1 //===--- AST.cpp - Utility AST functions -----------------------*- 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 #include "AST.h"
10
11 #include "FindTarget.h"
12 #include "SourceCode.h"
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/ASTTypeTraits.h"
15 #include "clang/AST/Decl.h"
16 #include "clang/AST/DeclBase.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclTemplate.h"
19 #include "clang/AST/DeclarationName.h"
20 #include "clang/AST/NestedNameSpecifier.h"
21 #include "clang/AST/PrettyPrinter.h"
22 #include "clang/AST/RecursiveASTVisitor.h"
23 #include "clang/AST/TemplateBase.h"
24 #include "clang/Basic/SourceLocation.h"
25 #include "clang/Basic/SourceManager.h"
26 #include "clang/Basic/Specifiers.h"
27 #include "clang/Index/USRGeneration.h"
28 #include "llvm/ADT/ArrayRef.h"
29 #include "llvm/ADT/Optional.h"
30 #include "llvm/ADT/STLExtras.h"
31 #include "llvm/ADT/StringRef.h"
32 #include "llvm/Support/Casting.h"
33 #include "llvm/Support/ScopedPrinter.h"
34 #include "llvm/Support/raw_ostream.h"
35 #include <string>
36 #include <vector>
37
38 namespace clang {
39 namespace clangd {
40
41 namespace {
42 llvm::Optional<llvm::ArrayRef<TemplateArgumentLoc>>
getTemplateSpecializationArgLocs(const NamedDecl & ND)43 getTemplateSpecializationArgLocs(const NamedDecl &ND) {
44 if (auto *Func = llvm::dyn_cast<FunctionDecl>(&ND)) {
45 if (const ASTTemplateArgumentListInfo *Args =
46 Func->getTemplateSpecializationArgsAsWritten())
47 return Args->arguments();
48 } else if (auto *Cls =
49 llvm::dyn_cast<ClassTemplatePartialSpecializationDecl>(&ND)) {
50 if (auto *Args = Cls->getTemplateArgsAsWritten())
51 return Args->arguments();
52 } else if (auto *Var =
53 llvm::dyn_cast<VarTemplatePartialSpecializationDecl>(&ND)) {
54 if (auto *Args = Var->getTemplateArgsAsWritten())
55 return Args->arguments();
56 } else if (auto *Var = llvm::dyn_cast<VarTemplateSpecializationDecl>(&ND))
57 return Var->getTemplateArgsInfo().arguments();
58 // We return None for ClassTemplateSpecializationDecls because it does not
59 // contain TemplateArgumentLoc information.
60 return llvm::None;
61 }
62
63 template <class T>
isTemplateSpecializationKind(const NamedDecl * D,TemplateSpecializationKind Kind)64 bool isTemplateSpecializationKind(const NamedDecl *D,
65 TemplateSpecializationKind Kind) {
66 if (const auto *TD = dyn_cast<T>(D))
67 return TD->getTemplateSpecializationKind() == Kind;
68 return false;
69 }
70
isTemplateSpecializationKind(const NamedDecl * D,TemplateSpecializationKind Kind)71 bool isTemplateSpecializationKind(const NamedDecl *D,
72 TemplateSpecializationKind Kind) {
73 return isTemplateSpecializationKind<FunctionDecl>(D, Kind) ||
74 isTemplateSpecializationKind<CXXRecordDecl>(D, Kind) ||
75 isTemplateSpecializationKind<VarDecl>(D, Kind);
76 }
77
78 // Store all UsingDirectiveDecls in parent contexts of DestContext, that were
79 // introduced before InsertionPoint.
80 llvm::DenseSet<const NamespaceDecl *>
getUsingNamespaceDirectives(const DeclContext * DestContext,SourceLocation Until)81 getUsingNamespaceDirectives(const DeclContext *DestContext,
82 SourceLocation Until) {
83 const auto &SM = DestContext->getParentASTContext().getSourceManager();
84 llvm::DenseSet<const NamespaceDecl *> VisibleNamespaceDecls;
85 for (const auto *DC = DestContext; DC; DC = DC->getLookupParent()) {
86 for (const auto *D : DC->decls()) {
87 if (!SM.isWrittenInSameFile(D->getLocation(), Until) ||
88 !SM.isBeforeInTranslationUnit(D->getLocation(), Until))
89 continue;
90 if (auto *UDD = llvm::dyn_cast<UsingDirectiveDecl>(D))
91 VisibleNamespaceDecls.insert(
92 UDD->getNominatedNamespace()->getCanonicalDecl());
93 }
94 }
95 return VisibleNamespaceDecls;
96 }
97
98 // Goes over all parents of SourceContext until we find a common ancestor for
99 // DestContext and SourceContext. Any qualifier including and above common
100 // ancestor is redundant, therefore we stop at lowest common ancestor.
