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llvm-project/clang-tools-extra/clangd/FindTarget.cpp

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//===--- FindTarget.cpp - What does an AST node refer to? -----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "FindTarget.h"
#include "AST.h"
#include "Logger.h"
#include "clang/AST/ASTTypeTraits.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLocVisitor.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
namespace clang {
namespace clangd {
namespace {
LLVM_ATTRIBUTE_UNUSED std::string
nodeToString(const ast_type_traits::DynTypedNode &N) {
std::string S = N.getNodeKind().asStringRef();
{
llvm::raw_string_ostream OS(S);
OS << ": ";
N.print(OS, PrintingPolicy(LangOptions()));
}
std::replace(S.begin(), S.end(), '\n', ' ');
return S;
}
// TargetFinder locates the entities that an AST node refers to.
//
// Typically this is (possibly) one declaration and (possibly) one type, but
// may be more:
// - for ambiguous nodes like OverloadExpr
// - if we want to include e.g. both typedefs and the underlying type
//
// This is organized as a set of mutually recursive helpers for particular node
// types, but for most nodes this is a short walk rather than a deep traversal.
//
// It's tempting to do e.g. typedef resolution as a second normalization step,
// after finding the 'primary' decl etc. But we do this monolithically instead
// because:
// - normalization may require these traversals again (e.g. unwrapping a
// typedef reveals a decltype which must be traversed)
// - it doesn't simplify that much, e.g. the first stage must still be able
// to yield multiple decls to handle OverloadExpr
// - there are cases where it's required for correctness. e.g:
// template<class X> using pvec = vector<x*>; pvec<int> x;
// There's no Decl `pvec<int>`, we must choose `pvec<X>` or `vector<int*>`
// and both are lossy. We must know upfront what the caller ultimately wants.
//
// FIXME: improve common dependent scope using name lookup in primary templates.
// e.g. template<typename T> int foo() { return std::vector<T>().size(); }
// formally size() is unresolved, but the primary template is a good guess.
// This affects:
// - DependentTemplateSpecializationType,
// - DependentScopeMemberExpr
// - DependentScopeDeclRefExpr
// - DependentNameType
struct TargetFinder {
using RelSet = DeclRelationSet;
using Rel = DeclRelation;
llvm::SmallDenseMap<const Decl *, RelSet> Decls;
RelSet Flags;
static const Decl *getTemplatePattern(const Decl *D) {
if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(D)) {
return CRD->getTemplateInstantiationPattern();
} else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
return FD->getTemplateInstantiationPattern();
} else if (auto *VD = dyn_cast<VarDecl>(D)) {
// Hmm: getTIP returns its arg if it's not an instantiation?!
VarDecl *T = VD->getTemplateInstantiationPattern();
return (T == D) ? nullptr : T;
} else if (const auto *ED = dyn_cast<EnumDecl>(D)) {
return ED->getInstantiatedFromMemberEnum();
} else if (isa<FieldDecl>(D) || isa<TypedefNameDecl>(D)) {
const auto *ND = cast<NamedDecl>(D);
if (const DeclContext *Parent = dyn_cast_or_null<DeclContext>(
getTemplatePattern(llvm::cast<Decl>(ND->getDeclContext()))))
for (const NamedDecl *BaseND : Parent->lookup(ND->getDeclName()))
if (!BaseND->isImplicit() && BaseND->getKind() == ND->getKind())
return BaseND;
} else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
if (const auto *ED = dyn_cast<EnumDecl>(ECD->getDeclContext())) {
if (const EnumDecl *Pattern = ED->getInstantiatedFromMemberEnum()) {
for (const NamedDecl *BaseECD : Pattern->lookup(ECD->getDeclName()))
return BaseECD;
}
}
}
return nullptr;
}
template <typename T> void debug(T &Node, RelSet Flags) {
dlog("visit [{0}] {1}", Flags,
nodeToString(ast_type_traits::DynTypedNode::create(Node)));
}
void report(const Decl *D, RelSet Flags) {
dlog("--> [{0}] {1}", Flags,
nodeToString(ast_type_traits::DynTypedNode::create(*D)));
Decls[D] |= Flags;
}
public:
void add(const Decl *D, RelSet Flags) {
if (!D)
return;
debug(*D, Flags);
if (const UsingDirectiveDecl *UDD = llvm::dyn_cast<UsingDirectiveDecl>(D))
D = UDD->getNominatedNamespaceAsWritten();
if (const TypedefNameDecl *TND = dyn_cast<TypedefNameDecl>(D)) {
add(TND->getUnderlyingType(), Flags | Rel::Underlying);
Flags |= Rel::Alias; // continue with the alias.
} else if (const UsingDecl *UD = dyn_cast<UsingDecl>(D)) {
for (const UsingShadowDecl *S : UD->shadows())
add(S->getUnderlyingDecl(), Flags | Rel::Underlying);
Flags |= Rel::Alias; // continue with the alias.
