1//===- TemplateName.h - C++ Template Name Representation --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the TemplateName interface and subclasses.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_AST_TEMPLATENAME_H
14#define LLVM_CLANG_AST_TEMPLATENAME_H
15
16#include "clang/AST/DependenceFlags.h"
17#include "clang/AST/NestedNameSpecifier.h"
18#include "clang/Basic/LLVM.h"
19#include "llvm/ADT/FoldingSet.h"
20#include "llvm/ADT/PointerIntPair.h"
21#include "llvm/ADT/PointerUnion.h"
22#include "llvm/Support/PointerLikeTypeTraits.h"
23#include <cassert>
24
25namespace clang {
26
27class ASTContext;
28class DependentTemplateName;
29class DiagnosticBuilder;
30class IdentifierInfo;
31class NamedDecl;
32class NestedNameSpecifier;
33enum OverloadedOperatorKind : int;
34class OverloadedTemplateStorage;
35class AssumedTemplateStorage;
36class PartialDiagnostic;
37struct PrintingPolicy;
38class QualifiedTemplateName;
39class SubstTemplateTemplateParmPackStorage;
40class SubstTemplateTemplateParmStorage;
41class TemplateArgument;
42class TemplateDecl;
43class TemplateTemplateParmDecl;
44
45/// Implementation class used to describe either a set of overloaded
46/// template names or an already-substituted template template parameter pack.
47class UncommonTemplateNameStorage {
48protected:
49 enum Kind {
50 Overloaded,
51 Assumed, // defined in DeclarationName.h
52 SubstTemplateTemplateParm,
53 SubstTemplateTemplateParmPack
54 };
55
56 struct BitsTag {
57 /// A Kind.
58 unsigned Kind : 2;
59
60 /// The number of stored templates or template arguments,
61 /// depending on which subclass we have.
62 unsigned Size : 30;
63 };
64
65 union {
66 struct BitsTag Bits;
67 void *PointerAlignment;
68 };
69
70 UncommonTemplateNameStorage(Kind kind, unsigned size) {
71 Bits.Kind = kind;
72 Bits.Size = size;
73 }
74
75public:
76 unsigned size() const { return Bits.Size; }
77
78 OverloadedTemplateStorage *getAsOverloadedStorage() {
79 return Bits.Kind == Overloaded
80 ? reinterpret_cast<OverloadedTemplateStorage *>(this)
81 : nullptr;
82 }
83
84 AssumedTemplateStorage *getAsAssumedTemplateName() {
85 return Bits.Kind == Assumed
86 ? reinterpret_cast<AssumedTemplateStorage *>(this)
87 : nullptr;
88 }
89
90 SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() {
91 return Bits.Kind == SubstTemplateTemplateParm
92 ? reinterpret_cast<SubstTemplateTemplateParmStorage *>(this)
93 : nullptr;
94 }
95
96 SubstTemplateTemplateParmPackStorage *getAsSubstTemplateTemplateParmPack() {
97 return Bits.Kind == SubstTemplateTemplateParmPack
98 ? reinterpret_cast<SubstTemplateTemplateParmPackStorage *>(this)
99 : nullptr;
100 }
101};
102
103/// A structure for storing the information associated with an
104/// overloaded template name.
105class OverloadedTemplateStorage : public UncommonTemplateNameStorage {
106 friend class ASTContext;
107
108 OverloadedTemplateStorage(unsigned size)
109 : UncommonTemplateNameStorage(Overloaded, size) {}
110
111 NamedDecl **getStorage() {
112 return reinterpret_cast<NamedDecl **>(this + 1);
113 }
114 NamedDecl * const *getStorage() const {
115 return reinterpret_cast<NamedDecl *const *>(this + 1);
116 }
117
118public:
119 using iterator = NamedDecl *const *;
120
121 iterator begin() const { return getStorage(); }
122 iterator end() const { return getStorage() + size(); }
123
124 llvm::ArrayRef<NamedDecl*> decls() const {
125 return llvm::makeArrayRef(begin(), end());
126 }
127};
128
129/// A structure for storing an already-substituted template template
130/// parameter pack.