101 // In addition to that stops early whenever IsVisible returns true. This can be
102 // used to implement support for "using namespace" decls.
103 std::string
getQualification(ASTContext & Context,const DeclContext * DestContext,const DeclContext * SourceContext,llvm::function_ref<bool (NestedNameSpecifier *)> IsVisible)104 getQualification(ASTContext &Context, const DeclContext *DestContext,
105 const DeclContext *SourceContext,
106 llvm::function_ref<bool(NestedNameSpecifier *)> IsVisible) {
107 std::vector<const NestedNameSpecifier *> Parents;
108 bool ReachedNS = false;
109 for (const DeclContext *CurContext = SourceContext; CurContext;
110 CurContext = CurContext->getLookupParent()) {
111 // Stop once we reach a common ancestor.
112 if (CurContext->Encloses(DestContext))
113 break;
114
115 NestedNameSpecifier *NNS = nullptr;
116 if (auto *TD = llvm::dyn_cast<TagDecl>(CurContext)) {
117 // There can't be any more tag parents after hitting a namespace.
118 assert(!ReachedNS);
119 NNS = NestedNameSpecifier::Create(Context, nullptr, false,
120 TD->getTypeForDecl());
121 } else {
122 ReachedNS = true;
123 auto *NSD = llvm::cast<NamespaceDecl>(CurContext);
124 NNS = NestedNameSpecifier::Create(Context, nullptr, NSD);
125 // Anonymous and inline namespace names are not spelled while qualifying a
126 // name, so skip those.
127 if (NSD->isAnonymousNamespace() || NSD->isInlineNamespace())
128 continue;
129 }
130 // Stop if this namespace is already visible at DestContext.
131 if (IsVisible(NNS))
132 break;
133
134 Parents.push_back(NNS);
135 }
136
137 // Go over name-specifiers in reverse order to create necessary qualification,
138 // since we stored inner-most parent first.
139 std::string Result;
140 llvm::raw_string_ostream OS(Result);
141 for (const auto *Parent : llvm::reverse(Parents))
142 Parent->print(OS, Context.getPrintingPolicy());
143 return OS.str();
144 }
145
146 } // namespace
147
isImplicitTemplateInstantiation(const NamedDecl * D)148 bool isImplicitTemplateInstantiation(const NamedDecl *D) {
149 return isTemplateSpecializationKind(D, TSK_ImplicitInstantiation);
150 }
151
isExplicitTemplateSpecialization(const NamedDecl * D)152 bool isExplicitTemplateSpecialization(const NamedDecl *D) {
153 return isTemplateSpecializationKind(D, TSK_ExplicitSpecialization);
154 }
155
isImplementationDetail(const Decl * D)156 bool isImplementationDetail(const Decl *D) {
157 return !isSpelledInSource(D->getLocation(),
158 D->getASTContext().getSourceManager());
159 }
160
nameLocation(const clang::Decl & D,const SourceManager & SM)161 SourceLocation nameLocation(const clang::Decl &D, const SourceManager &SM) {
162 auto L = D.getLocation();
163 if (isSpelledInSource(L, SM))
164 return SM.getSpellingLoc(L);
165 return SM.getExpansionLoc(L);
166 }
167
printQualifiedName(const NamedDecl & ND)168 std::string printQualifiedName(const NamedDecl &ND) {
169 std::string QName;
170 llvm::raw_string_ostream OS(QName);
171 PrintingPolicy Policy(ND.getASTContext().getLangOpts());
172 // Note that inline namespaces are treated as transparent scopes. This
173 // reflects the way they're most commonly used for lookup. Ideally we'd
174 // include them, but at query time it's hard to find all the inline
175 // namespaces to query: the preamble doesn't have a dedicated list.
