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llvm-project/clang/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 "Sema.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/Parse/DeclSpec.h"
#include <algorithm>
namespace clang {
/// \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
};
}
using namespace clang;
static Sema::TemplateDeductionResult
DeduceTemplateArguments(ASTContext &Context,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
const TemplateArgument &Arg,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &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 (ImplicitCastExpr *IC = dyn_cast<ImplicitCastExpr>(E))
E = IC->getSubExpr();
if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
return dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
return 0;
}
/// \brief Deduce the value of the given non-type template parameter
/// from the given constant.
static Sema::TemplateDeductionResult
DeduceNonTypeTemplateArgument(ASTContext &Context,
NonTypeTemplateParmDecl *NTTP,
llvm::APSInt Value,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument with depth > 0");
if (Deduced[NTTP->getIndex()].isNull()) {
QualType T = NTTP->getType();
// FIXME: Make sure we didn't overflow our data type!
unsigned AllowedBits = Context.getTypeSize(T);
if (Value.getBitWidth() != AllowedBits)
Value.extOrTrunc(AllowedBits);
Value.setIsSigned(T->isSignedIntegerType());
Deduced[NTTP->getIndex()] = TemplateArgument(Value, T);
return Sema::TDK_Success;
}
assert(Deduced[NTTP->getIndex()].getKind() == TemplateArgument::Integral);
// If the template argument was previously deduced to a negative value,
// then our deduction fails.
const llvm::APSInt *PrevValuePtr = Deduced[NTTP->getIndex()].getAsIntegral();
if (PrevValuePtr->isNegative()) {
Info.Param = NTTP;
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = TemplateArgument(Value, NTTP->getType());
return Sema::TDK_Inconsistent;
}
llvm::APSInt PrevValue = *PrevValuePtr;
if (Value.getBitWidth() > PrevValue.getBitWidth())
PrevValue.zext(Value.getBitWidth());
else if (Value.getBitWidth() < PrevValue.getBitWidth())
Value.zext(PrevValue.getBitWidth());
if (Value != PrevValue) {
Info.Param = NTTP;
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = TemplateArgument(Value, NTTP->getType());
return Sema::TDK_Inconsistent;
}
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(ASTContext &Context,
NonTypeTemplateParmDecl *NTTP,
Expr *Value,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &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.");
if (Deduced[NTTP->getIndex()].isNull()) {
// FIXME: Clone the Value?
Deduced[NTTP->getIndex()] = TemplateArgument(Value);
return Sema::TDK_Success;
}
if (Deduced[NTTP->getIndex()].getKind() == TemplateArgument::Integral) {
// Okay, we deduced a constant in one case and a dependent expression
// in another case. FIXME: Later, we will check that instantiating the
// dependent expression gives us the constant value.
return Sema::TDK_Success;
}
if (Deduced[NTTP->getIndex()].getKind() == TemplateArgument::Expression) {
// Compare the expressions for equality
llvm::FoldingSetNodeID ID1, ID2;
Deduced[NTTP->getIndex()].getAsExpr()->Profile(ID1, Context, true);
Value->Profile(ID2, Context, true);
if (ID1 == ID2)
return Sema::TDK_Success;
// FIXME: Fill in argument mismatch information
return Sema::TDK_NonDeducedMismatch;
}
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(ASTContext &Context,
NonTypeTemplateParmDecl *NTTP,
Decl *D,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
assert(NTTP->getDepth() == 0 &&
"Cannot deduce non-type template argument with depth > 0");
if (Deduced[NTTP->getIndex()].isNull()) {
Deduced[NTTP->getIndex()] = TemplateArgument(D->getCanonicalDecl());
return Sema::TDK_Success;
}
if (Deduced[NTTP->getIndex()].getKind() == TemplateArgument::Expression) {
// Okay, we deduced a declaration in one case and a dependent expression
// in another case.
return Sema::TDK_Success;
}
if (Deduced[NTTP->getIndex()].getKind() == TemplateArgument::Declaration) {
// Compare the declarations for equality
if (Deduced[NTTP->getIndex()].getAsDecl()->getCanonicalDecl() ==
D->getCanonicalDecl())
return Sema::TDK_Success;
// FIXME: Fill in argument mismatch information
return Sema::TDK_NonDeducedMismatch;
}
return Sema::TDK_Success;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(ASTContext &Context,
TemplateParameterList *TemplateParams,
TemplateName Param,
TemplateName Arg,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &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)) {
// Bind the template template parameter to the given template name.
TemplateArgument &ExistingArg = Deduced[TempParam->getIndex()];
if (ExistingArg.isNull()) {
// This is the first deduction for this template template parameter.
ExistingArg = TemplateArgument(Context.getCanonicalTemplateName(Arg));
return Sema::TDK_Success;
}
// Verify that the previous binding matches this deduction.
assert(ExistingArg.getKind() == TemplateArgument::Template);
if (Context.hasSameTemplateName(ExistingArg.getAsTemplate(), Arg))
return Sema::TDK_Success;
// Inconsistent deduction.
Info.Param = TempParam;
Info.FirstArg = ExistingArg;
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_Inconsistent;
}
// Verify that the two template names are equivalent.
if (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 Context the AST context in which this deduction occurs.
///
/// \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(ASTContext &Context,
TemplateParameterList *TemplateParams,
const TemplateSpecializationType *Param,
QualType Arg,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &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(Context, TemplateParams,
Param->getTemplateName(),
SpecArg->getTemplateName(),
Info, Deduced))
return Result;
// Perform template argument deduction on each template
// argument.
unsigned NumArgs = std::min(SpecArg->getNumArgs(), Param->getNumArgs());
for (unsigned I = 0; I != NumArgs; ++I)
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
Param->getArg(I),
SpecArg->getArg(I),
Info, Deduced))
return Result;
return Sema::TDK_Success;
}
// 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)
return Sema::TDK_NonDeducedMismatch;
ClassTemplateSpecializationDecl *SpecArg
= dyn_cast<ClassTemplateSpecializationDecl>(RecordArg->getDecl());
if (!SpecArg)
return Sema::TDK_NonDeducedMismatch;
// Perform template argument deduction for the template name.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context,
TemplateParams,
Param->getTemplateName(),
TemplateName(SpecArg->getSpecializedTemplate()),
Info, Deduced))
return Result;
unsigned NumArgs = Param->getNumArgs();
const TemplateArgumentList &ArgArgs = SpecArg->getTemplateArgs();
if (NumArgs != ArgArgs.size())
return Sema::TDK_NonDeducedMismatch;
for (unsigned I = 0; I != NumArgs; ++I)
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
Param->getArg(I),
ArgArgs.get(I),
Info, Deduced))
return Result;
return Sema::TDK_Success;
}
/// \brief Returns a completely-unqualified array type, capturing the
/// qualifiers in Quals.
