndices,
SmallVectorImpl<DeducedTemplateArgument> &SavedPacks,
SmallVectorImpl<
SmallVector<DeducedTemplateArgument, 4> > &NewlyDeducedPacks,
TemplateDeductionInfo &Info) {
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
for (unsigned I = 0, N = PackIndices.size(); I != N; ++I) {
if (HasAnyArguments && NewlyDeducedPacks[I].empty()) {
// We were not able to deduce anything for this parameter pack,
// so just restore the saved argument pack.
Deduced[PackIndices[I]] = SavedPacks[I];
continue;
}
DeducedTemplateArgument NewPack;
if (NewlyDeducedPacks[I].empty()) {
// If we deduced an empty argument pack, create it now.
NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
} else {
TemplateArgument *ArgumentPack
= new (S.Context) TemplateArgument [NewlyDeducedPacks[I].size()];
std::copy(NewlyDeducedPacks[I].begin(), NewlyDeducedPacks[I].end(),
ArgumentPack);
NewPack
= DeducedTemplateArgument(TemplateArgument(ArgumentPack,
NewlyDeducedPacks[I].size()),
NewlyDeducedPacks[I][0].wasDeducedFromArrayBound());
}
DeducedTemplateArgument Result
= checkDeducedTemplateArguments(S.Context, SavedPacks[I], NewPack);
if (Result.isNull()) {
Info.Param
= makeTemplateParameter(TemplateParams->getParam(PackIndices[I]));
Info.FirstArg = SavedPacks[I];
Info.SecondArg = NewPack;
return Sema::TDK_Inconsistent;
}
Deduced[PackIndices[I]] = Result;
}
return Sema::TDK_Success;
}
/// \brief Deduce the template arguments by comparing the list of parameter
/// types to the list of argument types, as in the parameter-type-lists of
/// function types (C++ [temp.deduct.type]p10).
///
/// \param S The semantic analysis object within which we are deducing
///
/// \param TemplateParams The template parameters that we are deducing
///
/// \param Params The list of parameter types
///
/// \param NumParams The number of types in \c Params
///
/// \param Args The list of argument types
///
/// \param NumArgs The number of types in \c Args
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
/// how template argument deduction is performed.
///
/// \param PartialOrdering If true, we are performing template argument
/// deduction for during partial ordering for a call
/// (C++0x [temp.deduct.partial]).
///
/// \param RefParamComparisons If we're performing template argument deduction
/// in the context of partial ordering, the set of qualifier comparisons.
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const QualType *Params, unsigned NumParams,
const QualType *Args, unsigned NumArgs,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
unsigned TDF,
bool PartialOrdering = false,
SmallVectorImpl<RefParamPartialOrderingComparison> *
RefParamComparisons = 0) {
// Fast-path check to see if we have too many/too few arguments.
if (NumParams != NumArgs &&
!(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
!(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
return Sema::TDK_MiscellaneousDeductionFailure;
// C++0x [temp.deduct.type]p10:
// Similarly, if P has a form that contains (T), then each parameter type
// Pi of the respective parameter-type- list of P is compared with the
// corresponding parameter type Ai of the corresponding parameter-type-list
// of A. [...]
unsigned ArgIdx = 0, ParamIdx = 0;
for (; ParamIdx != NumParams; ++ParamIdx) {
// Check argument types.
const PackExpansionType *Expansion
= dyn_cast<PackExpansionType>(Params[ParamIdx]);
if (!Expansion) {
// Simple case: compare the parameter and argument types at this point.
// Make sure we have an argument.
if (ArgIdx >= NumArgs)
return Sema::TDK_MiscellaneousDeductionFailure;
if (isa<PackExpansionType>(Args[ArgIdx])) {
// C++0x [temp.deduct.type]p22:
// If the original function parameter associated with A is a function
// parameter pack and the function parameter associated with P is not
// a function parameter pack, then template argument deduction fails.
return Sema::TDK_MiscellaneousDeductionFailure;
}
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
Params[ParamIdx], Args[ArgIdx],
Info, Deduced, TDF,
PartialOrdering,
RefParamComparisons))
return Result;
++ArgIdx;
continue;
}
// C++0x [temp.deduct.type]p5:
// The non-deduced contexts are:
// - A function parameter pack that does not occur at the end of the
// parameter-declaration-clause.
if (ParamIdx + 1 < NumParams)
return Sema::TDK_Success;
// C++0x [temp.deduct.type]p10:
// If the parameter-declaration corresponding to Pi is a function
// parameter pack, then the type of its declarator- id is compared with
// each remaining parameter type in the parameter-type-list of A. Each
// comparison deduces template arguments for subsequent positions in the
// template parameter packs expanded by the function parameter pack.
// Compute the set of template parameter indices that correspond to
// parameter packs expanded by the pack expansion.
SmallVector<unsigned, 2> PackIndices;
QualType Pattern = Expansion->getPattern();
{
llvm::SmallBitVector SawIndices(TemplateParams->size());
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
unsigned Depth, Index;
llvm::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
if (Depth == 0 && !SawIndices[Index]) {
SawIndices[Index] = true;
PackIndices.push_back(Index);
}
}
}
assert(!PackIndices.empty() && "Pack expansion without unexpanded packs?");
// Keep track of the deduced template arguments for each parameter pack
// expanded by this pack expansion (the outer index) and for each
// template argument (the inner SmallVectors).
SmallVector<SmallVector<DeducedTemplateArgument, 4>, 2>
NewlyDeducedPacks(PackIndices.size());
SmallVector<DeducedTemplateArgument, 2>
SavedPacks(PackIndices.size());
PrepareArgumentPackDeduction(S, Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks);
bool HasAnyArguments = false;
for (; ArgIdx < NumArgs; ++ArgIdx) {
HasAnyArguments = true;
// Deduce template arguments from the pattern.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, Pattern,
Args[ArgIdx], Info, Deduced,
TDF, PartialOrdering,
RefParamComparisons))
return Result;
// Capture the deduced template arguments for each parameter pack expanded
// by this pack expansion, add them to the list of arguments we've deduced
// for that pack, then clear out the deduced argument.
for (unsigned I = 0, N = PackIndices.size(); I != N; ++I) {
DeducedTemplateArgument &DeducedArg = Deduced[PackIndices[I]];
if (!DeducedArg.isNull()) {
NewlyDeducedPacks[I].push_back(DeducedArg);
DeducedArg = DeducedTemplateArgument();
}
}
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
if (Sema::TemplateDeductionResult Result
= FinishArgumentPackDeduction(S, TemplateParams, HasAnyArguments,
Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks, Info))
return Result;
}
// Make sure we don't have any extra arguments.
if (ArgIdx < NumArgs)
return Sema::TDK_MiscellaneousDeductionFailure;
return Sema::TDK_Success;
}
/// \brief Determine whether the parameter has qualifiers that are either
/// inconsistent with or a superset of the argument's qualifiers.
static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
QualType ArgType) {
Qualifiers ParamQs = ParamType.getQualifiers();
Qualifiers ArgQs = ArgType.getQualifiers();
if (ParamQs == ArgQs)
return false;
// Mismatched (but not missing) Objective-C GC attributes.
if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
ParamQs.hasObjCGCAttr())
return true;
// Mismatched (but not missing) address spaces.
if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
ParamQs.hasAddressSpace())
return true;
// Mismatched (but not missing) Objective-C lifetime qualifiers.
if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
ParamQs.hasObjCLifetime())
return true;
// CVR qualifier superset.
return (ParamQs.getCVRQualifiers() != ArgQs.getCVRQualifiers()) &&
((ParamQs.getCVRQualifiers() | ArgQs.getCVRQualifiers())
== ParamQs.getCVRQualifiers());
}
/// \brief Compare types for equality with respect to possibly compatible
/// function types (noreturn adjustment, implicit calling conventions). If any
/// of parameter and argument is not a function, just perform type comparison.
///
/// \param Param the template parameter type.
///
/// \param Arg the argument type.
bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
CanQualType Arg) {
const FunctionType *ParamFunction = Param->getAs<FunctionType>(),
*ArgFunction = Arg->getAs<FunctionType>();
// Just compare if not functions.
if (!ParamFunction || !ArgFunction)
return Param == Arg;
// Noreturn adjustment.
QualType AdjustedParam;
if (IsNoReturnConversion(Param, Arg, AdjustedParam))
return Arg == Context.getCanonicalType(AdjustedParam);
// FIXME: Compatible calling conventions.
return Param == Arg;
}
/// \brief Deduce the template arguments by comparing the parameter type and
/// the argument type (C++ [temp.deduct.type]).
///
/// \param S the semantic analysis object within which we are deducing
///
/// \param TemplateParams the template parameters that we are deducing
///
/// \param ParamIn the parameter type
///
/// \param ArgIn the argument type
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
/// how template argument deduction is performed.
///
/// \param PartialOrdering Whether we're performing template argument deduction
/// in the context of partial ordering (C++0x [temp.deduct.partial]).
///
/// \param RefParamComparisons If we're performing template argument deduction
/// in the context of partial ordering, the set of qualifier comparisons.
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static Sema::TemplateDeductionResult
DeduceTemplateArgumentsByTypeMatch(Sema &S,
TemplateParameterList *TemplateParams,
QualType ParamIn, QualType ArgIn,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
unsigned TDF,
bool PartialOrdering,
SmallVectorImpl<RefParamPartialOrderingComparison> *
RefParamComparisons) {
// We only want to look at the canonical types, since typedefs and
// sugar are not part of template argument deduction.
QualType Param = S.Context.getCanonicalType(ParamIn);
QualType Arg = S.Context.getCanonicalType(ArgIn);
// If the argument type is a pack expansion, look at its pattern.
// This isn't explicitly called out
if (const PackExpansionType *ArgExpansion
= dyn_cast<PackExpansionType>(Arg))
Arg = ArgExpansion->getPattern();
if (PartialOrdering) {
// C++0x [temp.deduct.partial]p5:
// Before the partial ordering is done, certain transformations are
// performed on the types used for partial ordering:
// - If P is a reference type, P is replaced by the type referred to.
const ReferenceType *ParamRef = Param->getAs<ReferenceType>();
if (ParamRef)
Param = ParamRef->getPointeeType();
// - If A is a reference type, A is replaced by the type referred to.
const ReferenceType *ArgRef = Arg->getAs<ReferenceType>();
if (ArgRef)
Arg = ArgRef->getPointeeType();
if (RefParamComparisons && ParamRef && ArgRef) {
// C++0x [temp.deduct.partial]p6:
// If both P and A were reference types (before being replaced with the
// type referred to above), determine which of the two types (if any) is
// more cv-qualified than the other; otherwise the types are considered
// to be equally cv-qualified for partial ordering purposes. The result
// of this determination will be used below.
//
// We save this information for later, using it only when deduction
// succeeds in both directions.
RefParamPartialOrderingComparison Comparison;
Comparison.ParamIsRvalueRef = ParamRef->getAs<RValueReferenceType>();
Comparison.ArgIsRvalueRef = ArgRef->getAs<RValueReferenceType>();
Comparison.Qualifiers = NeitherMoreQualified;
Qualifiers ParamQuals = Param.getQualifiers();
Qualifiers ArgQuals = Arg.getQualifiers();
if (ParamQuals.isStrictSupersetOf(ArgQuals))
Comparison.Qualifiers = ParamMoreQualified;
else if (ArgQuals.isStrictSupersetOf(ParamQuals))
Comparison.Qualifiers = ArgMoreQualified;
RefParamComparisons->push_back(Comparison);
}
// C++0x [temp.deduct.partial]p7:
// Remove any top-level cv-qualifiers:
// - If P is a cv-qualified type, P is replaced by the cv-unqualified
// version of P.
Param = Param.getUnqualifiedType();
// - If A is a cv-qualified type, A is replaced by the cv-unqualified
// version of A.
Arg = Arg.getUnqualifiedType();
} else {
// C++0x [temp.deduct.call]p4 bullet 1:
// - If the original P is a reference type, the deduced A (i.e., the type
// referred to by the reference) can be more cv-qualified than the
// transformed A.
if (TDF & TDF_ParamWithReferenceType) {
Qualifiers Quals;
QualType UnqualParam = S.Context.getUnqualifiedArrayType(Param, Quals);
Quals.setCVRQualifiers(Quals.getCVRQualifiers() &
Arg.getCVRQualifiers());
Param = S.Context.getQualifiedType(UnqualParam, Quals);
}
if ((TDF & TDF_TopLevelParameterTypeList) && !Param->isFunctionType()) {
// C++0x [temp.deduct.type]p10:
// If P and A are function types that originated from deduction when
// taking the address of a function template (14.8.2.2) or when deducing
// template arguments from a function declaration (14.8.2.6) and Pi and
// Ai are parameters of the top-level parameter-type-list of P and A,
// respectively, Pi is adjusted if it is an rvalue reference to a
// cv-unqualified template parameter and Ai is an lvalue reference, in
// which case the type of Pi is changed to be the template parameter
// type (i.e., T&& is changed to simply T). [ Note: As a result, when
// Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
// deduced as X&. - end note ]
TDF &= ~TDF_TopLevelParameterTypeList;
if (const RValueReferenceType *ParamRef
= Param->getAs<RValueReferenceType>()) {
if (isa<TemplateTypeParmType>(ParamRef->getPointeeType()) &&
!ParamRef->getPointeeType().getQualifiers())
if (Arg->isLValueReferenceType())
Param = ParamRef->getPointeeType();
}
}
}
// C++ [temp.deduct.type]p9:
// A template type argument T, a template template argument TT or a
// template non-type argument i can be deduced if P and A have one of
// the following forms:
//
// T
// cv-list T
if (const TemplateTypeParmType *TemplateTypeParm
= Param->getAs<TemplateTypeParmType>()) {
// Just skip any attempts to deduce from a placeholder type.
if (Arg->isPlaceholderType())
return Sema::TDK_Success;
unsigned Index = TemplateTypeParm->getIndex();
bool RecanonicalizeArg = false;
// If the argument type is an array type, move the qualifiers up to the
// top level, so they can be matched with the qualifiers on the parameter.
if (isa<ArrayType>(Arg)) {
Qualifiers Quals;
Arg = S.Context.getUnqualifiedArrayType(Arg, Quals);
if (Quals) {
Arg = S.Context.getQualifiedType(Arg, Quals);
RecanonicalizeArg = true;
}
}
// The argument type can not be less qualified than the parameter
// type.
if (!(TDF & TDF_IgnoreQualifiers) &&
hasInconsistentOrSupersetQualifiersOf(Param, Arg)) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = TemplateArgument(Param);
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_Underqualified;
}
assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0");
assert(Arg != S.Context.OverloadTy && "Unresolved overloaded function");
QualType DeducedType = Arg;
// Remove any qualifiers on the parameter from the deduced type.
// We checked the qualifiers for consistency above.