176 Policy.SuppressUnwrittenScope = true;
177 ND.printQualifiedName(OS, Policy);
178 OS.flush();
179 assert(!StringRef(QName).startswith("::"));
180 return QName;
181 }
182
isAnonymous(const DeclarationName & N)183 static bool isAnonymous(const DeclarationName &N) {
184 return N.isIdentifier() && !N.getAsIdentifierInfo();
185 }
186
getQualifierLoc(const NamedDecl & ND)187 NestedNameSpecifierLoc getQualifierLoc(const NamedDecl &ND) {
188 if (auto *V = llvm::dyn_cast<DeclaratorDecl>(&ND))
189 return V->getQualifierLoc();
190 if (auto *T = llvm::dyn_cast<TagDecl>(&ND))
191 return T->getQualifierLoc();
192 return NestedNameSpecifierLoc();
193 }
194
printUsingNamespaceName(const ASTContext & Ctx,const UsingDirectiveDecl & D)195 std::string printUsingNamespaceName(const ASTContext &Ctx,
196 const UsingDirectiveDecl &D) {
197 PrintingPolicy PP(Ctx.getLangOpts());
198 std::string Name;
199 llvm::raw_string_ostream Out(Name);
200
201 if (auto *Qual = D.getQualifier())
202 Qual->print(Out, PP);
203 D.getNominatedNamespaceAsWritten()->printName(Out);
204 return Out.str();
205 }
206
printName(const ASTContext & Ctx,const NamedDecl & ND)207 std::string printName(const ASTContext &Ctx, const NamedDecl &ND) {
208 std::string Name;
209 llvm::raw_string_ostream Out(Name);
210 PrintingPolicy PP(Ctx.getLangOpts());
211 // We don't consider a class template's args part of the constructor name.
212 PP.SuppressTemplateArgsInCXXConstructors = true;
213
214 // Handle 'using namespace'. They all have the same name - <using-directive>.
215 if (auto *UD = llvm::dyn_cast<UsingDirectiveDecl>(&ND)) {
216 Out << "using namespace ";
217 if (auto *Qual = UD->getQualifier())
218 Qual->print(Out, PP);
219 UD->getNominatedNamespaceAsWritten()->printName(Out);
220 return Out.str();
221 }
222
223 if (isAnonymous(ND.getDeclName())) {
224 // Come up with a presentation for an anonymous entity.
225 if (isa<NamespaceDecl>(ND))
226 return "(anonymous namespace)";
227 if (auto *Cls = llvm::dyn_cast<RecordDecl>(&ND)) {
228 if (Cls->isLambda())
229 return "(lambda)";
230 return ("(anonymous " + Cls->getKindName() + ")").str();
231 }
232 if (isa<EnumDecl>(ND))
233 return "(anonymous enum)";
234 return "(anonymous)";
235 }
236
237 // Print nested name qualifier if it was written in the source code.
238 if (auto *Qualifier = getQualifierLoc(ND).getNestedNameSpecifier())
239 Qualifier->print(Out, PP);
240 // Print the name itself.
241 ND.getDeclName().print(Out, PP);
242 // Print template arguments.
243 Out << printTemplateSpecializationArgs(ND);
244
245 return Out.str();
246 }
247
printTemplateSpecializationArgs(const NamedDecl & ND)248 std::string printTemplateSpecializationArgs(const NamedDecl &ND) {
249 std::string TemplateArgs;
250 llvm::raw_string_ostream OS(TemplateArgs);
251 PrintingPolicy Policy(ND.getASTContext().getLangOpts());
252 if (llvm::Optional<llvm::ArrayRef<TemplateArgumentLoc>> Args =
253 getTemplateSpecializationArgLocs(ND)) {
254 printTemplateArgumentList(OS, *Args, Policy);
255 } else if (auto *Cls = llvm::dyn_cast<ClassTemplateSpecializationDecl>(&ND)) {
256 if (const TypeSourceInfo *TSI = Cls->getTypeAsWritten()) {
257 // ClassTemplateSpecializationDecls do not contain
258 // TemplateArgumentTypeLocs, they only have TemplateArgumentTypes. So we
259 // create a new argument location list from TypeSourceInfo.
260 auto STL = TSI->getTypeLoc().getAs<TemplateSpecializationTypeLoc>();
261 llvm::SmallVector<TemplateArgumentLoc, 8> ArgLocs;
262 ArgLocs.reserve(STL.getNumArgs());
263 for (unsigned I = 0; I < STL.getNumArgs(); ++I)
264 ArgLocs.push_back(STL.getArgLoc(I));
265 printTemplateArgumentList(OS, ArgLocs, Policy);
266 } else {
267 // FIXME: Fix cases when getTypeAsWritten returns null inside clang AST,
268 // e.g. friend decls. Currently we fallback to Template Arguments without
269 // location information.