///
/// \param Context the AST context in which the array type was built.
///
/// \param T a canonical type that may be an array type.
///
/// \param Quals will receive the full set of qualifiers that were
/// applied to the element type of the array.
///
/// \returns if \p T is an array type, the completely unqualified array type
/// that corresponds to T. Otherwise, returns T.
static QualType getUnqualifiedArrayType(ASTContext &Context, QualType T,
Qualifiers &Quals) {
assert(T.isCanonical() && "Only operates on canonical types");
if (!isa<ArrayType>(T)) {
Quals = T.getLocalQualifiers();
return T.getLocalUnqualifiedType();
}
assert(!T.hasQualifiers() && "canonical array type has qualifiers!");
if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(T)) {
QualType Elt = getUnqualifiedArrayType(Context, CAT->getElementType(),
Quals);
if (Elt == CAT->getElementType())
return T;
return Context.getConstantArrayType(Elt, CAT->getSize(),
CAT->getSizeModifier(), 0);
}
if (const IncompleteArrayType *IAT = dyn_cast<IncompleteArrayType>(T)) {
QualType Elt = getUnqualifiedArrayType(Context, IAT->getElementType(),
Quals);
if (Elt == IAT->getElementType())
return T;
return Context.getIncompleteArrayType(Elt, IAT->getSizeModifier(), 0);
}
const DependentSizedArrayType *DSAT = cast<DependentSizedArrayType>(T);
QualType Elt = getUnqualifiedArrayType(Context, DSAT->getElementType(),
Quals);
if (Elt == DSAT->getElementType())
return T;
return Context.getDependentSizedArrayType(Elt, DSAT->getSizeExpr()->Retain(),
DSAT->getSizeModifier(), 0,
SourceRange());
}
/// \brief Deduce the template arguments by comparing the parameter type and
/// the argument type (C++ [temp.deduct.type]).
///
/// \param Context the AST context in which this deduction occurs.
///
/// \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.
///
/// \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(ASTContext &Context,
TemplateParameterList *TemplateParams,
QualType ParamIn, QualType ArgIn,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced,
unsigned TDF) {
// We only want to look at the canonical types, since typedefs and
// sugar are not part of template argument deduction.
QualType Param = Context.getCanonicalType(ParamIn);
QualType Arg = Context.getCanonicalType(ArgIn);
// 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 = Param.getQualifiers();
Quals.setCVRQualifiers(Quals.getCVRQualifiers() & Arg.getCVRQualifiers());
Param = Context.getQualifiedType(Param.getUnqualifiedType(), Quals);
}
// If the parameter type is not dependent, there is nothing to deduce.
if (!Param->isDependentType()) {
if (!(TDF & TDF_SkipNonDependent) && Param != Arg) {
return Sema::TDK_NonDeducedMismatch;
}
return Sema::TDK_Success;
}
// 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>()) {
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.
// FIXME: address spaces, ObjC GC qualifiers
if (isa<ArrayType>(Arg)) {
Qualifiers Quals;
Arg = getUnqualifiedArrayType(Context, Arg, Quals);
if (Quals) {
Arg = Context.getQualifiedType(Arg, Quals);
RecanonicalizeArg = true;
}
}
// The argument type can not be less qualified than the parameter
// type.
if (Param.isMoreQualifiedThan(Arg) && !(TDF & TDF_IgnoreQualifiers)) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = Deduced[Index];
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_InconsistentQuals;
}
assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0");
QualType DeducedType = Arg;
DeducedType.removeCVRQualifiers(Param.getCVRQualifiers());
if (RecanonicalizeArg)
DeducedType = Context.getCanonicalType(DeducedType);
if (Deduced[Index].isNull())
Deduced[Index] = TemplateArgument(DeducedType);
else {
// C++ [temp.deduct.type]p2:
// [...] If type deduction cannot be done for any P/A pair, or if for
// any pair the deduction leads to more than one possible set of
// deduced values, or if different pairs yield different deduced
// values, or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
if (Deduced[Index].getAsType() != DeducedType) {
Info.Param
= cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = Deduced[Index];
Info.SecondArg = TemplateArgument(Arg);
return Sema::TDK_Inconsistent;
}
}
return Sema::TDK_Success;
}
// Set up the template argument deduction information for a failure.
Info.FirstArg = TemplateArgument(ParamIn);
Info.SecondArg = TemplateArgument(ArgIn);
// Check the cv-qualifiers on the parameter and argument types.
