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//===------- SemaTemplate.h - C++ Templates ---------------------*- C++ -*-===/
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file provides types used in the semantic analysis of C++ templates.
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/Sema/Sema.h"
#include "llvm/ADT/SmallVector.h"
#include <cassert>
#include <utility>
namespace clang {
/// \brief Data structure that captures multiple levels of template argument
/// lists for use in template instantiation.
/// Multiple levels of template arguments occur when instantiating the
/// definitions of member templates. For example:
/// \code
/// template<typename T>
/// struct X {
/// template<T Value>
/// struct Y {
/// void f();
/// };
/// };
/// \endcode
/// When instantiating X<int>::Y<17>::f, the multi-level template argument
/// list will contain a template argument list (int) at depth 0 and a
/// template argument list (17) at depth 1.
class MultiLevelTemplateArgumentList {
/// \brief The template argument list at a certain template depth
typedef ArrayRef<TemplateArgument> ArgList;
/// \brief The template argument lists, stored from the innermost template
/// argument list (first) to the outermost template argument list (last).
SmallVector<ArgList, 4> TemplateArgumentLists;
/// \brief The number of outer levels of template arguments that are not
/// being substituted.
unsigned NumRetainedOuterLevels = 0;
/// \brief Construct an empty set of template argument lists.
MultiLevelTemplateArgumentList() { }
/// \brief Construct a single-level template argument list.
MultiLevelTemplateArgumentList(const TemplateArgumentList &TemplateArgs) {
/// \brief Determine the number of levels in this template argument
/// list.
unsigned getNumLevels() const {
return TemplateArgumentLists.size() + NumRetainedOuterLevels;
/// \brief Determine the number of substituted levels in this template
/// argument list.
unsigned getNumSubstitutedLevels() const {
return TemplateArgumentLists.size();
/// \brief Retrieve the template argument at a given depth and index.
const TemplateArgument &operator()(unsigned Depth, unsigned Index) const {
assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].size());
return TemplateArgumentLists[getNumLevels() - Depth - 1][Index];
/// \brief Determine whether there is a non-NULL template argument at the
/// given depth and index.
/// There must exist a template argument list at the given depth.
bool hasTemplateArgument(unsigned Depth, unsigned Index) const {
assert(Depth < getNumLevels());
if (Depth < NumRetainedOuterLevels)
return false;
if (Index >= TemplateArgumentLists[getNumLevels() - Depth - 1].size())
return false;
return !(*this)(Depth, Index).isNull();
/// \brief Clear out a specific template argument.
void setArgument(unsigned Depth, unsigned Index,
TemplateArgument Arg) {
assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].size());
TemplateArgumentLists[getNumLevels() - Depth - 1][Index])
= Arg;
/// \brief Add a new outermost level to the multi-level template argument
/// list.
void addOuterTemplateArguments(const TemplateArgumentList *TemplateArgs) {
/// \brief Add a new outmost level to the multi-level template argument
/// list.
void addOuterTemplateArguments(ArgList Args) {
assert(!NumRetainedOuterLevels &&
"substituted args outside retained args?");
/// \brief Add an outermost level that we are not substituting. We have no
/// arguments at this level, and do not remove it from the depth of inner
/// template parameters that we instantiate.
void addOuterRetainedLevel() {
/// \brief Retrieve the innermost template argument list.
const ArgList &getInnermost() const {
return TemplateArgumentLists.front();
/// \brief The context in which partial ordering of function templates occurs.
enum TPOC {
/// \brief Partial ordering of function templates for a function call.
/// \brief Partial ordering of function templates for a call to a
/// conversion function.
/// \brief Partial ordering of function templates in other contexts, e.g.,
/// taking the address of a function template or matching a function
/// template specialization to a function template.
// This is lame but unavoidable in a world without forward
// declarations of enums. The alternatives are to either pollute
// Sema.h (by including this file) or sacrifice type safety (by
// making Sema.h declare things as enums).
class TemplatePartialOrderingContext {
TPOC Value;
TemplatePartialOrderingContext(TPOC Value) : Value(Value) {}
operator TPOC() const { return Value; }
/// \brief Captures a template argument whose value has been deduced
/// via c++ template argument deduction.
class DeducedTemplateArgument : public TemplateArgument {
/// \brief For a non-type template argument, whether the value was
/// deduced from an array bound.
bool DeducedFromArrayBound;
: TemplateArgument(), DeducedFromArrayBound(false) { }
DeducedTemplateArgument(const TemplateArgument &Arg,
bool DeducedFromArrayBound = false)
: TemplateArgument(Arg), DeducedFromArrayBound(DeducedFromArrayBound) { }
/// \brief Construct an integral non-type template argument that
/// has been deduced, possibly from an array bound.
