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gerrit-public.fairphone.software / toolchain / llvm-project / 2d435306e52445d173e289e98dc343afe94c7fa8 / . / clang / lib / Sema / SemaLookup.cpp
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//===--------------------- SemaLookup.cpp - Name Lookup ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements name lookup for C, C++, Objective-C, and
// Objective-C++.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "Lookup.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/Parse/DeclSpec.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/LangOptions.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/ErrorHandling.h"
#include <list>
#include <set>
#include <vector>
#include <iterator>
#include <utility>
#include <algorithm>
using namespace clang;
namespace {
class UnqualUsingEntry {
const DeclContext *Nominated;
const DeclContext *CommonAncestor;
public:
UnqualUsingEntry(const DeclContext *Nominated,
const DeclContext *CommonAncestor)
: Nominated(Nominated), CommonAncestor(CommonAncestor) {
}
const DeclContext *getCommonAncestor() const {
return CommonAncestor;
}
const DeclContext *getNominatedNamespace() const {
return Nominated;
}
// Sort by the pointer value of the common ancestor.
struct Comparator {
bool operator()(const UnqualUsingEntry &L, const UnqualUsingEntry &R) {
return L.getCommonAncestor() < R.getCommonAncestor();
}
bool operator()(const UnqualUsingEntry &E, const DeclContext *DC) {
return E.getCommonAncestor() < DC;
}
bool operator()(const DeclContext *DC, const UnqualUsingEntry &E) {
return DC < E.getCommonAncestor();
}
};
};
/// A collection of using directives, as used by C++ unqualified
/// lookup.
class UnqualUsingDirectiveSet {
typedef llvm::SmallVector<UnqualUsingEntry, 8> ListTy;
ListTy list;
llvm::SmallPtrSet<DeclContext*, 8> visited;
public:
UnqualUsingDirectiveSet() {}
void visitScopeChain(Scope *S, Scope *InnermostFileScope) {
// C++ [namespace.udir]p1:
// During unqualified name lookup, the names appear as if they
// were declared in the nearest enclosing namespace which contains
// both the using-directive and the nominated namespace.
DeclContext *InnermostFileDC
= static_cast<DeclContext*>(InnermostFileScope->getEntity());
assert(InnermostFileDC && InnermostFileDC->isFileContext());
for (; S; S = S->getParent()) {
if (DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity())) {
DeclContext *EffectiveDC = (Ctx->isFileContext() ? Ctx : InnermostFileDC);
visit(Ctx, EffectiveDC);
} else {
Scope::udir_iterator I = S->using_directives_begin(),
End = S->using_directives_end();
for (; I != End; ++I)
visit(I->getAs<UsingDirectiveDecl>(), InnermostFileDC);
}
}
}
// Visits a context and collect all of its using directives
// recursively. Treats all using directives as if they were
// declared in the context.
//
// A given context is only every visited once, so it is important
// that contexts be visited from the inside out in order to get
// the effective DCs right.
void visit(DeclContext *DC, DeclContext *EffectiveDC) {
if (!visited.insert(DC))
return;
addUsingDirectives(DC, EffectiveDC);
}
// Visits a using directive and collects all of its using
// directives recursively. Treats all using directives as if they
// were declared in the effective DC.
void visit(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
DeclContext *NS = UD->getNominatedNamespace();
if (!visited.insert(NS))
return;
addUsingDirective(UD, EffectiveDC);
addUsingDirectives(NS, EffectiveDC);
}
// Adds all the using directives in a context (and those nominated
// by its using directives, transitively) as if they appeared in
// the given effective context.
void addUsingDirectives(DeclContext *DC, DeclContext *EffectiveDC) {
llvm::SmallVector<DeclContext*,4> queue;
while (true) {
DeclContext::udir_iterator I, End;
for (llvm::tie(I, End) = DC->getUsingDirectives(); I != End; ++I) {
UsingDirectiveDecl *UD = *I;
DeclContext *NS = UD->getNominatedNamespace();
if (visited.insert(NS)) {
addUsingDirective(UD, EffectiveDC);
queue.push_back(NS);
}
}
if (queue.empty())
return;
DC = queue.back();
queue.pop_back();
}
}
// Add a using directive as if it had been declared in the given
// context. This helps implement C++ [namespace.udir]p3:
// The using-directive is transitive: if a scope contains a
// using-directive that nominates a second namespace that itself
// contains using-directives, the effect is as if the
// using-directives from the second namespace also appeared in
// the first.
void addUsingDirective(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
// Find the common ancestor between the effective context and
// the nominated namespace.
DeclContext *Common = UD->getNominatedNamespace();
while (!Common->Encloses(EffectiveDC))
Common = Common->getParent();
Common = Common->getPrimaryContext();
list.push_back(UnqualUsingEntry(UD->getNominatedNamespace(), Common));
}
void done() {
std::sort(list.begin(), list.end(), UnqualUsingEntry::Comparator());
}
typedef ListTy::iterator iterator;
typedef ListTy::const_iterator const_iterator;
iterator begin() { return list.begin(); }
iterator end() { return list.end(); }
const_iterator begin() const { return list.begin(); }
const_iterator end() const { return list.end(); }
std::pair<const_iterator,const_iterator>
getNamespacesFor(DeclContext *DC) const {
return std::equal_range(begin(), end(), DC->getPrimaryContext(),
UnqualUsingEntry::Comparator());
}
};
}
static bool IsAcceptableIDNS(NamedDecl *D, unsigned IDNS) {
return D->isInIdentifierNamespace(IDNS);
}
static bool IsAcceptableOperatorName(NamedDecl *D, unsigned IDNS) {
return D->isInIdentifierNamespace(IDNS) &&
!D->getDeclContext()->isRecord();
}
static bool IsAcceptableNestedNameSpecifierName(NamedDecl *D, unsigned IDNS) {
// This lookup ignores everything that isn't a type.