if (!(TDF & TDF_IgnoreQualifiers)) {
if (TDF & TDF_ParamWithReferenceType) {
if (Param.isMoreQualifiedThan(Arg))
return Sema::TDK_NonDeducedMismatch;
} else {
if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
return Sema::TDK_NonDeducedMismatch;
}
}
switch (Param->getTypeClass()) {
// No deduction possible for these types
case Type::Builtin:
return Sema::TDK_NonDeducedMismatch;
// T *
case Type::Pointer: {
const PointerType *PointerArg = Arg->getAs<PointerType>();
if (!PointerArg)
return Sema::TDK_NonDeducedMismatch;
unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass);
return DeduceTemplateArguments(Context, TemplateParams,
cast<PointerType>(Param)->getPointeeType(),
PointerArg->getPointeeType(),
Info, Deduced, SubTDF);
}
// T &
case Type::LValueReference: {
const LValueReferenceType *ReferenceArg = Arg->getAs<LValueReferenceType>();
if (!ReferenceArg)
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArguments(Context, 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 DeduceTemplateArguments(Context, TemplateParams,
cast<RValueReferenceType>(Param)->getPointeeType(),
ReferenceArg->getPointeeType(),
Info, Deduced, 0);
}
// T [] (implied, but not stated explicitly)
case Type::IncompleteArray: {
const IncompleteArrayType *IncompleteArrayArg =
Context.getAsIncompleteArrayType(Arg);
if (!IncompleteArrayArg)
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArguments(Context, TemplateParams,
Context.getAsIncompleteArrayType(Param)->getElementType(),
IncompleteArrayArg->getElementType(),
Info, Deduced, 0);
}
// T [integer-constant]
case Type::ConstantArray: {
const ConstantArrayType *ConstantArrayArg =
Context.getAsConstantArrayType(Arg);
if (!ConstantArrayArg)
return Sema::TDK_NonDeducedMismatch;
const ConstantArrayType *ConstantArrayParm =
Context.getAsConstantArrayType(Param);
if (ConstantArrayArg->getSize() != ConstantArrayParm->getSize())
return Sema::TDK_NonDeducedMismatch;
return DeduceTemplateArguments(Context, TemplateParams,
ConstantArrayParm->getElementType(),
ConstantArrayArg->getElementType(),
Info, Deduced, 0);
}
// type [i]
case Type::DependentSizedArray: {
const ArrayType *ArrayArg = dyn_cast<ArrayType>(Arg);
if (!ArrayArg)
return Sema::TDK_NonDeducedMismatch;
// Check the element type of the arrays
const DependentSizedArrayType *DependentArrayParm
= cast<DependentSizedArrayType>(Param);
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
DependentArrayParm->getElementType(),
ArrayArg->getElementType(),
Info, Deduced, 0))
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(Context, NTTP, Size,
Info, Deduced);
}
if (const DependentSizedArrayType *DependentArrayArg
= dyn_cast<DependentSizedArrayType>(ArrayArg))
return DeduceNonTypeTemplateArgument(Context, 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: {
const FunctionProtoType *FunctionProtoArg =
dyn_cast<FunctionProtoType>(Arg);
if (!FunctionProtoArg)
return Sema::TDK_NonDeducedMismatch;
const FunctionProtoType *FunctionProtoParam =
cast<FunctionProtoType>(Param);
if (FunctionProtoParam->getTypeQuals() !=
FunctionProtoArg->getTypeQuals())
return Sema::TDK_NonDeducedMismatch;
if (FunctionProtoParam->getNumArgs() != FunctionProtoArg->getNumArgs())
return Sema::TDK_NonDeducedMismatch;
if (FunctionProtoParam->isVariadic() != FunctionProtoArg->isVariadic())
return Sema::TDK_NonDeducedMismatch;
// Check return types.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
FunctionProtoParam->getResultType(),
FunctionProtoArg->getResultType(),
Info, Deduced, 0))
return Result;
for (unsigned I = 0, N = FunctionProtoParam->getNumArgs(); I != N; ++I) {
// Check argument types.
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
FunctionProtoParam->getArgType(I),
FunctionProtoArg->getArgType(I),
Info, Deduced, 0))
return Result;
}
return Sema::TDK_Success;
}
// 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(Context, 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 = dyn_cast<RecordType>(Arg)) {
// 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;
llvm::SmallVector<const RecordType *, 8> ToVisit;
ToVisit.push_back(RecordT);
bool Successful = false;
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) {
Sema::TemplateDeductionResult BaseResult
= DeduceTemplateArguments(Context, TemplateParams, SpecParam,
QualType(NextT, 0), Info, Deduced);
// If template argument deduction for this base was successful,
// note that we had some success.
if (BaseResult == Sema::TDK_Success)
Successful = true;
}
// 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
= DeduceTemplateArguments(Context, TemplateParams,
MemPtrParam->getPointeeType(),
MemPtrArg->getPointeeType(),
Info, Deduced,
TDF & TDF_IgnoreQualifiers))
return Result;
return DeduceTemplateArguments(Context, TemplateParams,
QualType(MemPtrParam->getClass(), 0),
QualType(MemPtrArg->getClass(), 0),
Info, Deduced, 0);
}
// (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 DeduceTemplateArguments(Context, TemplateParams,
BlockPtrParam->getPointeeType(),
BlockPtrArg->getPointeeType(), Info,
Deduced, 0);
}
case Type::TypeOfExpr:
case Type::TypeOf:
case Type::Typename:
// No template argument deduction for these types
return Sema::TDK_Success;
default:
break;
}
// FIXME: Many more cases to go (to go).
return Sema::TDK_Success;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(ASTContext &Context,
TemplateParameterList *TemplateParams,
const TemplateArgument &Param,
const TemplateArgument &Arg,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
switch (Param.getKind()) {
case TemplateArgument::Null:
assert(false && "Null template argument in parameter list");
break;
case TemplateArgument::Type:
if (Arg.getKind() == TemplateArgument::Type)
return DeduceTemplateArguments(Context, 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(Context, TemplateParams,
Param.getAsTemplate(),
Arg.getAsTemplate(), Info, Deduced);
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Declaration:
if (Arg.getKind() == TemplateArgument::Declaration &&
Param.getAsDecl()->getCanonicalDecl() ==
Arg.getAsDecl()->getCanonicalDecl())
return Sema::TDK_Success;
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Integral:
if (Arg.getKind() == TemplateArgument::Integral) {
// FIXME: Zero extension + sign checking here?