DeducedTemplateArgument(ASTContext &Ctx,
const llvm::APSInt &Value,
QualType ValueType,
bool DeducedFromArrayBound)
: TemplateArgument(Ctx, Value, ValueType),
DeducedFromArrayBound(DeducedFromArrayBound) { }
/// \brief For a non-type template argument, determine whether the
/// template argument was deduced from an array bound.
bool wasDeducedFromArrayBound() const { return DeducedFromArrayBound; }
/// \brief Specify whether the given non-type template argument
/// was deduced from an array bound.
void setDeducedFromArrayBound(bool Deduced) {
DeducedFromArrayBound = Deduced;
/// \brief A stack-allocated class that identifies which local
/// variable declaration instantiations are present in this scope.
/// A new instance of this class type will be created whenever we
/// instantiate a new function declaration, which will have its own
/// set of parameter declarations.
class LocalInstantiationScope {
/// \brief A set of declarations.
typedef SmallVector<ParmVarDecl *, 4> DeclArgumentPack;
/// \brief Reference to the semantic analysis that is performing
/// this template instantiation.
Sema &SemaRef;
typedef llvm::SmallDenseMap<
const Decl *, llvm::PointerUnion<Decl *, DeclArgumentPack *>, 4>
/// \brief A mapping from local declarations that occur
/// within a template to their instantiations.
/// This mapping is used during instantiation to keep track of,
/// e.g., function parameter and variable declarations. For example,
/// given:
/// \code
/// template<typename T> T add(T x, T y) { return x + y; }
/// \endcode
/// when we instantiate add<int>, we will introduce a mapping from
/// the ParmVarDecl for 'x' that occurs in the template to the
/// instantiated ParmVarDecl for 'x'.
/// For a parameter pack, the local instantiation scope may contain a
/// set of instantiated parameters. This is stored as a DeclArgumentPack
/// pointer.
LocalDeclsMap LocalDecls;
/// \brief The set of argument packs we've allocated.
SmallVector<DeclArgumentPack *, 1> ArgumentPacks;
/// \brief The outer scope, which contains local variable
/// definitions from some other instantiation (that may not be
/// relevant to this particular scope).
LocalInstantiationScope *Outer;
/// \brief Whether we have already exited this scope.
bool Exited;
/// \brief Whether to combine this scope with the outer scope, such that
/// lookup will search our outer scope.
bool CombineWithOuterScope;
/// \brief If non-NULL, the template parameter pack that has been
/// partially substituted per C++0x [temp.arg.explicit]p9.
NamedDecl *PartiallySubstitutedPack;
/// \brief If \c PartiallySubstitutedPack is non-null, the set of
/// explicitly-specified template arguments in that pack.
const TemplateArgument *ArgsInPartiallySubstitutedPack;
/// \brief If \c PartiallySubstitutedPack, the number of
/// explicitly-specified template arguments in
/// ArgsInPartiallySubstitutedPack.
unsigned NumArgsInPartiallySubstitutedPack;
// This class is non-copyable
const LocalInstantiationScope &) = delete;
void operator=(const LocalInstantiationScope &) = delete;
LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
: SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
Exited(false), CombineWithOuterScope(CombineWithOuterScope),
SemaRef.CurrentInstantiationScope = this;
~LocalInstantiationScope() {
const Sema &getSema() const { return SemaRef; }
/// \brief Exit this local instantiation scope early.
void Exit() {
if (Exited)
for (unsigned I = 0, N = ArgumentPacks.size(); I != N; ++I)
delete ArgumentPacks[I];
SemaRef.CurrentInstantiationScope = Outer;
Exited = true;
/// \brief Clone this scope, and all outer scopes, down to the given
/// outermost scope.