// This is a fast check for the far most common case.
if (D->isInIdentifierNamespace(Decl::IDNS_Tag))
return true;
if (isa<UsingShadowDecl>(D))
D = cast<UsingShadowDecl>(D)->getTargetDecl();
return isa<TypeDecl>(D);
}
static bool IsAcceptableNamespaceName(NamedDecl *D, unsigned IDNS) {
// We don't need to look through using decls here because
// using decls aren't allowed to name namespaces.
return isa<NamespaceDecl>(D) || isa<NamespaceAliasDecl>(D);
}
/// Gets the default result filter for the given lookup.
static inline
LookupResult::ResultFilter getResultFilter(Sema::LookupNameKind NameKind) {
switch (NameKind) {
case Sema::LookupOrdinaryName:
case Sema::LookupTagName:
case Sema::LookupMemberName:
case Sema::LookupRedeclarationWithLinkage: // FIXME: check linkage, scoping
case Sema::LookupUsingDeclName:
case Sema::LookupObjCProtocolName:
case Sema::LookupObjCImplementationName:
return &IsAcceptableIDNS;
case Sema::LookupOperatorName:
return &IsAcceptableOperatorName;
case Sema::LookupNestedNameSpecifierName:
return &IsAcceptableNestedNameSpecifierName;
case Sema::LookupNamespaceName:
return &IsAcceptableNamespaceName;
}
llvm_unreachable("unkknown lookup kind");
return 0;
}
// Retrieve the set of identifier namespaces that correspond to a
// specific kind of name lookup.
static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
bool CPlusPlus,
bool Redeclaration) {
unsigned IDNS = 0;
switch (NameKind) {
case Sema::LookupOrdinaryName:
case Sema::LookupOperatorName:
case Sema::LookupRedeclarationWithLinkage:
IDNS = Decl::IDNS_Ordinary;
if (CPlusPlus) {
IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member;
if (Redeclaration) IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
}
break;
case Sema::LookupTagName:
IDNS = Decl::IDNS_Tag;
if (CPlusPlus && Redeclaration)
IDNS |= Decl::IDNS_TagFriend;
break;
case Sema::LookupMemberName:
IDNS = Decl::IDNS_Member;
if (CPlusPlus)
IDNS |= Decl::IDNS_Tag | Decl::IDNS_Ordinary;
break;
case Sema::LookupNestedNameSpecifierName:
case Sema::LookupNamespaceName:
IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member;
break;
case Sema::LookupUsingDeclName:
IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag
| Decl::IDNS_Member | Decl::IDNS_Using;
break;
case Sema::LookupObjCProtocolName:
IDNS = Decl::IDNS_ObjCProtocol;
break;
case Sema::LookupObjCImplementationName:
IDNS = Decl::IDNS_ObjCImplementation;
break;
}
return IDNS;
}
void LookupResult::configure() {
IDNS = getIDNS(LookupKind,
SemaRef.getLangOptions().CPlusPlus,
isForRedeclaration());
IsAcceptableFn = getResultFilter(LookupKind);
}
// Necessary because CXXBasePaths is not complete in Sema.h
void LookupResult::deletePaths(CXXBasePaths *Paths) {
delete Paths;
}
/// Resolves the result kind of this lookup.
void LookupResult::resolveKind() {
unsigned N = Decls.size();
// Fast case: no possible ambiguity.
if (N == 0) {
assert(ResultKind == NotFound);
return;
}
// If there's a single decl, we need to examine it to decide what
// kind of lookup this is.
if (N == 1) {
if (isa<FunctionTemplateDecl>(Decls[0]))
ResultKind = FoundOverloaded;
else if (isa<UnresolvedUsingValueDecl>(Decls[0]))
ResultKind = FoundUnresolvedValue;
return;
}
// Don't do any extra resolution if we've already resolved as ambiguous.
if (ResultKind == Ambiguous) return;
llvm::SmallPtrSet<NamedDecl*, 16> Unique;
bool Ambiguous = false;
bool HasTag = false, HasFunction = false, HasNonFunction = false;
bool HasFunctionTemplate = false, HasUnresolved = false;
unsigned UniqueTagIndex = 0;
unsigned I = 0;
while (I < N) {
NamedDecl *D = Decls[I]->getUnderlyingDecl();
D = cast<NamedDecl>(D->getCanonicalDecl());
if (!Unique.insert(D)) {
// If it's not unique, pull something off the back (and
// continue at this index).
Decls[I] = Decls[--N];
} else {
// Otherwise, do some decl type analysis and then continue.
if (isa<UnresolvedUsingValueDecl>(D)) {
HasUnresolved = true;
} else if (isa<TagDecl>(D)) {
if (HasTag)
Ambiguous = true;
UniqueTagIndex = I;
HasTag = true;
} else if (isa<FunctionTemplateDecl>(D)) {
HasFunction = true;
HasFunctionTemplate = true;
} else if (isa<FunctionDecl>(D)) {
HasFunction = true;
} else {
if (HasNonFunction)
Ambiguous = true;
HasNonFunction = true;
}
I++;
}
}
// C++ [basic.scope.hiding]p2:
// A class name or enumeration name can be hidden by the name of
// an object, function, or enumerator declared in the same
// scope. If a class or enumeration name and an object, function,
// or enumerator are declared in the same scope (in any order)
// with the same name, the class or enumeration name is hidden
// wherever the object, function, or enumerator name is visible.