Qualifiers DeducedQs = DeducedType.getQualifiers();
Qualifiers ParamQs = Param.getQualifiers();
DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
if (ParamQs.hasObjCGCAttr())
DeducedQs.removeObjCGCAttr();
if (ParamQs.hasAddressSpace())
DeducedQs.removeAddressSpace();
if (ParamQs.hasObjCLifetime())
DeducedQs.removeObjCLifetime();
// Objective-C ARC:
// If template deduction would produce a lifetime qualifier on a type
// that is not a lifetime type, template argument deduction fails.
if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
!DeducedType->isDependentType()) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = TemplateArgument(Param);
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_Underqualified;
}
// Objective-C ARC:
// If template deduction would produce an argument type with lifetime type
// but no lifetime qualifier, the __strong lifetime qualifier is inferred.
if (S.getLangOpts().ObjCAutoRefCount &&
DeducedType->isObjCLifetimeType() &&
!DeducedQs.hasObjCLifetime())
DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
DeducedQs);
if (RecanonicalizeArg)
DeducedType = S.Context.getCanonicalType(DeducedType);
DeducedTemplateArgument NewDeduced(DeducedType);
DeducedTemplateArgument Result = checkDeducedTemplateArguments(S.Context,
Deduced[Index],
NewDeduced);
if (Result.isNull()) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = Deduced[Index];
Info.SecondArg = NewDeduced;
return Sema::TDK_Inconsistent;
}
Deduced[Index] = Result;
return Sema::TDK_Success;
}
// Set up the template argument deduction information for a failure.
Info.FirstArg = TemplateArgument(ParamIn);
Info.SecondArg = TemplateArgument(ArgIn);
// If the parameter is an already-substituted template parameter
// pack, do nothing: we don't know which of its arguments to look
// at, so we have to wait until all of the parameter packs in this
// expansion have arguments.
if (isa<SubstTemplateTypeParmPackType>(Param))
return Sema::TDK_Success;
// Check the cv-qualifiers on the parameter and argument types.
CanQualType CanParam = S.Context.getCanonicalType(Param);
CanQualType CanArg = S.Context.getCanonicalType(Arg);
if (!(TDF & TDF_IgnoreQualifiers)) {
if (TDF & TDF_ParamWithReferenceType) {
if (hasInconsistentOrSupersetQualifiersOf(Param, Arg))
return Sema::TDK_NonDeducedMismatch;
} else if (!IsPossiblyOpaquelyQualifiedType(Param)) {
if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
return Sema::TDK_NonDeducedMismatch;
}
// If the parameter type is not dependent, there is nothing to deduce.
if (!Param->isDependentType()) {
if (!(TDF & TDF_SkipNonDependent)) {
bool NonDeduced = (TDF & TDF_InOverloadResolution)?
!S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
Param != Arg;
if (NonDeduced) {
return Sema::TDK_NonDeducedMismatch;
}
}
return Sema::TDK_Success;
}
} else if (!Param->isDependentType()) {
CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
ArgUnqualType = CanArg.getUnqualifiedType();
bool Success = (TDF & TDF_InOverloadResolution)?
S.isSameOrCompatibleFunctionType(ParamUnqualType,
ArgUnqualType) :
ParamUnqualType == ArgUnqualType;
if (Success)
return Sema::TDK_Success;
}
switch (Param->getTypeClass()) {
// Non-canonical types cannot appear here.
#define NON_CANONICAL_TYPE(Class, Base) \
case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
#define TYPE(Class, Base)
#include "clang/AST/TypeNodes.def"
case Type::TemplateTypeParm:
case Type::SubstTemplateTypeParmPack:
llvm_unreachable("Type nodes handled above");
// These types cannot be dependent, so simply check whether the types are
// the same.
case Type::Builtin:
case Type::VariableArray:
case Type::Vector:
case Type::FunctionNoProto:
case Type::Record:
case Type::Enum:
case Type::ObjCObject:
case Type::ObjCInterface:
case Type::ObjCObjectPointer: {
if (TDF & TDF_SkipNonDependent)
return Sema::TDK_Success;
if (TDF & TDF_IgnoreQualifiers) {
Param = Param.getUnqualifiedType();
Arg = Arg.getUnqualifiedType();
}
return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
}
// _Complex T [placeholder extension]
case Type::Complex:
if (const ComplexType *ComplexArg = Arg->getAs<ComplexType>())
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
cast<ComplexType>(Param)->getElementType(),
ComplexArg->getElementType(),
Info, Deduced, TDF);
return Sema::TDK_NonDeducedMismatch;
// _Atomic T [extension]
case Type::Atomic:
if (const AtomicType *AtomicArg = Arg->getAs<AtomicType>())
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
cast<AtomicType>(Param)->getValueType(),
AtomicArg->getValueType(),
Info, Deduced, TDF);
return Sema::TDK_NonDeducedMismatch;
// T *
case Type::Pointer: {
QualType PointeeType;
if (const PointerType *PointerArg = Arg->getAs<PointerType>()) {
PointeeType = PointerArg->getPointeeType();
} else if (const ObjCObjectPointerType *PointerArg
= Arg->getAs<ObjCObjectPointerType>()) {
PointeeType = PointerArg->getPointeeType();
} else {
return Sema::TDK_NonDeducedMismatch;
}
unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
cast<PointerType>(Param)->getPointeeType(),
PointeeType,
Info, Deduced, SubTDF);
}
// T &
case Type::LValueReference: {
const LValueReferenceType *ReferenceArg = Arg->getAs<LValueReferenceType>();
if (!ReferenceArg)
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
cast<LValueReferenceType>(Param)->getPointeeType(),
ReferenceArg->getPointeeType(), Info, Deduced, 0);
}
// T && [C++0x]
case Type::RValueReference: {
const RValueReferenceType *ReferenceArg = Arg->getAs<RValueReferenceType>();
if (!ReferenceArg)
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
cast<RValueReferenceType>(Param)->getPointeeType(),
ReferenceArg->getPointeeType(),
Info, Deduced, 0);
}
// T [] (implied, but not stated explicitly)
case Type::IncompleteArray: {
const IncompleteArrayType *IncompleteArrayArg =
S.Context.getAsIncompleteArrayType(Arg);
if (!IncompleteArrayArg)
return Sema::TDK_NonDeducedMismatch;
unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
S.Context.getAsIncompleteArrayType(Param)->getElementType(),
IncompleteArrayArg->getElementType(),
Info, Deduced, SubTDF);
}
// T [integer-constant]
case Type::ConstantArray: {
const ConstantArrayType *ConstantArrayArg =
S.Context.getAsConstantArrayType(Arg);
if (!ConstantArrayArg)
return Sema::TDK_NonDeducedMismatch;
const ConstantArrayType *ConstantArrayParm =
S.Context.getAsConstantArrayType(Param);
if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
return Sema::TDK_NonDeducedMismatch;
unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
ConstantArrayParm->getElementType(),
ConstantArrayArg->getElementType(),
Info, Deduced, SubTDF);
}
// type [i]
case Type::DependentSizedArray: {
const ArrayType *ArrayArg = S.Context.getAsArrayType(Arg);
if (!ArrayArg)
return Sema::TDK_NonDeducedMismatch;
unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
// Check the element type of the arrays
const DependentSizedArrayType *DependentArrayParm
= S.Context.getAsDependentSizedArrayType(Param);
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
DependentArrayParm->getElementType(),
ArrayArg->getElementType(),
Info, Deduced, SubTDF))
return Result;
// Determine the array bound is something we can deduce.
NonTypeTemplateParmDecl *NTTP
= getDeducedParameterFromExpr(DependentArrayParm->getSizeExpr());
if (!NTTP)
return Sema::TDK_Success;
// We can perform template argument deduction for the given non-type
// template parameter.
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument at depth > 0");
if (const ConstantArrayType *ConstantArrayArg
= dyn_cast<ConstantArrayType>(ArrayArg)) {
llvm::APSInt Size(ConstantArrayArg->getSize());
return DeduceNonTypeTemplateArgument(S, NTTP, Size,
S.Context.getSizeType(),
/*ArrayBound=*/true,
Info, Deduced);
}
if (const DependentSizedArrayType *DependentArrayArg
= dyn_cast<DependentSizedArrayType>(ArrayArg))
if (DependentArrayArg->getSizeExpr())
return DeduceNonTypeTemplateArgument(S, NTTP,
DependentArrayArg->getSizeExpr(),
Info, Deduced);
// Incomplete type does not match a dependently-sized array type
return Sema::TDK_NonDeducedMismatch;
}
// type(*)(T)
// T(*)()
// T(*)(T)
case Type::FunctionProto: {
unsigned SubTDF = TDF & TDF_TopLevelParameterTypeList;
const FunctionProtoType *FunctionProtoArg =
dyn_cast<FunctionProtoType>(Arg);
if (!FunctionProtoArg)
return Sema::TDK_NonDeducedMismatch;
const FunctionProtoType *FunctionProtoParam =
cast<FunctionProtoType>(Param);
if (FunctionProtoParam->getTypeQuals()
!= FunctionProtoArg->getTypeQuals() ||
FunctionProtoParam->getRefQualifier()
!= FunctionProtoArg->getRefQualifier() ||
FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
return Sema::TDK_NonDeducedMismatch;
// Check return types.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
FunctionProtoParam->getResultType(),
FunctionProtoArg->getResultType(),
Info, Deduced, 0))
return Result;
return DeduceTemplateArguments(S, TemplateParams,
FunctionProtoParam->arg_type_begin(),
FunctionProtoParam->getNumArgs(),
FunctionProtoArg->arg_type_begin(),
FunctionProtoArg->getNumArgs(),
Info, Deduced, SubTDF);
}
case Type::InjectedClassName: {
// Treat a template's injected-class-name as if the template
// specialization type had been used.
Param = cast<InjectedClassNameType>(Param)
->getInjectedSpecializationType();
assert(isa<TemplateSpecializationType>(Param) &&
"injected class name is not a template specialization type");
// fall through
}
// template-name<T> (where template-name refers to a class template)
// template-name<i>
// TT<T>
// TT<i>
// TT<>
case Type::TemplateSpecialization: {
const TemplateSpecializationType *SpecParam
= cast<TemplateSpecializationType>(Param);
// Try to deduce template arguments from the template-id.
Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S, TemplateParams, SpecParam, Arg,
Info, Deduced);
if (Result && (TDF & TDF_DerivedClass)) {
// C++ [temp.deduct.call]p3b3:
// If P is a class, and P has the form template-id, then A can be a
// derived class of the deduced A. Likewise, if P is a pointer to a
// class of the form template-id, A can be a pointer to a derived
// class pointed to by the deduced A.
//
// More importantly:
// These alternatives are considered only if type deduction would
// otherwise fail.
if (const RecordType *RecordT = Arg->getAs<RecordType>()) {
// We cannot inspect base classes as part of deduction when the type
// is incomplete, so either instantiate any templates necessary to
// complete the type, or skip over it if it cannot be completed.
if (S.RequireCompleteType(Info.getLocation(), Arg, 0))
return Result;
// Use data recursion to crawl through the list of base classes.
// Visited contains the set of nodes we have already visited, while
// ToVisit is our stack of records that we still need to visit.
llvm::SmallPtrSet<const RecordType *, 8> Visited;
SmallVector<const RecordType *, 8> ToVisit;
ToVisit.push_back(RecordT);
bool Successful = false;
SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
Deduced.end());
while (!ToVisit.empty()) {
// Retrieve the next class in the inheritance hierarchy.
const RecordType *NextT = ToVisit.back();
ToVisit.pop_back();
// If we have already seen this type, skip it.
if (!Visited.insert(NextT))
continue;
// If this is a base class, try to perform template argument
// deduction from it.
if (NextT != RecordT) {
TemplateDeductionInfo BaseInfo(Info.getLocation());
Sema::TemplateDeductionResult BaseResult
= DeduceTemplateArguments(S, TemplateParams, SpecParam,
QualType(NextT, 0), BaseInfo,
Deduced);
// If template argument deduction for this base was successful,
// note that we had some success. Otherwise, ignore any deductions
// from this base class.
if (BaseResult == Sema::TDK_Success) {
Successful = true;
DeducedOrig.clear();
DeducedOrig.append(Deduced.begin(), Deduced.end());
Info.Param = BaseInfo.Param;
Info.FirstArg = BaseInfo.FirstArg;
Info.SecondArg = BaseInfo.SecondArg;
}
else
Deduced = DeducedOrig;
}
// Visit base classes
CXXRecordDecl *Next = cast<CXXRecordDecl>(NextT->getDecl());
for (CXXRecordDecl::base_class_iterator Base = Next->bases_begin(),
BaseEnd = Next->bases_end();
Base != BaseEnd; ++Base) {
assert(Base->getType()->isRecordType() &&
"Base class that isn't a record?");
ToVisit.push_back(Base->getType()->getAs<RecordType>());
}
}
if (Successful)
return Sema::TDK_Success;
}
}
return Result;
}
// T type::*
// T T::*
// T (type::*)()
// type (T::*)()
// type (type::*)(T)
// type (T::*)(T)
// T (type::*)(T)
// T (T::*)()
// T (T::*)(T)
case Type::MemberPointer: {
const MemberPointerType *MemPtrParam = cast<MemberPointerType>(Param);
const MemberPointerType *MemPtrArg = dyn_cast<MemberPointerType>(Arg);
if (!MemPtrArg)
return Sema::TDK_NonDeducedMismatch;
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
MemPtrParam->getPointeeType(),
MemPtrArg->getPointeeType(),
Info, Deduced,
TDF & TDF_IgnoreQualifiers))
return Result;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
QualType(MemPtrParam->getClass(), 0),
QualType(MemPtrArg->getClass(), 0),
Info, Deduced,
TDF & TDF_IgnoreQualifiers);
}
// (clang extension)
//
// type(^)(T)
// T(^)()
// T(^)(T)
case Type::BlockPointer: {
const BlockPointerType *BlockPtrParam = cast<BlockPointerType>(Param);
const BlockPointerType *BlockPtrArg = dyn_cast<BlockPointerType>(Arg);
if (!BlockPtrArg)
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
BlockPtrParam->getPointeeType(),
BlockPtrArg->getPointeeType(),
Info, Deduced, 0);
}
// (clang extension)
//
// T __attribute__(((ext_vector_type(<integral constant>))))
case Type::ExtVector: {
const ExtVectorType *VectorParam = cast<ExtVectorType>(Param);
if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
// Make sure that the vectors have the same number of elements.
if (VectorParam->getNumElements() != VectorArg->getNumElements())
return Sema::TDK_NonDeducedMismatch;
// Perform deduction on the element types.
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
VectorParam->getElementType(),
VectorArg->getElementType(),
Info, Deduced, TDF);
}
if (const DependentSizedExtVectorType *VectorArg
= dyn_cast<DependentSizedExtVectorType>(Arg)) {
// We can't check the number of elements, since the argument has a
// dependent number of elements. This can only occur during partial
// ordering.
// Perform deduction on the element types.
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
VectorParam->getElementType(),
VectorArg->getElementType(),
Info, Deduced, TDF);
}
return Sema::TDK_NonDeducedMismatch;
}
// (clang extension)
//
// T __attribute__(((ext_vector_type(N))))
case Type::DependentSizedExtVector: {
const DependentSizedExtVectorType *VectorParam
= cast<DependentSizedExtVectorType>(Param);
if (const ExtVectorType *VectorArg = dyn_cast<ExtVectorType>(Arg)) {
// Perform deduction on the element types.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
VectorParam->getElementType(),
VectorArg->getElementType(),
Info, Deduced, TDF))
return Result;
// Perform deduction on the vector size, if we can.
NonTypeTemplateParmDecl *NTTP
= getDeducedParameterFromExpr(VectorParam->getSizeExpr());
if (!NTTP)
return Sema::TDK_Success;
llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
ArgSize = VectorArg->getNumElements();
return DeduceNonTypeTemplateArgument(S, NTTP, ArgSize, S.Context.IntTy,
false, Info, Deduced);
}
if (const DependentSizedExtVectorType *VectorArg
= dyn_cast<DependentSizedExtVectorType>(Arg)) {
// Perform deduction on the element types.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
VectorParam->getElementType(),
VectorArg->getElementType(),
Info, Deduced, TDF))
return Result;
// Perform deduction on the vector size, if we can.
