//===------- 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 "llvm/Support/Compiler.h" #include 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 &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(E)) E = IC->getSubExpr(); if (DeclRefExpr *DRE = dyn_cast(E)) return dyn_cast(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 &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(SourceLocation(), 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(SourceLocation(), 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(SourceLocation(), 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 &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; } // FIXME: Compare the expressions for equality! return Sema::TDK_Success; } static Sema::TemplateDeductionResult DeduceTemplateArguments(ASTContext &Context, TemplateName Param, TemplateName Arg, Sema::TemplateDeductionInfo &Info, llvm::SmallVectorImpl &Deduced) { // FIXME: Implement template argument deduction for template // template parameters. // FIXME: this routine does not have enough information to produce // good diagnostics. TemplateDecl *ParamDecl = Param.getAsTemplateDecl(); TemplateDecl *ArgDecl = Arg.getAsTemplateDecl(); if (!ParamDecl || !ArgDecl) { // FIXME: fill in Info.Param/Info.FirstArg return Sema::TDK_Inconsistent; } ParamDecl = cast(ParamDecl->getCanonicalDecl()); ArgDecl = cast(ArgDecl->getCanonicalDecl()); if (ParamDecl != ArgDecl) { // FIXME: fill in Info.Param/Info.FirstArg return Sema::TDK_Inconsistent; } return Sema::TDK_Success; } /// \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 &Deduced) { assert(Arg->isCanonical() && "Argument type must be canonical"); // Check whether the template argument is a dependent template-id. // FIXME: This is untested code; it can be tested when we implement // partial ordering of class template partial specializations. if (const TemplateSpecializationType *SpecArg = dyn_cast(Arg)) { // Perform template argument deduction for the template name. if (Sema::TemplateDeductionResult Result = DeduceTemplateArguments(Context, Param->getTemplateName(), SpecArg->getTemplateName(), Info, Deduced)) return Result; unsigned NumArgs = Param->getNumArgs(); // FIXME: When one of the template-names refers to a // declaration with default template arguments, do we need to // fill in those default template arguments here? Most likely, // the answer is "yes", but I don't see any references. This // issue may be resolved elsewhere, because we may want to // instantiate default template arguments when we actually write // the template-id. if (SpecArg->getNumArgs() != NumArgs) return Sema::TDK_NonDeducedMismatch; // Perform template argument deduction on each template // argument. 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(Arg); if (!RecordArg) return Sema::TDK_NonDeducedMismatch; ClassTemplateSpecializationDecl *SpecArg = dyn_cast(RecordArg->getDecl()); if (!SpecArg) return Sema::TDK_NonDeducedMismatch; // Perform template argument deduction for the template name. if (Sema::TemplateDeductionResult Result = DeduceTemplateArguments(Context, Param->getTemplateName(), TemplateName(SpecArg->getSpecializedTemplate()), Info, Deduced)) return Result; // FIXME: Can the # of arguments in the parameter and the argument // differ due to default arguments? 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 CVRQuals. /// /// \param Context the AST context in which the array type was built. /// /// \param T a canonical type that may be an array type. /// /// \param CVRQuals will receive the set of const/volatile/restrict 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, unsigned &CVRQuals) { assert(T->isCanonical() && "Only operates on canonical types"); if (!isa(T)) { CVRQuals = T.getCVRQualifiers(); return T.getUnqualifiedType(); } if (const ConstantArrayType *CAT = dyn_cast(T)) { QualType Elt = getUnqualifiedArrayType(Context, CAT->getElementType(), CVRQuals); if (Elt == CAT->getElementType()) return T; return Context.getConstantArrayType(Elt, CAT->getSize(), CAT->getSizeModifier(), 0); } if (const IncompleteArrayType *IAT = dyn_cast(T)) { QualType Elt = getUnqualifiedArrayType(Context, IAT->getElementType(), CVRQuals); if (Elt == IAT->getElementType()) return T; return Context.getIncompleteArrayType(Elt, IAT->getSizeModifier(), 0); } const DependentSizedArrayType *DSAT = cast(T); QualType Elt = getUnqualifiedArrayType(Context, DSAT->getElementType(), CVRQuals); 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 &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) { unsigned ExtraQualsOnParam = Param.getCVRQualifiers() & ~Arg.getCVRQualifiers(); Param.setCVRQualifiers(Param.getCVRQualifiers() & ~ExtraQualsOnParam); } // 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->getAsTemplateTypeParmType()) { 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(Arg)) { unsigned CVRQuals = 0; Arg = getUnqualifiedArrayType(Context, Arg, CVRQuals); if (CVRQuals) { Arg = Arg.getWithAdditionalQualifiers(CVRQuals); RecanonicalizeArg = true; } } // The argument type can not be less qualified than the parameter // type. if (Param.isMoreQualifiedThan(Arg) && !(TDF & TDF_IgnoreQualifiers)) { Info.Param = cast(TemplateParams->getParam(Index)); Info.FirstArg = Deduced[Index]; Info.SecondArg = TemplateArgument(SourceLocation(), Arg); return Sema::TDK_InconsistentQuals; } assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0"); unsigned Quals = Arg.getCVRQualifiers() & ~Param.getCVRQualifiers(); QualType DeducedType = Arg.getQualifiedType(Quals); if (RecanonicalizeArg) DeducedType = Context.getCanonicalType(DeducedType); if (Deduced[Index].isNull()) Deduced[Index] = TemplateArgument(SourceLocation(), 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(TemplateParams->getParam(Index)); Info.FirstArg = Deduced[Index]; Info.SecondArg = TemplateArgument(SourceLocation(), Arg); return Sema::TDK_Inconsistent; } } return Sema::TDK_Success; } // Set up the template argument deduction information for a failure. Info.FirstArg = TemplateArgument(SourceLocation(), ParamIn); Info.SecondArg = TemplateArgument(SourceLocation(), 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(); if (!PointerArg) return Sema::TDK_NonDeducedMismatch; unsigned SubTDF = TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass); return DeduceTemplateArguments(Context, TemplateParams, cast(Param)->getPointeeType(), PointerArg->getPointeeType(), Info, Deduced, SubTDF); } // T & case Type::LValueReference: { const LValueReferenceType *ReferenceArg = Arg->getAs(); if (!ReferenceArg) return Sema::TDK_NonDeducedMismatch; return DeduceTemplateArguments(Context, TemplateParams, cast(Param)->getPointeeType(), ReferenceArg->getPointeeType(), Info, Deduced, 0); } // T && [C++0x] case Type::RValueReference: { const RValueReferenceType *ReferenceArg = Arg->getAs(); if (!ReferenceArg) return Sema::TDK_NonDeducedMismatch; return DeduceTemplateArguments(Context, TemplateParams, cast(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(Arg); if (!ArrayArg) return Sema::TDK_NonDeducedMismatch; // Check the element type of the arrays const DependentSizedArrayType *DependentArrayParm = cast(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(ArrayArg)) { llvm::APSInt Size(ConstantArrayArg->getSize()); return DeduceNonTypeTemplateArgument(Context, NTTP, Size, Info, Deduced); } if (const DependentSizedArrayType *DependentArrayArg = dyn_cast(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(Arg); if (!FunctionProtoArg) return Sema::TDK_NonDeducedMismatch; const FunctionProtoType *FunctionProtoParam = cast(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 (where template-name refers to a class template) // template-name // TT (TODO) // TT (TODO) // TT<> (TODO) case Type::TemplateSpecialization: { const TemplateSpecializationType *SpecParam = cast(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) && Result != Sema::TDK_Inconsistent) { // 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(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 Visited; llvm::SmallVector 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; // If deduction against this base resulted in an inconsistent // set of deduced template arguments, template argument // deduction fails. else if (BaseResult == Sema::TDK_Inconsistent) return BaseResult; } // Visit base classes CXXRecordDecl *Next = cast(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()); } } 