clang 17.0.0git
TemplateDeduction.h
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1//===- TemplateDeduction.h - C++ template argument deduction ----*- 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 provides types used with Sema's template argument deduction
10// routines.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_SEMA_TEMPLATEDEDUCTION_H
15#define LLVM_CLANG_SEMA_TEMPLATEDEDUCTION_H
16
25#include "llvm/ADT/SmallVector.h"
26#include <cassert>
27#include <cstddef>
28#include <optional>
29#include <utility>
30
31namespace clang {
32
33class Decl;
34struct DeducedPack;
35class Sema;
36
37namespace sema {
38
39/// Provides information about an attempted template argument
40/// deduction, whose success or failure was described by a
41/// TemplateDeductionResult value.
43 /// The deduced template argument list.
44 TemplateArgumentList *DeducedSugared = nullptr, *DeducedCanonical = nullptr;
45
46 /// The source location at which template argument
47 /// deduction is occurring.
49
50 /// Have we suppressed an error during deduction?
51 bool HasSFINAEDiagnostic = false;
52
53 /// The template parameter depth for which we're performing deduction.
54 unsigned DeducedDepth;
55
56 /// The number of parameters with explicitly-specified template arguments,
57 /// up to and including the partially-specified pack (if any).
58 unsigned ExplicitArgs = 0;
59
60 /// Warnings (and follow-on notes) that were suppressed due to
61 /// SFINAE while performing template argument deduction.
62 SmallVector<PartialDiagnosticAt, 4> SuppressedDiagnostics;
63
64public:
65 TemplateDeductionInfo(SourceLocation Loc, unsigned DeducedDepth = 0)
66 : Loc(Loc), DeducedDepth(DeducedDepth) {}
69
71 /// Create temporary template deduction info for speculatively deducing
72 /// against a base class of an argument's type.
74 : DeducedSugared(Info.DeducedSugared), Loc(Info.Loc),
75 DeducedDepth(Info.DeducedDepth), ExplicitArgs(Info.ExplicitArgs) {}
76
77 /// Returns the location at which template argument is
78 /// occurring.
80 return Loc;
81 }
82
83 /// The depth of template parameters for which deduction is being
84 /// performed.
85 unsigned getDeducedDepth() const {
86 return DeducedDepth;
87 }
88
89 /// Get the number of explicitly-specified arguments.
90 unsigned getNumExplicitArgs() const {
91 return ExplicitArgs;
92 }
93
94 /// Take ownership of the deduced template argument lists.
96 TemplateArgumentList *Result = DeducedSugared;
97 DeducedSugared = nullptr;
98 return Result;
99 }
101 TemplateArgumentList *Result = DeducedCanonical;
102 DeducedCanonical = nullptr;
103 return Result;
104 }
105
106 /// Take ownership of the SFINAE diagnostic.
108 assert(HasSFINAEDiagnostic);
109 PD.first = SuppressedDiagnostics.front().first;
110 PD.second.swap(SuppressedDiagnostics.front().second);
112 }
113
114 /// Discard any SFINAE diagnostics.
116 SuppressedDiagnostics.clear();
117 HasSFINAEDiagnostic = false;
118 }
119
120 /// Peek at the SFINAE diagnostic.
122 assert(HasSFINAEDiagnostic);
123 return SuppressedDiagnostics.front();
124 }
125
126 /// Provide an initial template argument list that contains the
127 /// explicitly-specified arguments.
128 void setExplicitArgs(TemplateArgumentList *NewDeducedSugared,
129 TemplateArgumentList *NewDeducedCanonical) {
130 assert(NewDeducedSugared->size() == NewDeducedCanonical->size());
131 DeducedSugared = NewDeducedSugared;
132 DeducedCanonical = NewDeducedCanonical;
133 ExplicitArgs = DeducedSugared->size();
134 }
135
136 /// Provide a new template argument list that contains the
137 /// results of template argument deduction.
138 void reset(TemplateArgumentList *NewDeducedSugared,
139 TemplateArgumentList *NewDeducedCanonical) {
140 DeducedSugared = NewDeducedSugared;
141 DeducedCanonical = NewDeducedCanonical;
142 }
143
144 /// Is a SFINAE diagnostic available?
145 bool hasSFINAEDiagnostic() const {
146 return HasSFINAEDiagnostic;
147 }
148
149 /// Set the diagnostic which caused the SFINAE failure.
151 // Only collect the first diagnostic.