if (*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;
}
assert(false && "Type/value mismatch");
Info.FirstArg = Param;
Info.SecondArg = Arg;
return Sema::TDK_NonDeducedMismatch;
case TemplateArgument::Expression: {
if (NonTypeTemplateParmDecl *NTTP
= getDeducedParameterFromExpr(Param.getAsExpr())) {
if (Arg.getKind() == TemplateArgument::Integral)
// FIXME: Sign problems here
return DeduceNonTypeTemplateArgument(Context, NTTP,
*Arg.getAsIntegral(),
Info, Deduced);
if (Arg.getKind() == TemplateArgument::Expression)
return DeduceNonTypeTemplateArgument(Context, NTTP, Arg.getAsExpr(),
Info, Deduced);
if (Arg.getKind() == TemplateArgument::Declaration)
return DeduceNonTypeTemplateArgument(Context, NTTP, Arg.getAsDecl(),
Info, Deduced);
assert(false && "Type/value mismatch");
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:
assert(0 && "FIXME: Implement!");
break;
}
return Sema::TDK_Success;
}
static Sema::TemplateDeductionResult
DeduceTemplateArguments(ASTContext &Context,
TemplateParameterList *TemplateParams,
const TemplateArgumentList &ParamList,
const TemplateArgumentList &ArgList,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
assert(ParamList.size() == ArgList.size());
for (unsigned I = 0, N = ParamList.size(); I != N; ++I) {
if (Sema::TemplateDeductionResult Result
= DeduceTemplateArguments(Context, TemplateParams,
ParamList[I], ArgList[I],
Info, Deduced))
return Result;
}
return Sema::TDK_Success;
}
/// \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:
assert(false && "Comparing NULL template argument");
break;
case TemplateArgument::Type:
return Context.getCanonicalType(X.getAsType()) ==
Context.getCanonicalType(Y.getAsType());
case TemplateArgument::Declaration:
return X.getAsDecl()->getCanonicalDecl() ==
Y.getAsDecl()->getCanonicalDecl();
case TemplateArgument::Template:
return Context.getCanonicalTemplateName(X.getAsTemplate())
.getAsVoidPointer() ==
Context.getCanonicalTemplateName(Y.getAsTemplate())
.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;
}
return false;
}
/// \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 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) {
// 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).
SFINAETrap Trap(*this);
llvm::SmallVector<TemplateArgument, 4> Deduced;
Deduced.resize(Partial->getTemplateParameters()->size());
if (TemplateDeductionResult Result
= ::DeduceTemplateArguments(Context,
Partial->getTemplateParameters(),
Partial->getTemplateArgs(),
TemplateArgs, Info, Deduced))
return Result;
InstantiatingTemplate Inst(*this, Partial->getLocation(), Partial,
Deduced.data(), Deduced.size());
if (Inst)
return TDK_InstantiationDepth;
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
TemplateArgumentListBuilder Builder(Partial->getTemplateParameters(),
Deduced.size());
for (unsigned I = 0, N = Deduced.size(); I != N; ++I) {
if (Deduced[I].isNull()) {
Decl *Param
= const_cast<NamedDecl *>(
Partial->getTemplateParameters()->getParam(I));
if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
Info.Param = TTP;
else if (NonTypeTemplateParmDecl *NTTP
= dyn_cast<NonTypeTemplateParmDecl>(Param))
Info.Param = NTTP;
else
Info.Param = cast<TemplateTemplateParmDecl>(Param);
return TDK_Incomplete;
}
Builder.Append(Deduced[I]);
}
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *DeducedArgumentList
= new (Context) TemplateArgumentList(Context, Builder, /*TakeArgs=*/true);
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.
ClassTemplateDecl *ClassTemplate = Partial->getSpecializedTemplate();
const TemplateArgumentLoc *PartialTemplateArgs
= Partial->getTemplateArgsAsWritten();
unsigned N = Partial->getNumTemplateArgsAsWritten();
// Note that we don't provide the langle and rangle locations.
TemplateArgumentListInfo InstArgs;
for (unsigned I = 0; I != N; ++I) {
Decl *Param = const_cast<NamedDecl *>(
ClassTemplate->getTemplateParameters()->getParam(I));
TemplateArgumentLoc InstArg;
if (Subst(PartialTemplateArgs[I], InstArg,
MultiLevelTemplateArgumentList(*DeducedArgumentList))) {
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = PartialTemplateArgs[I].getArgument();
return TDK_SubstitutionFailure;
}
InstArgs.addArgument(InstArg);
}
TemplateArgumentListBuilder ConvertedInstArgs(
ClassTemplate->getTemplateParameters(), N);
if (CheckTemplateArgumentList(ClassTemplate, Partial->getLocation(),
InstArgs, false, ConvertedInstArgs)) {
// FIXME: fail with more useful information?
return TDK_SubstitutionFailure;
}
for (unsigned I = 0, E = ConvertedInstArgs.flatSize(); I != E; ++I) {
TemplateArgument InstArg = ConvertedInstArgs.getFlatArguments()[I];
Decl *Param = const_cast<NamedDecl *>(
ClassTemplate->getTemplateParameters()->getParam(I));
if (InstArg.getKind() == TemplateArgument::Expression) {
// When the argument is an expression, check the expression result
// against the actual template parameter to get down to the canonical
// template argument.
Expr *InstExpr = InstArg.getAsExpr();
if (NonTypeTemplateParmDecl *NTTP
= dyn_cast<NonTypeTemplateParmDecl>(Param)) {
if (CheckTemplateArgument(NTTP, NTTP->getType(), InstExpr, InstArg)) {
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = Partial->getTemplateArgs()[I];
return TDK_SubstitutionFailure;
}
}
}
if (!isSameTemplateArg(Context, TemplateArgs[I], InstArg)) {
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = TemplateArgs[I];
Info.SecondArg = InstArg;
return TDK_NonDeducedMismatch;
}
}
if (Trap.hasErrorOccurred())
return TDK_SubstitutionFailure;
return TDK_Success;
}
/// \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 ExplicitTemplateArguments 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,
const TemplateArgumentListInfo &ExplicitTemplateArgs,
llvm::SmallVectorImpl<TemplateArgument> &Deduced,
llvm::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;
}
// Substitution of the explicit template arguments into a function template
/// is a SFINAE context. Trap any errors that might occur.
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.
TemplateArgumentListBuilder Builder(TemplateParams,
ExplicitTemplateArgs.size());
// 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.
InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
FunctionTemplate, Deduced.data(), Deduced.size(),
ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution);
if (Inst)
return TDK_InstantiationDepth;
if (CheckTemplateArgumentList(FunctionTemplate,
SourceLocation(),
ExplicitTemplateArgs,
true,
Builder) || Trap.hasErrorOccurred())
return TDK_InvalidExplicitArguments;
// Form the template argument list from the explicitly-specified
// template arguments.