} else if (const auto *NAD = dyn_cast<NamespaceAliasDecl>(D)) {
add(NAD->getUnderlyingDecl(), Flags | Rel::Underlying);
Flags |= Rel::Alias; // continue with the alias
} else if (const UsingShadowDecl *USD = dyn_cast<UsingShadowDecl>(D)) {
// Include the using decl, but don't traverse it. This may end up
// including *all* shadows, which we don't want.
report(USD->getUsingDecl(), Flags | Rel::Alias);
// Shadow decls are synthetic and not themselves interesting.
// Record the underlying decl instead, if allowed.
D = USD->getTargetDecl();
Flags |= Rel::Underlying; // continue with the underlying decl.
}
if (const Decl *Pat = getTemplatePattern(D)) {
assert(Pat != D);
add(Pat, Flags | Rel::TemplatePattern);
// Now continue with the instantiation.
Flags |= Rel::TemplateInstantiation;
}
report(D, Flags);
}
void add(const Stmt *S, RelSet Flags) {
if (!S)
return;
debug(*S, Flags);
struct Visitor : public ConstStmtVisitor<Visitor> {
TargetFinder &Outer;
RelSet Flags;
Visitor(TargetFinder &Outer, RelSet Flags) : Outer(Outer), Flags(Flags) {}
void VisitDeclRefExpr(const DeclRefExpr *DRE) {
const Decl *D = DRE->getDecl();
// UsingShadowDecl allows us to record the UsingDecl.
// getFoundDecl() returns the wrong thing in other cases (templates).
if (auto *USD = llvm::dyn_cast<UsingShadowDecl>(DRE->getFoundDecl()))
D = USD;
Outer.add(D, Flags);
}
void VisitMemberExpr(const MemberExpr *ME) {
const Decl *D = ME->getMemberDecl();
if (auto *USD =
llvm::dyn_cast<UsingShadowDecl>(ME->getFoundDecl().getDecl()))
D = USD;
Outer.add(D, Flags);
}
void VisitCXXConstructExpr(const CXXConstructExpr *CCE) {
Outer.add(CCE->getConstructor(), Flags);
}
void VisitDesignatedInitExpr(const DesignatedInitExpr *DIE) {
for (const DesignatedInitExpr::Designator &D :
llvm::reverse(DIE->designators()))
if (D.isFieldDesignator()) {
Outer.add(D.getField(), Flags);
// We don't know which designator was intended, we assume the outer.
break;
}
}
void VisitObjCIvarRefExpr(const ObjCIvarRefExpr *OIRE) {
Outer.add(OIRE->getDecl(), Flags);
}
void VisitObjCMessageExpr(const ObjCMessageExpr *OME) {
Outer.add(OME->getMethodDecl(), Flags);
}
void VisitObjCPropertyRefExpr(const ObjCPropertyRefExpr *OPRE) {
if (OPRE->isExplicitProperty())
Outer.add(OPRE->getExplicitProperty(), Flags);
else {
if (OPRE->isMessagingGetter())
Outer.add(OPRE->getImplicitPropertyGetter(), Flags);
if (OPRE->isMessagingSetter())
Outer.add(OPRE->getImplicitPropertySetter(), Flags);
}
}
void VisitObjCProtocolExpr(const ObjCProtocolExpr *OPE) {
Outer.add(OPE->getProtocol(), Flags);
}
};
Visitor(*this, Flags).Visit(S);
}
void add(QualType T, RelSet Flags) {
if (T.isNull())
return;
debug(T, Flags);
struct Visitor : public TypeVisitor<Visitor> {
TargetFinder &Outer;
RelSet Flags;
Visitor(TargetFinder &Outer, RelSet Flags) : Outer(Outer), Flags(Flags) {}
void VisitTagType(const TagType *TT) {
Outer.add(TT->getAsTagDecl(), Flags);
}
void VisitDecltypeType(const DecltypeType *DTT) {
Outer.add(DTT->getUnderlyingType(), Flags | Rel::Underlying);
}
void VisitDeducedType(const DeducedType *DT) {
// FIXME: In practice this doesn't work: the AutoType you find inside
// TypeLoc never has a deduced type. https://llvm.org/PR42914
Outer.add(DT->getDeducedType(), Flags | Rel::Underlying);
}
void VisitTypedefType(const TypedefType *TT) {
Outer.add(TT->getDecl(), Flags);
}
void
VisitTemplateSpecializationType(const TemplateSpecializationType *TST) {
// Have to handle these case-by-case.
// templated type aliases: there's no specialized/instantiated using
// decl to point to. So try to find a decl for the underlying type
// (after substitution), and failing that point to the (templated) using
// decl.
if (TST->isTypeAlias()) {
Outer.add(TST->getAliasedType(), Flags | Rel::Underlying);
// Don't *traverse* the alias, which would result in traversing the
// template of the underlying type.
