Template.h revision 23323e0253716ff03c95a00fb6903019daafe3aa 
1//===------- SemaTemplate.h - C++ Templates ---------------------*- C++ -*-===/
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//===----------------------------------------------------------------------===/
8//
9//  This file provides types used in the semantic analysis of C++ templates.
10//
11//===----------------------------------------------------------------------===/
12#ifndef LLVM_CLANG_SEMA_TEMPLATE_H
13#define LLVM_CLANG_SEMA_TEMPLATE_H
14
15#include "clang/AST/DeclTemplate.h"
16#include "clang/AST/DeclVisitor.h"
17#include "llvm/ADT/SmallVector.h"
18#include <cassert>
19#include <utility>
20
21namespace clang {
22  /// \brief Data structure that captures multiple levels of template argument
23  /// lists for use in template instantiation.
24  ///
25  /// Multiple levels of template arguments occur when instantiating the
26  /// definitions of member templates. For example:
27  ///
28  /// \code
29  /// template<typename T>
30  /// struct X {
31  ///   template<T Value>
32  ///   struct Y {
33  ///     void f();
34  ///   };
35  /// };
36  /// \endcode
37  ///
38  /// When instantiating X<int>::Y<17>::f, the multi-level template argument
39  /// list will contain a template argument list (int) at depth 0 and a
40  /// template argument list (17) at depth 1.
41  class MultiLevelTemplateArgumentList {
42  public:
43    typedef std::pair<const TemplateArgument *, unsigned> ArgList;
44
45  private:
46    /// \brief The template argument lists, stored from the innermost template
47    /// argument list (first) to the outermost template argument list (last).
48    SmallVector<ArgList, 4> TemplateArgumentLists;
49
50  public:
51    /// \brief Construct an empty set of template argument lists.
52    MultiLevelTemplateArgumentList() { }
53
54    /// \brief Construct a single-level template argument list.
55    explicit
56    MultiLevelTemplateArgumentList(const TemplateArgumentList &TemplateArgs) {
57      addOuterTemplateArguments(&TemplateArgs);
58    }
59
60    /// \brief Determine the number of levels in this template argument
61    /// list.
62    unsigned getNumLevels() const { return TemplateArgumentLists.size(); }
63
64    /// \brief Retrieve the template argument at a given depth and index.
65    const TemplateArgument &operator()(unsigned Depth, unsigned Index) const {
66      assert(Depth < TemplateArgumentLists.size());
67      assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].second);
68      return TemplateArgumentLists[getNumLevels() - Depth - 1].first[Index];
69    }
70
71    /// \brief Determine whether there is a non-NULL template argument at the
72    /// given depth and index.
73    ///
74    /// There must exist a template argument list at the given depth.
75    bool hasTemplateArgument(unsigned Depth, unsigned Index) const {
76      assert(Depth < TemplateArgumentLists.size());
77
78      if (Index >= TemplateArgumentLists[getNumLevels() - Depth - 1].second)
79        return false;
80
81      return !(*this)(Depth, Index).isNull();
82    }
83
84    /// \brief Clear out a specific template argument.
85    void setArgument(unsigned Depth, unsigned Index,
86                     TemplateArgument Arg) {
87      assert(Depth < TemplateArgumentLists.size());
88      assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].second);
89      const_cast<TemplateArgument&>(
90                TemplateArgumentLists[getNumLevels() - Depth - 1].first[Index])
91        = Arg;
92    }
93
94    /// \brief Add a new outermost level to the multi-level template argument
95    /// list.
96    void addOuterTemplateArguments(const TemplateArgumentList *TemplateArgs) {
97      TemplateArgumentLists.push_back(ArgList(TemplateArgs->data(),
98                                              TemplateArgs->size()));
99    }
100
101    /// \brief Add a new outmost level to the multi-level template argument
102    /// list.
103    void addOuterTemplateArguments(const TemplateArgument *Args,
104                                   unsigned NumArgs) {
105      TemplateArgumentLists.push_back(ArgList(Args, NumArgs));
106    }
107
108    /// \brief Retrieve the innermost template argument list.