270 printTemplateArgumentList(OS, Cls->getTemplateArgs().asArray(), Policy);
271 }
272 }
273 OS.flush();
274 return TemplateArgs;
275 }
276
printNamespaceScope(const DeclContext & DC)277 std::string printNamespaceScope(const DeclContext &DC) {
278 for (const auto *Ctx = &DC; Ctx != nullptr; Ctx = Ctx->getParent())
279 if (const auto *NS = dyn_cast<NamespaceDecl>(Ctx))
280 if (!NS->isAnonymousNamespace() && !NS->isInlineNamespace())
281 return printQualifiedName(*NS) + "::";
282 return "";
283 }
284
getSymbolID(const Decl * D)285 llvm::Optional<SymbolID> getSymbolID(const Decl *D) {
286 llvm::SmallString<128> USR;
287 if (index::generateUSRForDecl(D, USR))
288 return None;
289 return SymbolID(USR);
290 }
291
getSymbolID(const llvm::StringRef MacroName,const MacroInfo * MI,const SourceManager & SM)292 llvm::Optional<SymbolID> getSymbolID(const llvm::StringRef MacroName,
293 const MacroInfo *MI,
294 const SourceManager &SM) {
295 if (MI == nullptr)
296 return None;
297 llvm::SmallString<128> USR;
298 if (index::generateUSRForMacro(MacroName, MI->getDefinitionLoc(), SM, USR))
299 return None;
300 return SymbolID(USR);
301 }
302
303 // FIXME: This should be handled while printing underlying decls instead.
printType(const QualType QT,const DeclContext & CurContext)304 std::string printType(const QualType QT, const DeclContext &CurContext) {
305 std::string Result;
306 llvm::raw_string_ostream OS(Result);
307 auto Decls = explicitReferenceTargets(
308 ast_type_traits::DynTypedNode::create(QT), DeclRelation::Alias);
309 if (!Decls.empty())
310 OS << getQualification(CurContext.getParentASTContext(), &CurContext,
311 Decls.front(),
312 /*VisibleNamespaces=*/llvm::ArrayRef<std::string>{});
313 PrintingPolicy PP(CurContext.getParentASTContext().getPrintingPolicy());
314 PP.SuppressScope = true;
315 PP.SuppressTagKeyword = true;
316 QT.print(OS, PP);
317 return OS.str();
318 }
319
declaredType(const TypeDecl * D)320 QualType declaredType(const TypeDecl *D) {
321 if (const auto *CTSD = llvm::dyn_cast<ClassTemplateSpecializationDecl>(D))
322 if (const auto *TSI = CTSD->getTypeAsWritten())
323 return TSI->getType();
324 return D->getASTContext().getTypeDeclType(D);
325 }
326
327 namespace {
328 /// Computes the deduced type at a given location by visiting the relevant
329 /// nodes. We use this to display the actual type when hovering over an "auto"
330 /// keyword or "decltype()" expression.
331 /// FIXME: This could have been a lot simpler by visiting AutoTypeLocs but it
332 /// seems that the AutoTypeLocs that can be visited along with their AutoType do
333 /// not have the deduced type set. Instead, we have to go to the appropriate
334 /// DeclaratorDecl/FunctionDecl and work our back to the AutoType that does have
335 /// a deduced type set. The AST should be improved to simplify this scenario.
336 class DeducedTypeVisitor : public RecursiveASTVisitor<DeducedTypeVisitor> {
337 SourceLocation SearchedLocation;
338
339 public:
DeducedTypeVisitor(SourceLocation SearchedLocation)340 DeducedTypeVisitor(SourceLocation SearchedLocation)
341 : SearchedLocation(SearchedLocation) {}
342
343 // Handle auto initializers:
344 //- auto i = 1;
345 //- decltype(auto) i = 1;
346 //- auto& i = 1;
347 //- auto* i = &a;
VisitDeclaratorDecl(DeclaratorDecl * D)348 bool VisitDeclaratorDecl(DeclaratorDecl *D) {
349 if (!D->getTypeSourceInfo() ||
350 D->getTypeSourceInfo()->getTypeLoc().getBeginLoc() != SearchedLocation)
351 return true;
352
353 if (auto *AT = D->getType()->getContainedAutoType()) {
354 if (!AT->getDeducedType().isNull())
355 DeducedType = AT->getDeducedType();
356 }
357 return true;
358 }
359
360 // Handle auto return types:
361 //- auto foo() {}
362 //- auto& foo() {}
363 //- auto foo() -> int {}
364 //- auto foo() -> decltype(1+1) {}
365 //- operator auto() const { return 10; }
VisitFunctionDecl(FunctionDecl * D)366 bool VisitFunctionDecl(FunctionDecl *D) {
367 if (!D->getTypeSourceInfo())
368 return true;
369 // Loc of auto in return type (c++14).
370 auto CurLoc = D->getReturnTypeSourceRange().getBegin();
371 // Loc of "auto" in operator auto()
372 if (CurLoc.isInvalid() && dyn_cast<CXXConversionDecl>(D))
373 CurLoc = D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
374 // Loc of "auto" in function with trailing return type (c++11).