TemplateArgumentList *ExplicitArgumentList
= new (Context) TemplateArgumentList(Context, Builder, /*TakeArgs=*/true);
Info.reset(ExplicitArgumentList);
// Instantiate the types of each of the function parameters given the
// explicitly-specified template arguments.
for (FunctionDecl::param_iterator P = Function->param_begin(),
PEnd = Function->param_end();
P != PEnd;
++P) {
QualType ParamType
= SubstType((*P)->getType(),
MultiLevelTemplateArgumentList(*ExplicitArgumentList),
(*P)->getLocation(), (*P)->getDeclName());
if (ParamType.isNull() || Trap.hasErrorOccurred())
return TDK_SubstitutionFailure;
ParamTypes.push_back(ParamType);
}
// If the caller wants a full function type back, instantiate the return
// type and form that function type.
if (FunctionType) {
// FIXME: exception-specifications?
const FunctionProtoType *Proto
= Function->getType()->getAs<FunctionProtoType>();
assert(Proto && "Function template does not have a prototype?");
QualType ResultType
= SubstType(Proto->getResultType(),
MultiLevelTemplateArgumentList(*ExplicitArgumentList),
Function->getTypeSpecStartLoc(),
Function->getDeclName());
if (ResultType.isNull() || Trap.hasErrorOccurred())
return TDK_SubstitutionFailure;
*FunctionType = BuildFunctionType(ResultType,
ParamTypes.data(), ParamTypes.size(),
Proto->isVariadic(),
Proto->getTypeQuals(),
Function->getLocation(),
Function->getDeclName());
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.
Deduced.reserve(TemplateParams->size());
for (unsigned I = 0, N = ExplicitArgumentList->size(); I != N; ++I)
Deduced.push_back(ExplicitArgumentList->get(I));
return TDK_Success;
}
/// \brief Finish template argument deduction for a function template,
/// checking the deduced template arguments for completeness and forming
/// the function template specialization.
Sema::TemplateDeductionResult
Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
llvm::SmallVectorImpl<TemplateArgument> &Deduced,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info) {
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
// Template argument deduction for function templates in a SFINAE context.
// Trap any errors that might occur.
SFINAETrap Trap(*this);
// Enter a new template instantiation context while we instantiate the
// actual function declaration.
InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
FunctionTemplate, Deduced.data(), Deduced.size(),
ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution);
if (Inst)
return TDK_InstantiationDepth;
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
TemplateArgumentListBuilder Builder(TemplateParams, Deduced.size());
for (unsigned I = 0, N = Deduced.size(); I != N; ++I) {
if (!Deduced[I].isNull()) {
Builder.Append(Deduced[I]);
continue;
}
// Substitute into the default template argument, if available.
NamedDecl *Param = FunctionTemplate->getTemplateParameters()->getParam(I);
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(),
Builder)) {
Info.Param = makeTemplateParameter(
const_cast<NamedDecl *>(TemplateParams->getParam(I)));
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
= new (Context) TemplateArgumentList(Context, Builder, /*TakeArgs=*/true);
Info.reset(DeducedArgumentList);
// Substitute the deduced template arguments into the function template
// declaration to produce the function template specialization.
Specialization = cast_or_null<FunctionDecl>(
SubstDecl(FunctionTemplate->getTemplatedDecl(),
FunctionTemplate->getDeclContext(),
MultiLevelTemplateArgumentList(*DeducedArgumentList)));
if (!Specialization)
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)
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;
}
return TDK_Success;
}
/// \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 HasExplicitTemplateArgs whether any template arguments were
/// explicitly specified.
///
/// \param ExplicitTemplateArguments when @p HasExplicitTemplateArgs is true,
/// the explicitly-specified template arguments.
///
/// \param NumExplicitTemplateArguments when @p HasExplicitTemplateArgs is true,
/// the number of explicitly-specified template arguments in
/// @p ExplicitTemplateArguments. This value may be zero.
///
/// \param Args the function call arguments
///
/// \param NumArgs the number of arguments in Args
///
/// \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,
const TemplateArgumentListInfo *ExplicitTemplateArgs,
Expr **Args, unsigned NumArgs,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info) {
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 = NumArgs;
if (NumArgs < Function->getMinRequiredArguments())
return TDK_TooFewArguments;
else if (NumArgs > Function->getNumParams()) {
const FunctionProtoType *Proto
= Function->getType()->getAs<FunctionProtoType>();
if (!Proto->isVariadic())
return TDK_TooManyArguments;
CheckArgs = Function->getNumParams();
}
// The types of the parameters from which we will perform template argument
// deduction.
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
llvm::SmallVector<TemplateArgument, 4> Deduced;
llvm::SmallVector<QualType, 4> ParamTypes;
if (ExplicitTemplateArgs) {
TemplateDeductionResult Result =
SubstituteExplicitTemplateArguments(FunctionTemplate,
*ExplicitTemplateArgs,
Deduced,
ParamTypes,
0,
Info);
if (Result)
return Result;
} else {
// Just fill in the parameter types from the function declaration.
for (unsigned I = 0; I != CheckArgs; ++I)
ParamTypes.push_back(Function->getParamDecl(I)->getType());
}
// Deduce template arguments from the function parameters.
Deduced.resize(TemplateParams->size());
for (unsigned I = 0; I != CheckArgs; ++I) {
QualType ParamType = ParamTypes[I];
QualType ArgType = Args[I]->getType();
// C++ [temp.deduct.call]p2:
// If P is not a reference type:
QualType CanonParamType = Context.getCanonicalType(ParamType);
bool ParamWasReference = isa<ReferenceType>(CanonParamType);
if (!ParamWasReference) {
// - 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 = 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 = 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.
QualType CanonArgType = Context.getCanonicalType(ArgType);
if (CanonArgType.getLocalCVRQualifiers())
ArgType = CanonArgType.getLocalUnqualifiedType();
}
}
// 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 (CanonParamType.getLocalCVRQualifiers())
ParamType = CanonParamType.getLocalUnqualifiedType();
if (const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>()) {
// [...] If P is a reference type, the type referred to by P is used
// for type deduction.