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(Param); const MemberPointerType *MemPtrArg = dyn_cast(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(Param); const BlockPointerType *BlockPtrArg = dyn_cast(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 &Deduced) { switch (Param.getKind()) { case TemplateArgument::Null: assert(false && "Null template argument in parameter list"); break; case TemplateArgument::Type: assert(Arg.getKind() == TemplateArgument::Type && "Type/value mismatch"); return DeduceTemplateArguments(Context, TemplateParams, Param.getAsType(), Arg.getAsType(), Info, Deduced, 0); case TemplateArgument::Declaration: // FIXME: Implement this check assert(false && "Unimplemented template argument deduction case"); 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); 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 &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::Integral: return *X.getAsIntegral() == *Y.getAsIntegral(); case TemplateArgument::Expression: // FIXME: We assume that all expressions are distinct, but we should // really check their canonical forms. return false; 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(D)) return TemplateParameter(TTP); else if (NonTypeTemplateParmDecl *NTTP = dyn_cast(D)) return TemplateParameter(NTTP); return TemplateParameter(cast(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 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(Partial->getTemplateParameters()->getParam(I)); if (TemplateTypeParmDecl *TTP = dyn_cast(Param)) Info.Param = TTP; else if (NonTypeTemplateParmDecl *NTTP = dyn_cast(Param)) Info.Param = NTTP; else Info.Param = cast(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 TemplateArgumentList &PartialTemplateArgs = Partial->getTemplateArgs(); for (unsigned I = 0, N = PartialTemplateArgs.flat_size(); I != N; ++I) { Decl *Param = const_cast( ClassTemplate->getTemplateParameters()->getParam(I)); TemplateArgument InstArg = Subst(PartialTemplateArgs[I], MultiLevelTemplateArgumentList(*DeducedArgumentList)); if (InstArg.isNull()) { Info.Param = makeTemplateParameter(Param); Info.FirstArg = PartialTemplateArgs[I]; return TDK_SubstitutionFailure; } 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(Param)) { if (CheckTemplateArgument(NTTP, NTTP->getType(), InstExpr, InstArg)) { Info.Param = makeTemplateParameter(Param); Info.FirstArg = PartialTemplateArgs[I]; return TDK_SubstitutionFailure; } } else if (TemplateTemplateParmDecl *TTP = dyn_cast(Param)) { // FIXME: template template arguments should really resolve to decls DeclRefExpr *DRE = dyn_cast(InstExpr); if (!DRE || CheckTemplateArgument(TTP, DRE)) { Info.Param = makeTemplateParameter(Param); Info.FirstArg = PartialTemplateArgs[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->getAsTemplateSpecializationType()) 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 NumExplicitTemplateArguments the number of explicitly-specified /// template arguments in @p ExplicitTemplateArguments. This value may be zero. /// /// \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 TemplateArgument *ExplicitTemplateArgs, unsigned NumExplicitTemplateArgs, llvm::SmallVectorImpl &Deduced, llvm::SmallVectorImpl &ParamTypes, QualType *FunctionType, TemplateDeductionInfo &Info) { FunctionDecl *Function = FunctionTemplate->getTemplatedDecl(); TemplateParameterList *TemplateParams = FunctionTemplate->getTemplateParameters(); if (NumExplicitTemplateArgs == 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, NumExplicitTemplateArgs); // 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(), SourceLocation(), ExplicitTemplateArgs, NumExplicitTemplateArgs, SourceLocation(), 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()->getAsFunctionProtoType(); 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 &Deduced, FunctionDecl *&Specialization, TemplateDeductionInfo &Info) { TemplateParameterList *TemplateParams = FunctionTemplate->getTemplateParameters(); // 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()) { Info.Param = makeTemplateParameter( const_cast(TemplateParams->getParam(I))); 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); // 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; // Substitute