NonTypeTemplateParmDecl *NTTP
= getDeducedParameterFromExpr(VectorParam->getSizeExpr());
if (!NTTP)
return Sema::TDK_Success;
return DeduceNonTypeTemplateArgument(S, NTTP, VectorArg->getSizeExpr(),
Info, Deduced);
}
return Sema::TDK_NonDeducedMismatch;
}
case Type::TypeOfExpr:
case Type::TypeOf:
case Type::DependentName:
case Type::UnresolvedUsing:
case Type::Decltype:
case Type::UnaryTransform:
case Type::Auto:
case Type::DependentTemplateSpecialization:
case Type::PackExpansion:
// No template argument deduction for these types
return Sema::TDK_Success;
}
llvm_unreachable("Invalid Type Class!");
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
TemplateArgument Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
// If the template argument is a pack expansion, perform template argument
// deduction against the pattern of that expansion. This only occurs during
// partial ordering.
if (Arg.isPackExpansion())
Arg = Arg.getPackExpansionPattern();
switch (Param.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Null template argument in parameter list");
case TemplateArgument::Type:
if (Arg.getKind() == TemplateArgument::Type)
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
Param.getAsType(),
Arg.getAsType(),
Info, Deduced, 0);
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Template:
if (Arg.getKind() == TemplateArgument::Template)
return DeduceTemplateArguments(S, TemplateParams,
Param.getAsTemplate(),
Arg.getAsTemplate(), Info, Deduced);
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::TemplateExpansion:
llvm_unreachable("caller should handle pack expansions");
case TemplateArgument::Declaration:
if (Arg.getKind() == TemplateArgument::Declaration &&
isSameDeclaration(Param.getAsDecl(), Arg.getAsDecl()) &&
Param.isDeclForReferenceParam() == Arg.isDeclForReferenceParam())
return Sema::TDK_Success;
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::NullPtr:
if (Arg.getKind() == TemplateArgument::NullPtr &&
S.Context.hasSameType(Param.getNullPtrType(), Arg.getNullPtrType()))
return Sema::TDK_Success;
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Integral:
if (Arg.getKind() == TemplateArgument::Integral) {
if (hasSameExtendedValue(Param.getAsIntegral(), Arg.getAsIntegral()))
return Sema::TDK_Success;
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
}
if (Arg.getKind() == TemplateArgument::Expression) {
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
}
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Expression: {
if (NonTypeTemplateParmDecl *NTTP
= getDeducedParameterFromExpr(Param.getAsExpr())) {
if (Arg.getKind() == TemplateArgument::Integral)
return DeduceNonTypeTemplateArgument(S, NTTP,
Arg.getAsIntegral(),
Arg.getIntegralType(),
/*ArrayBound=*/false,
Info, Deduced);
if (Arg.getKind() == TemplateArgument::Expression)
return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsExpr(),
Info, Deduced);
if (Arg.getKind() == TemplateArgument::Declaration)
return DeduceNonTypeTemplateArgument(S, NTTP, Arg.getAsDecl(),
Info, Deduced);
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
}
// Can't deduce anything, but that's okay.
return Sema::TDK_Success;
}
case TemplateArgument::Pack:
llvm_unreachable("Argument packs should be expanded by the caller!");
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// \brief Determine whether there is a template argument to be used for
/// deduction.
///
/// This routine "expands" argument packs in-place, overriding its input
/// parameters so that \c Args[ArgIdx] will be the available template argument.
///
/// \returns true if there is another template argument (which will be at
/// \c Args[ArgIdx]), false otherwise.
static bool hasTemplateArgumentForDeduction(const TemplateArgument *&Args,
unsigned &ArgIdx,
unsigned &NumArgs) {
if (ArgIdx == NumArgs)
return false;
const TemplateArgument &Arg = Args[ArgIdx];
if (Arg.getKind() != TemplateArgument::Pack)
return true;
assert(ArgIdx == NumArgs - 1 && "Pack not at the end of argument list?");
Args = Arg.pack_begin();
NumArgs = Arg.pack_size();
ArgIdx = 0;
return ArgIdx < NumArgs;
}
/// \brief Determine whether the given set of template arguments has a pack
/// expansion that is not the last template argument.
static bool hasPackExpansionBeforeEnd(const TemplateArgument *Args,
unsigned NumArgs) {
unsigned ArgIdx = 0;
while (ArgIdx < NumArgs) {
const TemplateArgument &Arg = Args[ArgIdx];
// Unwrap argument packs.
if (Args[ArgIdx].getKind() == TemplateArgument::Pack) {
Args = Arg.pack_begin();
NumArgs = Arg.pack_size();
ArgIdx = 0;
continue;
}
++ArgIdx;
if (ArgIdx == NumArgs)
return false;
if (Arg.isPackExpansion())
return true;
}
return false;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgument *Params, unsigned NumParams,
const TemplateArgument *Args, unsigned NumArgs,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (hasPackExpansionBeforeEnd(Params, NumParams))
return Sema::TDK_Success;
// C++0x [temp.deduct.type]p9:
// If P has a form that contains <T> or <i>, then each argument Pi of the
// respective template argument list P is compared with the corresponding
// argument Ai of the corresponding template argument list of A.
unsigned ArgIdx = 0, ParamIdx = 0;
for (; hasTemplateArgumentForDeduction(Params, ParamIdx, NumParams);
++ParamIdx) {
if (!Params[ParamIdx].isPackExpansion()) {
// The simple case: deduce template arguments by matching Pi and Ai.
// Check whether we have enough arguments.
if (!hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs))
return Sema::TDK_Success;
if (Args[ArgIdx].isPackExpansion()) {
// FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here,
// but applied to pack expansions that are template arguments.
return Sema::TDK_MiscellaneousDeductionFailure;
}
// Perform deduction for this Pi/Ai pair.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S, TemplateParams,
Params[ParamIdx], Args[ArgIdx],
Info, Deduced))
return Result;
// Move to the next argument.
++ArgIdx;
continue;
}
// The parameter is a pack expansion.
// C++0x [temp.deduct.type]p9:
// If Pi is a pack expansion, then the pattern of Pi is compared with
// each remaining argument in the template argument list of A. Each
// comparison deduces template arguments for subsequent positions in the
// template parameter packs expanded by Pi.
TemplateArgument Pattern = Params[ParamIdx].getPackExpansionPattern();
// Compute the set of template parameter indices that correspond to
// parameter packs expanded by the pack expansion.
SmallVector<unsigned, 2> PackIndices;
{
llvm::SmallBitVector SawIndices(TemplateParams->size());
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
unsigned Depth, Index;
llvm::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
if (Depth == 0 && !SawIndices[Index]) {
SawIndices[Index] = true;
PackIndices.push_back(Index);
}
}
}
assert(!PackIndices.empty() && "Pack expansion without unexpanded packs?");
// FIXME: If there are no remaining arguments, we can bail out early
// and set any deduced parameter packs to an empty argument pack.
// The latter part of this is a (minor) correctness issue.
// Save the deduced template arguments for each parameter pack expanded
// by this pack expansion, then clear out the deduction.
SmallVector<DeducedTemplateArgument, 2>
SavedPacks(PackIndices.size());
SmallVector<SmallVector<DeducedTemplateArgument, 4>, 2>
NewlyDeducedPacks(PackIndices.size());
PrepareArgumentPackDeduction(S, Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks);
// Keep track of the deduced template arguments for each parameter pack
// expanded by this pack expansion (the outer index) and for each
// template argument (the inner SmallVectors).
bool HasAnyArguments = false;
while (hasTemplateArgumentForDeduction(Args, ArgIdx, NumArgs)) {
HasAnyArguments = true;
// Deduce template arguments from the pattern.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(S, TemplateParams, Pattern, Args[ArgIdx],
Info, Deduced))
return Result;
// Capture the deduced template arguments for each parameter pack expanded
// by this pack expansion, add them to the list of arguments we've deduced
// for that pack, then clear out the deduced argument.
for (unsigned I = 0, N = PackIndices.size(); I != N; ++I) {
DeducedTemplateArgument &DeducedArg = Deduced[PackIndices[I]];
if (!DeducedArg.isNull()) {
NewlyDeducedPacks[I].push_back(DeducedArg);
DeducedArg = DeducedTemplateArgument();
}
}
++ArgIdx;
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
if (Sema::TemplateDeductionResult Result
= FinishArgumentPackDeduction(S, TemplateParams, HasAnyArguments,
Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks, Info))
return Result;
}
return Sema::TDK_Success;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(Sema &S,
TemplateParameterList *TemplateParams,
const TemplateArgumentList &ParamList,
const TemplateArgumentList &ArgList,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced) {
return DeduceTemplateArguments(S, TemplateParams,
ParamList.data(), ParamList.size(),
ArgList.data(), ArgList.size(),
Info, Deduced);
}
/// \brief Determine whether two template arguments are the same.
static bool isSameTemplateArg(ASTContext &Context,
const TemplateArgument &X,
const TemplateArgument &Y) {
if (X.getKind() != Y.getKind())
return false;
switch (X.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Comparing NULL template argument");
case TemplateArgument::Type:
return Context.getCanonicalType(X.getAsType()) ==
Context.getCanonicalType(Y.getAsType());
case TemplateArgument::Declaration:
return isSameDeclaration(X.getAsDecl(), Y.getAsDecl()) &&
X.isDeclForReferenceParam() == Y.isDeclForReferenceParam();
case TemplateArgument::NullPtr:
return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion:
return Context.getCanonicalTemplateName(
X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
Context.getCanonicalTemplateName(
Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
case TemplateArgument::Integral:
return X.getAsIntegral() == Y.getAsIntegral();
case TemplateArgument::Expression: {
llvm::FoldingSetNodeID XID, YID;
X.getAsExpr()->Profile(XID, Context, true);
Y.getAsExpr()->Profile(YID, Context, true);
return XID == YID;
}
case TemplateArgument::Pack:
if (X.pack_size() != Y.pack_size())
return false;
for (TemplateArgument::pack_iterator XP = X.pack_begin(),
XPEnd = X.pack_end(),
YP = Y.pack_begin();
XP != XPEnd; ++XP, ++YP)
if (!isSameTemplateArg(Context, *XP, *YP))
return false;
return true;
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// \brief Allocate a TemplateArgumentLoc where all locations have
/// been initialized to the given location.
///
/// \param S The semantic analysis object.
///
/// \param Arg The template argument we are producing template argument
/// location information for.
///
/// \param NTTPType For a declaration template argument, the type of
/// the non-type template parameter that corresponds to this template
/// argument.
///
/// \param Loc The source location to use for the resulting template
/// argument.
static TemplateArgumentLoc
getTrivialTemplateArgumentLoc(Sema &S,
const TemplateArgument &Arg,
QualType NTTPType,
SourceLocation Loc) {
switch (Arg.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Can't get a NULL template argument here");
case TemplateArgument::Type:
return TemplateArgumentLoc(Arg,
S.Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
case TemplateArgument::Declaration: {
Expr *E
= S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
.takeAs<Expr>();
return TemplateArgumentLoc(TemplateArgument(E), E);
}
case TemplateArgument::NullPtr: {
Expr *E
= S.BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
.takeAs<Expr>();
return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
E);
}
case TemplateArgument::Integral: {
Expr *E
= S.BuildExpressionFromIntegralTemplateArgument(Arg, Loc).takeAs<Expr>();
return TemplateArgumentLoc(TemplateArgument(E), E);
}
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion: {
NestedNameSpecifierLocBuilder Builder;
TemplateName Template = Arg.getAsTemplate();
if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
Builder.MakeTrivial(S.Context, DTN->getQualifier(), Loc);
else if (QualifiedTemplateName *QTN = Template.getAsQualifiedTemplateName())
Builder.MakeTrivial(S.Context, QTN->getQualifier(), Loc);
if (Arg.getKind() == TemplateArgument::Template)
return TemplateArgumentLoc(Arg,
Builder.getWithLocInContext(S.Context),
Loc);
return TemplateArgumentLoc(Arg, Builder.getWithLocInContext(S.Context),
Loc, Loc);
}
case TemplateArgument::Expression:
return TemplateArgumentLoc(Arg, Arg.getAsExpr());
case TemplateArgument::Pack:
return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// \brief Convert the given deduced template argument and add it to the set of
/// fully-converted template arguments.
static bool ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
DeducedTemplateArgument Arg,
NamedDecl *Template,
QualType NTTPType,
unsigned ArgumentPackIndex,
TemplateDeductionInfo &Info,
bool InFunctionTemplate,
SmallVectorImpl<TemplateArgument> &Output) {
if (Arg.getKind() == TemplateArgument::Pack) {
// This is a template argument pack, so check each of its arguments against
// the template parameter.
SmallVector<TemplateArgument, 2> PackedArgsBuilder;
for (TemplateArgument::pack_iterator PA = Arg.pack_begin(),
PAEnd = Arg.pack_end();
PA != PAEnd; ++PA) {
// When converting the deduced template argument, append it to the
// general output list. We need to do this so that the template argument
// checking logic has all of the prior template arguments available.
DeducedTemplateArgument InnerArg(*PA);
InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
if (ConvertDeducedTemplateArgument(S, Param, InnerArg, Template,
NTTPType, PackedArgsBuilder.size(),
Info, InFunctionTemplate, Output))
return true;
// Move the converted template argument into our argument pack.
PackedArgsBuilder.push_back(Output.back());
Output.pop_back();
}
// Create the resulting argument pack.
Output.push_back(TemplateArgument::CreatePackCopy(S.Context,
PackedArgsBuilder.data(),
PackedArgsBuilder.size()));
return false;
}
// Convert the deduced template argument into a template
// argument that we can check, almost as if the user had written
// the template argument explicitly.
TemplateArgumentLoc ArgLoc = getTrivialTemplateArgumentLoc(S, Arg, NTTPType,
Info.getLocation());
// Check the template argument, converting it as necessary.
return S.CheckTemplateArgument(Param, ArgLoc,
Template,
Template->getLocation(),
Template->getSourceRange().getEnd(),
ArgumentPackIndex,
Output,
InFunctionTemplate
? (Arg.wasDeducedFromArrayBound()
? Sema::CTAK_DeducedFromArrayBound
: Sema::CTAK_Deduced)
: Sema::CTAK_Specified);
}
/// Complete template argument deduction for a class template partial
/// specialization.
static Sema::TemplateDeductionResult
FinishTemplateArgumentDeduction(Sema &S,
ClassTemplatePartialSpecializationDecl *Partial,
const TemplateArgumentList &TemplateArgs,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info) {
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
Sema::SFINAETrap Trap(S);
Sema::ContextRAII SavedContext(S, Partial);
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
SmallVector<TemplateArgument, 4> Builder;
TemplateParameterList *PartialParams = Partial->getTemplateParameters();
for (unsigned I = 0, N = PartialParams->size(); I != N; ++I) {
NamedDecl *Param = PartialParams->getParam(I);
if (Deduced[I].isNull()) {
Info.Param = makeTemplateParameter(Param);
return Sema::TDK_Incomplete;
}
// We have deduced this argument, so it still needs to be
// checked and converted.
// First, for a non-type template parameter type that is
// initialized by a declaration, we need the type of the
// corresponding non-type template parameter.