ParamType = ParamRefType->getPointeeType();
// [...] 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 (isa<RValueReferenceType>(ParamRefType) &&
ParamRefType->getAs<TemplateTypeParmType>() &&
Args[I]->isLvalue(Context) == Expr::LV_Valid)
ArgType = Context.getLValueReferenceType(ArgType);
}
// 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). [...]
unsigned 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 (ParamWasReference)
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())
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;
if (TemplateDeductionResult Result
= ::DeduceTemplateArguments(Context, TemplateParams,
ParamType, ArgType, Info, Deduced,
TDF))
return Result;
// FIXME: C++0x [temp.deduct.call] paragraphs 6-9 deal with function
// pointer parameters.
// FIXME: we need to check that the deduced A is the same as A,
// modulo the various allowed differences.
}
return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
Specialization, Info);
}
/// \brief Deduce template arguments when taking the address of a function
/// template (C++ [temp.deduct.funcaddr]) or matching a
///
/// \param FunctionTemplate the function template for which we are performing
/// template argument deduction.
///
/// \param HasExplicitTemplateArgs whether any template arguments were
/// explicitly specified.
///
/// \param ExplicitTemplateArguments when @p HasExplicitTemplateArgs is true,
/// the explicitly-specified template arguments.
///
/// \param NumExplicitTemplateArguments when @p HasExplicitTemplateArgs is true,
/// the number of explicitly-specified template arguments in
/// @p ExplicitTemplateArguments. This value may be zero.
///
/// \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.
///
/// \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,
const TemplateArgumentListInfo *ExplicitTemplateArgs,
QualType ArgFunctionType,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info) {
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
QualType FunctionType = Function->getType();
// Substitute any explicit template arguments.
llvm::SmallVector<TemplateArgument, 4> Deduced;
llvm::SmallVector<QualType, 4> ParamTypes;
if (ExplicitTemplateArgs) {
if (TemplateDeductionResult Result
= SubstituteExplicitTemplateArguments(FunctionTemplate,
*ExplicitTemplateArgs,
Deduced, ParamTypes,
&FunctionType, Info))
return Result;
}
// Template argument deduction for function templates in a SFINAE context.
// Trap any errors that might occur.
SFINAETrap Trap(*this);
// Deduce template arguments from the function type.
Deduced.resize(TemplateParams->size());
if (TemplateDeductionResult Result
= ::DeduceTemplateArguments(Context, TemplateParams,
FunctionType, ArgFunctionType, Info,
Deduced, 0))
return Result;
return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
Specialization, Info);
}
/// \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) {
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]p3:
// 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]p3:
// 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();
// C++ [temp.deduct.conv]p2:
//
// 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]p3:
// If A is a cv-qualified type, the top level cv-qualifiers of A’s
// type are ignored for type deduction.
A = A.getUnqualifiedType();
}
// Template argument deduction for function templates in a SFINAE context.
// Trap any errors that might occur.
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();
llvm::SmallVector<TemplateArgument, 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() && P->isMemberPointerType()))
TDF |= TDF_IgnoreQualifiers;
if (TemplateDeductionResult Result
= ::DeduceTemplateArguments(Context, TemplateParams,
P, A, Info, Deduced, TDF))
return Result;
// FIXME: we need to check that the deduced A is the same as A,
// modulo the various allowed differences.
// Finish template argument deduction.
FunctionDecl *Spec = 0;
TemplateDeductionResult Result
= FinishTemplateArgumentDeduction(FunctionTemplate, Deduced, Spec, Info);
Specialization = cast_or_null<CXXConversionDecl>(Spec);
return Result;
}
/// \brief Stores the result of comparing the qualifiers of two types.
enum DeductionQualifierComparison {
NeitherMoreQualified = 0,
ParamMoreQualified,
ArgMoreQualified
};
/// \brief Deduce the template arguments during partial ordering by comparing
/// the parameter type and the argument type (C++0x [temp.deduct.partial]).
///
/// \param Context the AST context in which this deduction occurs.
///
/// \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
///
/// \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
DeduceTemplateArgumentsDuringPartialOrdering(ASTContext &Context,
TemplateParameterList *TemplateParams,
QualType ParamIn, QualType ArgIn,
Sema::TemplateDeductionInfo &Info,
llvm::SmallVectorImpl<TemplateArgument> &Deduced,
llvm::SmallVectorImpl<DeductionQualifierComparison> *QualifierComparisons) {
CanQualType Param = Context.getCanonicalType(ParamIn);
CanQualType Arg = Context.getCanonicalType(ArgIn);
// 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.
CanQual<ReferenceType> ParamRef = Param->getAs<ReferenceType>();
if (!ParamRef.isNull())
Param = ParamRef->getPointeeType();
// - If A is a reference type, A is replaced by the type referred to.
CanQual<ReferenceType> ArgRef = Arg->getAs<ReferenceType>();
if (!ArgRef.isNull())
Arg = ArgRef->getPointeeType();
if (QualifierComparisons && !ParamRef.isNull() && !ArgRef.isNull()) {
// 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.