the deduced template arguments into the function template // declaration to produce the function template specialization. Specialization = cast_or_null( SubstDecl(FunctionTemplate->getTemplatedDecl(), FunctionTemplate->getDeclContext(), MultiLevelTemplateArgumentList(*DeducedArgumentList))); if (!Specialization) return TDK_SubstitutionFailure; // 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, bool HasExplicitTemplateArgs, const TemplateArgument *ExplicitTemplateArgs, unsigned NumExplicitTemplateArgs, 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()->getAsFunctionProtoType(); 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 Deduced; llvm::SmallVector ParamTypes; if (NumExplicitTemplateArgs) { TemplateDeductionResult Result = SubstituteExplicitTemplateArguments(FunctionTemplate, ExplicitTemplateArgs, NumExplicitTemplateArgs, 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(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.getCVRQualifiers()) ArgType = CanonArgType.getUnqualifiedType(); } } // 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.getCVRQualifiers()) ParamType = CanonParamType.getUnqualifiedType(); if (const ReferenceType *ParamRefType = ParamType->getAs()) { // [...] 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(ParamRefType) && ParamRefType->getAsTemplateTypeParmType() && 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(ParamType) && isSimpleTemplateIdType( ParamType->getAs()->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]). /// /// \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, bool HasExplicitTemplateArgs, const TemplateArgument *ExplicitTemplateArgs, unsigned NumExplicitTemplateArgs, 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 Deduced; llvm::SmallVector ParamTypes; if (HasExplicitTemplateArgs) { if (TemplateDeductionResult Result = SubstituteExplicitTemplateArguments(FunctionTemplate, ExplicitTemplateArgs, NumExplicitTemplateArgs, 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(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()) 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()) 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 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(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 &Deduced, llvm::SmallVectorImpl *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 ParamRef = Param->getAs(); if (ParamRef) Param = ParamRef->getPointeeType(); // - If A is a reference type, A is replaced by the type referred to. CanQual ArgRef = Arg->getAs(); if (ArgRef) Arg = ArgRef->getPointeeType(); if (QualifierComparisons && 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. 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 MarkDeducedTemplateParameters(Sema &SemaRef, QualType T, llvm::SmallVectorImpl &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 *QualifierComparisons) { FunctionDecl *FD1 = FT1->getTemplatedDecl(); FunctionDecl *FD2 = FT2->getTemplatedDecl(); const FunctionProtoType *Proto1 = FD1->getType()->getAs(); const FunctionProtoType *Proto2 = FD2->getType()->getAs(); assert(Proto1 && Proto2 && "Function templates must have prototypes"); TemplateParameterList *TemplateParams = FT2->getTemplateParameters(); llvm::SmallVector 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; } // FIXME: MarkDeducedTemplateParameters needs to become // MarkUsedTemplateParameters with a flag that tells us whether to mark // template parameters that are used in non-deduced contexts. llvm::SmallVector 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) ::MarkDeducedTemplateParameters(S, Proto2->getArgType(I), UsedParameters); break; } case TPOC_Conversion: ::MarkDeducedTemplateParameters(S, Proto2->getResultType(), UsedParameters); break; case TPOC_Other: ::MarkDeducedTemplateParameters(S, FD2->getType(), 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 specialization 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 specialization function template. If neither /// template is more specialized, returns NULL. FunctionTemplateDecl * Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, TemplatePartialOrderingContext TPOC) { // FIXME: Implement this llvm::SmallVector 