131///
132/// This kind of template names occurs when the parameter pack has been
133/// provided with a template template argument pack in a context where its
134/// enclosing pack expansion could not be fully expanded.
135class SubstTemplateTemplateParmPackStorage
136 : public UncommonTemplateNameStorage, public llvm::FoldingSetNode
137{
138 TemplateTemplateParmDecl *Parameter;
139 const TemplateArgument *Arguments;
140
141public:
142 SubstTemplateTemplateParmPackStorage(TemplateTemplateParmDecl *Parameter,
143 unsigned Size,
144 const TemplateArgument *Arguments)
145 : UncommonTemplateNameStorage(SubstTemplateTemplateParmPack, Size),
146 Parameter(Parameter), Arguments(Arguments) {}
147
148 /// Retrieve the template template parameter pack being substituted.
149 TemplateTemplateParmDecl *getParameterPack() const {
150 return Parameter;
151 }
152
153 /// Retrieve the template template argument pack with which this
154 /// parameter was substituted.
155 TemplateArgument getArgumentPack() const;
156
157 void Profile(llvm::FoldingSetNodeID &ID, ASTContext &Context);
158
159 static void Profile(llvm::FoldingSetNodeID &ID,
160 ASTContext &Context,
161 TemplateTemplateParmDecl *Parameter,
162 const TemplateArgument &ArgPack);
163};
164
165/// Represents a C++ template name within the type system.
166///
167/// A C++ template name refers to a template within the C++ type
168/// system. In most cases, a template name is simply a reference to a
169/// class template, e.g.
170///
171/// \code
172/// template<typename T> class X { };
173///
174/// X<int> xi;
175/// \endcode
176///
177/// Here, the 'X' in \c X<int> is a template name that refers to the
178/// declaration of the class template X, above. Template names can
179/// also refer to function templates, C++0x template aliases, etc.
180///
181/// Some template names are dependent. For example, consider:
182///
183/// \code
184/// template<typename MetaFun, typename T1, typename T2> struct apply2 {
185/// typedef typename MetaFun::template apply<T1, T2>::type type;
186/// };
187/// \endcode
188///
189/// Here, "apply" is treated as a template name within the typename
190/// specifier in the typedef. "apply" is a nested template, and can
191/// only be understood in the context of
192class TemplateName {
193 using StorageType =
194 llvm::PointerUnion<TemplateDecl *, UncommonTemplateNameStorage *,
195 QualifiedTemplateName *, DependentTemplateName *>;
196
197 StorageType Storage;
198
199 explicit TemplateName(void *Ptr);
200
201public:
202 // Kind of name that is actually stored.
203 enum NameKind {
204 /// A single template declaration.
205 Template,
206
207 /// A set of overloaded template declarations.
208 OverloadedTemplate,
209
210 /// An unqualified-id that has been assumed to name a function template
211 /// that will be found by ADL.
212 AssumedTemplate,
213
214 /// A qualified template name, where the qualification is kept
215 /// to describe the source code as written.
216 QualifiedTemplate,
217
218 /// A dependent template name that has not been resolved to a
219 /// template (or set of templates).
220 DependentTemplate,
221
222 /// A template template parameter that has been substituted
223 /// for some other template name.
224 SubstTemplateTemplateParm,
225
226 /// A template template parameter pack that has been substituted for
227 /// a template template argument pack, but has not yet been expanded into
228 /// individual arguments.
229 SubstTemplateTemplateParmPack
230 };
231
232 TemplateName() = default;
233 explicit TemplateName(TemplateDecl *Template);
234 explicit TemplateName(OverloadedTemplateStorage *Storage);
235 explicit TemplateName(AssumedTemplateStorage *Storage);
236 explicit TemplateName(SubstTemplateTemplateParmStorage *Storage);
237 explicit TemplateName(SubstTemplateTemplateParmPackStorage *Storage);
238 explicit TemplateName(QualifiedTemplateName *Qual);
239 explicit TemplateName(DependentTemplateName *Dep);
240
241 /// Determine whether this template name is NULL.