// But it's still an error if there are distinct tag types found,
// even if they're not visible. (ref?)
if (HideTags && HasTag && !Ambiguous &&
(HasFunction || HasNonFunction || HasUnresolved))
Decls[UniqueTagIndex] = Decls[--N];
Decls.set_size(N);
if (HasNonFunction && (HasFunction || HasUnresolved))
Ambiguous = true;
if (Ambiguous)
setAmbiguous(LookupResult::AmbiguousReference);
else if (HasUnresolved)
ResultKind = LookupResult::FoundUnresolvedValue;
else if (N > 1 || HasFunctionTemplate)
ResultKind = LookupResult::FoundOverloaded;
else
ResultKind = LookupResult::Found;
}
void LookupResult::addDeclsFromBasePaths(const CXXBasePaths &P) {
CXXBasePaths::paths_iterator I, E;
DeclContext::lookup_iterator DI, DE;
for (I = P.begin(), E = P.end(); I != E; ++I)
for (llvm::tie(DI,DE) = I->Decls; DI != DE; ++DI)
addDecl(*DI);
}
void LookupResult::setAmbiguousBaseSubobjects(CXXBasePaths &P) {
Paths = new CXXBasePaths;
Paths->swap(P);
addDeclsFromBasePaths(*Paths);
resolveKind();
setAmbiguous(AmbiguousBaseSubobjects);
}
void LookupResult::setAmbiguousBaseSubobjectTypes(CXXBasePaths &P) {
Paths = new CXXBasePaths;
Paths->swap(P);
addDeclsFromBasePaths(*Paths);
resolveKind();
setAmbiguous(AmbiguousBaseSubobjectTypes);
}
void LookupResult::print(llvm::raw_ostream &Out) {
Out << Decls.size() << " result(s)";
if (isAmbiguous()) Out << ", ambiguous";
if (Paths) Out << ", base paths present";
for (iterator I = begin(), E = end(); I != E; ++I) {
Out << "\n";
(*I)->print(Out, 2);
}
}
// Adds all qualifying matches for a name within a decl context to the
// given lookup result. Returns true if any matches were found.
static bool LookupDirect(LookupResult &R, const DeclContext *DC) {
bool Found = false;
DeclContext::lookup_const_iterator I, E;
for (llvm::tie(I, E) = DC->lookup(R.getLookupName()); I != E; ++I)
if (R.isAcceptableDecl(*I))
R.addDecl(*I), Found = true;
return Found;
}
// Performs C++ unqualified lookup into the given file context.
static bool
CppNamespaceLookup(LookupResult &R, ASTContext &Context, DeclContext *NS,
UnqualUsingDirectiveSet &UDirs) {
assert(NS && NS->isFileContext() && "CppNamespaceLookup() requires namespace!");
// Perform direct name lookup into the LookupCtx.
bool Found = LookupDirect(R, NS);
// Perform direct name lookup into the namespaces nominated by the
// using directives whose common ancestor is this namespace.
UnqualUsingDirectiveSet::const_iterator UI, UEnd;
llvm::tie(UI, UEnd) = UDirs.getNamespacesFor(NS);
for (; UI != UEnd; ++UI)
if (LookupDirect(R, UI->getNominatedNamespace()))
Found = true;
R.resolveKind();
return Found;
}
static bool isNamespaceOrTranslationUnitScope(Scope *S) {
if (DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity()))
return Ctx->isFileContext();
return false;
}
// Find the next outer declaration context corresponding to this scope.
static DeclContext *findOuterContext(Scope *S) {
for (S = S->getParent(); S; S = S->getParent())
if (S->getEntity())
return static_cast<DeclContext *>(S->getEntity())->getPrimaryContext();
return 0;
}
bool Sema::CppLookupName(LookupResult &R, Scope *S) {
assert(getLangOptions().CPlusPlus && "Can perform only C++ lookup");
DeclarationName Name = R.getLookupName();
Scope *Initial = S;
IdentifierResolver::iterator
I = IdResolver.begin(Name),
IEnd = IdResolver.end();
// First we lookup local scope.
// We don't consider using-directives, as per 7.3.4.p1 [namespace.udir]
// ...During unqualified name lookup (3.4.1), the names appear as if
// they were declared in the nearest enclosing namespace which contains
// both the using-directive and the nominated namespace.
// [Note: in this context, "contains" means "contains directly or
// indirectly".
//
// For example:
// namespace A { int i; }
// void foo() {
// int i;
// {
// using namespace A;
// ++i; // finds local 'i', A::i appears at global scope
// }
// }
//
for (; S && !isNamespaceOrTranslationUnitScope(S); S = S->getParent()) {
// Check whether the IdResolver has anything in this scope.
bool Found = false;
for (; I != IEnd && S->isDeclScope(DeclPtrTy::make(*I)); ++I) {
if (R.isAcceptableDecl(*I)) {
Found = true;
R.addDecl(*I);
}
}
if (Found) {
R.resolveKind();
return true;
}
if (DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity())) {
DeclContext *OuterCtx = findOuterContext(S);
for (; Ctx && Ctx->getPrimaryContext() != OuterCtx;
Ctx = Ctx->getLookupParent()) {
// We do not directly look into function or method contexts
// (since all local variables are found via the identifier
// changes) or in transparent contexts (since those entities
// will be found in the nearest enclosing non-transparent
// context).
if (Ctx->isFunctionOrMethod() || Ctx->isTransparentContext())
continue;
// Perform qualified name lookup into this context.
// FIXME: In some cases, we know that every name that could be found by
// this qualified name lookup will also be on the identifier chain. For
// example, inside a class without any base classes, we never need to
// perform qualified lookup because all of the members are on top of the
// identifier chain.
if (LookupQualifiedName(R, Ctx))
return true;
}
}
}
// Stop if we ran out of scopes.