QualType NTTPType;
if (NonTypeTemplateParmDecl *NTTP
= dyn_cast<NonTypeTemplateParmDecl>(Param)) {
NTTPType = NTTP->getType();
if (NTTPType->isDependentType()) {
TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
Builder.data(), Builder.size());
NTTPType = S.SubstType(NTTPType,
MultiLevelTemplateArgumentList(TemplateArgs),
NTTP->getLocation(),
NTTP->getDeclName());
if (NTTPType.isNull()) {
Info.Param = makeTemplateParameter(Param);
// FIXME: These template arguments are temporary. Free them!
Info.reset(TemplateArgumentList::CreateCopy(S.Context,
Builder.data(),
Builder.size()));
return Sema::TDK_SubstitutionFailure;
}
}
}
if (ConvertDeducedTemplateArgument(S, Param, Deduced[I],
Partial, NTTPType, 0, Info, false,
Builder)) {
Info.Param = makeTemplateParameter(Param);
// FIXME: These template arguments are temporary. Free them!
Info.reset(TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
Builder.size()));
return Sema::TDK_SubstitutionFailure;
}
}
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *DeducedArgumentList
= TemplateArgumentList::CreateCopy(S.Context, Builder.data(),
Builder.size());
Info.reset(DeducedArgumentList);
// Substitute the deduced template arguments into the template
// arguments of the class template partial specialization, and
// verify that the instantiated template arguments are both valid
// and are equivalent to the template arguments originally provided
// to the class template.
LocalInstantiationScope InstScope(S);
ClassTemplateDecl *ClassTemplate = Partial->getSpecializedTemplate();
const TemplateArgumentLoc *PartialTemplateArgs
= Partial->getTemplateArgsAsWritten();
// Note that we don't provide the langle and rangle locations.
TemplateArgumentListInfo InstArgs;
if (S.Subst(PartialTemplateArgs,
Partial->getNumTemplateArgsAsWritten(),
InstArgs, MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
if (ParamIdx >= Partial->getTemplateParameters()->size())
ParamIdx = Partial->getTemplateParameters()->size() - 1;
Decl *Param
= const_cast<NamedDecl *>(
Partial->getTemplateParameters()->getParam(ParamIdx));
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = PartialTemplateArgs[ArgIdx].getArgument();
return Sema::TDK_SubstitutionFailure;
}
SmallVector<TemplateArgument, 4> ConvertedInstArgs;
if (S.CheckTemplateArgumentList(ClassTemplate, Partial->getLocation(),
InstArgs, false, ConvertedInstArgs))
return Sema::TDK_SubstitutionFailure;
TemplateParameterList *TemplateParams
= ClassTemplate->getTemplateParameters();
for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
TemplateArgument InstArg = ConvertedInstArgs.data()[I];
if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg)) {
Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
Info.FirstArg = TemplateArgs[I];
Info.SecondArg = InstArg;
return Sema::TDK_NonDeducedMismatch;
}
}
if (Trap.hasErrorOccurred())
return Sema::TDK_SubstitutionFailure;
return Sema::TDK_Success;
}
/// \brief Perform template argument deduction to determine whether
/// the given template arguments match the given class template
/// partial specialization per C++ [temp.class.spec.match].
Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
const TemplateArgumentList &TemplateArgs,
TemplateDeductionInfo &Info) {
if (Partial->isInvalidDecl())
return TDK_Invalid;
// C++ [temp.class.spec.match]p2:
// A partial specialization matches a given actual template
// argument list if the template arguments of the partial
// specialization can be deduced from the actual template argument
// list (14.8.2).
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
SFINAETrap Trap(*this);
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(Partial->getTemplateParameters()->size());
if (TemplateDeductionResult Result
= ::DeduceTemplateArguments(*this,
Partial->getTemplateParameters(),
Partial->getTemplateArgs(),
TemplateArgs, Info, Deduced))
return Result;
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
InstantiatingTemplate Inst(*this, Partial->getLocation(), Partial,
DeducedArgs, Info);
if (Inst)
return TDK_InstantiationDepth;
if (Trap.hasErrorOccurred())
return Sema::TDK_SubstitutionFailure;
return ::FinishTemplateArgumentDeduction(*this, Partial, TemplateArgs,
Deduced, Info);
}
/// \brief Determine whether the given type T is a simple-template-id type.
static bool isSimpleTemplateIdType(QualType T) {
if (const TemplateSpecializationType *Spec
= T->getAs<TemplateSpecializationType>())
return Spec->getTemplateName().getAsTemplateDecl() != 0;
return false;
}
/// \brief Substitute the explicitly-provided template arguments into the
/// given function template according to C++ [temp.arg.explicit].
///
/// \param FunctionTemplate the function template into which the explicit
/// template arguments will be substituted.
///
/// \param ExplicitTemplateArgs the explicitly-specified template
/// arguments.
///
/// \param Deduced the deduced template arguments, which will be populated
/// with the converted and checked explicit template arguments.
///
/// \param ParamTypes will be populated with the instantiated function
/// parameters.
///
/// \param FunctionType if non-NULL, the result type of the function template
/// will also be instantiated and the pointed-to value will be updated with
/// the instantiated function type.
///
/// \param Info if substitution fails for any reason, this object will be
/// populated with more information about the failure.
///
/// \returns TDK_Success if substitution was successful, or some failure
/// condition.
Sema::TemplateDeductionResult
Sema::SubstituteExplicitTemplateArguments(
FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo &ExplicitTemplateArgs,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
SmallVectorImpl<QualType> &ParamTypes,
QualType *FunctionType,
TemplateDeductionInfo &Info) {
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
if (ExplicitTemplateArgs.size() == 0) {
// No arguments to substitute; just copy over the parameter types and
// fill in the function type.
for (FunctionDecl::param_iterator P = Function->param_begin(),
PEnd = Function->param_end();
P != PEnd;
++P)
ParamTypes.push_back((*P)->getType());
if (FunctionType)
*FunctionType = Function->getType();
return TDK_Success;
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
SFINAETrap Trap(*this);
// C++ [temp.arg.explicit]p3:
// Template arguments that are present shall be specified in the
// declaration order of their corresponding template-parameters. The
// template argument list shall not specify more template-arguments than
// there are corresponding template-parameters.
SmallVector<TemplateArgument, 4> Builder;
// Enter a new template instantiation context where we check the
// explicitly-specified template arguments against this function template,
// and then substitute them into the function parameter types.
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
FunctionTemplate, DeducedArgs,
ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
Info);
if (Inst)
return TDK_InstantiationDepth;
if (CheckTemplateArgumentList(FunctionTemplate,
SourceLocation(),
ExplicitTemplateArgs,
true,
Builder) || Trap.hasErrorOccurred()) {
unsigned Index = Builder.size();
if (Index >= TemplateParams->size())
Index = TemplateParams->size() - 1;
Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
return TDK_InvalidExplicitArguments;
}
// Form the template argument list from the explicitly-specified
// template arguments.
TemplateArgumentList *ExplicitArgumentList
= TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
Info.reset(ExplicitArgumentList);
// Template argument deduction and the final substitution should be
// done in the context of the templated declaration. Explicit
// argument substitution, on the other hand, needs to happen in the
// calling context.
ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
// If we deduced template arguments for a template parameter pack,
// note that the template argument pack is partially substituted and record
// the explicit template arguments. They'll be used as part of deduction
// for this template parameter pack.
for (unsigned I = 0, N = Builder.size(); I != N; ++I) {
const TemplateArgument &Arg = Builder[I];
if (Arg.getKind() == TemplateArgument::Pack) {
CurrentInstantiationScope->SetPartiallySubstitutedPack(
TemplateParams->getParam(I),
Arg.pack_begin(),
Arg.pack_size());
break;
}
}
const FunctionProtoType *Proto
= Function->getType()->getAs<FunctionProtoType>();
assert(Proto && "Function template does not have a prototype?");
// Instantiate the types of each of the function parameters given the
// explicitly-specified template arguments. If the function has a trailing
// return type, substitute it after the arguments to ensure we substitute
// in lexical order.
if (Proto->hasTrailingReturn()) {
if (SubstParmTypes(Function->getLocation(),
Function->param_begin(), Function->getNumParams(),
MultiLevelTemplateArgumentList(*ExplicitArgumentList),
ParamTypes))
return TDK_SubstitutionFailure;
}
// Instantiate the return type.
// FIXME: exception-specifications?
QualType ResultType;
{
// C++11 [expr.prim.general]p3:
// If a declaration declares a member function or member function
// template of a class X, the expression this is a prvalue of type
// "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
// and the end of the function-definition, member-declarator, or
// declarator.
unsigned ThisTypeQuals = 0;
CXXRecordDecl *ThisContext = 0;
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
ThisContext = Method->getParent();
ThisTypeQuals = Method->getTypeQualifiers();
}
CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
getLangOpts().CPlusPlus11);
ResultType = SubstType(Proto->getResultType(),
MultiLevelTemplateArgumentList(*ExplicitArgumentList),
Function->getTypeSpecStartLoc(),
Function->getDeclName());
if (ResultType.isNull() || Trap.hasErrorOccurred())
return TDK_SubstitutionFailure;
}
// Instantiate the types of each of the function parameters given the
// explicitly-specified template arguments if we didn't do so earlier.
if (!Proto->hasTrailingReturn() &&
SubstParmTypes(Function->getLocation(),
Function->param_begin(), Function->getNumParams(),
MultiLevelTemplateArgumentList(*ExplicitArgumentList),
ParamTypes))
return TDK_SubstitutionFailure;
if (FunctionType) {
*FunctionType = BuildFunctionType(ResultType, ParamTypes,
Function->getLocation(),
Function->getDeclName(),
Proto->getExtProtoInfo());
if (FunctionType->isNull() || Trap.hasErrorOccurred())
return TDK_SubstitutionFailure;
}
// C++ [temp.arg.explicit]p2:
// Trailing template arguments that can be deduced (14.8.2) may be
// omitted from the list of explicit template-arguments. If all of the
// template arguments can be deduced, they may all be omitted; in this
// case, the empty template argument list <> itself may also be omitted.
//
// Take all of the explicitly-specified arguments and put them into
// the set of deduced template arguments. Explicitly-specified
// parameter packs, however, will be set to NULL since the deduction
// mechanisms handle explicitly-specified argument packs directly.
Deduced.reserve(TemplateParams->size());
for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I) {
const TemplateArgument &Arg = ExplicitArgumentList->get(I);
if (Arg.getKind() == TemplateArgument::Pack)
Deduced.push_back(DeducedTemplateArgument());
else
Deduced.push_back(Arg);
}
return TDK_Success;
}
/// \brief Check whether the deduced argument type for a call to a function
/// template matches the actual argument type per C++ [temp.deduct.call]p4.
static bool
CheckOriginalCallArgDeduction(Sema &S, Sema::OriginalCallArg OriginalArg,
QualType DeducedA) {
ASTContext &Context = S.Context;
QualType A = OriginalArg.OriginalArgType;
QualType OriginalParamType = OriginalArg.OriginalParamType;
// Check for type equality (top-level cv-qualifiers are ignored).
if (Context.hasSameUnqualifiedType(A, DeducedA))
return false;
// Strip off references on the argument types; they aren't needed for
// the following checks.
if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
DeducedA = DeducedARef->getPointeeType();
if (const ReferenceType *ARef = A->getAs<ReferenceType>())
A = ARef->getPointeeType();
// C++ [temp.deduct.call]p4:
// [...] However, there are three cases that allow a difference:
// - If the original P is a reference type, the deduced A (i.e., the
// type referred to by the reference) can be more cv-qualified than
// the transformed A.
if (const ReferenceType *OriginalParamRef
= OriginalParamType->getAs<ReferenceType>()) {
// We don't want to keep the reference around any more.
OriginalParamType = OriginalParamRef->getPointeeType();
Qualifiers AQuals = A.getQualifiers();
Qualifiers DeducedAQuals = DeducedA.getQualifiers();
// Under Objective-C++ ARC, the deduced type may have implicitly been
// given strong lifetime. If so, update the original qualifiers to
// include this strong lifetime.
if (S.getLangOpts().ObjCAutoRefCount &&
DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
AQuals.getObjCLifetime() == Qualifiers::OCL_None) {
AQuals.setObjCLifetime(Qualifiers::OCL_Strong);
}
if (AQuals == DeducedAQuals) {
// Qualifiers match; there's nothing to do.
} else if (!DeducedAQuals.compatiblyIncludes(AQuals)) {
return true;
} else {
// Qualifiers are compatible, so have the argument type adopt the
// deduced argument type's qualifiers as if we had performed the
// qualification conversion.
A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
}
}
// - The transformed A can be another pointer or pointer to member
// type that can be converted to the deduced A via a qualification
// conversion.
//
// Also allow conversions which merely strip [[noreturn]] from function types
// (recursively) as an extension.
// FIXME: Currently, this doesn't place nicely with qualfication conversions.
bool ObjCLifetimeConversion = false;
QualType ResultTy;
if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
(S.IsQualificationConversion(A, DeducedA, false,
ObjCLifetimeConversion) ||
S.IsNoReturnConversion(A, DeducedA, ResultTy)))
return false;
// - If P is a class and P has the form simple-template-id, then the
// transformed A can be a derived class of the deduced A. [...]
// [...] Likewise, if P is a pointer to a class of the form
// simple-template-id, the transformed A can be a pointer to a
// derived class pointed to by the deduced A.
if (const PointerType *OriginalParamPtr
= OriginalParamType->getAs<PointerType>()) {
if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
if (const PointerType *APtr = A->getAs<PointerType>()) {
if (A->getPointeeType()->isRecordType()) {
OriginalParamType = OriginalParamPtr->getPointeeType();
DeducedA = DeducedAPtr->getPointeeType();
A = APtr->getPointeeType();
}
}
}
}
if (Context.hasSameUnqualifiedType(A, DeducedA))
return false;
if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
S.IsDerivedFrom(A, DeducedA))
return false;
return true;
}
/// \brief Finish template argument deduction for a function template,
/// checking the deduced template arguments for completeness and forming
/// the function template specialization.
///
/// \param OriginalCallArgs If non-NULL, the original call arguments against
/// which the deduced argument types should be compared.
Sema::TemplateDeductionResult
Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
unsigned NumExplicitlySpecified,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info,
SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs) {
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
SFINAETrap Trap(*this);
// Enter a new template instantiation context while we instantiate the
// actual function declaration.
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
FunctionTemplate, DeducedArgs,
ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
Info);
if (Inst)
return TDK_InstantiationDepth;
ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
SmallVector<TemplateArgument, 4> Builder;
for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
NamedDecl *Param = TemplateParams->getParam(I);
if (!Deduced[I].isNull()) {
if (I < NumExplicitlySpecified) {
// We have already fully type-checked and converted this
// argument, because it was explicitly-specified. Just record the
// presence of this argument.
Builder.push_back(Deduced[I]);
continue;
}
// We have deduced this argument, so it still needs to be
// checked and converted.
// First, for a non-type template parameter type that is
// initialized by a declaration, we need the type of the
// corresponding non-type template parameter.
QualType NTTPType;
if (NonTypeTemplateParmDecl *NTTP
= dyn_cast<NonTypeTemplateParmDecl>(Param)) {
NTTPType = NTTP->getType();
if (NTTPType->isDependentType()) {
TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
Builder.data(), Builder.size());
NTTPType = SubstType(NTTPType,
MultiLevelTemplateArgumentList(TemplateArgs),
NTTP->getLocation(),
NTTP->getDeclName());
if (NTTPType.isNull()) {
Info.Param = makeTemplateParameter(Param);
// FIXME: These template arguments are temporary. Free them!