109    const ArgList &getInnermost() const {
110      return TemplateArgumentLists.front();
111    }
112  };
113
114  /// \brief The context in which partial ordering of function templates occurs.
115  enum TPOC {
116    /// \brief Partial ordering of function templates for a function call.
117    TPOC_Call,
118    /// \brief Partial ordering of function templates for a call to a
119    /// conversion function.
120    TPOC_Conversion,
121    /// \brief Partial ordering of function templates in other contexts, e.g.,
122    /// taking the address of a function template or matching a function
123    /// template specialization to a function template.
124    TPOC_Other
125  };
126
127  // This is lame but unavoidable in a world without forward
128  // declarations of enums.  The alternatives are to either pollute
129  // Sema.h (by including this file) or sacrifice type safety (by
130  // making Sema.h declare things as enums).
131  class TemplatePartialOrderingContext {
132    TPOC Value;
133  public:
134    TemplatePartialOrderingContext(TPOC Value) : Value(Value) {}
135    operator TPOC() const { return Value; }
136  };
137
138  /// \brief Captures a template argument whose value has been deduced
139  /// via c++ template argument deduction.
140  class DeducedTemplateArgument : public TemplateArgument {
141    /// \brief For a non-type template argument, whether the value was
142    /// deduced from an array bound.
143    bool DeducedFromArrayBound;
144
145  public:
146    DeducedTemplateArgument()
147      : TemplateArgument(), DeducedFromArrayBound(false) { }
148
149    DeducedTemplateArgument(const TemplateArgument &Arg,
150                            bool DeducedFromArrayBound = false)
151      : TemplateArgument(Arg), DeducedFromArrayBound(DeducedFromArrayBound) { }
152
153    /// \brief Construct an integral non-type template argument that
154    /// has been deduced, possibly from an array bound.
155    DeducedTemplateArgument(const llvm::APSInt &Value,
156                            QualType ValueType,
157                            bool DeducedFromArrayBound)
158      : TemplateArgument(Value, ValueType),
159        DeducedFromArrayBound(DeducedFromArrayBound) { }
160
161    /// \brief For a non-type template argument, determine whether the
162    /// template argument was deduced from an array bound.
163    bool wasDeducedFromArrayBound() const { return DeducedFromArrayBound; }
164
165    /// \brief Specify whether the given non-type template argument
166    /// was deduced from an array bound.
167    void setDeducedFromArrayBound(bool Deduced) {
168      DeducedFromArrayBound = Deduced;
169    }
170  };
171
172  /// \brief A stack-allocated class that identifies which local
173  /// variable declaration instantiations are present in this scope.
174  ///
175  /// A new instance of this class type will be created whenever we
176  /// instantiate a new function declaration, which will have its own
177  /// set of parameter declarations.
178  class LocalInstantiationScope {
179  public:
180    /// \brief A set of declarations.
181    typedef SmallVector<Decl *, 4> DeclArgumentPack;
182
183  private:
184    /// \brief Reference to the semantic analysis that is performing
185    /// this template instantiation.
186    Sema &SemaRef;
187
188    typedef llvm::DenseMap<const Decl *,
189                           llvm::PointerUnion<Decl *, DeclArgumentPack *> >
190      LocalDeclsMap;
191
192    /// \brief A mapping from local declarations that occur
193    /// within a template to their instantiations.
194    ///
195    /// This mapping is used during instantiation to keep track of,
196    /// e.g., function parameter and variable declarations. For example,
197    /// given:
198    ///
199    /// \code
200    ///   template<typename T> T add(T x, T y) { return x + y; }
201    /// \endcode
202    ///
203    /// when we instantiate add<int>, we will introduce a mapping from
204    /// the ParmVarDecl for 'x' that occurs in the template to the
205    /// instantiated ParmVarDecl for 'x'.
206    ///
207    /// For a parameter pack, the local instantiation scope may contain a
208    /// set of instantiated parameters. This is stored as a DeclArgumentPack
209    /// pointer.
210    LocalDeclsMap LocalDecls;
211
212    /// \brief The set of argument packs we've allocated.