152 if (HasSFINAEDiagnostic)
153 return;
154 SuppressedDiagnostics.clear();
155 SuppressedDiagnostics.emplace_back(Loc, std::move(PD));
156 HasSFINAEDiagnostic = true;
157 }
158
159 /// Add a new diagnostic to the set of diagnostics
162 if (HasSFINAEDiagnostic)
163 return;
164 SuppressedDiagnostics.emplace_back(Loc, std::move(PD));
165 }
166
167 /// Iterator over the set of suppressed diagnostics.
169
170 /// Returns an iterator at the beginning of the sequence of suppressed
171 /// diagnostics.
172 diag_iterator diag_begin() const { return SuppressedDiagnostics.begin(); }
173
174 /// Returns an iterator at the end of the sequence of suppressed
175 /// diagnostics.
176 diag_iterator diag_end() const { return SuppressedDiagnostics.end(); }
177
178 /// The template parameter to which a template argument
179 /// deduction failure refers.
180 ///
181 /// Depending on the result of template argument deduction, this
182 /// template parameter may have different meanings:
183 ///
184 /// TDK_Incomplete: this is the first template parameter whose
185 /// corresponding template argument was not deduced.
186 ///
187 /// TDK_IncompletePack: this is the expanded parameter pack for
188 /// which we deduced too few arguments.
189 ///
190 /// TDK_Inconsistent: this is the template parameter for which
191 /// two different template argument values were deduced.
193
194 /// The first template argument to which the template
195 /// argument deduction failure refers.
196 ///
197 /// Depending on the result of the template argument deduction,
198 /// this template argument may have different meanings:
199 ///
200 /// TDK_IncompletePack: this is the number of arguments we deduced
201 /// for the pack.
202 ///
203 /// TDK_Inconsistent: this argument is the first value deduced
204 /// for the corresponding template parameter.
205 ///
206 /// TDK_SubstitutionFailure: this argument is the template
207 /// argument we were instantiating when we encountered an error.
208 ///
209 /// TDK_DeducedMismatch: this is the parameter type, after substituting
210 /// deduced arguments.
211 ///
212 /// TDK_NonDeducedMismatch: this is the component of the 'parameter'
213 /// of the deduction, directly provided in the source code.
215
216 /// The second template argument to which the template
217 /// argument deduction failure refers.
218 ///
219 /// TDK_Inconsistent: this argument is the second value deduced
220 /// for the corresponding template parameter.
221 ///
222 /// TDK_DeducedMismatch: this is the (adjusted) call argument type.
223 ///
224 /// TDK_NonDeducedMismatch: this is the mismatching component of the
225 /// 'argument' of the deduction, from which we are deducing arguments.
226 ///
227 /// FIXME: Finish documenting this.
229
230 /// The index of the function argument that caused a deduction
231 /// failure.
232 ///
233 /// TDK_DeducedMismatch: this is the index of the argument that had a
234 /// different argument type from its substituted parameter type.
235 unsigned CallArgIndex = 0;
236
237 /// Information on packs that we're currently expanding.
238 ///
239 /// FIXME: This should be kept internal to SemaTemplateDeduction.
241
242 /// \brief The constraint satisfaction details resulting from the associated
243 /// constraints satisfaction tests.
245};
246
247} // namespace sema
248
249/// A structure used to record information about a failed
250/// template argument deduction, for diagnosis.
252 /// A Sema::TemplateDeductionResult.
253 unsigned Result : 8;
254
255 /// Indicates whether a diagnostic is stored in Diagnostic.
256 unsigned HasDiagnostic : 1;
257
258 /// Opaque pointer containing additional data about
259 /// this deduction failure.
260 void *Data;
261
262 /// A diagnostic indicating why deduction failed.
264
265 /// Retrieve the diagnostic which caused this deduction failure,
266 /// if any.
268
269 /// Retrieve the template parameter this deduction failure
270 /// refers to, if any.
272
273 /// Retrieve the template argument list associated with this
274 /// deduction failure, if any.
276
277 /// Return the first template argument this deduction failure
278 /// refers to, if any.
280
281 /// Return the second template argument this deduction failure
282 /// refers to, if any.
284
285 /// Return the index of the call argument that this deduction
286 /// failure refers to, if any.
287 std::optional<unsigned> getCallArgIndex();
288
289 /// Free any memory associated with this deduction failure.
290 void Destroy();
291};
292
293/// TemplateSpecCandidate - This is a generalization of OverloadCandidate
294/// which keeps track of template argument deduction failure info, when
295/// handling explicit specializations (and instantiations) of templates
296/// beyond function overloading.