Info.reset(TemplateArgumentList::CreateCopy(Context,
Builder.data(),
Builder.size()));
return TDK_SubstitutionFailure;
}
}
}
if (ConvertDeducedTemplateArgument(*this, Param, Deduced[I],
FunctionTemplate, NTTPType, 0, Info,
true, Builder)) {
Info.Param = makeTemplateParameter(Param);
// FIXME: These template arguments are temporary. Free them!
Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
Builder.size()));
return TDK_SubstitutionFailure;
}
continue;
}
// C++0x [temp.arg.explicit]p3:
// A trailing template parameter pack (14.5.3) not otherwise deduced will
// be deduced to an empty sequence of template arguments.
// FIXME: Where did the word "trailing" come from?
if (Param->isTemplateParameterPack()) {
// We may have had explicitly-specified template arguments for this
// template parameter pack. If so, our empty deduction extends the
// explicitly-specified set (C++0x [temp.arg.explicit]p9).
const TemplateArgument *ExplicitArgs;
unsigned NumExplicitArgs;
if (CurrentInstantiationScope &&
CurrentInstantiationScope->getPartiallySubstitutedPack(&ExplicitArgs,
&NumExplicitArgs)
== Param) {
Builder.push_back(TemplateArgument(ExplicitArgs, NumExplicitArgs));
// Forget the partially-substituted pack; it's substitution is now
// complete.
CurrentInstantiationScope->ResetPartiallySubstitutedPack();
} else {
Builder.push_back(TemplateArgument::getEmptyPack());
}
continue;
}
// Substitute into the default template argument, if available.
TemplateArgumentLoc DefArg
= SubstDefaultTemplateArgumentIfAvailable(FunctionTemplate,
FunctionTemplate->getLocation(),
FunctionTemplate->getSourceRange().getEnd(),
Param,
Builder);
// If there was no default argument, deduction is incomplete.
if (DefArg.getArgument().isNull()) {
Info.Param = makeTemplateParameter(
const_cast<NamedDecl *>(TemplateParams->getParam(I)));
return TDK_Incomplete;
}
// Check whether we can actually use the default argument.
if (CheckTemplateArgument(Param, DefArg,
FunctionTemplate,
FunctionTemplate->getLocation(),
FunctionTemplate->getSourceRange().getEnd(),
0, Builder,
CTAK_Specified)) {
Info.Param = makeTemplateParameter(
const_cast<NamedDecl *>(TemplateParams->getParam(I)));
// FIXME: These template arguments are temporary. Free them!
Info.reset(TemplateArgumentList::CreateCopy(Context, Builder.data(),
Builder.size()));
return TDK_SubstitutionFailure;
}
// If we get here, we successfully used the default template argument.
}
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *DeducedArgumentList
= TemplateArgumentList::CreateCopy(Context, Builder.data(), Builder.size());
Info.reset(DeducedArgumentList);
// Substitute the deduced template arguments into the function template
// declaration to produce the function template specialization.
DeclContext *Owner = FunctionTemplate->getDeclContext();
if (FunctionTemplate->getFriendObjectKind())
Owner = FunctionTemplate->getLexicalDeclContext();
Specialization = cast_or_null<FunctionDecl>(
SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner,
MultiLevelTemplateArgumentList(*DeducedArgumentList)));
if (!Specialization || Specialization->isInvalidDecl())
return TDK_SubstitutionFailure;
assert(Specialization->getPrimaryTemplate()->getCanonicalDecl() ==
FunctionTemplate->getCanonicalDecl());
// If the template argument list is owned by the function template
// specialization, release it.
if (Specialization->getTemplateSpecializationArgs() == DeducedArgumentList &&
!Trap.hasErrorOccurred())
Info.take();
// There may have been an error that did not prevent us from constructing a
// declaration. Mark the declaration invalid and return with a substitution
// failure.
if (Trap.hasErrorOccurred()) {
Specialization->setInvalidDecl(true);
return TDK_SubstitutionFailure;
}
if (OriginalCallArgs) {
// C++ [temp.deduct.call]p4:
// In general, the deduction process attempts to find template argument
// values that will make the deduced A identical to A (after the type A
// is transformed as described above). [...]
for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
unsigned ParamIdx = OriginalArg.ArgIdx;
if (ParamIdx >= Specialization->getNumParams())
continue;
QualType DeducedA = Specialization->getParamDecl(ParamIdx)->getType();
if (CheckOriginalCallArgDeduction(*this, OriginalArg, DeducedA))
return Sema::TDK_SubstitutionFailure;
}
}
// If we suppressed any diagnostics while performing template argument
// deduction, and if we haven't already instantiated this declaration,
// keep track of these diagnostics. They'll be emitted if this specialization
// is actually used.
if (Info.diag_begin() != Info.diag_end()) {
llvm::DenseMap<Decl *, SmallVector<PartialDiagnosticAt, 1> >::iterator
Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
if (Pos == SuppressedDiagnostics.end())
SuppressedDiagnostics[Specialization->getCanonicalDecl()]
.append(Info.diag_begin(), Info.diag_end());
}
return TDK_Success;
}
/// Gets the type of a function for template-argument-deducton
/// purposes when it's considered as part of an overload set.
static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
FunctionDecl *Fn) {
// We may need to deduce the return type of the function now.
if (S.getLangOpts().CPlusPlus1y && Fn->getResultType()->isUndeducedType() &&
S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/false))
return QualType();
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
if (Method->isInstance()) {
// An instance method that's referenced in a form that doesn't
// look like a member pointer is just invalid.
if (!R.HasFormOfMemberPointer) return QualType();
return S.Context.getMemberPointerType(Fn->getType(),
S.Context.getTypeDeclType(Method->getParent()).getTypePtr());
}
if (!R.IsAddressOfOperand) return Fn->getType();
return S.Context.getPointerType(Fn->getType());
}
/// Apply the deduction rules for overload sets.
///
/// \return the null type if this argument should be treated as an
/// undeduced context
static QualType
ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
Expr *Arg, QualType ParamType,
bool ParamWasReference) {
OverloadExpr::FindResult R = OverloadExpr::find(Arg);
OverloadExpr *Ovl = R.Expression;
// C++0x [temp.deduct.call]p4
unsigned TDF = 0;
if (ParamWasReference)
TDF |= TDF_ParamWithReferenceType;
if (R.IsAddressOfOperand)
TDF |= TDF_IgnoreQualifiers;
// C++0x [temp.deduct.call]p6:
// When P is a function type, pointer to function type, or pointer
// to member function type:
if (!ParamType->isFunctionType() &&
!ParamType->isFunctionPointerType() &&
!ParamType->isMemberFunctionPointerType()) {
if (Ovl->hasExplicitTemplateArgs()) {
// But we can still look for an explicit specialization.
if (FunctionDecl *ExplicitSpec
= S.ResolveSingleFunctionTemplateSpecialization(Ovl))
return GetTypeOfFunction(S, R, ExplicitSpec);
}
return QualType();
}
// Gather the explicit template arguments, if any.
TemplateArgumentListInfo ExplicitTemplateArgs;
if (Ovl->hasExplicitTemplateArgs())
Ovl->getExplicitTemplateArgs().copyInto(ExplicitTemplateArgs);
QualType Match;
for (UnresolvedSetIterator I = Ovl->decls_begin(),
E = Ovl->decls_end(); I != E; ++I) {
NamedDecl *D = (*I)->getUnderlyingDecl();
if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
// - If the argument is an overload set containing one or more
// function templates, the parameter is treated as a
// non-deduced context.
if (!Ovl->hasExplicitTemplateArgs())
return QualType();
// Otherwise, see if we can resolve a function type
FunctionDecl *Specialization = 0;
TemplateDeductionInfo Info(Ovl->getNameLoc());
if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
Specialization, Info))
continue;
D = Specialization;
}
FunctionDecl *Fn = cast<FunctionDecl>(D);
QualType ArgType = GetTypeOfFunction(S, R, Fn);
if (ArgType.isNull()) continue;
// Function-to-pointer conversion.
if (!ParamWasReference && ParamType->isPointerType() &&
ArgType->isFunctionType())
ArgType = S.Context.getPointerType(ArgType);
// - If the argument is an overload set (not containing function
// templates), trial argument deduction is attempted using each
// of the members of the set. If deduction succeeds for only one
// of the overload set members, that member is used as the
// argument value for the deduction. If deduction succeeds for
// more than one member of the overload set the parameter is
// treated as a non-deduced context.
// We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
// Type deduction is done independently for each P/A pair, and
// the deduced template argument values are then combined.
// So we do not reject deductions which were made elsewhere.
SmallVector<DeducedTemplateArgument, 8>
Deduced(TemplateParams->size());
TemplateDeductionInfo Info(Ovl->getNameLoc());
Sema::TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
ArgType, Info, Deduced, TDF);
if (Result) continue;
if (!Match.isNull()) return QualType();
Match = ArgType;
}
return Match;
}
/// \brief Perform the adjustments to the parameter and argument types
/// described in C++ [temp.deduct.call].
///
/// \returns true if the caller should not attempt to perform any template
/// argument deduction based on this P/A pair because the argument is an
/// overloaded function set that could not be resolved.
static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
TemplateParameterList *TemplateParams,
QualType &ParamType,
QualType &ArgType,
Expr *Arg,
unsigned &TDF) {
// C++0x [temp.deduct.call]p3:
// If P is a cv-qualified type, the top level cv-qualifiers of P's type
// are ignored for type deduction.
if (ParamType.hasQualifiers())
ParamType = ParamType.getUnqualifiedType();
const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
if (ParamRefType) {
QualType PointeeType = ParamRefType->getPointeeType();
// If the argument has incomplete array type, try to complete its type.
if (ArgType->isIncompleteArrayType() && !S.RequireCompleteExprType(Arg, 0))
ArgType = Arg->getType();
// [C++0x] If P is an rvalue reference to a cv-unqualified
// template parameter and the argument is an lvalue, the type
// "lvalue reference to A" is used in place of A for type
// deduction.
if (isa<RValueReferenceType>(ParamType)) {
if (!PointeeType.getQualifiers() &&
isa<TemplateTypeParmType>(PointeeType) &&
Arg->Classify(S.Context).isLValue() &&
Arg->getType() != S.Context.OverloadTy &&
Arg->getType() != S.Context.BoundMemberTy)
ArgType = S.Context.getLValueReferenceType(ArgType);
}
// [...] If P is a reference type, the type referred to by P is used
// for type deduction.
ParamType = PointeeType;
}
// Overload sets usually make this parameter an undeduced
// context, but there are sometimes special circumstances.
if (ArgType == S.Context.OverloadTy) {
ArgType = ResolveOverloadForDeduction(S, TemplateParams,
Arg, ParamType,
ParamRefType != 0);
if (ArgType.isNull())
return true;
}
if (ParamRefType) {
// C++0x [temp.deduct.call]p3:
// [...] If P is of the form T&&, where T is a template parameter, and
// the argument is an lvalue, the type A& is used in place of A for
// type deduction.
if (ParamRefType->isRValueReferenceType() &&
ParamRefType->getAs<TemplateTypeParmType>() &&
Arg->isLValue())
ArgType = S.Context.getLValueReferenceType(ArgType);
} else {
// C++ [temp.deduct.call]p2:
// If P is not a reference type:
// - If A is an array type, the pointer type produced by the
// array-to-pointer standard conversion (4.2) is used in place of
// A for type deduction; otherwise,
if (ArgType->isArrayType())
ArgType = S.Context.getArrayDecayedType(ArgType);
// - If A is a function type, the pointer type produced by the
// function-to-pointer standard conversion (4.3) is used in place
// of A for type deduction; otherwise,
else if (ArgType->isFunctionType())
ArgType = S.Context.getPointerType(ArgType);
else {
// - If A is a cv-qualified type, the top level cv-qualifiers of A's
// type are ignored for type deduction.
ArgType = ArgType.getUnqualifiedType();
}
}
// C++0x [temp.deduct.call]p4:
// In general, the deduction process attempts to find template argument
// values that will make the deduced A identical to A (after the type A
// is transformed as described above). [...]
TDF = TDF_SkipNonDependent;
// - If the original P is a reference type, the deduced A (i.e., the
// type referred to by the reference) can be more cv-qualified than
// the transformed A.
if (ParamRefType)
TDF |= TDF_ParamWithReferenceType;
// - The transformed A can be another pointer or pointer to member
// type that can be converted to the deduced A via a qualification
// conversion (4.4).
if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
ArgType->isObjCObjectPointerType())
TDF |= TDF_IgnoreQualifiers;
// - If P is a class and P has the form simple-template-id, then the
// transformed A can be a derived class of the deduced A. Likewise,
// if P is a pointer to a class of the form simple-template-id, the
// transformed A can be a pointer to a derived class pointed to by
// the deduced A.
if (isSimpleTemplateIdType(ParamType) ||
(isa<PointerType>(ParamType) &&
isSimpleTemplateIdType(
ParamType->getAs<PointerType>()->getPointeeType())))
TDF |= TDF_DerivedClass;
return false;
}
static bool hasDeducibleTemplateParameters(Sema &S,
FunctionTemplateDecl *FunctionTemplate,
QualType T);
/// \brief Perform template argument deduction by matching a parameter type
/// against a single expression, where the expression is an element of
/// an initializer list that was originally matched against a parameter
/// of type \c initializer_list\<ParamType\>.
static Sema::TemplateDeductionResult
DeduceTemplateArgumentByListElement(Sema &S,
TemplateParameterList *TemplateParams,
QualType ParamType, Expr *Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
unsigned TDF) {
// Handle the case where an init list contains another init list as the
// element.
if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
QualType X;
if (!S.isStdInitializerList(ParamType.getNonReferenceType(), &X))
return Sema::TDK_Success; // Just ignore this expression.
// Recurse down into the init list.
for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
if (Sema::TemplateDeductionResult Result =
DeduceTemplateArgumentByListElement(S, TemplateParams, X,
ILE->getInit(i),
Info, Deduced, TDF))
return Result;
}
return Sema::TDK_Success;
}
// For all other cases, just match by type.
QualType ArgType = Arg->getType();
if (AdjustFunctionParmAndArgTypesForDeduction(S, TemplateParams, ParamType,
ArgType, Arg, TDF)) {
Info.Expression = Arg;
return Sema::TDK_FailedOverloadResolution;
}
return DeduceTemplateArgumentsByTypeMatch(S, TemplateParams, ParamType,
ArgType, Info, Deduced, TDF);
}
/// \brief Perform template argument deduction from a function call
/// (C++ [temp.deduct.call]).
///
/// \param FunctionTemplate the function template for which we are performing
/// template argument deduction.
///
/// \param ExplicitTemplateArgs the explicit template arguments provided
/// for this call.
///
/// \param Args the function call arguments
///
/// \param Specialization if template argument deduction was successful,
/// this will be set to the function template specialization produced by
/// template argument deduction.
///
/// \param Info the argument will be updated to provide additional information
/// about template argument deduction.
///
/// \returns the result of template argument deduction.
Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs,
llvm::ArrayRef<Expr *> Args,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info) {
if (FunctionTemplate->isInvalidDecl())
return TDK_Invalid;
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
// C++ [temp.deduct.call]p1:
// Template argument deduction is done by comparing each function template
// parameter type (call it P) with the type of the corresponding argument
// of the call (call it A) as described below.
unsigned CheckArgs = Args.size();
if (Args.size() < Function->getMinRequiredArguments())
return TDK_TooFewArguments;
else if (Args.size() > Function->getNumParams()) {
const FunctionProtoType *Proto
= Function->getType()->getAs<FunctionProtoType>();
if (Proto->isTemplateVariadic())
/* Do nothing */;
else if (Proto->isVariadic())
CheckArgs = Function->getNumParams();
else
return TDK_TooManyArguments;
}
// The types of the parameters from which we will perform template argument
// deduction.
LocalInstantiationScope InstScope(*this);
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced;
SmallVector<QualType, 4> ParamTypes;
unsigned NumExplicitlySpecified = 0;
if (ExplicitTemplateArgs) {
TemplateDeductionResult Result =
SubstituteExplicitTemplateArguments(FunctionTemplate,
*ExplicitTemplateArgs,
Deduced,
ParamTypes,
0,
Info);
if (Result)
return Result;
NumExplicitlySpecified = Deduced.size();
} else {
// Just fill in the parameter types from the function declaration.
for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
ParamTypes.push_back(Function->getParamDecl(I)->getType());
}
// Deduce template arguments from the function parameters.
Deduced.resize(TemplateParams->size());
unsigned ArgIdx = 0;
SmallVector<OriginalCallArg, 4> OriginalCallArgs;
for (unsigned ParamIdx = 0, NumParams = ParamTypes.size();
ParamIdx != NumParams; ++ParamIdx) {
QualType OrigParamType = ParamTypes[ParamIdx];
QualType ParamType = OrigParamType;
const PackExpansionType *ParamExpansion
= dyn_cast<PackExpansionType>(ParamType);
if (!ParamExpansion) {
// Simple case: matching a function parameter to a function argument.
if (ArgIdx >= CheckArgs)
break;
Expr *Arg = Args[ArgIdx++];
QualType ArgType = Arg->getType();
unsigned TDF = 0;
if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
ParamType, ArgType, Arg,
TDF))
continue;
// If we have nothing to deduce, we're done.
if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
continue;
// If the argument is an initializer list ...
if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
// ... then the parameter is an undeduced context, unless the parameter
// type is (reference to cv) std::initializer_list<P'>, in which case
// deduction is done for each element of the initializer list, and the
// result is the deduced type if it's the same for all elements.
QualType X;
// Removing references was already done.
if (!isStdInitializerList(ParamType, &X))
continue;
for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
if (TemplateDeductionResult Result =
DeduceTemplateArgumentByListElement(*this, TemplateParams, X,
ILE->getInit(i),
Info, Deduced, TDF))
return Result;
}
// Don't track the argument type, since an initializer list has none.
continue;
}
// Keep track of the argument type and corresponding parameter index,
// so we can check for compatibility between the deduced A and A.
OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx-1,
ArgType));
if (TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
ParamType, ArgType,
Info, Deduced, TDF))
return Result;
continue;
}
// C++0x [temp.deduct.call]p1:
// For a function parameter pack that occurs at the end of the
// parameter-declaration-list, the type A of each remaining argument of
// the call is compared with the type P of the declarator-id of the
// function parameter pack. Each comparison deduces template arguments
// for subsequent positions in the template parameter packs expanded by
// the function parameter pack. For a function parameter pack that does
// not occur at the end of the parameter-declaration-list, the type of
// the parameter pack is a non-deduced context.
if (ParamIdx + 1 < NumParams)
break;
QualType ParamPattern = ParamExpansion->getPattern();
SmallVector<unsigned, 2> PackIndices;
{
llvm::SmallBitVector SawIndices(TemplateParams->size());
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
collectUnexpandedParameterPacks(ParamPattern, Unexpanded);
for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
unsigned Depth, Index;
llvm::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
if (Depth == 0 && !SawIndices[Index]) {
SawIndices[Index] = true;
PackIndices.push_back(Index);
}
}
}
assert(!PackIndices.empty() && "Pack expansion without unexpanded packs?");
// Keep track of the deduced template arguments for each parameter pack
// expanded by this pack expansion (the outer index) and for each
// template argument (the inner SmallVectors).
SmallVector<SmallVector<DeducedTemplateArgument, 4>, 2>
NewlyDeducedPacks(PackIndices.size());
SmallVector<DeducedTemplateArgument, 2>
SavedPacks(PackIndices.size());
PrepareArgumentPackDeduction(*this, Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks);
bool HasAnyArguments = false;
for (; ArgIdx < Args.size(); ++ArgIdx) {
HasAnyArguments = true;
QualType OrigParamType = ParamPattern;
ParamType = OrigParamType;
Expr *Arg = Args[ArgIdx];
QualType ArgType = Arg->getType();
unsigned TDF = 0;
if (AdjustFunctionParmAndArgTypesForDeduction(*this, TemplateParams,
ParamType, ArgType, Arg,
TDF)) {
// We can't actually perform any deduction for this argument, so stop
// deduction at this point.
++ArgIdx;
break;
}
// As above, initializer lists need special handling.
if (InitListExpr *ILE = dyn_cast<InitListExpr>(Arg)) {
QualType X;
if (!isStdInitializerList(ParamType, &X)) {
++ArgIdx;
break;
}
for (unsigned i = 0, e = ILE->getNumInits(); i < e; ++i) {
if (TemplateDeductionResult Result =
DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams, X,
ILE->getInit(i)->getType(),
Info, Deduced, TDF))
return Result;
}
} else {
// Keep track of the argument type and corresponding argument index,
// so we can check for compatibility between the deduced A and A.
if (hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
OriginalCallArgs.push_back(OriginalCallArg(OrigParamType, ArgIdx,
ArgType));
if (TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
ParamType, ArgType, Info,
Deduced, TDF))
return Result;
}
// Capture the deduced template arguments for each parameter pack expanded
// by this pack expansion, add them to the list of arguments we've deduced
// for that pack, then clear out the deduced argument.
for (unsigned I = 0, N = PackIndices.size(); I != N; ++I) {
DeducedTemplateArgument &DeducedArg = Deduced[PackIndices[I]];
if (!DeducedArg.isNull()) {
NewlyDeducedPacks[I].push_back(DeducedArg);
DeducedArg = DeducedTemplateArgument();
}
}
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
if (Sema::TemplateDeductionResult Result
= FinishArgumentPackDeduction(*this, TemplateParams, HasAnyArguments,
Deduced, PackIndices, SavedPacks,
NewlyDeducedPacks, Info))
return Result;
// After we've matching against a parameter pack, we're done.
break;
}
return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
NumExplicitlySpecified,
Specialization, Info, &OriginalCallArgs);
}
/// \brief Deduce template arguments when taking the address of a function
/// template (C++ [temp.deduct.funcaddr]) or matching a specialization to
/// a template.
///
/// \param FunctionTemplate the function template for which we are performing
/// template argument deduction.
///
/// \param ExplicitTemplateArgs the explicitly-specified template
/// arguments.
///
/// \param ArgFunctionType the function type that will be used as the
/// "argument" type (A) when performing template argument deduction from the
/// function template's function type. This type may be NULL, if there is no
/// argument type to compare against, in C++0x [temp.arg.explicit]p3.
///
/// \param Specialization if template argument deduction was successful,
/// this will be set to the function template specialization produced by
/// template argument deduction.
///
/// \param Info the argument will be updated to provide additional information
/// about template argument deduction.
///
/// \returns the result of template argument deduction.
Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs,
QualType ArgFunctionType,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info,
bool InOverloadResolution) {
if (FunctionTemplate->isInvalidDecl())
return TDK_Invalid;
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
QualType FunctionType = Function->getType();
// Substitute any explicit template arguments.
LocalInstantiationScope InstScope(*this);
SmallVector<DeducedTemplateArgument, 4> Deduced;
unsigned NumExplicitlySpecified = 0;
SmallVector<QualType, 4> ParamTypes;
if (ExplicitTemplateArgs) {
if (TemplateDeductionResult Result
= SubstituteExplicitTemplateArguments(FunctionTemplate,
*ExplicitTemplateArgs,
Deduced, ParamTypes,
&FunctionType, Info))
return Result;
NumExplicitlySpecified = Deduced.size();
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
SFINAETrap Trap(*this);
Deduced.resize(TemplateParams->size());
// If the function has a deduced return type, substitute it for a dependent
// type so that we treat it as a non-deduced context in what follows.
bool HasUndeducedReturnType = false;
if (getLangOpts().CPlusPlus1y && InOverloadResolution &&
Function->getResultType()->isUndeducedType()) {
FunctionType = SubstAutoType(FunctionType, Context.DependentTy);
HasUndeducedReturnType = true;
}
if (!ArgFunctionType.isNull()) {
unsigned TDF = TDF_TopLevelParameterTypeList;
if (InOverloadResolution) TDF |= TDF_InOverloadResolution;
// Deduce template arguments from the function type.
if (TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
FunctionType, ArgFunctionType,
Info, Deduced, TDF))
return Result;
}
if (TemplateDeductionResult Result
= FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
NumExplicitlySpecified,
Specialization, Info))
return Result;
// If the function has a deduced return type, deduce it now, so we can check
// that the deduced function type matches the requested type.
if (HasUndeducedReturnType &&
Specialization->getResultType()->isUndeducedType() &&
DeduceReturnType(Specialization, Info.getLocation(), false))
return TDK_MiscellaneousDeductionFailure;
// If the requested function type does not match the actual type of the
// specialization with respect to arguments of compatible pointer to function
// types, template argument deduction fails.
if (!ArgFunctionType.isNull()) {
if (InOverloadResolution && !isSameOrCompatibleFunctionType(
Context.getCanonicalType(Specialization->getType()),
Context.getCanonicalType(ArgFunctionType)))
return TDK_MiscellaneousDeductionFailure;
else if(!InOverloadResolution &&
!Context.hasSameType(Specialization->getType(), ArgFunctionType))
return TDK_MiscellaneousDeductionFailure;
}
return TDK_Success;
}
/// \brief Deduce template arguments for a templated conversion
/// function (C++ [temp.deduct.conv]) and, if successful, produce a
/// conversion function template specialization.
Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
QualType ToType,
CXXConversionDecl *&Specialization,
TemplateDeductionInfo &Info) {
if (FunctionTemplate->isInvalidDecl())
return TDK_Invalid;
CXXConversionDecl *Conv
= cast<CXXConversionDecl>(FunctionTemplate->getTemplatedDecl());
QualType FromType = Conv->getConversionType();
// Canonicalize the types for deduction.
QualType P = Context.getCanonicalType(FromType);
QualType A = Context.getCanonicalType(ToType);
// C++0x [temp.deduct.conv]p2:
// If P is a reference type, the type referred to by P is used for
// type deduction.
if (const ReferenceType *PRef = P->getAs<ReferenceType>())
P = PRef->getPointeeType();
// C++0x [temp.deduct.conv]p4:
// [...] If A is a reference type, the type referred to by A is used
// for type deduction.
if (const ReferenceType *ARef = A->getAs<ReferenceType>())
A = ARef->getPointeeType().getUnqualifiedType();
// C++ [temp.deduct.conv]p3:
//
// If A is not a reference type:
else {
assert(!A->isReferenceType() && "Reference types were handled above");
// - If P is an array type, the pointer type produced by the
// array-to-pointer standard conversion (4.2) is used in place
// of P for type deduction; otherwise,
if (P->isArrayType())
P = Context.getArrayDecayedType(P);
// - If P is a function type, the pointer type produced by the
// function-to-pointer standard conversion (4.3) is used in
// place of P for type deduction; otherwise,
else if (P->isFunctionType())
P = Context.getPointerType(P);
// - If P is a cv-qualified type, the top level cv-qualifiers of
// P's type are ignored for type deduction.
else
P = P.getUnqualifiedType();
// C++0x [temp.deduct.conv]p4:
// If A is a cv-qualified type, the top level cv-qualifiers of A's
// type are ignored for type deduction. If A is a reference type, the type
// referred to by A is used for type deduction.
A = A.getUnqualifiedType();
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
SFINAETrap Trap(*this);
// C++ [temp.deduct.conv]p1:
// Template argument deduction is done by comparing the return
// type of the template conversion function (call it P) with the
// type that is required as the result of the conversion (call it
// A) as described in 14.8.2.4.
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(TemplateParams->size());
// C++0x [temp.deduct.conv]p4:
// In general, the deduction process attempts to find template
// argument values that will make the deduced A identical to
// A. However, there are two cases that allow a difference:
unsigned TDF = 0;
// - If the original A is a reference type, A can be more
// cv-qualified than the deduced A (i.e., the type referred to
// by the reference)
if (ToType->isReferenceType())
TDF |= TDF_ParamWithReferenceType;
// - The deduced A can be another pointer or pointer to member
// type that can be converted to A via a qualification
// conversion.
//
// (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
// both P and A are pointers or member pointers. In this case, we
// just ignore cv-qualifiers completely).
if ((P->isPointerType() && A->isPointerType()) ||
(P->isMemberPointerType() && A->isMemberPointerType()))
TDF |= TDF_IgnoreQualifiers;
if (TemplateDeductionResult Result
= DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
P, A, Info, Deduced, TDF))
return Result;
// Finish template argument deduction.
LocalInstantiationScope InstScope(*this);
FunctionDecl *Spec = 0;
TemplateDeductionResult Result
= FinishTemplateArgumentDeduction(FunctionTemplate, Deduced, 0, Spec,
Info);
Specialization = cast_or_null<CXXConversionDecl>(Spec);
return Result;
}
/// \brief Deduce template arguments for a function template when there is
/// nothing to deduce against (C++0x [temp.arg.explicit]p3).
///
/// \param FunctionTemplate the function template for which we are performing
/// template argument deduction.
///
/// \param ExplicitTemplateArgs the explicitly-specified template
/// arguments.
///
/// \param Specialization if template argument deduction was successful,
/// this will be set to the function template specialization produced by
/// template argument deduction.
///
/// \param Info the argument will be updated to provide additional information
/// about template argument deduction.
///
/// \returns the result of template argument deduction.
Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info,
bool InOverloadResolution) {
return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
QualType(), Specialization, Info,
InOverloadResolution);
}
namespace {
/// Substitute the 'auto' type specifier within a type for a given replacement
/// type.
class SubstituteAutoTransform :
public TreeTransform<SubstituteAutoTransform> {
QualType Replacement;
public:
SubstituteAutoTransform(Sema &SemaRef, QualType Replacement) :
TreeTransform<SubstituteAutoTransform>(SemaRef), Replacement(Replacement) {
}
QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
// If we're building the type pattern to deduce against, don't wrap the
// substituted type in an AutoType. Certain template deduction rules
// apply only when a template type parameter appears directly (and not if
// the parameter is found through desugaring). For instance:
// auto &&lref = lvalue;
// must transform into "rvalue reference to T" not "rvalue reference to
// auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
if (!Replacement.isNull() && isa<TemplateTypeParmType>(Replacement)) {
QualType Result = Replacement;
TemplateTypeParmTypeLoc NewTL =
TLB.push<TemplateTypeParmTypeLoc>(Result);
NewTL.setNameLoc(TL.getNameLoc());
return Result;
} else {
bool Dependent =
!Replacement.isNull() && Replacement->isDependentType();
QualType Result =
SemaRef.Context.getAutoType(Dependent ? QualType() : Replacement,
TL.getTypePtr()->isDecltypeAuto(),
Dependent);
AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
NewTL.setNameLoc(TL.getNameLoc());
return Result;
}
}
ExprResult TransformLambdaExpr(LambdaExpr *E) {
// Lambdas never need to be transformed.
return E;
}
QualType Apply(TypeLoc TL) {
// Create some scratch storage for the transformed type locations.