DeductionQualifierComparison QualifierResult = NeitherMoreQualified;
if (Param.isMoreQualifiedThan(Arg))
QualifierResult = ParamMoreQualified;
else if (Arg.isMoreQualifiedThan(Param))
QualifierResult = ArgMoreQualified;
QualifierComparisons->push_back(QualifierResult);
}
// 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();
// C++0x [temp.deduct.partial]p8:
// Using the resulting types P and A the deduction is then done as
// described in 14.9.2.5. If deduction succeeds for a given type, the type
// from the argument template is considered to be at least as specialized
// as the type from the parameter template.
return DeduceTemplateArguments(Context, TemplateParams, Param, Arg, Info,
Deduced, TDF_None);
}
static void
MarkUsedTemplateParameters(Sema &SemaRef, QualType T,
bool OnlyDeduced,
unsigned Level,
llvm::SmallVectorImpl<bool> &Deduced);
/// \brief Determine whether the function template \p FT1 is at least as
/// specialized as \p FT2.
static bool isAtLeastAsSpecializedAs(Sema &S,
FunctionTemplateDecl *FT1,
FunctionTemplateDecl *FT2,
TemplatePartialOrderingContext TPOC,
llvm::SmallVectorImpl<DeductionQualifierComparison> *QualifierComparisons) {
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();
llvm::SmallVector<TemplateArgument, 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:
Sema::TemplateDeductionInfo Info(S.Context);
switch (TPOC) {
case TPOC_Call: {
// - In the context of a function call, the function parameter types are
// used.
unsigned NumParams = std::min(Proto1->getNumArgs(), Proto2->getNumArgs());
for (unsigned I = 0; I != NumParams; ++I)
if (DeduceTemplateArgumentsDuringPartialOrdering(S.Context,
TemplateParams,
Proto2->getArgType(I),
Proto1->getArgType(I),
Info,
Deduced,
QualifierComparisons))
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 (DeduceTemplateArgumentsDuringPartialOrdering(S.Context,
TemplateParams,
Proto2->getResultType(),
Proto1->getResultType(),
Info,
Deduced,
QualifierComparisons))
return false;
break;
case TPOC_Other:
// - In other contexts (14.6.6.2) the function template’s function type
// is used.
if (DeduceTemplateArgumentsDuringPartialOrdering(S.Context,
TemplateParams,
FD2->getType(),
FD1->getType(),
Info,
Deduced,
QualifierComparisons))
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::SmallVector<bool, 4> UsedParameters;
UsedParameters.resize(TemplateParams->size());
switch (TPOC) {
case TPOC_Call: {
unsigned NumParams = std::min(Proto1->getNumArgs(), Proto2->getNumArgs());
for (unsigned I = 0; I != NumParams; ++I)
::MarkUsedTemplateParameters(S, Proto2->getArgType(I), false,
TemplateParams->getDepth(),
UsedParameters);
break;
}
case TPOC_Conversion:
::MarkUsedTemplateParameters(S, Proto2->getResultType(), false,
TemplateParams->getDepth(),
UsedParameters);
break;
case TPOC_Other:
::MarkUsedTemplateParameters(S, 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 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.
///
/// \returns the more specialized function template. If neither
/// template is more specialized, returns NULL.
FunctionTemplateDecl *
Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
FunctionTemplateDecl *FT2,
TemplatePartialOrderingContext TPOC) {
llvm::SmallVector<DeductionQualifierComparison, 4> QualifierComparisons;
bool Better1 = isAtLeastAsSpecializedAs(*this, FT1, FT2, TPOC, 0);
bool Better2 = isAtLeastAsSpecializedAs(*this, FT2, FT1, TPOC,
&QualifierComparisons);
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 = QualifierComparisons.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 if the type
// from the argument template is more cv-qualified than the type from the
// parameter template (as described above) that type is considered to be
// more specialized than the other. If neither type is more cv-qualified
// than the other then neither type is more specialized than the other.
switch (QualifierComparisons[I]) {
case NeitherMoreQualified:
break;
case ParamMoreQualified:
Better1 = true;
if (Better2)
return 0;
break;
case ArgMoreQualified:
Better2 = true;
if (Better1)
return 0;
break;
}
}
assert(!(Better1 && Better2) && "Should have broken out in the loop above");
if (Better1)
return FT1;
else if (Better2)
return FT2;
else
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 Specializations the set of function template specializations that
/// we will be comparing.
///
/// \param NumSpecializations the number of function template specializations in
/// \p Specializations
///
/// \param TPOC the partial ordering context to use to compare the function
/// template specializations.
///
/// \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.
///
/// \param Index if non-NULL and the result of this function is non-nULL,
/// receives the index corresponding to the resulting function template
/// specialization.
///
/// \returns the most specialized function template specialization, if
/// found. Otherwise, returns NULL.
///
/// \todo FIXME: Consider passing in the "also-ran" candidates that failed
/// template argument deduction.
FunctionDecl *Sema::getMostSpecialized(FunctionDecl **Specializations,
unsigned NumSpecializations,
TemplatePartialOrderingContext TPOC,
SourceLocation Loc,
const PartialDiagnostic &NoneDiag,
const PartialDiagnostic &AmbigDiag,
const PartialDiagnostic &CandidateDiag,
unsigned *Index) {
if (NumSpecializations == 0) {
Diag(Loc, NoneDiag);
return 0;
}
if (NumSpecializations == 1) {
if (Index)
*Index = 0;
return Specializations[0];
}
// Find the function template that is better than all of the templates it
// has been compared to.
unsigned Best = 0;
FunctionTemplateDecl *BestTemplate
= Specializations[Best]->getPrimaryTemplate();
assert(BestTemplate && "Not a function template specialization?");
for (unsigned I = 1; I != NumSpecializations; ++I) {
FunctionTemplateDecl *Challenger = Specializations[I]->getPrimaryTemplate();
assert(Challenger && "Not a function template specialization?");
if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
TPOC),
Challenger)) {
Best = I;
BestTemplate = Challenger;
}
}
// Make sure that the "best" function template is more specialized than all
// of the others.
bool Ambiguous = false;
for (unsigned I = 0; I != NumSpecializations; ++I) {
FunctionTemplateDecl *Challenger = Specializations[I]->getPrimaryTemplate();
if (I != Best &&
!isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
TPOC),
BestTemplate)) {
Ambiguous = true;
break;
}
}
if (!Ambiguous) {
// We found an answer. Return it.
if (Index)
*Index = Best;
return Specializations[Best];
}
// Diagnose the ambiguity.