// FIXME: This really, really shouldn't be happening.
if (!S) return false;
// Collect UsingDirectiveDecls in all scopes, and recursively all
// nominated namespaces by those using-directives.
//
// FIXME: Cache this sorted list in Scope structure, and DeclContext, so we
// don't build it for each lookup!
UnqualUsingDirectiveSet UDirs;
UDirs.visitScopeChain(Initial, S);
UDirs.done();
// Lookup namespace scope, and global scope.
// Unqualified name lookup in C++ requires looking into scopes
// that aren't strictly lexical, and therefore we walk through the
// context as well as walking through the scopes.
for (; S; S = S->getParent()) {
DeclContext *Ctx = static_cast<DeclContext *>(S->getEntity());
if (Ctx->isTransparentContext())
continue;
assert(Ctx && Ctx->isFileContext() &&
"We should have been looking only at file context here already.");
// Check whether the IdResolver has anything in this scope.
bool Found = false;
for (; I != IEnd && S->isDeclScope(DeclPtrTy::make(*I)); ++I) {
if (R.isAcceptableDecl(*I)) {
// We found something. Look for anything else in our scope
// with this same name and in an acceptable identifier
// namespace, so that we can construct an overload set if we
// need to.
Found = true;
R.addDecl(*I);
}
}
// Look into context considering using-directives.
if (CppNamespaceLookup(R, Context, Ctx, UDirs))
Found = true;
if (Found) {
R.resolveKind();
return true;
}
if (R.isForRedeclaration() && !Ctx->isTransparentContext())
return false;
}
return !R.empty();
}
/// @brief Perform unqualified name lookup starting from a given
/// scope.
///
/// Unqualified name lookup (C++ [basic.lookup.unqual], C99 6.2.1) is
/// used to find names within the current scope. For example, 'x' in
/// @code
/// int x;
/// int f() {
/// return x; // unqualified name look finds 'x' in the global scope
/// }
/// @endcode
///
/// Different lookup criteria can find different names. For example, a
/// particular scope can have both a struct and a function of the same
/// name, and each can be found by certain lookup criteria. For more
/// information about lookup criteria, see the documentation for the
/// class LookupCriteria.
///
/// @param S The scope from which unqualified name lookup will
/// begin. If the lookup criteria permits, name lookup may also search
/// in the parent scopes.
///
/// @param Name The name of the entity that we are searching for.
///
/// @param Loc If provided, the source location where we're performing
/// name lookup. At present, this is only used to produce diagnostics when
/// C library functions (like "malloc") are implicitly declared.
///
/// @returns The result of name lookup, which includes zero or more
/// declarations and possibly additional information used to diagnose
/// ambiguities.
bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
DeclarationName Name = R.getLookupName();
if (!Name) return false;
LookupNameKind NameKind = R.getLookupKind();
if (!getLangOptions().CPlusPlus) {
// Unqualified name lookup in C/Objective-C is purely lexical, so
// search in the declarations attached to the name.
if (NameKind == Sema::LookupRedeclarationWithLinkage) {
// Find the nearest non-transparent declaration scope.
while (!(S->getFlags() & Scope::DeclScope) ||
(S->getEntity() &&
static_cast<DeclContext *>(S->getEntity())
->isTransparentContext()))
S = S->getParent();
}
unsigned IDNS = R.getIdentifierNamespace();
// Scan up the scope chain looking for a decl that matches this
// identifier that is in the appropriate namespace. This search
// should not take long, as shadowing of names is uncommon, and
// deep shadowing is extremely uncommon.
bool LeftStartingScope = false;
for (IdentifierResolver::iterator I = IdResolver.begin(Name),
IEnd = IdResolver.end();
I != IEnd; ++I)
if ((*I)->isInIdentifierNamespace(IDNS)) {
if (NameKind == LookupRedeclarationWithLinkage) {
// Determine whether this (or a previous) declaration is
// out-of-scope.
if (!LeftStartingScope && !S->isDeclScope(DeclPtrTy::make(*I)))
LeftStartingScope = true;
// If we found something outside of our starting scope that
// does not have linkage, skip it.
if (LeftStartingScope && !((*I)->hasLinkage()))
continue;
}
R.addDecl(*I);
if ((*I)->getAttr<OverloadableAttr>()) {
// If this declaration has the "overloadable" attribute, we
// might have a set of overloaded functions.
// Figure out what scope the identifier is in.
while (!(S->getFlags() & Scope::DeclScope) ||
!S->isDeclScope(DeclPtrTy::make(*I)))
S = S->getParent();
// Find the last declaration in this scope (with the same
// name, naturally).
IdentifierResolver::iterator LastI = I;
for (++LastI; LastI != IEnd; ++LastI) {
if (!S->isDeclScope(DeclPtrTy::make(*LastI)))
break;
R.addDecl(*LastI);
}
}
R.resolveKind();
return true;
}
} else {
// Perform C++ unqualified name lookup.
if (CppLookupName(R, S))
return true;
}
// If we didn't find a use of this identifier, and if the identifier
// corresponds to a compiler builtin, create the decl object for the builtin
// now, injecting it into translation unit scope, and return it.
if (NameKind == LookupOrdinaryName ||
NameKind == LookupRedeclarationWithLinkage) {
IdentifierInfo *II = Name.getAsIdentifierInfo();
if (II && AllowBuiltinCreation) {
// If this is a builtin on this (or all) targets, create the decl.
if (unsigned BuiltinID = II->getBuiltinID()) {
// In C++, we don't have any predefined library functions like
// 'malloc'. Instead, we'll just error.
if (getLangOptions().CPlusPlus &&
Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
return false;
NamedDecl *D = LazilyCreateBuiltin((IdentifierInfo *)II, BuiltinID,
S, R.isForRedeclaration(),
R.getNameLoc());
if (D) R.addDecl(D);
return (D != NULL);
}
}
}
return false;
}
/// @brief Perform qualified name lookup in the namespaces nominated by
/// using directives by the given context.