297/// For now, assume that the candidates are non-matching specializations.
298/// TODO: In the future, we may need to unify/generalize this with
299/// OverloadCandidate.
301 /// The declaration that was looked up, together with its access.
302 /// Might be a UsingShadowDecl, but usually a FunctionTemplateDecl.
304
305 /// Specialization - The actual specialization that this candidate
306 /// represents. When NULL, this may be a built-in candidate.
308
309 /// Template argument deduction info
311
312 void set(DeclAccessPair Found, Decl *Spec, DeductionFailureInfo Info) {
313 FoundDecl = Found;
314 Specialization = Spec;
315 DeductionFailure = Info;
316 }
317
318 /// Diagnose a template argument deduction failure.
319 void NoteDeductionFailure(Sema &S, bool ForTakingAddress);
320};
321
322/// TemplateSpecCandidateSet - A set of generalized overload candidates,
323/// used in template specializations.
324/// TODO: In the future, we may need to unify/generalize this with
325/// OverloadCandidateSet.
328 SourceLocation Loc;
329
330 // Stores whether we're taking the address of these candidates. This helps us
331 // produce better error messages when dealing with the pass_object_size
332 // attribute on parameters.
333 bool ForTakingAddress;
334
335 void destroyCandidates();
336
337public:
338 TemplateSpecCandidateSet(SourceLocation Loc, bool ForTakingAddress = false)
339 : Loc(Loc), ForTakingAddress(ForTakingAddress) {}
343 ~TemplateSpecCandidateSet() { destroyCandidates(); }
344
345 SourceLocation getLocation() const { return Loc; }
346
347 /// Clear out all of the candidates.
348 /// TODO: This may be unnecessary.
349 void clear();
350
352
353 iterator begin() { return Candidates.begin(); }
354 iterator end() { return Candidates.end(); }
355
356 size_t size() const { return Candidates.size(); }
357 bool empty() const { return Candidates.empty(); }
358
359 /// Add a new candidate with NumConversions conversion sequence slots
360 /// to the overload set.
362 Candidates.emplace_back();
363 return Candidates.back();
364 }
365
366 void NoteCandidates(Sema &S, SourceLocation Loc);
367
368 void NoteCandidates(Sema &S, SourceLocation Loc) const {
369 const_cast<TemplateSpecCandidateSet *>(this)->NoteCandidates(S, Loc);
370 }
371};
372
373} // namespace clang
374
375#endif // LLVM_CLANG_SEMA_TEMPLATEDEDUCTION_H
This file provides AST data structures related to concepts.
Defines the C++ template declaration subclasses.
Implements a partial diagnostic that can be emitted anwyhere in a DiagnosticBuilder stream.
Defines the clang::SourceLocation class and associated facilities.
The result of a constraint satisfaction check, containing the necessary information to diagnose an un...
Definition: ASTConcept.h:28
A POD class for pairing a NamedDecl* with an access specifier.
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:83
A little helper class (which is basically a smart pointer that forwards info from DiagnosticsEngine) ...
Definition: Diagnostic.h:1566
Sema - This implements semantic analysis and AST building for C.
Definition: Sema.h:358
Encodes a location in the source.
A template argument list.
Definition: DeclTemplate.h:238
unsigned size() const
Retrieve the number of template arguments in this template argument list.
Definition: DeclTemplate.h:296
Represents a template argument.
Definition: TemplateBase.h:60
TemplateSpecCandidateSet - A set of generalized overload candidates, used in template specializations...
SmallVector< TemplateSpecCandidate, 16 >::iterator iterator
void NoteCandidates(Sema &S, SourceLocation Loc)
NoteCandidates - When no template specialization match is found, prints diagnostic messages containin...
TemplateSpecCandidateSet & operator=(const TemplateSpecCandidateSet &)=delete
void clear()
Clear out all of the candidates.
SourceLocation getLocation() const
TemplateSpecCandidateSet(const TemplateSpecCandidateSet &)=delete
TemplateSpecCandidate & addCandidate()
Add a new candidate with NumConversions conversion sequence slots to the overload set.
TemplateSpecCandidateSet(SourceLocation Loc, bool ForTakingAddress=false)
void NoteCandidates(Sema &S, SourceLocation Loc) const
Provides information about an attempted template argument deduction, whose success or failure was des...
TemplateDeductionInfo & operator=(const TemplateDeductionInfo &)=delete
void setExplicitArgs(TemplateArgumentList *NewDeducedSugared, TemplateArgumentList *NewDeducedCanonical)
Provide an initial template argument list that contains the explicitly-specified arguments.