242 bool isNull() const;
243
244 // Get the kind of name that is actually stored.
245 NameKind getKind() const;
246
247 /// Retrieve the underlying template declaration that
248 /// this template name refers to, if known.
249 ///
250 /// \returns The template declaration that this template name refers
251 /// to, if any. If the template name does not refer to a specific
252 /// declaration because it is a dependent name, or if it refers to a
253 /// set of function templates, returns NULL.
254 TemplateDecl *getAsTemplateDecl() const;
255
256 /// Retrieve the underlying, overloaded function template
257 /// declarations that this template name refers to, if known.
258 ///
259 /// \returns The set of overloaded function templates that this template
260 /// name refers to, if known. If the template name does not refer to a
261 /// specific set of function templates because it is a dependent name or
262 /// refers to a single template, returns NULL.
263 OverloadedTemplateStorage *getAsOverloadedTemplate() const;
264
265 /// Retrieve information on a name that has been assumed to be a
266 /// template-name in order to permit a call via ADL.
267 AssumedTemplateStorage *getAsAssumedTemplateName() const;
268
269 /// Retrieve the substituted template template parameter, if
270 /// known.
271 ///
272 /// \returns The storage for the substituted template template parameter,
273 /// if known. Otherwise, returns NULL.
274 SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() const;
275
276 /// Retrieve the substituted template template parameter pack, if
277 /// known.
278 ///
279 /// \returns The storage for the substituted template template parameter pack,
280 /// if known. Otherwise, returns NULL.
281 SubstTemplateTemplateParmPackStorage *
282 getAsSubstTemplateTemplateParmPack() const;
283
284 /// Retrieve the underlying qualified template name
285 /// structure, if any.
286 QualifiedTemplateName *getAsQualifiedTemplateName() const;
287
288 /// Retrieve the underlying dependent template name
289 /// structure, if any.
290 DependentTemplateName *getAsDependentTemplateName() const;
291
292 TemplateName getUnderlying() const;
293
294 /// Get the template name to substitute when this template name is used as a
295 /// template template argument. This refers to the most recent declaration of
296 /// the template, including any default template arguments.
297 TemplateName getNameToSubstitute() const;
298
299 TemplateNameDependence getDependence() const;
300
301 /// Determines whether this is a dependent template name.
302 bool isDependent() const;
303
304 /// Determines whether this is a template name that somehow
305 /// depends on a template parameter.
306 bool isInstantiationDependent() const;
307
308 /// Determines whether this template name contains an
309 /// unexpanded parameter pack (for C++0x variadic templates).
310 bool containsUnexpandedParameterPack() const;
311
312 /// Print the template name.
313 ///
314 /// \param OS the output stream to which the template name will be
315 /// printed.
316 ///
317 /// \param SuppressNNS if true, don't print the
318 /// nested-name-specifier that precedes the template name (if it has
319 /// one).
320 void print(raw_ostream &OS, const PrintingPolicy &Policy,
321 bool SuppressNNS = false) const;
322
323 /// Debugging aid that dumps the template name.
324 void dump(raw_ostream &OS) const;
325
326 /// Debugging aid that dumps the template name to standard
327 /// error.
328 void dump() const;
329
330 void Profile(llvm::FoldingSetNodeID &ID) {
331 ID.AddPointer(Storage.getOpaqueValue());
332 }
333
334 /// Retrieve the template name as a void pointer.
335 void *getAsVoidPointer() const { return Storage.getOpaqueValue(); }
336
337 /// Build a template name from a void pointer.
338 static TemplateName getFromVoidPointer(void *Ptr) {
339 return TemplateName(Ptr);
340 }
341};
342
343/// Insertion operator for diagnostics. This allows sending TemplateName's
344/// into a diagnostic with <<.
345const StreamingDiagnostic &operator<<(const StreamingDiagnostic &DB,
346 TemplateName N);
347
348/// A structure for storing the information associated with a
349/// substituted template template parameter.