///
/// C++98 [namespace.qual]p2:
/// Given X::m (where X is a user-declared namespace), or given ::m
/// (where X is the global namespace), let S be the set of all
/// declarations of m in X and in the transitive closure of all
/// namespaces nominated by using-directives in X and its used
/// namespaces, except that using-directives are ignored in any
/// namespace, including X, directly containing one or more
/// declarations of m. No namespace is searched more than once in
/// the lookup of a name. If S is the empty set, the program is
/// ill-formed. Otherwise, if S has exactly one member, or if the
/// context of the reference is a using-declaration
/// (namespace.udecl), S is the required set of declarations of
/// m. Otherwise if the use of m is not one that allows a unique
/// declaration to be chosen from S, the program is ill-formed.
/// C++98 [namespace.qual]p5:
/// During the lookup of a qualified namespace member name, if the
/// lookup finds more than one declaration of the member, and if one
/// declaration introduces a class name or enumeration name and the
/// other declarations either introduce the same object, the same
/// enumerator or a set of functions, the non-type name hides the
/// class or enumeration name if and only if the declarations are
/// from the same namespace; otherwise (the declarations are from
/// different namespaces), the program is ill-formed.
static bool LookupQualifiedNameInUsingDirectives(LookupResult &R,
DeclContext *StartDC) {
assert(StartDC->isFileContext() && "start context is not a file context");
DeclContext::udir_iterator I = StartDC->using_directives_begin();
DeclContext::udir_iterator E = StartDC->using_directives_end();
if (I == E) return false;
// We have at least added all these contexts to the queue.
llvm::DenseSet<DeclContext*> Visited;
Visited.insert(StartDC);
// We have not yet looked into these namespaces, much less added
// their "using-children" to the queue.
llvm::SmallVector<NamespaceDecl*, 8> Queue;
// We have already looked into the initial namespace; seed the queue
// with its using-children.
for (; I != E; ++I) {
NamespaceDecl *ND = (*I)->getNominatedNamespace()->getOriginalNamespace();
if (Visited.insert(ND).second)
Queue.push_back(ND);
}
// The easiest way to implement the restriction in [namespace.qual]p5
// is to check whether any of the individual results found a tag
// and, if so, to declare an ambiguity if the final result is not
// a tag.
bool FoundTag = false;
bool FoundNonTag = false;
LookupResult LocalR(LookupResult::Temporary, R);
bool Found = false;
while (!Queue.empty()) {
NamespaceDecl *ND = Queue.back();
Queue.pop_back();
// We go through some convolutions here to avoid copying results
// between LookupResults.
bool UseLocal = !R.empty();
LookupResult &DirectR = UseLocal ? LocalR : R;
bool FoundDirect = LookupDirect(DirectR, ND);
if (FoundDirect) {
// First do any local hiding.
DirectR.resolveKind();
// If the local result is a tag, remember that.
if (DirectR.isSingleTagDecl())
FoundTag = true;
else
FoundNonTag = true;
// Append the local results to the total results if necessary.
if (UseLocal) {
R.addAllDecls(LocalR);
LocalR.clear();
}
}
// If we find names in this namespace, ignore its using directives.
if (FoundDirect) {
Found = true;
continue;
}
for (llvm::tie(I,E) = ND->getUsingDirectives(); I != E; ++I) {
NamespaceDecl *Nom = (*I)->getNominatedNamespace();
if (Visited.insert(Nom).second)
Queue.push_back(Nom);
}
}
if (Found) {
if (FoundTag && FoundNonTag)
R.setAmbiguousQualifiedTagHiding();
else
R.resolveKind();
}
return Found;
}
/// @brief Perform qualified name lookup into a given context.
///
/// Qualified name lookup (C++ [basic.lookup.qual]) is used to find
/// names when the context of those names is explicit specified, e.g.,
/// "std::vector" or "x->member".
///
/// Different lookup criteria can find different names. For example, a
/// particular scope can have both a struct and a function of the same
/// name, and each can be found by certain lookup criteria. For more
/// information about lookup criteria, see the documentation for the
/// class LookupCriteria.
///
/// @param LookupCtx The context in which qualified name lookup will
/// search. If the lookup criteria permits, name lookup may also search
/// in the parent contexts or (for C++ classes) base classes.
///
/// @param Name The name of the entity that we are searching for.
///
/// @param Criteria The criteria that this routine will use to
/// determine which names are visible and which names will be
/// found. Note that name lookup will find a name that is visible by
/// the given criteria, but the entity itself may not be semantically
/// correct or even the kind of entity expected based on the
/// lookup. For example, searching for a nested-name-specifier name
/// might result in an EnumDecl, which is visible but is not permitted
/// as a nested-name-specifier in C++03.
///
/// @returns The result of name lookup, which includes zero or more
/// declarations and possibly additional information used to diagnose
/// ambiguities.
bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx) {
assert(LookupCtx && "Sema::LookupQualifiedName requires a lookup context");
if (!R.getLookupName())
return false;
// Make sure that the declaration context is complete.
assert((!isa<TagDecl>(LookupCtx) ||
LookupCtx->isDependentContext() ||
cast<TagDecl>(LookupCtx)->isDefinition() ||
Context.getTypeDeclType(cast<TagDecl>(LookupCtx))->getAs<TagType>()
->isBeingDefined()) &&
"Declaration context must already be complete!");
// Perform qualified name lookup into the LookupCtx.
if (LookupDirect(R, LookupCtx)) {
R.resolveKind();
return true;
}
// Don't descend into implied contexts for redeclarations.