LocalInstantiationScope *cloneScopes(LocalInstantiationScope *Outermost) {
if (this == Outermost) return this;
// Save the current scope from SemaRef since the LocalInstantiationScope
// will overwrite it on construction
LocalInstantiationScope *oldScope = SemaRef.CurrentInstantiationScope;
LocalInstantiationScope *newScope =
new LocalInstantiationScope(SemaRef, CombineWithOuterScope);
newScope->Outer = nullptr;
if (Outer)
newScope->Outer = Outer->cloneScopes(Outermost);
newScope->PartiallySubstitutedPack = PartiallySubstitutedPack;
newScope->ArgsInPartiallySubstitutedPack = ArgsInPartiallySubstitutedPack;
newScope->NumArgsInPartiallySubstitutedPack =
for (LocalDeclsMap::iterator I = LocalDecls.begin(), E = LocalDecls.end();
I != E; ++I) {
const Decl *D = I->first;
llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored =
if (I-><Decl *>()) {
Stored = I->second.get<Decl *>();
} else {
DeclArgumentPack *OldPack = I->second.get<DeclArgumentPack *>();
DeclArgumentPack *NewPack = new DeclArgumentPack(*OldPack);
Stored = NewPack;
// Restore the saved scope to SemaRef
SemaRef.CurrentInstantiationScope = oldScope;
return newScope;
/// \brief deletes the given scope, and all otuer scopes, down to the
/// given outermost scope.
static void deleteScopes(LocalInstantiationScope *Scope,
LocalInstantiationScope *Outermost) {
while (Scope && Scope != Outermost) {
LocalInstantiationScope *Out = Scope->Outer;
delete Scope;
Scope = Out;
/// \brief Find the instantiation of the declaration D within the current
/// instantiation scope.
/// \param D The declaration whose instantiation we are searching for.
/// \returns A pointer to the declaration or argument pack of declarations
/// to which the declaration \c D is instantiated, if found. Otherwise,
/// returns NULL.
llvm::PointerUnion<Decl *, DeclArgumentPack *> *
findInstantiationOf(const Decl *D);
void InstantiatedLocal(const Decl *D, Decl *Inst);
void InstantiatedLocalPackArg(const Decl *D, ParmVarDecl *Inst);
void MakeInstantiatedLocalArgPack(const Decl *D);
/// \brief Note that the given parameter pack has been partially substituted
/// via explicit specification of template arguments
/// (C++0x [temp.arg.explicit]p9).
/// \param Pack The parameter pack, which will always be a template
/// parameter pack.
/// \param ExplicitArgs The explicitly-specified template arguments provided
/// for this parameter pack.
/// \param NumExplicitArgs The number of explicitly-specified template
/// arguments provided for this parameter pack.
void SetPartiallySubstitutedPack(NamedDecl *Pack,
const TemplateArgument *ExplicitArgs,
unsigned NumExplicitArgs);
/// \brief Reset the partially-substituted pack when it is no longer of
/// interest.
void ResetPartiallySubstitutedPack() {
assert(PartiallySubstitutedPack && "No partially-substituted pack");
PartiallySubstitutedPack = nullptr;
ArgsInPartiallySubstitutedPack = nullptr;
NumArgsInPartiallySubstitutedPack = 0;
/// \brief Retrieve the partially-substitued template parameter pack.
/// If there is no partially-substituted parameter pack, returns NULL.
NamedDecl *
getPartiallySubstitutedPack(const TemplateArgument **ExplicitArgs = nullptr,
unsigned *NumExplicitArgs = nullptr) const;
class TemplateDeclInstantiator
: public DeclVisitor<TemplateDeclInstantiator, Decl *>
Sema &SemaRef;
Sema::ArgumentPackSubstitutionIndexRAII SubstIndex;
DeclContext *Owner;
const MultiLevelTemplateArgumentList &TemplateArgs;
Sema::LateInstantiatedAttrVec* LateAttrs;
LocalInstantiationScope *StartingScope;
/// \brief A list of out-of-line class template partial
/// specializations that will need to be instantiated after the
/// enclosing class's instantiation is complete.
SmallVector<std::pair<ClassTemplateDecl *,
ClassTemplatePartialSpecializationDecl *>, 4>
/// \brief A list of out-of-line variable template partial
/// specializations that will need to be instantiated after the
/// enclosing variable's instantiation is complete.