213    SmallVector<DeclArgumentPack *, 1> ArgumentPacks;
214
215    /// \brief The outer scope, which contains local variable
216    /// definitions from some other instantiation (that may not be
217    /// relevant to this particular scope).
218    LocalInstantiationScope *Outer;
219
220    /// \brief Whether we have already exited this scope.
221    bool Exited;
222
223    /// \brief Whether to combine this scope with the outer scope, such that
224    /// lookup will search our outer scope.
225    bool CombineWithOuterScope;
226
227    /// \brief If non-NULL, the template parameter pack that has been
228    /// partially substituted per C++0x [temp.arg.explicit]p9.
229    NamedDecl *PartiallySubstitutedPack;
230
231    /// \brief If \c PartiallySubstitutedPack is non-null, the set of
232    /// explicitly-specified template arguments in that pack.
233    const TemplateArgument *ArgsInPartiallySubstitutedPack;
234
235    /// \brief If \c PartiallySubstitutedPack, the number of
236    /// explicitly-specified template arguments in
237    /// ArgsInPartiallySubstitutedPack.
238    unsigned NumArgsInPartiallySubstitutedPack;
239
240    // This class is non-copyable
241    LocalInstantiationScope(const LocalInstantiationScope &);
242    LocalInstantiationScope &operator=(const LocalInstantiationScope &);
243
244  public:
245    LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
246      : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
247        Exited(false), CombineWithOuterScope(CombineWithOuterScope),
248        PartiallySubstitutedPack(0)
249    {
250      SemaRef.CurrentInstantiationScope = this;
251    }
252
253    ~LocalInstantiationScope() {
254      Exit();
255    }
256
257    const Sema &getSema() const { return SemaRef; }
258
259    /// \brief Exit this local instantiation scope early.
260    void Exit() {
261      if (Exited)
262        return;
263
264      for (unsigned I = 0, N = ArgumentPacks.size(); I != N; ++I)
265        delete ArgumentPacks[I];
266
267      SemaRef.CurrentInstantiationScope = Outer;
268      Exited = true;
269    }
270
271    /// \brief Clone this scope, and all outer scopes, down to the given
272    /// outermost scope.
273    LocalInstantiationScope *cloneScopes(LocalInstantiationScope *Outermost) {
274      if (this == Outermost) return this;
275      LocalInstantiationScope *newScope =
276        new LocalInstantiationScope(SemaRef, CombineWithOuterScope);
277
278      newScope->Outer = 0;
279      if (Outer)
280        newScope->Outer = Outer->cloneScopes(Outermost);
281
282      newScope->PartiallySubstitutedPack = PartiallySubstitutedPack;
283      newScope->ArgsInPartiallySubstitutedPack = ArgsInPartiallySubstitutedPack;
284      newScope->NumArgsInPartiallySubstitutedPack =
285        NumArgsInPartiallySubstitutedPack;
286
287      for (LocalDeclsMap::iterator I = LocalDecls.begin(), E = LocalDecls.end();
288           I != E; ++I) {
289        const Decl *D = I->first;
290        llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored =
291          newScope->LocalDecls[D];
292        if (I->second.is<Decl *>()) {
293          Stored = I->second.get<Decl *>();
294        } else {
295          DeclArgumentPack *OldPack = I->second.get<DeclArgumentPack *>();
296          DeclArgumentPack *NewPack = new DeclArgumentPack(*OldPack);
297          Stored = NewPack;
298          newScope->ArgumentPacks.push_back(NewPack);
299        }
300      }
301      return newScope;
302    }
303
304    /// \brief deletes the given scope, and all otuer scopes, down to the
305    /// given outermost scope.
306    static void deleteScopes(LocalInstantiationScope *Scope,
307                             LocalInstantiationScope *Outermost) {
308      while (Scope && Scope != Outermost) {
309        LocalInstantiationScope *Out = Scope->Outer;
310        delete Scope;
311        Scope = Out;
312      }
313    }
314
315    /// \brief Find the instantiation of the declaration D within the current
316    /// instantiation scope.
317    ///
318    /// \param D The declaration whose instantiation we are searching for.