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; } static void MarkDeducedTemplateParameters(Sema &SemaRef, const TemplateArgument &TemplateArg, llvm::SmallVectorImpl &Deduced); /// \brief Mark the template arguments that are deduced by the given /// expression. static void MarkDeducedTemplateParameters(const Expr *E, llvm::SmallVectorImpl &Deduced) { const DeclRefExpr *DRE = dyn_cast(E); if (!E) return; const NonTypeTemplateParmDecl *NTTP = dyn_cast(DRE->getDecl()); if (!NTTP) return; Deduced[NTTP->getIndex()] = true; } /// \brief Mark the template parameters that are deduced by the given /// type. static void MarkDeducedTemplateParameters(Sema &SemaRef, QualType T, llvm::SmallVectorImpl &Deduced) { // Non-dependent types have nothing deducible if (!T->isDependentType()) return; T = SemaRef.Context.getCanonicalType(T); switch (T->getTypeClass()) { case Type::ExtQual: MarkDeducedTemplateParameters(SemaRef, QualType(cast(T)->getBaseType(), 0), Deduced); break; case Type::Pointer: MarkDeducedTemplateParameters(SemaRef, cast(T)->getPointeeType(), Deduced); break; case Type::BlockPointer: MarkDeducedTemplateParameters(SemaRef, cast(T)->getPointeeType(), Deduced); break; case Type::LValueReference: case Type::RValueReference: MarkDeducedTemplateParameters(SemaRef, cast(T)->getPointeeType(), Deduced); break; case Type::MemberPointer: { const MemberPointerType *MemPtr = cast(T.getTypePtr()); MarkDeducedTemplateParameters(SemaRef, MemPtr->getPointeeType(), Deduced); MarkDeducedTemplateParameters(SemaRef, QualType(MemPtr->getClass(), 0), Deduced); break; } case Type::DependentSizedArray: MarkDeducedTemplateParameters(cast(T)->getSizeExpr(), Deduced); // Fall through to check the element type case Type::ConstantArray: case Type::IncompleteArray: MarkDeducedTemplateParameters(SemaRef, cast(T)->getElementType(), Deduced); break; case Type::Vector: case Type::ExtVector: MarkDeducedTemplateParameters(SemaRef, cast(T)->getElementType(), Deduced); break; case Type::DependentSizedExtVector: { const DependentSizedExtVectorType *VecType = cast(T); MarkDeducedTemplateParameters(SemaRef, VecType->getElementType(), Deduced); MarkDeducedTemplateParameters(VecType->getSizeExpr(), Deduced); break; } case Type::FunctionProto: { const FunctionProtoType *Proto = cast(T); MarkDeducedTemplateParameters(SemaRef, Proto->getResultType(), Deduced); for (unsigned I = 0, N = Proto->getNumArgs(); I != N; ++I) MarkDeducedTemplateParameters(SemaRef, Proto->getArgType(I), Deduced); break; } case Type::TemplateTypeParm: Deduced[cast(T)->getIndex()] = true; break; case Type::TemplateSpecialization: { const TemplateSpecializationType *Spec = cast(T); if (TemplateDecl *Template = Spec->getTemplateName().getAsTemplateDecl()) if (TemplateTemplateParmDecl *TTP = dyn_cast(Template)) Deduced[TTP->getIndex()] = true; for (unsigned I = 0, N = Spec->getNumArgs(); I != N; ++I) MarkDeducedTemplateParameters(SemaRef, Spec->getArg(I), Deduced); break; } // None of these types have any deducible parts. case Type::Builtin: case Type::FixedWidthInt: case Type::Complex: case Type::VariableArray: case Type::FunctionNoProto: case Type::Record: case Type::Enum: case Type::Typename: 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 deduced by this /// template argument. static void MarkDeducedTemplateParameters(Sema &SemaRef, const TemplateArgument &TemplateArg, llvm::SmallVectorImpl &Deduced) { switch (TemplateArg.getKind()) { case TemplateArgument::Null: case TemplateArgument::Integral: break; case TemplateArgument::Type: MarkDeducedTemplateParameters(SemaRef, TemplateArg.getAsType(), Deduced); break; case TemplateArgument::Declaration: if (TemplateTemplateParmDecl *TTP = dyn_cast(TemplateArg.getAsDecl())) Deduced[TTP->getIndex()] = true; break; case TemplateArgument::Expression: MarkDeducedTemplateParameters(TemplateArg.getAsExpr(), Deduced); break; case TemplateArgument::Pack: assert(0 && "FIXME: Implement!"); 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::MarkDeducedTemplateParameters(const TemplateArgumentList &TemplateArgs, llvm::SmallVectorImpl &Deduced) { for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I) ::MarkDeducedTemplateParameters(*this, TemplateArgs[I], Deduced); }