Diag(Loc, AmbigDiag);
// FIXME: Can we order the candidates in some sane way?
for (unsigned I = 0; I != NumSpecializations; ++I)
Diag(Specializations[I]->getLocation(), CandidateDiag)
<< getTemplateArgumentBindingsText(
Specializations[I]->getPrimaryTemplate()->getTemplateParameters(),
*Specializations[I]->getTemplateSpecializationArgs());
return 0;
}
/// \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) {
// 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 deduc
llvm::SmallVector<TemplateArgument, 4> Deduced;
Sema::TemplateDeductionInfo Info(Context);
// Determine whether PS1 is at least as specialized as PS2
Deduced.resize(PS2->getTemplateParameters()->size());
bool Better1 = !DeduceTemplateArgumentsDuringPartialOrdering(Context,
PS2->getTemplateParameters(),
Context.getTypeDeclType(PS2),
Context.getTypeDeclType(PS1),
Info,
Deduced,
0);
// Determine whether PS2 is at least as specialized as PS1
Deduced.clear();
Deduced.resize(PS1->getTemplateParameters()->size());
bool Better2 = !DeduceTemplateArgumentsDuringPartialOrdering(Context,
PS1->getTemplateParameters(),
Context.getTypeDeclType(PS1),
Context.getTypeDeclType(PS2),
Info,
Deduced,
0);
if (Better1 == Better2)
return 0;
return Better1? PS1 : PS2;
}
static void
MarkUsedTemplateParameters(Sema &SemaRef,
const TemplateArgument &TemplateArg,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &Used);
/// \brief Mark the template parameters that are used by the given
/// expression.
static void
MarkUsedTemplateParameters(Sema &SemaRef,
const Expr *E,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &Used) {
// 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 (!E)
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(Sema &SemaRef,
NestedNameSpecifier *NNS,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &Used) {
if (!NNS)
return;
MarkUsedTemplateParameters(SemaRef, NNS->getPrefix(), OnlyDeduced, Depth,
Used);
MarkUsedTemplateParameters(SemaRef, QualType(NNS->getAsType(), 0),
OnlyDeduced, Depth, Used);
}
/// \brief Mark the template parameters that are used by the given
/// template name.
static void
MarkUsedTemplateParameters(Sema &SemaRef,
TemplateName Name,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &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(SemaRef, QTN->getQualifier(), OnlyDeduced,
Depth, Used);
if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
MarkUsedTemplateParameters(SemaRef, DTN->getQualifier(), OnlyDeduced,
Depth, Used);
}
/// \brief Mark the template parameters that are used by the given
/// type.
static void
MarkUsedTemplateParameters(Sema &SemaRef, QualType T,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &Used) {
if (T.isNull())
return;
// Non-dependent types have nothing deducible
if (!T->isDependentType())
return;
T = SemaRef.Context.getCanonicalType(T);
switch (T->getTypeClass()) {
case Type::Pointer:
MarkUsedTemplateParameters(SemaRef,
cast<PointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::BlockPointer:
MarkUsedTemplateParameters(SemaRef,
cast<BlockPointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::LValueReference:
case Type::RValueReference:
MarkUsedTemplateParameters(SemaRef,
cast<ReferenceType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::MemberPointer: {
const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
MarkUsedTemplateParameters(SemaRef, MemPtr->getPointeeType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(SemaRef, QualType(MemPtr->getClass(), 0),
OnlyDeduced, Depth, Used);
break;
}
case Type::DependentSizedArray:
MarkUsedTemplateParameters(SemaRef,
cast<DependentSizedArrayType>(T)->getSizeExpr(),
OnlyDeduced, Depth, Used);
// Fall through to check the element type
case Type::ConstantArray:
case Type::IncompleteArray:
MarkUsedTemplateParameters(SemaRef,
cast<ArrayType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Vector:
case Type::ExtVector:
MarkUsedTemplateParameters(SemaRef,
cast<VectorType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentSizedExtVector: {
const DependentSizedExtVectorType *VecType
= cast<DependentSizedExtVectorType>(T);
MarkUsedTemplateParameters(SemaRef, VecType->getElementType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(SemaRef, VecType->getSizeExpr(), OnlyDeduced,
Depth, Used);
break;
}
case Type::FunctionProto: {
const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
MarkUsedTemplateParameters(SemaRef, Proto->getResultType(), OnlyDeduced,
Depth, Used);
for (unsigned I = 0, N = Proto->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(SemaRef, 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::TemplateSpecialization: {
const TemplateSpecializationType *Spec
= cast<TemplateSpecializationType>(T);
MarkUsedTemplateParameters(SemaRef, Spec->getTemplateName(), OnlyDeduced,
Depth, Used);
for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I)
MarkUsedTemplateParameters(SemaRef, Spec->getArg(I), OnlyDeduced, Depth,
Used);
break;
}
case Type::Complex:
if (!OnlyDeduced)
MarkUsedTemplateParameters(SemaRef,
cast<ComplexType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Typename:
if (!OnlyDeduced)
MarkUsedTemplateParameters(SemaRef,
cast<TypenameType>(T)->getQualifier(),
OnlyDeduced, Depth, Used);
break;
// None of these types have any template parameters in them.
case Type::Builtin:
case Type::FixedWidthInt:
case Type::VariableArray:
case Type::FunctionNoProto:
case Type::Record:
case Type::Enum:
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
#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(Sema &SemaRef,
const TemplateArgument &TemplateArg,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallVectorImpl<bool> &Used) {
switch (TemplateArg.getKind()) {
case TemplateArgument::Null:
case TemplateArgument::Integral:
case TemplateArgument::Declaration:
break;
case TemplateArgument::Type:
MarkUsedTemplateParameters(SemaRef, TemplateArg.getAsType(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Template:
MarkUsedTemplateParameters(SemaRef, TemplateArg.getAsTemplate(),
OnlyDeduced, Depth, Used);
break;
case TemplateArgument::Expression:
MarkUsedTemplateParameters(SemaRef, 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(SemaRef, *P, OnlyDeduced, Depth, Used);
break;
}
}
/// \brief Mark the template parameters can be deduced by the given
/// template argument list.
///
/// \param TemplateArgs the template argument list from which template
/// parameters will be deduced.
///
/// \param Deduced 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::SmallVectorImpl<bool> &Used) {
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
::MarkUsedTemplateParameters(*this, 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(FunctionTemplateDecl *FunctionTemplate,
llvm::SmallVectorImpl<bool> &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(*this, Function->getParamDecl(I)->getType(),
true, TemplateParams->getDepth(), Deduced);
}
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