Outer.report(
TST->getTemplateName().getAsTemplateDecl()->getTemplatedDecl(),
Flags | Rel::Alias | Rel::TemplatePattern);
}
// specializations of template template parameters aren't instantiated
// into decls, so they must refer to the parameter itself.
else if (const auto *Parm =
llvm::dyn_cast_or_null<TemplateTemplateParmDecl>(
TST->getTemplateName().getAsTemplateDecl()))
Outer.add(Parm, Flags);
// class template specializations have a (specialized) CXXRecordDecl.
else if (const CXXRecordDecl *RD = TST->getAsCXXRecordDecl())
Outer.add(RD, Flags); // add(Decl) will despecialize if needed.
else {
// fallback: the (un-specialized) declaration from primary template.
if (auto *TD = TST->getTemplateName().getAsTemplateDecl())
Outer.add(TD->getTemplatedDecl(), Flags | Rel::TemplatePattern);
}
}
void VisitTemplateTypeParmType(const TemplateTypeParmType *TTPT) {
Outer.add(TTPT->getDecl(), Flags);
}
void VisitObjCInterfaceType(const ObjCInterfaceType *OIT) {
Outer.add(OIT->getDecl(), Flags);
}
void VisitObjCObjectType(const ObjCObjectType *OOT) {
// FIXME: ObjCObjectTypeLoc has no children for the protocol list, so
// there is no node in id<Foo> that refers to ObjCProtocolDecl Foo.
if (OOT->isObjCQualifiedId() && OOT->getNumProtocols() == 1)
Outer.add(OOT->getProtocol(0), Flags);
}
};
Visitor(*this, Flags).Visit(T.getTypePtr());
}
void add(const NestedNameSpecifier *NNS, RelSet Flags) {
if (!NNS)
return;
debug(*NNS, Flags);
switch (NNS->getKind()) {
case NestedNameSpecifier::Identifier:
return;
case NestedNameSpecifier::Namespace:
add(NNS->getAsNamespace(), Flags);
return;
case NestedNameSpecifier::NamespaceAlias:
add(NNS->getAsNamespaceAlias(), Flags);
return;
case NestedNameSpecifier::TypeSpec:
case NestedNameSpecifier::TypeSpecWithTemplate:
add(QualType(NNS->getAsType(), 0), Flags);
return;
case NestedNameSpecifier::Global:
// This should be TUDecl, but we can't get a pointer to it!
return;
case NestedNameSpecifier::Super:
add(NNS->getAsRecordDecl(), Flags);
return;
}
llvm_unreachable("unhandled NestedNameSpecifier::SpecifierKind");
}
void add(const CXXCtorInitializer *CCI, RelSet Flags) {
if (!CCI)
return;
debug(*CCI, Flags);
if (CCI->isAnyMemberInitializer())
add(CCI->getAnyMember(), Flags);
// Constructor calls contain a TypeLoc node, so we don't handle them here.
}
};
} // namespace
llvm::SmallVector<std::pair<const Decl *, DeclRelationSet>, 1>
allTargetDecls(const ast_type_traits::DynTypedNode &N) {
dlog("allTargetDecls({0})", nodeToString(N));
TargetFinder Finder;
DeclRelationSet Flags;
if (const Decl *D = N.get<Decl>())
Finder.add(D, Flags);
else if (const Stmt *S = N.get<Stmt>())
Finder.add(S, Flags);
else if (const NestedNameSpecifierLoc *NNSL = N.get<NestedNameSpecifierLoc>())
Finder.add(NNSL->getNestedNameSpecifier(), Flags);
else if (const NestedNameSpecifier *NNS = N.get<NestedNameSpecifier>())
Finder.add(NNS, Flags);
else if (const TypeLoc *TL = N.get<TypeLoc>())
Finder.add(TL->getType(), Flags);
else if (const QualType *QT = N.get<QualType>())
Finder.add(*QT, Flags);
else if (const CXXCtorInitializer *CCI = N.get<CXXCtorInitializer>())
Finder.add(CCI, Flags);
return {Finder.Decls.begin(), Finder.Decls.end()};
}
llvm::SmallVector<const Decl *, 1>
targetDecl(const ast_type_traits::DynTypedNode &N, DeclRelationSet Mask) {
llvm::SmallVector<const Decl *, 1> Result;
for (const auto &Entry : allTargetDecls(N))
if (!(Entry.second & ~Mask))
Result.push_back(Entry.first);
return Result;
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, DeclRelation R) {
switch (R) {
#define REL_CASE(X) \
case DeclRelation::X: \
return OS << #X;
REL_CASE(Alias);
REL_CASE(Underlying);
REL_CASE(TemplateInstantiation);
REL_CASE(TemplatePattern);
#undef REL_CASE
}
llvm_unreachable("Unhandled DeclRelation enum");
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, DeclRelationSet RS) {
const char *Sep = "";
for (unsigned I = 0; I < RS.S.size(); ++I) {
if (RS.S.test(I)) {
OS << Sep << static_cast<DeclRelation>(I);
Sep = "|";
}
}
return OS;
}
} // namespace clangd
} // namespace clang
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