TemplateArgumentList * takeCanonical()
TemplateArgumentList * takeSugared()
Take ownership of the deduced template argument lists.
TemplateDeductionInfo(ForBaseTag, const TemplateDeductionInfo &Info)
Create temporary template deduction info for speculatively deducing against a base class of an argume...
unsigned getNumExplicitArgs() const
Get the number of explicitly-specified arguments.
SourceLocation getLocation() const
Returns the location at which template argument is occurring.
void addSuppressedDiagnostic(SourceLocation Loc, PartialDiagnostic PD)
Add a new diagnostic to the set of diagnostics.
void clearSFINAEDiagnostic()
Discard any SFINAE diagnostics.
TemplateArgument SecondArg
The second template argument to which the template argument deduction failure refers.
TemplateParameter Param
The template parameter to which a template argument deduction failure refers.
diag_iterator diag_end() const
Returns an iterator at the end of the sequence of suppressed diagnostics.
SmallVectorImpl< PartialDiagnosticAt >::const_iterator diag_iterator
Iterator over the set of suppressed diagnostics.
TemplateDeductionInfo(SourceLocation Loc, unsigned DeducedDepth=0)
void reset(TemplateArgumentList *NewDeducedSugared, TemplateArgumentList *NewDeducedCanonical)
Provide a new template argument list that contains the results of template argument deduction.
void addSFINAEDiagnostic(SourceLocation Loc, PartialDiagnostic PD)
Set the diagnostic which caused the SFINAE failure.
unsigned getDeducedDepth() const
The depth of template parameters for which deduction is being performed.
diag_iterator diag_begin() const
Returns an iterator at the beginning of the sequence of suppressed diagnostics.
bool hasSFINAEDiagnostic() const
Is a SFINAE diagnostic available?
SmallVector< DeducedPack *, 8 > PendingDeducedPacks
Information on packs that we're currently expanding.
TemplateArgument FirstArg
The first template argument to which the template argument deduction failure refers.
ConstraintSatisfaction AssociatedConstraintsSatisfaction
The constraint satisfaction details resulting from the associated constraints satisfaction tests.
const PartialDiagnosticAt & peekSFINAEDiagnostic() const
Peek at the SFINAE diagnostic.
TemplateDeductionInfo(const TemplateDeductionInfo &)=delete
void takeSFINAEDiagnostic(PartialDiagnosticAt &PD)
Take ownership of the SFINAE diagnostic.
unsigned CallArgIndex
The index of the function argument that caused a deduction failure.
@ Decl
The l-value was an access to a declared entity or something equivalently strong, like the address of ...
@ Result
The result type of a method or function.
llvm::PointerUnion< TemplateTypeParmDecl *, NonTypeTemplateParmDecl *, TemplateTemplateParmDecl * > TemplateParameter
Stores a template parameter of any kind.
Definition: DeclTemplate.h:65
std::pair< SourceLocation, PartialDiagnostic > PartialDiagnosticAt
A partial diagnostic along with the source location where this diagnostic occurs.
A structure used to record information about a failed template argument deduction,...
void * Data
Opaque pointer containing additional data about this deduction failure.
const TemplateArgument * getSecondArg()
Return the second template argument this deduction failure refers to, if any.
unsigned Result
A Sema::TemplateDeductionResult.
PartialDiagnosticAt * getSFINAEDiagnostic()
Retrieve the diagnostic which caused this deduction failure, if any.
std::optional< unsigned > getCallArgIndex()
Return the index of the call argument that this deduction failure refers to, if any.
unsigned HasDiagnostic
Indicates whether a diagnostic is stored in Diagnostic.
void Destroy()
Free any memory associated with this deduction failure.
TemplateParameter getTemplateParameter()
Retrieve the template parameter this deduction failure refers to, if any.
TemplateArgumentList * getTemplateArgumentList()
Retrieve the template argument list associated with this deduction failure, if any.
const TemplateArgument * getFirstArg()
Return the first template argument this deduction failure refers to, if any.
TemplateSpecCandidate - This is a generalization of OverloadCandidate which keeps track of template a...
void NoteDeductionFailure(Sema &S, bool ForTakingAddress)
Diagnose a template argument deduction failure.
DeductionFailureInfo DeductionFailure
Template argument deduction info.
Decl * Specialization
Specialization - The actual specialization that this candidate represents.
DeclAccessPair FoundDecl
The declaration that was looked up, together with its access.
void set(DeclAccessPair Found, Decl *Spec, DeductionFailureInfo Info)