/// FIXME: Verify that this is needed.
std::pair<VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>, 4>
TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
const MultiLevelTemplateArgumentList &TemplateArgs)
: SemaRef(SemaRef),
SubstIndex(SemaRef, SemaRef.ArgumentPackSubstitutionIndex),
Owner(Owner), TemplateArgs(TemplateArgs), LateAttrs(nullptr),
StartingScope(nullptr) {}
// Define all the decl visitors using
Decl *Visit ## DERIVED ## Decl(DERIVED ## Decl *D);
// Decls which never appear inside a class or function.
// Decls which use special-case instantiation code.
#include "clang/AST/"
// A few supplemental visitor functions.
Decl *VisitCXXMethodDecl(CXXMethodDecl *D,
TemplateParameterList *TemplateParams,
bool IsClassScopeSpecialization = false);
Decl *VisitFunctionDecl(FunctionDecl *D,
TemplateParameterList *TemplateParams);
Decl *VisitDecl(Decl *D);
Decl *VisitVarDecl(VarDecl *D, bool InstantiatingVarTemplate,
ArrayRef<BindingDecl *> *Bindings = nullptr);
// Enable late instantiation of attributes. Late instantiated attributes
// will be stored in LA.
void enableLateAttributeInstantiation(Sema::LateInstantiatedAttrVec *LA) {
LateAttrs = LA;
StartingScope = SemaRef.CurrentInstantiationScope;
// Disable late instantiation of attributes.
void disableLateAttributeInstantiation() {
LateAttrs = nullptr;
StartingScope = nullptr;
LocalInstantiationScope *getStartingScope() const { return StartingScope; }
SmallVectorImpl<std::pair<ClassTemplateDecl *,
ClassTemplatePartialSpecializationDecl *> >
typedef SmallVectorImpl<std::pair<
VarTemplateDecl *, VarTemplatePartialSpecializationDecl *> >::iterator
/// \brief Return an iterator to the beginning of the set of
/// "delayed" partial specializations, which must be passed to
/// InstantiateClassTemplatePartialSpecialization once the class
/// definition has been completed.
delayed_partial_spec_iterator delayed_partial_spec_begin() {
return OutOfLinePartialSpecs.begin();
delayed_var_partial_spec_iterator delayed_var_partial_spec_begin() {
return OutOfLineVarPartialSpecs.begin();
/// \brief Return an iterator to the end of the set of
/// "delayed" partial specializations, which must be passed to
/// InstantiateClassTemplatePartialSpecialization once the class
/// definition has been completed.
delayed_partial_spec_iterator delayed_partial_spec_end() {
return OutOfLinePartialSpecs.end();
delayed_var_partial_spec_iterator delayed_var_partial_spec_end() {
return OutOfLineVarPartialSpecs.end();
// Helper functions for instantiating methods.
TypeSourceInfo *SubstFunctionType(FunctionDecl *D,
SmallVectorImpl<ParmVarDecl *> &Params);
bool InitFunctionInstantiation(FunctionDecl *New, FunctionDecl *Tmpl);
bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
TemplateParameterList *
SubstTemplateParams(TemplateParameterList *List);
bool SubstQualifier(const DeclaratorDecl *OldDecl,
DeclaratorDecl *NewDecl);
bool SubstQualifier(const TagDecl *OldDecl,
TagDecl *NewDecl);
Decl *VisitVarTemplateSpecializationDecl(
VarTemplateDecl *VarTemplate, VarDecl *FromVar, void *InsertPos,
const TemplateArgumentListInfo &TemplateArgsInfo,
ArrayRef<TemplateArgument> Converted);
Decl *InstantiateTypedefNameDecl(TypedefNameDecl *D, bool IsTypeAlias);
ClassTemplatePartialSpecializationDecl *
ClassTemplateDecl *ClassTemplate,
ClassTemplatePartialSpecializationDecl *PartialSpec);
VarTemplatePartialSpecializationDecl *
VarTemplateDecl *VarTemplate,
VarTemplatePartialSpecializationDecl *PartialSpec);
void InstantiateEnumDefinition(EnumDecl *Enum, EnumDecl *Pattern);
template<typename T>
Decl *instantiateUnresolvedUsingDecl(T *D,
bool InstantiatingPackElement = false);