// FIXME: We're just going to throw this information away. Don't build it.
TypeLocBuilder TLB;
TLB.reserve(TL.getFullDataSize());
return TransformType(TLB, TL);
}
};
}
Sema::DeduceAutoResult
Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init, QualType &Result) {
return DeduceAutoType(Type->getTypeLoc(), Init, Result);
}
/// \brief Deduce the type for an auto type-specifier (C++11 [dcl.spec.auto]p6)
///
/// \param Type the type pattern using the auto type-specifier.
/// \param Init the initializer for the variable whose type is to be deduced.
/// \param Result if type deduction was successful, this will be set to the
/// deduced type.
Sema::DeduceAutoResult
Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result) {
if (Init->getType()->isNonOverloadPlaceholderType()) {
ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
if (NonPlaceholder.isInvalid())
return DAR_FailedAlreadyDiagnosed;
Init = NonPlaceholder.take();
}
if (Init->isTypeDependent() || Type.getType()->isDependentType()) {
Result = SubstituteAutoTransform(*this, Context.DependentTy).Apply(Type);
assert(!Result.isNull() && "substituting DependentTy can't fail");
return DAR_Succeeded;
}
// If this is a 'decltype(auto)' specifier, do the decltype dance.
// Since 'decltype(auto)' can only occur at the top of the type, we
// don't need to go digging for it.
if (const AutoType *AT = Type.getType()->getAs<AutoType>()) {
if (AT->isDecltypeAuto()) {
if (isa<InitListExpr>(Init)) {
Diag(Init->getLocStart(), diag::err_decltype_auto_initializer_list);
return DAR_FailedAlreadyDiagnosed;
}
QualType Deduced = BuildDecltypeType(Init, Init->getLocStart());
// FIXME: Support a non-canonical deduced type for 'auto'.
Deduced = Context.getCanonicalType(Deduced);
Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);
if (Result.isNull())
return DAR_FailedAlreadyDiagnosed;
return DAR_Succeeded;
}
}
SourceLocation Loc = Init->getExprLoc();
LocalInstantiationScope InstScope(*this);
// Build template<class TemplParam> void Func(FuncParam);
TemplateTypeParmDecl *TemplParam =
TemplateTypeParmDecl::Create(Context, 0, SourceLocation(), Loc, 0, 0, 0,
false, false);
QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
NamedDecl *TemplParamPtr = TemplParam;
FixedSizeTemplateParameterList<1> TemplateParams(Loc, Loc, &TemplParamPtr,
Loc);
QualType FuncParam = SubstituteAutoTransform(*this, TemplArg).Apply(Type);
assert(!FuncParam.isNull() &&
"substituting template parameter for 'auto' failed");
// Deduce type of TemplParam in Func(Init)
SmallVector<DeducedTemplateArgument, 1> Deduced;
Deduced.resize(1);
QualType InitType = Init->getType();
unsigned TDF = 0;
TemplateDeductionInfo Info(Loc);
InitListExpr *InitList = dyn_cast<InitListExpr>(Init);
if (InitList) {
for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
if (DeduceTemplateArgumentByListElement(*this, &TemplateParams,
TemplArg,
InitList->getInit(i),
Info, Deduced, TDF))
return DAR_Failed;
}
} else {
if (AdjustFunctionParmAndArgTypesForDeduction(*this, &TemplateParams,
FuncParam, InitType, Init,
TDF))
return DAR_Failed;
if (DeduceTemplateArgumentsByTypeMatch(*this, &TemplateParams, FuncParam,
InitType, Info, Deduced, TDF))
return DAR_Failed;
}
if (Deduced[0].getKind() != TemplateArgument::Type)
return DAR_Failed;
QualType DeducedType = Deduced[0].getAsType();
if (InitList) {
DeducedType = BuildStdInitializerList(DeducedType, Loc);
if (DeducedType.isNull())
return DAR_FailedAlreadyDiagnosed;
}
Result = SubstituteAutoTransform(*this, DeducedType).Apply(Type);
if (Result.isNull())
return DAR_FailedAlreadyDiagnosed;
// Check that the deduced argument type is compatible with the original
// argument type per C++ [temp.deduct.call]p4.
if (!InitList && !Result.isNull() &&
CheckOriginalCallArgDeduction(*this,
Sema::OriginalCallArg(FuncParam,0,InitType),
Result)) {
Result = QualType();
return DAR_Failed;
}
return DAR_Succeeded;
}
QualType Sema::SubstAutoType(QualType Type, QualType Deduced) {
return SubstituteAutoTransform(*this, Deduced).TransformType(Type);
}
void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
if (isa<InitListExpr>(Init))
Diag(VDecl->getLocation(),
diag::err_auto_var_deduction_failure_from_init_list)
<< VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
else
Diag(VDecl->getLocation(), diag::err_auto_var_deduction_failure)
<< VDecl->getDeclName() << VDecl->getType() << Init->getType()
<< Init->getSourceRange();
}
bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
bool Diagnose) {
assert(FD->getResultType()->isUndeducedType());
if (FD->getTemplateInstantiationPattern())
InstantiateFunctionDefinition(Loc, FD);
bool StillUndeduced = FD->getResultType()->isUndeducedType();
if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
Diag(FD->getLocation(), diag::note_callee_decl) << FD;
}
return StillUndeduced;
}
static void
MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
bool OnlyDeduced,
unsigned Level,
llvm::SmallBitVector &Deduced);
/// \brief If this is a non-static member function,
static void AddImplicitObjectParameterType(ASTContext &Context,
CXXMethodDecl *Method,
SmallVectorImpl<QualType> &ArgTypes) {
// C++11 [temp.func.order]p3:
// [...] The new parameter is of type "reference to cv A," where cv are
// the cv-qualifiers of the function template (if any) and A is
// the class of which the function template is a member.
//
// The standard doesn't say explicitly, but we pick the appropriate kind of
// reference type based on [over.match.funcs]p4.
QualType ArgTy = Context.getTypeDeclType(Method->getParent());
ArgTy = Context.getQualifiedType(ArgTy,
Qualifiers::fromCVRMask(Method->getTypeQualifiers()));
if (Method->getRefQualifier() == RQ_RValue)
ArgTy = Context.getRValueReferenceType(ArgTy);
else
ArgTy = Context.getLValueReferenceType(ArgTy);
ArgTypes.push_back(ArgTy);
}
/// \brief Determine whether the function template \p FT1 is at least as
/// specialized as \p FT2.
static bool isAtLeastAsSpecializedAs(Sema &S,
SourceLocation Loc,
FunctionTemplateDecl *FT1,
FunctionTemplateDecl *FT2,
TemplatePartialOrderingContext TPOC,
unsigned NumCallArguments,
SmallVectorImpl<RefParamPartialOrderingComparison> *RefParamComparisons) {
FunctionDecl *FD1 = FT1->getTemplatedDecl();
FunctionDecl *FD2 = FT2->getTemplatedDecl();
const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
assert(Proto1 && Proto2 && "Function templates must have prototypes");
TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(TemplateParams->size());
// C++0x [temp.deduct.partial]p3:
// The types used to determine the ordering depend on the context in which
// the partial ordering is done:
TemplateDeductionInfo Info(Loc);
CXXMethodDecl *Method1 = 0;
CXXMethodDecl *Method2 = 0;
bool IsNonStatic2 = false;
bool IsNonStatic1 = false;
unsigned Skip2 = 0;
switch (TPOC) {
case TPOC_Call: {
// - In the context of a function call, the function parameter types are
// used.
Method1 = dyn_cast<CXXMethodDecl>(FD1);
Method2 = dyn_cast<CXXMethodDecl>(FD2);
IsNonStatic1 = Method1 && !Method1->isStatic();
IsNonStatic2 = Method2 && !Method2->isStatic();
// C++11 [temp.func.order]p3:
// [...] If only one of the function templates is a non-static
// member, that function template is considered to have a new
// first parameter inserted in its function parameter list. The
// new parameter is of type "reference to cv A," where cv are
// the cv-qualifiers of the function template (if any) and A is
// the class of which the function template is a member.
//
// Note that we interpret this to mean "if one of the function
// templates is a non-static member and the other is a non-member";
// otherwise, the ordering rules for static functions against non-static
// functions don't make any sense.
//
// C++98/03 doesn't have this provision, so instead we drop the
// first argument of the free function, which seems to match
// existing practice.
SmallVector<QualType, 4> Args1;
unsigned Skip1 = !S.getLangOpts().CPlusPlus11 && IsNonStatic2 && !Method1;
if (S.getLangOpts().CPlusPlus11 && IsNonStatic1 && !Method2)
AddImplicitObjectParameterType(S.Context, Method1, Args1);
Args1.insert(Args1.end(),
Proto1->arg_type_begin() + Skip1, Proto1->arg_type_end());
SmallVector<QualType, 4> Args2;
Skip2 = !S.getLangOpts().CPlusPlus11 && IsNonStatic1 && !Method2;
if (S.getLangOpts().CPlusPlus11 && IsNonStatic2 && !Method1)
AddImplicitObjectParameterType(S.Context, Method2, Args2);
Args2.insert(Args2.end(),
Proto2->arg_type_begin() + Skip2, Proto2->arg_type_end());
// C++ [temp.func.order]p5:
// The presence of unused ellipsis and default arguments has no effect on
// the partial ordering of function templates.
if (Args1.size() > NumCallArguments)
Args1.resize(NumCallArguments);
if (Args2.size() > NumCallArguments)
Args2.resize(NumCallArguments);
if (DeduceTemplateArguments(S, TemplateParams, Args2.data(), Args2.size(),
Args1.data(), Args1.size(), Info, Deduced,
TDF_None, /*PartialOrdering=*/true,
RefParamComparisons))
return false;
break;
}
case TPOC_Conversion:
// - In the context of a call to a conversion operator, the return types
// of the conversion function templates are used.
if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
Proto2->getResultType(),
Proto1->getResultType(),
Info, Deduced, TDF_None,
/*PartialOrdering=*/true,
RefParamComparisons))
return false;
break;
case TPOC_Other:
// - In other contexts (14.6.6.2) the function template's function type
// is used.
if (DeduceTemplateArgumentsByTypeMatch(S, TemplateParams,
FD2->getType(), FD1->getType(),
Info, Deduced, TDF_None,
/*PartialOrdering=*/true,
RefParamComparisons))
return false;
break;
}
// C++0x [temp.deduct.partial]p11:
// In most cases, all template parameters must have values in order for
// deduction to succeed, but for partial ordering purposes a template
// parameter may remain without a value provided it is not used in the
// types being used for partial ordering. [ Note: a template parameter used
// in a non-deduced context is considered used. -end note]
unsigned ArgIdx = 0, NumArgs = Deduced.size();
for (; ArgIdx != NumArgs; ++ArgIdx)
if (Deduced[ArgIdx].isNull())
break;
if (ArgIdx == NumArgs) {
// All template arguments were deduced. FT1 is at least as specialized
// as FT2.
return true;
}
// Figure out which template parameters were used.
llvm::SmallBitVector UsedParameters(TemplateParams->size());
switch (TPOC) {
case TPOC_Call: {
unsigned NumParams = std::min(NumCallArguments,
std::min(Proto1->getNumArgs(),
Proto2->getNumArgs()));
if (S.getLangOpts().CPlusPlus11 && IsNonStatic2 && !IsNonStatic1)
::MarkUsedTemplateParameters(S.Context, Method2->getThisType(S.Context),
false,
TemplateParams->getDepth(), UsedParameters);
for (unsigned I = Skip2; I < NumParams; ++I)
::MarkUsedTemplateParameters(S.Context, Proto2->getArgType(I), false,
TemplateParams->getDepth(),
UsedParameters);
break;
}
case TPOC_Conversion:
::MarkUsedTemplateParameters(S.Context, Proto2->getResultType(), false,
TemplateParams->getDepth(),
UsedParameters);
break;
case TPOC_Other:
::MarkUsedTemplateParameters(S.Context, FD2->getType(), false,
TemplateParams->getDepth(),
UsedParameters);
break;
}
for (; ArgIdx != NumArgs; ++ArgIdx)
// If this argument had no value deduced but was used in one of the types
// used for partial ordering, then deduction fails.
if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
return false;
return true;
}
/// \brief Determine whether this a function template whose parameter-type-list
/// ends with a function parameter pack.
static bool isVariadicFunctionTemplate(FunctionTemplateDecl *FunTmpl) {
FunctionDecl *Function = FunTmpl->getTemplatedDecl();
unsigned NumParams = Function->getNumParams();
if (NumParams == 0)
return false;
ParmVarDecl *Last = Function->getParamDecl(NumParams - 1);
if (!Last->isParameterPack())
return false;
// Make sure that no previous parameter is a parameter pack.
while (--NumParams > 0) {
if (Function->getParamDecl(NumParams - 1)->isParameterPack())
return false;
}
return true;
}
/// \brief Returns the more specialized function template according
/// to the rules of function template partial ordering (C++ [temp.func.order]).
///
/// \param FT1 the first function template
///
/// \param FT2 the second function template
///
/// \param TPOC the context in which we are performing partial ordering of
/// function templates.
///
/// \param NumCallArguments The number of arguments in a call, used only
/// when \c TPOC is \c TPOC_Call.
///
/// \returns the more specialized function template. If neither
/// template is more specialized, returns NULL.
FunctionTemplateDecl *
Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
FunctionTemplateDecl *FT2,
SourceLocation Loc,
TemplatePartialOrderingContext TPOC,
unsigned NumCallArguments) {
SmallVector<RefParamPartialOrderingComparison, 4> RefParamComparisons;
bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
NumCallArguments, 0);
bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
NumCallArguments,
&RefParamComparisons);
if (Better1 != Better2) // We have a clear winner
return Better1? FT1 : FT2;
if (!Better1 && !Better2) // Neither is better than the other
return 0;
// C++0x [temp.deduct.partial]p10:
// If for each type being considered a given template is at least as
// specialized for all types and more specialized for some set of types and
// the other template is not more specialized for any types or is not at
// least as specialized for any types, then the given template is more
// specialized than the other template. Otherwise, neither template is more
// specialized than the other.
Better1 = false;
Better2 = false;
for (unsigned I = 0, N = RefParamComparisons.size(); I != N; ++I) {
// C++0x [temp.deduct.partial]p9:
// If, for a given type, deduction succeeds in both directions (i.e., the
// types are identical after the transformations above) and both P and A
// were reference types (before being replaced with the type referred to
// above):
// -- if the type from the argument template was an lvalue reference
// and the type from the parameter template was not, the argument
// type is considered to be more specialized than the other;
// otherwise,
if (!RefParamComparisons[I].ArgIsRvalueRef &&
RefParamComparisons[I].ParamIsRvalueRef) {
Better2 = true;
if (Better1)
return 0;
continue;
} else if (!RefParamComparisons[I].ParamIsRvalueRef &&
RefParamComparisons[I].ArgIsRvalueRef) {
Better1 = true;
if (Better2)
return 0;
continue;
}
// -- if the type from the argument template is more cv-qualified than
// the type from the parameter template (as described above), the
// argument type is considered to be more specialized than the
// other; otherwise,
switch (RefParamComparisons[I].Qualifiers) {
case NeitherMoreQualified:
break;
case ParamMoreQualified:
Better1 = true;
if (Better2)
return 0;
continue;
case ArgMoreQualified:
Better2 = true;
if (Better1)
return 0;
continue;
}
// -- neither type is more specialized than the other.