// C++98 [namespace.qual]p6:
// In a declaration for a namespace member in which the
// declarator-id is a qualified-id, given that the qualified-id
// for the namespace member has the form
// nested-name-specifier unqualified-id
// the unqualified-id shall name a member of the namespace
// designated by the nested-name-specifier.
// See also [class.mfct]p5 and [class.static.data]p2.
if (R.isForRedeclaration())
return false;
// If this is a namespace, look it up in the implied namespaces.
if (LookupCtx->isFileContext())
return LookupQualifiedNameInUsingDirectives(R, LookupCtx);
// If this isn't a C++ class, we aren't allowed to look into base
// classes, we're done.
if (!isa<CXXRecordDecl>(LookupCtx))
return false;
// Perform lookup into our base classes.
CXXRecordDecl *LookupRec = cast<CXXRecordDecl>(LookupCtx);
CXXBasePaths Paths;
Paths.setOrigin(LookupRec);
// Look for this member in our base classes
CXXRecordDecl::BaseMatchesCallback *BaseCallback = 0;
switch (R.getLookupKind()) {
case LookupOrdinaryName:
case LookupMemberName:
case LookupRedeclarationWithLinkage:
BaseCallback = &CXXRecordDecl::FindOrdinaryMember;
break;
case LookupTagName:
BaseCallback = &CXXRecordDecl::FindTagMember;
break;
case LookupUsingDeclName:
// This lookup is for redeclarations only.
case LookupOperatorName:
case LookupNamespaceName:
case LookupObjCProtocolName:
case LookupObjCImplementationName:
// These lookups will never find a member in a C++ class (or base class).
return false;
case LookupNestedNameSpecifierName:
BaseCallback = &CXXRecordDecl::FindNestedNameSpecifierMember;
break;
}
if (!LookupRec->lookupInBases(BaseCallback,
R.getLookupName().getAsOpaquePtr(), Paths))
return false;
// C++ [class.member.lookup]p2:
// [...] If the resulting set of declarations are not all from
// sub-objects of the same type, or the set has a nonstatic member
// and includes members from distinct sub-objects, there is an
// ambiguity and the program is ill-formed. Otherwise that set is
// the result of the lookup.
// FIXME: support using declarations!
QualType SubobjectType;
int SubobjectNumber = 0;
for (CXXBasePaths::paths_iterator Path = Paths.begin(), PathEnd = Paths.end();
Path != PathEnd; ++Path) {
const CXXBasePathElement &PathElement = Path->back();
// Determine whether we're looking at a distinct sub-object or not.
if (SubobjectType.isNull()) {
// This is the first subobject we've looked at. Record its type.
SubobjectType = Context.getCanonicalType(PathElement.Base->getType());
SubobjectNumber = PathElement.SubobjectNumber;
} else if (SubobjectType
!= Context.getCanonicalType(PathElement.Base->getType())) {
// We found members of the given name in two subobjects of
// different types. This lookup is ambiguous.
R.setAmbiguousBaseSubobjectTypes(Paths);
return true;
} else if (SubobjectNumber != PathElement.SubobjectNumber) {
// We have a different subobject of the same type.
// C++ [class.member.lookup]p5:
// A static member, a nested type or an enumerator defined in
// a base class T can unambiguously be found even if an object
// has more than one base class subobject of type T.
Decl *FirstDecl = *Path->Decls.first;
if (isa<VarDecl>(FirstDecl) ||
isa<TypeDecl>(FirstDecl) ||
isa<EnumConstantDecl>(FirstDecl))
continue;
if (isa<CXXMethodDecl>(FirstDecl)) {
// Determine whether all of the methods are static.
bool AllMethodsAreStatic = true;
for (DeclContext::lookup_iterator Func = Path->Decls.first;
Func != Path->Decls.second; ++Func) {
if (!isa<CXXMethodDecl>(*Func)) {
assert(isa<TagDecl>(*Func) && "Non-function must be a tag decl");
break;
}
if (!cast<CXXMethodDecl>(*Func)->isStatic()) {
AllMethodsAreStatic = false;
break;
}
}
if (AllMethodsAreStatic)
continue;
}
// We have found a nonstatic member name in multiple, distinct
// subobjects. Name lookup is ambiguous.
R.setAmbiguousBaseSubobjects(Paths);
return true;
}
}
// Lookup in a base class succeeded; return these results.
DeclContext::lookup_iterator I, E;
for (llvm::tie(I,E) = Paths.front().Decls; I != E; ++I)
R.addDecl(*I);
R.resolveKind();
return true;
}
/// @brief Performs name lookup for a name that was parsed in the
/// source code, and may contain a C++ scope specifier.
///
/// This routine is a convenience routine meant to be called from
/// contexts that receive a name and an optional C++ scope specifier
/// (e.g., "N::M::x"). It will then perform either qualified or
/// unqualified name lookup (with LookupQualifiedName or LookupName,
/// respectively) on the given name and return those results.
///
/// @param S The scope from which unqualified name lookup will
/// begin.
///
/// @param SS An optional C++ scope-specifier, e.g., "::N::M".
///
/// @param Name The name of the entity that name lookup will
/// search for.
///
/// @param Loc If provided, the source location where we're performing
/// name lookup. At present, this is only used to produce diagnostics when
/// C library functions (like "malloc") are implicitly declared.
///
/// @param EnteringContext Indicates whether we are going to enter the
/// context of the scope-specifier SS (if present).