375 if (CurLoc.isInvalid())
376 CurLoc = D->getSourceRange().getBegin();
377 if (CurLoc != SearchedLocation)
378 return true;
379
380 const AutoType *AT = D->getReturnType()->getContainedAutoType();
381 if (AT && !AT->getDeducedType().isNull()) {
382 DeducedType = AT->getDeducedType();
383 } else if (auto DT = dyn_cast<DecltypeType>(D->getReturnType())) {
384 // auto in a trailing return type just points to a DecltypeType and
385 // getContainedAutoType does not unwrap it.
386 if (!DT->getUnderlyingType().isNull())
387 DeducedType = DT->getUnderlyingType();
388 } else if (!D->getReturnType().isNull()) {
389 DeducedType = D->getReturnType();
390 }
391 return true;
392 }
393
394 // Handle non-auto decltype, e.g.:
395 // - auto foo() -> decltype(expr) {}
396 // - decltype(expr);
VisitDecltypeTypeLoc(DecltypeTypeLoc TL)397 bool VisitDecltypeTypeLoc(DecltypeTypeLoc TL) {
398 if (TL.getBeginLoc() != SearchedLocation)
399 return true;
400
401 // A DecltypeType's underlying type can be another DecltypeType! E.g.
402 // int I = 0;
403 // decltype(I) J = I;
404 // decltype(J) K = J;
405 const DecltypeType *DT = dyn_cast<DecltypeType>(TL.getTypePtr());
406 while (DT && !DT->getUnderlyingType().isNull()) {
407 DeducedType = DT->getUnderlyingType();
408 DT = dyn_cast<DecltypeType>(DeducedType.getTypePtr());
409 }
410 return true;
411 }
412
413 QualType DeducedType;
414 };
415 } // namespace
416
getDeducedType(ASTContext & ASTCtx,SourceLocation Loc)417 llvm::Optional<QualType> getDeducedType(ASTContext &ASTCtx,
418 SourceLocation Loc) {
419 if (!Loc.isValid())
420 return {};
421 DeducedTypeVisitor V(Loc);
422 V.TraverseAST(ASTCtx);
423 if (V.DeducedType.isNull())
424 return llvm::None;
425 return V.DeducedType;
426 }
427
getQualification(ASTContext & Context,const DeclContext * DestContext,SourceLocation InsertionPoint,const NamedDecl * ND)428 std::string getQualification(ASTContext &Context,
429 const DeclContext *DestContext,
430 SourceLocation InsertionPoint,
431 const NamedDecl *ND) {
432 auto VisibleNamespaceDecls =
433 getUsingNamespaceDirectives(DestContext, InsertionPoint);
434 return getQualification(
435 Context, DestContext, ND->getDeclContext(),
436 [&](NestedNameSpecifier *NNS) {
437 if (NNS->getKind() != NestedNameSpecifier::Namespace)
438 return false;
439 const auto *CanonNSD = NNS->getAsNamespace()->getCanonicalDecl();
440 return llvm::any_of(VisibleNamespaceDecls,
441 [CanonNSD](const NamespaceDecl *NSD) {
442 return NSD->getCanonicalDecl() == CanonNSD;
443 });
444 });
445 }
446
getQualification(ASTContext & Context,const DeclContext * DestContext,const NamedDecl * ND,llvm::ArrayRef<std::string> VisibleNamespaces)447 std::string getQualification(ASTContext &Context,
448 const DeclContext *DestContext,
449 const NamedDecl *ND,
450 llvm::ArrayRef<std::string> VisibleNamespaces) {
451 for (llvm::StringRef NS : VisibleNamespaces) {
452 assert(NS.endswith("::"));
453 (void)NS;
454 }
455 return getQualification(
456 Context, DestContext, ND->getDeclContext(),
457 [&](NestedNameSpecifier *NNS) {
458 return llvm::any_of(VisibleNamespaces, [&](llvm::StringRef Namespace) {
459 std::string NS;
460 llvm::raw_string_ostream OS(NS);
461 NNS->print(OS, Context.getPrintingPolicy());
462 return OS.str() == Namespace;
463 });
464 });
465 }
466
hasUnstableLinkage(const Decl * D)467 bool hasUnstableLinkage(const Decl *D) {
468 // Linkage of a ValueDecl depends on the type.
469 // If that's not deduced yet, deducing it may change the linkage.
470 auto *VD = llvm::dyn_cast_or_null<ValueDecl>(D);
471 return VD && !VD->getType().isNull() && VD->getType()->isUndeducedType();
472 }
473
474 } // namespace clangd
475 } // namespace clang
476