350class SubstTemplateTemplateParmStorage
351 : public UncommonTemplateNameStorage, public llvm::FoldingSetNode {
352 friend class ASTContext;
353
354 TemplateTemplateParmDecl *Parameter;
355 TemplateName Replacement;
356
357 SubstTemplateTemplateParmStorage(TemplateTemplateParmDecl *parameter,
358 TemplateName replacement)
359 : UncommonTemplateNameStorage(SubstTemplateTemplateParm, 0),
360 Parameter(parameter), Replacement(replacement) {}
361
362public:
363 TemplateTemplateParmDecl *getParameter() const { return Parameter; }
364 TemplateName getReplacement() const { return Replacement; }
365
366 void Profile(llvm::FoldingSetNodeID &ID);
367
368 static void Profile(llvm::FoldingSetNodeID &ID,
369 TemplateTemplateParmDecl *parameter,
370 TemplateName replacement);
371};
372
373inline TemplateName TemplateName::getUnderlying() const {
374 if (SubstTemplateTemplateParmStorage *subst
375 = getAsSubstTemplateTemplateParm())
376 return subst->getReplacement().getUnderlying();
377 return *this;
378}
379
380/// Represents a template name that was expressed as a
381/// qualified name.
382///
383/// This kind of template name refers to a template name that was
384/// preceded by a nested name specifier, e.g., \c std::vector. Here,
385/// the nested name specifier is "std::" and the template name is the
386/// declaration for "vector". The QualifiedTemplateName class is only
387/// used to provide "sugar" for template names that were expressed
388/// with a qualified name, and has no semantic meaning. In this
389/// manner, it is to TemplateName what ElaboratedType is to Type,
390/// providing extra syntactic sugar for downstream clients.
391class QualifiedTemplateName : public llvm::FoldingSetNode {
392 friend class ASTContext;
393
394 /// The nested name specifier that qualifies the template name.
395 ///
396 /// The bit is used to indicate whether the "template" keyword was
397 /// present before the template name itself. Note that the
398 /// "template" keyword is always redundant in this case (otherwise,
399 /// the template name would be a dependent name and we would express
400 /// this name with DependentTemplateName).
401 llvm::PointerIntPair<NestedNameSpecifier *, 1> Qualifier;
402
403 /// The template declaration or set of overloaded function templates
404 /// that this qualified name refers to.
405 TemplateDecl *Template;
406
407 QualifiedTemplateName(NestedNameSpecifier *NNS, bool TemplateKeyword,
408 TemplateDecl *Template)
409 : Qualifier(NNS, TemplateKeyword? 1 : 0), Template(Template) {}
410
411public:
412 /// Return the nested name specifier that qualifies this name.
413 NestedNameSpecifier *getQualifier() const { return Qualifier.getPointer(); }
414
415 /// Whether the template name was prefixed by the "template"
416 /// keyword.
417 bool hasTemplateKeyword() const { return Qualifier.getInt(); }
418
419 /// The template declaration that this qualified name refers
420 /// to.
421 TemplateDecl *getDecl() const { return Template; }
422
423 /// The template declaration to which this qualified name
424 /// refers.
425 TemplateDecl *getTemplateDecl() const { return Template; }
426
427 void Profile(llvm::FoldingSetNodeID &ID) {
428 Profile(ID, getQualifier(), hasTemplateKeyword(), getTemplateDecl());
429 }
430
431 static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
432 bool TemplateKeyword, TemplateDecl *Template) {
433 ID.AddPointer(NNS);
434 ID.AddBoolean(TemplateKeyword);
435 ID.AddPointer(Template);
436 }
437};
438
439/// Represents a dependent template name that cannot be
440/// resolved prior to template instantiation.
441///
442/// This kind of template name refers to a dependent template name,
443/// including its nested name specifier (if any). For example,
444/// DependentTemplateName can refer to "MetaFun::template apply",
445/// where "MetaFun::" is the nested name specifier and "apply" is the
446/// template name referenced. The "template" keyword is implied.
447class DependentTemplateName : public llvm::FoldingSetNode {
448 friend class ASTContext;
449
450 /// The nested name specifier that qualifies the template
451 /// name.