}
assert(!(Better1 && Better2) && "Should have broken out in the loop above");
if (Better1)
return FT1;
else if (Better2)
return FT2;
// FIXME: This mimics what GCC implements, but doesn't match up with the
// proposed resolution for core issue 692. This area needs to be sorted out,
// but for now we attempt to maintain compatibility.
bool Variadic1 = isVariadicFunctionTemplate(FT1);
bool Variadic2 = isVariadicFunctionTemplate(FT2);
if (Variadic1 != Variadic2)
return Variadic1? FT2 : FT1;
return 0;
}
/// \brief Determine if the two templates are equivalent.
static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
if (T1 == T2)
return true;
if (!T1 || !T2)
return false;
return T1->getCanonicalDecl() == T2->getCanonicalDecl();
}
/// \brief Retrieve the most specialized of the given function template
/// specializations.
///
/// \param SpecBegin the start iterator of the function template
/// specializations that we will be comparing.
///
/// \param SpecEnd the end iterator of the function template
/// specializations, paired with \p SpecBegin.
///
/// \param TPOC the partial ordering context to use to compare the function
/// template specializations.
///
/// \param NumCallArguments The number of arguments in a call, used only
/// when \c TPOC is \c TPOC_Call.
///
/// \param Loc the location where the ambiguity or no-specializations
/// diagnostic should occur.
///
/// \param NoneDiag partial diagnostic used to diagnose cases where there are
/// no matching candidates.
///
/// \param AmbigDiag partial diagnostic used to diagnose an ambiguity, if one
/// occurs.
///
/// \param CandidateDiag partial diagnostic used for each function template
/// specialization that is a candidate in the ambiguous ordering. One parameter
/// in this diagnostic should be unbound, which will correspond to the string
/// describing the template arguments for the function template specialization.
///
/// \returns the most specialized function template specialization, if
/// found. Otherwise, returns SpecEnd.
///
/// \todo FIXME: Consider passing in the "also-ran" candidates that failed
/// template argument deduction.
UnresolvedSetIterator
Sema::getMostSpecialized(UnresolvedSetIterator SpecBegin,
UnresolvedSetIterator SpecEnd,
TemplatePartialOrderingContext TPOC,
unsigned NumCallArguments,
SourceLocation Loc,
const PartialDiagnostic &NoneDiag,
const PartialDiagnostic &AmbigDiag,
const PartialDiagnostic &CandidateDiag,
bool Complain,
QualType TargetType) {
if (SpecBegin == SpecEnd) {
if (Complain)
Diag(Loc, NoneDiag);
return SpecEnd;
}
if (SpecBegin + 1 == SpecEnd)
return SpecBegin;
// Find the function template that is better than all of the templates it
// has been compared to.
UnresolvedSetIterator Best = SpecBegin;
FunctionTemplateDecl *BestTemplate
= cast<FunctionDecl>(*Best)->getPrimaryTemplate();
assert(BestTemplate && "Not a function template specialization?");
for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
FunctionTemplateDecl *Challenger
= cast<FunctionDecl>(*I)->getPrimaryTemplate();
assert(Challenger && "Not a function template specialization?");
if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
Loc, TPOC, NumCallArguments),
Challenger)) {
Best = I;
BestTemplate = Challenger;
}
}
// Make sure that the "best" function template is more specialized than all
// of the others.
bool Ambiguous = false;
for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
FunctionTemplateDecl *Challenger
= cast<FunctionDecl>(*I)->getPrimaryTemplate();
if (I != Best &&
!isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
Loc, TPOC, NumCallArguments),
BestTemplate)) {
Ambiguous = true;
break;
}
}
if (!Ambiguous) {
// We found an answer. Return it.
return Best;
}
// Diagnose the ambiguity.
if (Complain) {
Diag(Loc, AmbigDiag);
// FIXME: Can we order the candidates in some sane way?
for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
PartialDiagnostic PD = CandidateDiag;
PD << getTemplateArgumentBindingsText(
cast<FunctionDecl>(*I)->getPrimaryTemplate()->getTemplateParameters(),
*cast<FunctionDecl>(*I)->getTemplateSpecializationArgs());
if (!TargetType.isNull())
HandleFunctionTypeMismatch(PD, cast<FunctionDecl>(*I)->getType(),
TargetType);
Diag((*I)->getLocation(), PD);
}
}
return SpecEnd;
}
/// \brief Returns the more specialized class template partial specialization
/// according to the rules of partial ordering of class template partial
/// specializations (C++ [temp.class.order]).
///
/// \param PS1 the first class template partial specialization
///
/// \param PS2 the second class template partial specialization
///
/// \returns the more specialized class template partial specialization. If
/// neither partial specialization is more specialized, returns NULL.
ClassTemplatePartialSpecializationDecl *
Sema::getMoreSpecializedPartialSpecialization(
ClassTemplatePartialSpecializationDecl *PS1,
ClassTemplatePartialSpecializationDecl *PS2,
SourceLocation Loc) {
// C++ [temp.class.order]p1:
// For two class template partial specializations, the first is at least as
// specialized as the second if, given the following rewrite to two
// function templates, the first function template is at least as
// specialized as the second according to the ordering rules for function
// templates (14.6.6.2):
// - the first function template has the same template parameters as the
// first partial specialization and has a single function parameter
// whose type is a class template specialization with the template
// arguments of the first partial specialization, and
// - the second function template has the same template parameters as the
// second partial specialization and has a single function parameter
// whose type is a class template specialization with the template
// arguments of the second partial specialization.
//
// Rather than synthesize function templates, we merely perform the
// equivalent partial ordering by performing deduction directly on
// the template arguments of the class template partial
// specializations. This computation is slightly simpler than the
// general problem of function template partial ordering, because
// class template partial specializations are more constrained. We
// know that every template parameter is deducible from the class
// template partial specialization's template arguments, for
// example.
SmallVector<DeducedTemplateArgument, 4> Deduced;
TemplateDeductionInfo Info(Loc);
QualType PT1 = PS1->getInjectedSpecializationType();
QualType PT2 = PS2->getInjectedSpecializationType();
// Determine whether PS1 is at least as specialized as PS2
Deduced.resize(PS2->getTemplateParameters()->size());
bool Better1 = !DeduceTemplateArgumentsByTypeMatch(*this,
PS2->getTemplateParameters(),
PT2, PT1, Info, Deduced, TDF_None,
/*PartialOrdering=*/true,
/*RefParamComparisons=*/0);
if (Better1) {
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
InstantiatingTemplate Inst(*this, PS2->getLocation(), PS2,
DeducedArgs, Info);
Better1 = !::FinishTemplateArgumentDeduction(*this, PS2,
PS1->getTemplateArgs(),
Deduced, Info);
}
// Determine whether PS2 is at least as specialized as PS1
Deduced.clear();
Deduced.resize(PS1->getTemplateParameters()->size());
bool Better2 = !DeduceTemplateArgumentsByTypeMatch(*this,
PS1->getTemplateParameters(),
PT1, PT2, Info, Deduced, TDF_None,
/*PartialOrdering=*/true,
/*RefParamComparisons=*/0);
if (Better2) {
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),Deduced.end());
InstantiatingTemplate Inst(*this, PS1->getLocation(), PS1,
DeducedArgs, Info);
Better2 = !::FinishTemplateArgumentDeduction(*this, PS1,
PS2->getTemplateArgs(),
Deduced, Info);
}
if (Better1 == Better2)
return 0;
return Better1? PS1 : PS2;
}
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
const TemplateArgument &TemplateArg,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used);
/// \brief Mark the template parameters that are used by the given
/// expression.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
const Expr *E,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
// We can deduce from a pack expansion.
if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
E = Expansion->getPattern();
// Skip through any implicit casts we added while type-checking, and any
// substitutions performed by template alias expansion.
while (1) {
if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
E = ICE->getSubExpr();
else if (const SubstNonTypeTemplateParmExpr *Subst =
dyn_cast<SubstNonTypeTemplateParmExpr>(E))
E = Subst->getReplacement();
else
break;
}
// FIXME: if !OnlyDeduced, we have to walk the whole subexpression to
// find other occurrences of template parameters.
const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
if (!DRE)
return;
const NonTypeTemplateParmDecl *NTTP
= dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
if (!NTTP)
return;
if (NTTP->getDepth() == Depth)
Used[NTTP->getIndex()] = true;
}
/// \brief Mark the template parameters that are used by the given
/// nested name specifier.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
NestedNameSpecifier *NNS,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (!NNS)
return;
MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
Used);
MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
OnlyDeduced, Depth, Used);
}
/// \brief Mark the template parameters that are used by the given
/// template name.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
TemplateName Name,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
if (TemplateTemplateParmDecl *TTP
= dyn_cast<TemplateTemplateParmDecl>(Template)) {
if (TTP->getDepth() == Depth)
Used[TTP->getIndex()] = true;
}
return;
}
if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
Depth, Used);
if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
Depth, Used);
}
/// \brief Mark the template parameters that are used by the given
/// type.
static void
MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (T.isNull())
return;
// Non-dependent types have nothing deducible
if (!T->isDependentType())
return;
T = Ctx.getCanonicalType(T);
switch (T->getTypeClass()) {
case Type::Pointer:
MarkUsedTemplateParameters(Ctx,
cast<PointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::BlockPointer:
MarkUsedTemplateParameters(Ctx,
cast<BlockPointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::LValueReference:
case Type::RValueReference:
MarkUsedTemplateParameters(Ctx,
cast<ReferenceType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::MemberPointer: {
const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx, QualType(MemPtr->getClass(), 0),
OnlyDeduced, Depth, Used);
break;
}
case Type::DependentSizedArray:
MarkUsedTemplateParameters(Ctx,
cast<DependentSizedArrayType>(T)->getSizeExpr(),
OnlyDeduced, Depth, Used);
// Fall through to check the element type
case Type::ConstantArray:
case Type::IncompleteArray:
MarkUsedTemplateParameters(Ctx,
cast<ArrayType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Vector:
case Type::ExtVector:
MarkUsedTemplateParameters(Ctx,
cast<VectorType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentSizedExtVector: {
const DependentSizedExtVectorType *VecType
= cast<DependentSizedExtVectorType>(T);
MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
Depth, Used);
break;
}
case Type::FunctionProto: {
const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
MarkUsedTemplateParameters(Ctx, Proto->getResultType(), OnlyDeduced,
Depth, Used);
for (unsigned I = 0, N = Proto->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(Ctx, Proto->getArgType(I), OnlyDeduced,
Depth, Used);
break;
}
case Type::TemplateTypeParm: {
const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
if (TTP->getDepth() == Depth)
Used[TTP->getIndex()] = true;
break;
}
case Type::SubstTemplateTypeParmPack: {
const SubstTemplateTypeParmPackType *Subst
= cast<SubstTemplateTypeParmPackType>(T);
MarkUsedTemplateParameters(Ctx,
QualType(Subst->getReplacedParameter(), 0),
OnlyDeduced, Depth, Used);
MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
OnlyDeduced, Depth, Used);
break;
}
case Type::InjectedClassName:
T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
// fall through
case Type::TemplateSpecialization: {
const TemplateSpecializationType *Spec
= cast<TemplateSpecializationType>(T);
MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
Depth, Used);
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
break;
for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
Used);
break;
}
case Type::Complex:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<ComplexType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Atomic:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<AtomicType>(T)->getValueType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentName:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<DependentNameType>(T)->getQualifier(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentTemplateSpecialization: {
const DependentTemplateSpecializationType *Spec
= cast<DependentTemplateSpecializationType>(T);
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx, Spec->getQualifier(),
OnlyDeduced, Depth, Used);
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(Spec->getArgs(), Spec->getNumArgs()))
break;
for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(Ctx, Spec->getArg(I), OnlyDeduced, Depth,
Used);
break;
}
case Type::TypeOf:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<TypeOfType>(T)->getUnderlyingType(),
OnlyDeduced, Depth, Used);
break;
case Type::TypeOfExpr:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<TypeOfExprType>(T)->getUnderlyingExpr(),
OnlyDeduced, Depth, Used);
break;
case Type::Decltype:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<DecltypeType>(T)->getUnderlyingExpr(),
OnlyDeduced, Depth, Used);
break;
case Type::UnaryTransform:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<UnaryTransformType>(T)->getUnderlyingType(),
OnlyDeduced, Depth, Used);
break;
case Type::PackExpansion:
MarkUsedTemplateParameters(Ctx,
cast<PackExpansionType>(T)->getPattern(),
OnlyDeduced, Depth, Used);
break;
case Type::Auto:
MarkUsedTemplateParameters(Ctx,
cast<AutoType>(T)->getDeducedType(),
OnlyDeduced, Depth, Used);
// None of these types have any template parameters in them.
case Type::Builtin:
case Type::VariableArray:
case Type::FunctionNoProto:
case Type::Record:
case Type::Enum:
case Type::ObjCInterface:
case Type::ObjCObject:
case Type::ObjCObjectPointer:
case Type::UnresolvedUsing:
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define DEPENDENT_TYPE(Class, Base)
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.def"
break;
}
}
/// \brief Mark the template parameters that are used by this
/// template argument.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
const TemplateArgument &TemplateArg,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
switch (TemplateArg.getKind()) {
case TemplateArgument::Null:
case TemplateArgument::Integral:
case TemplateArgument::Declaration:
break;
case TemplateArgument::NullPtr:
MarkUsedTemplateParameters(Ctx, TemplateArg.getNullPtrType(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Type:
MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion:
MarkUsedTemplateParameters(Ctx,
TemplateArg.getAsTemplateOrTemplatePattern(),
OnlyDeduced, Depth, Used);
break;
case TemplateArgument::Expression:
MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Pack:
for (TemplateArgument::pack_iterator P = TemplateArg.pack_begin(),
PEnd = TemplateArg.pack_end();
P != PEnd; ++P)
MarkUsedTemplateParameters(Ctx, *P, OnlyDeduced, Depth, Used);
break;
}
}
/// \brief Mark which template parameters can be deduced from a given
/// template argument list.
///
/// \param TemplateArgs the template argument list from which template
/// parameters will be deduced.
///
/// \param Used a bit vector whose elements will be set to \c true
/// to indicate when the corresponding template parameter will be
/// deduced.
void
Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
bool OnlyDeduced, unsigned Depth,
llvm::SmallBitVector &Used) {
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(TemplateArgs.data(), TemplateArgs.size()))
return;
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
Depth, Used);
}
/// \brief Marks all of the template parameters that will be deduced by a
/// call to the given function template.
void
Sema::MarkDeducedTemplateParameters(ASTContext &Ctx,
const FunctionTemplateDecl *FunctionTemplate,
llvm::SmallBitVector &Deduced) {
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
Deduced.clear();
Deduced.resize(TemplateParams->size());
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
true, TemplateParams->getDepth(), Deduced);
}
bool hasDeducibleTemplateParameters(Sema &S,
FunctionTemplateDecl *FunctionTemplate,
QualType T) {
if (!T->isDependentType())
return false;
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
llvm::SmallBitVector Deduced(TemplateParams->size());
::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
Deduced);
return Deduced.any();
}