319    ///
320    /// \returns A pointer to the declaration or argument pack of declarations
321    /// to which the declaration \c D is instantiataed, if found. Otherwise,
322    /// returns NULL.
323    llvm::PointerUnion<Decl *, DeclArgumentPack *> *
324    findInstantiationOf(const Decl *D);
325
326    void InstantiatedLocal(const Decl *D, Decl *Inst);
327    void InstantiatedLocalPackArg(const Decl *D, Decl *Inst);
328    void MakeInstantiatedLocalArgPack(const Decl *D);
329
330    /// \brief Note that the given parameter pack has been partially substituted
331    /// via explicit specification of template arguments
332    /// (C++0x [temp.arg.explicit]p9).
333    ///
334    /// \param Pack The parameter pack, which will always be a template
335    /// parameter pack.
336    ///
337    /// \param ExplicitArgs The explicitly-specified template arguments provided
338    /// for this parameter pack.
339    ///
340    /// \param NumExplicitArgs The number of explicitly-specified template
341    /// arguments provided for this parameter pack.
342    void SetPartiallySubstitutedPack(NamedDecl *Pack,
343                                     const TemplateArgument *ExplicitArgs,
344                                     unsigned NumExplicitArgs);
345
346    /// \brief Retrieve the partially-substitued template parameter pack.
347    ///
348    /// If there is no partially-substituted parameter pack, returns NULL.
349    NamedDecl *getPartiallySubstitutedPack(
350                                      const TemplateArgument **ExplicitArgs = 0,
351                                           unsigned *NumExplicitArgs = 0) const;
352  };
353
354  class TemplateDeclInstantiator
355    : public DeclVisitor<TemplateDeclInstantiator, Decl *>
356  {
357    Sema &SemaRef;
358    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex;
359    DeclContext *Owner;
360    const MultiLevelTemplateArgumentList &TemplateArgs;
361    Sema::LateInstantiatedAttrVec* LateAttrs;
362    LocalInstantiationScope *StartingScope;
363
364    /// \brief A list of out-of-line class template partial
365    /// specializations that will need to be instantiated after the
366    /// enclosing class's instantiation is complete.
367    SmallVector<std::pair<ClassTemplateDecl *,
368                                ClassTemplatePartialSpecializationDecl *>, 4>
369      OutOfLinePartialSpecs;
370
371  public:
372    TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
373                             const MultiLevelTemplateArgumentList &TemplateArgs)
374      : SemaRef(SemaRef), SubstIndex(SemaRef, -1), Owner(Owner),
375        TemplateArgs(TemplateArgs), LateAttrs(0), StartingScope(0) { }
376
377    // FIXME: Once we get closer to completion, replace these manually-written
378    // declarations with automatically-generated ones from
379    // clang/AST/DeclNodes.inc.
380    Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
381    Decl *VisitLabelDecl(LabelDecl *D);
382    Decl *VisitNamespaceDecl(NamespaceDecl *D);
383    Decl *VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
384    Decl *VisitTypedefDecl(TypedefDecl *D);
385    Decl *VisitTypeAliasDecl(TypeAliasDecl *D);
386    Decl *VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
387    Decl *VisitVarDecl(VarDecl *D);
388    Decl *VisitAccessSpecDecl(AccessSpecDecl *D);
389    Decl *VisitFieldDecl(FieldDecl *D);
390    Decl *VisitIndirectFieldDecl(IndirectFieldDecl *D);
391    Decl *VisitStaticAssertDecl(StaticAssertDecl *D);
392    Decl *VisitEnumDecl(EnumDecl *D);
393    Decl *VisitEnumConstantDecl(EnumConstantDecl *D);
394    Decl *VisitFriendDecl(FriendDecl *D);
395    Decl *VisitFunctionDecl(FunctionDecl *D,
396                            TemplateParameterList *TemplateParams = 0);
397    Decl *VisitCXXRecordDecl(CXXRecordDecl *D);
398    Decl *VisitCXXMethodDecl(CXXMethodDecl *D,
399                             TemplateParameterList *TemplateParams = 0,
400                             bool IsClassScopeSpecialization = false);
401    Decl *VisitCXXConstructorDecl(CXXConstructorDecl *D);
402    Decl *VisitCXXDestructorDecl(CXXDestructorDecl *D);
403    Decl *VisitCXXConversionDecl(CXXConversionDecl *D);
404    ParmVarDecl *VisitParmVarDecl(ParmVarDecl *D);
405    Decl *VisitClassTemplateDecl(ClassTemplateDecl *D);
406    Decl *VisitClassTemplatePartialSpecializationDecl(
407                                    ClassTemplatePartialSpecializationDecl *D);
408    Decl *VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
409    Decl *VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
410    Decl *VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
411    Decl *VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
412    Decl *VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
413    Decl *VisitUsingDecl(UsingDecl *D);
414    Decl *VisitUsingShadowDecl(UsingShadowDecl *D);
415    Decl *VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
416    Decl *VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
417    Decl *VisitClassScopeFunctionSpecializationDecl(
418                                      ClassScopeFunctionSpecializationDecl *D);
419
420    // Base case. FIXME: Remove once we can instantiate everything.