452 ///
453 /// The bit stored in this qualifier describes whether the \c Name field
454 /// is interpreted as an IdentifierInfo pointer (when clear) or as an
455 /// overloaded operator kind (when set).
456 llvm::PointerIntPair<NestedNameSpecifier *, 1, bool> Qualifier;
457
458 /// The dependent template name.
459 union {
460 /// The identifier template name.
461 ///
462 /// Only valid when the bit on \c Qualifier is clear.
463 const IdentifierInfo *Identifier;
464
465 /// The overloaded operator name.
466 ///
467 /// Only valid when the bit on \c Qualifier is set.
468 OverloadedOperatorKind Operator;
469 };
470
471 /// The canonical template name to which this dependent
472 /// template name refers.
473 ///
474 /// The canonical template name for a dependent template name is
475 /// another dependent template name whose nested name specifier is
476 /// canonical.
477 TemplateName CanonicalTemplateName;
478
479 DependentTemplateName(NestedNameSpecifier *Qualifier,
480 const IdentifierInfo *Identifier)
481 : Qualifier(Qualifier, false), Identifier(Identifier),
482 CanonicalTemplateName(this) {}
483
484 DependentTemplateName(NestedNameSpecifier *Qualifier,
485 const IdentifierInfo *Identifier,
486 TemplateName Canon)
487 : Qualifier(Qualifier, false), Identifier(Identifier),
488 CanonicalTemplateName(Canon) {}
489
490 DependentTemplateName(NestedNameSpecifier *Qualifier,
491 OverloadedOperatorKind Operator)
492 : Qualifier(Qualifier, true), Operator(Operator),
493 CanonicalTemplateName(this) {}
494
495 DependentTemplateName(NestedNameSpecifier *Qualifier,
496 OverloadedOperatorKind Operator,
497 TemplateName Canon)
498 : Qualifier(Qualifier, true), Operator(Operator),
499 CanonicalTemplateName(Canon) {}
500
501public:
502 /// Return the nested name specifier that qualifies this name.
503 NestedNameSpecifier *getQualifier() const { return Qualifier.getPointer(); }
504
505 /// Determine whether this template name refers to an identifier.
506 bool isIdentifier() const { return !Qualifier.getInt(); }
507
508 /// Returns the identifier to which this template name refers.
509 const IdentifierInfo *getIdentifier() const {
510 assert(isIdentifier() && "Template name isn't an identifier?");
511 return Identifier;
512 }
513
514 /// Determine whether this template name refers to an overloaded
515 /// operator.
516 bool isOverloadedOperator() const { return Qualifier.getInt(); }
517
518 /// Return the overloaded operator to which this template name refers.
519 OverloadedOperatorKind getOperator() const {
520 assert(isOverloadedOperator() &&
521 "Template name isn't an overloaded operator?");
522 return Operator;
523 }
524
525 void Profile(llvm::FoldingSetNodeID &ID) {
526 if (isIdentifier())
527 Profile(ID, getQualifier(), getIdentifier());
528 else
529 Profile(ID, getQualifier(), getOperator());
530 }
531
532 static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
533 const IdentifierInfo *Identifier) {
534 ID.AddPointer(NNS);
535 ID.AddBoolean(false);
536 ID.AddPointer(Identifier);
537 }
538
539 static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
540 OverloadedOperatorKind Operator) {
541 ID.AddPointer(NNS);
542 ID.AddBoolean(true);
543 ID.AddInteger(Operator);
544 }
545};
546
547} // namespace clang.
548
549namespace llvm {
550
551/// The clang::TemplateName class is effectively a pointer.
552template<>
553struct PointerLikeTypeTraits<clang::TemplateName> {
554 static inline void *getAsVoidPointer(clang::TemplateName TN) {
555 return TN.getAsVoidPointer();
556 }
557
558 static inline clang::TemplateName getFromVoidPointer(void *Ptr) {
559 return clang::TemplateName::getFromVoidPointer(Ptr);
560 }
561
562 // No bits are available!
563 static constexpr int NumLowBitsAvailable = 0;
564};
565
566} // namespace llvm.
567
568#endif // LLVM_CLANG_AST_TEMPLATENAME_H
569