///
/// @returns True if any decls were found (but possibly ambiguous)
bool Sema::LookupParsedName(LookupResult &R, Scope *S, const CXXScopeSpec *SS,
bool AllowBuiltinCreation, bool EnteringContext) {
if (SS && SS->isInvalid()) {
// When the scope specifier is invalid, don't even look for
// anything.
return false;
}
if (SS && SS->isSet()) {
if (DeclContext *DC = computeDeclContext(*SS, EnteringContext)) {
// We have resolved the scope specifier to a particular declaration
// contex, and will perform name lookup in that context.
if (!DC->isDependentContext() && RequireCompleteDeclContext(*SS))
return false;
R.setContextRange(SS->getRange());
return LookupQualifiedName(R, DC);
}
// We could not resolve the scope specified to a specific declaration
// context, which means that SS refers to an unknown specialization.
// Name lookup can't find anything in this case.
return false;
}
// Perform unqualified name lookup starting in the given scope.
return LookupName(R, S, AllowBuiltinCreation);
}
/// @brief Produce a diagnostic describing the ambiguity that resulted
/// from name lookup.
///
/// @param Result The ambiguous name lookup result.
///
/// @param Name The name of the entity that name lookup was
/// searching for.
///
/// @param NameLoc The location of the name within the source code.
///
/// @param LookupRange A source range that provides more
/// source-location information concerning the lookup itself. For
/// example, this range might highlight a nested-name-specifier that
/// precedes the name.
///
/// @returns true
bool Sema::DiagnoseAmbiguousLookup(LookupResult &Result) {
assert(Result.isAmbiguous() && "Lookup result must be ambiguous");
DeclarationName Name = Result.getLookupName();
SourceLocation NameLoc = Result.getNameLoc();
SourceRange LookupRange = Result.getContextRange();
switch (Result.getAmbiguityKind()) {
case LookupResult::AmbiguousBaseSubobjects: {
CXXBasePaths *Paths = Result.getBasePaths();
QualType SubobjectType = Paths->front().back().Base->getType();
Diag(NameLoc, diag::err_ambiguous_member_multiple_subobjects)
<< Name << SubobjectType << getAmbiguousPathsDisplayString(*Paths)
<< LookupRange;
DeclContext::lookup_iterator Found = Paths->front().Decls.first;
while (isa<CXXMethodDecl>(*Found) &&
cast<CXXMethodDecl>(*Found)->isStatic())
++Found;
Diag((*Found)->getLocation(), diag::note_ambiguous_member_found);
return true;
}
case LookupResult::AmbiguousBaseSubobjectTypes: {
Diag(NameLoc, diag::err_ambiguous_member_multiple_subobject_types)
<< Name << LookupRange;
CXXBasePaths *Paths = Result.getBasePaths();
std::set<Decl *> DeclsPrinted;
for (CXXBasePaths::paths_iterator Path = Paths->begin(),
PathEnd = Paths->end();
Path != PathEnd; ++Path) {
Decl *D = *Path->Decls.first;
if (DeclsPrinted.insert(D).second)
Diag(D->getLocation(), diag::note_ambiguous_member_found);
}
return true;
}
case LookupResult::AmbiguousTagHiding: {
Diag(NameLoc, diag::err_ambiguous_tag_hiding) << Name << LookupRange;
llvm::SmallPtrSet<NamedDecl*,8> TagDecls;
LookupResult::iterator DI, DE = Result.end();
for (DI = Result.begin(); DI != DE; ++DI)
if (TagDecl *TD = dyn_cast<TagDecl>(*DI)) {
TagDecls.insert(TD);
Diag(TD->getLocation(), diag::note_hidden_tag);
}
for (DI = Result.begin(); DI != DE; ++DI)
if (!isa<TagDecl>(*DI))
Diag((*DI)->getLocation(), diag::note_hiding_object);
// For recovery purposes, go ahead and implement the hiding.
Result.hideDecls(TagDecls);
return true;
}
case LookupResult::AmbiguousReference: {
Diag(NameLoc, diag::err_ambiguous_reference) << Name << LookupRange;
LookupResult::iterator DI = Result.begin(), DE = Result.end();
for (; DI != DE; ++DI)
Diag((*DI)->getLocation(), diag::note_ambiguous_candidate) << *DI;
return true;
}
}
llvm_unreachable("unknown ambiguity kind");
return true;
}
static void
addAssociatedClassesAndNamespaces(QualType T,
ASTContext &Context,
Sema::AssociatedNamespaceSet &AssociatedNamespaces,
Sema::AssociatedClassSet &AssociatedClasses);
static void CollectNamespace(Sema::AssociatedNamespaceSet &Namespaces,
DeclContext *Ctx) {
if (Ctx->isFileContext())
Namespaces.insert(Ctx);
}
// \brief Add the associated classes and namespaces for argument-dependent
// lookup that involves a template argument (C++ [basic.lookup.koenig]p2).
static void
addAssociatedClassesAndNamespaces(const TemplateArgument &Arg,
ASTContext &Context,
Sema::AssociatedNamespaceSet &AssociatedNamespaces,
Sema::AssociatedClassSet &AssociatedClasses) {
// C++ [basic.lookup.koenig]p2, last bullet:
// -- [...] ;
switch (Arg.getKind()) {
case TemplateArgument::Null:
break;
case TemplateArgument::Type:
// [...] the namespaces and classes associated with the types of the
// template arguments provided for template type parameters (excluding
// template template parameters)
addAssociatedClassesAndNamespaces(Arg.getAsType(), Context,
AssociatedNamespaces,
AssociatedClasses);
break;
case TemplateArgument::Template: {
// [...] the namespaces in which any template template arguments are
// defined; and the classes in which any member templates used as
// template template arguments are defined.