421    Decl *VisitDecl(Decl *D) {
422      unsigned DiagID = SemaRef.getDiagnostics().getCustomDiagID(
423                                                   DiagnosticsEngine::Error,
424                                                   "cannot instantiate %0 yet");
425      SemaRef.Diag(D->getLocation(), DiagID)
426        << D->getDeclKindName();
427
428      return 0;
429    }
430
431    // Enable late instantiation of attributes.  Late instantiated attributes
432    // will be stored in LA.
433    void enableLateAttributeInstantiation(Sema::LateInstantiatedAttrVec *LA) {
434      LateAttrs = LA;
435      StartingScope = SemaRef.CurrentInstantiationScope;
436    }
437
438    // Disable late instantiation of attributes.
439    void disableLateAttributeInstantiation() {
440      LateAttrs = 0;
441      StartingScope = 0;
442    }
443
444    LocalInstantiationScope *getStartingScope() const { return StartingScope; }
445
446    typedef
447      SmallVectorImpl<std::pair<ClassTemplateDecl *,
448                                     ClassTemplatePartialSpecializationDecl *> >
449        ::iterator
450      delayed_partial_spec_iterator;
451
452    /// \brief Return an iterator to the beginning of the set of
453    /// "delayed" partial specializations, which must be passed to
454    /// InstantiateClassTemplatePartialSpecialization once the class
455    /// definition has been completed.
456    delayed_partial_spec_iterator delayed_partial_spec_begin() {
457      return OutOfLinePartialSpecs.begin();
458    }
459
460    /// \brief Return an iterator to the end of the set of
461    /// "delayed" partial specializations, which must be passed to
462    /// InstantiateClassTemplatePartialSpecialization once the class
463    /// definition has been completed.
464    delayed_partial_spec_iterator delayed_partial_spec_end() {
465      return OutOfLinePartialSpecs.end();
466    }
467
468    // Helper functions for instantiating methods.
469    TypeSourceInfo *SubstFunctionType(FunctionDecl *D,
470                             SmallVectorImpl<ParmVarDecl *> &Params);
471    bool InitFunctionInstantiation(FunctionDecl *New, FunctionDecl *Tmpl);
472    bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
473
474    TemplateParameterList *
475      SubstTemplateParams(TemplateParameterList *List);
476
477    bool SubstQualifier(const DeclaratorDecl *OldDecl,
478                        DeclaratorDecl *NewDecl);
479    bool SubstQualifier(const TagDecl *OldDecl,
480                        TagDecl *NewDecl);
481
482    Decl *InstantiateTypedefNameDecl(TypedefNameDecl *D, bool IsTypeAlias);
483    ClassTemplatePartialSpecializationDecl *
484    InstantiateClassTemplatePartialSpecialization(
485                                              ClassTemplateDecl *ClassTemplate,
486                           ClassTemplatePartialSpecializationDecl *PartialSpec);
487  };
488}
489
490#endif // LLVM_CLANG_SEMA_TEMPLATE_H
491