TemplateName Template = Arg.getAsTemplate();
if (ClassTemplateDecl *ClassTemplate
= dyn_cast<ClassTemplateDecl>(Template.getAsTemplateDecl())) {
DeclContext *Ctx = ClassTemplate->getDeclContext();
if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
AssociatedClasses.insert(EnclosingClass);
// Add the associated namespace for this class.
while (Ctx->isRecord())
Ctx = Ctx->getParent();
CollectNamespace(AssociatedNamespaces, Ctx);
}
break;
}
case TemplateArgument::Declaration:
case TemplateArgument::Integral:
case TemplateArgument::Expression:
// [Note: non-type template arguments do not contribute to the set of
// associated namespaces. ]
break;
case TemplateArgument::Pack:
for (TemplateArgument::pack_iterator P = Arg.pack_begin(),
PEnd = Arg.pack_end();
P != PEnd; ++P)
addAssociatedClassesAndNamespaces(*P, Context,
AssociatedNamespaces,
AssociatedClasses);
break;
}
}
// \brief Add the associated classes and namespaces for
// argument-dependent lookup with an argument of class type
// (C++ [basic.lookup.koenig]p2).
static void
addAssociatedClassesAndNamespaces(CXXRecordDecl *Class,
ASTContext &Context,
Sema::AssociatedNamespaceSet &AssociatedNamespaces,
Sema::AssociatedClassSet &AssociatedClasses) {
// C++ [basic.lookup.koenig]p2:
// [...]
// -- If T is a class type (including unions), its associated
// classes are: the class itself; the class of which it is a
// member, if any; and its direct and indirect base
// classes. Its associated namespaces are the namespaces in
// which its associated classes are defined.
// Add the class of which it is a member, if any.
DeclContext *Ctx = Class->getDeclContext();
if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
AssociatedClasses.insert(EnclosingClass);
// Add the associated namespace for this class.
while (Ctx->isRecord())
Ctx = Ctx->getParent();
CollectNamespace(AssociatedNamespaces, Ctx);
// Add the class itself. If we've already seen this class, we don't
// need to visit base classes.
if (!AssociatedClasses.insert(Class))
return;
// -- If T is a template-id, its associated namespaces and classes are
// the namespace in which the template is defined; for member
// templates, the member template’s class; the namespaces and classes
// associated with the types of the template arguments provided for
// template type parameters (excluding template template parameters); the
// namespaces in which any template template arguments are defined; and
// the classes in which any member templates used as template template
// arguments are defined. [Note: non-type template arguments do not
// contribute to the set of associated namespaces. ]
if (ClassTemplateSpecializationDecl *Spec
= dyn_cast<ClassTemplateSpecializationDecl>(Class)) {
DeclContext *Ctx = Spec->getSpecializedTemplate()->getDeclContext();
if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
AssociatedClasses.insert(EnclosingClass);
// Add the associated namespace for this class.
while (Ctx->isRecord())
Ctx = Ctx->getParent();
CollectNamespace(AssociatedNamespaces, Ctx);
const TemplateArgumentList &TemplateArgs = Spec->getTemplateArgs();
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
addAssociatedClassesAndNamespaces(TemplateArgs[I], Context,
AssociatedNamespaces,
AssociatedClasses);
}
// Add direct and indirect base classes along with their associated
// namespaces.
llvm::SmallVector<CXXRecordDecl *, 32> Bases;
Bases.push_back(Class);
while (!Bases.empty()) {
// Pop this class off the stack.
Class = Bases.back();
Bases.pop_back();
// Visit the base classes.
for (CXXRecordDecl::base_class_iterator Base = Class->bases_begin(),
BaseEnd = Class->bases_end();
Base != BaseEnd; ++Base) {
const RecordType *BaseType = Base->getType()->getAs<RecordType>();
// In dependent contexts, we do ADL twice, and the first time around,
// the base type might be a dependent TemplateSpecializationType, or a
// TemplateTypeParmType. If that happens, simply ignore it.
// FIXME: If we want to support export, we probably need to add the
// namespace of the template in a TemplateSpecializationType, or even
// the classes and namespaces of known non-dependent arguments.
if (!BaseType)
continue;
CXXRecordDecl *BaseDecl = cast<CXXRecordDecl>(BaseType->getDecl());
if (AssociatedClasses.insert(BaseDecl)) {
// Find the associated namespace for this base class.
DeclContext *BaseCtx = BaseDecl->getDeclContext();
while (BaseCtx->isRecord())
BaseCtx = BaseCtx->getParent();
CollectNamespace(AssociatedNamespaces, BaseCtx);
// Make sure we visit the bases of this base class.
if (BaseDecl->bases_begin() != BaseDecl->bases_end())
Bases.push_back(BaseDecl);
}
}
}
}
// \brief Add the associated classes and namespaces for
// argument-dependent lookup with an argument of type T
// (C++ [basic.lookup.koenig]p2).
static void
addAssociatedClassesAndNamespaces(QualType T,
ASTContext &Context,
Sema::AssociatedNamespaceSet &AssociatedNamespaces,
Sema::AssociatedClassSet &AssociatedClasses) {
// C++ [basic.lookup.koenig]p2:
//
// For each argument type T in the function call, there is a set
// of zero or more associated namespaces and a set of zero or more
// associated classes to be considered. The sets of namespaces and
// classes is determined entirely by the types of the function
// arguments (and the namespace of any template template
// argument). Typedef names and using-declarations used to specify
// the types do not contribute to this set. The sets of namespaces
// and classes are determined in the following way:
T = Context.getCanonicalType(T).getUnqualifiedType();
// -- If T is a pointer to U or an array of U, its associated
// namespaces and classes are those associated with U.
//
// We handle this by unwrapping pointer and array types immediately,
// to avoid unnecessary recursion.
while (true) {
if (const PointerType *Ptr = T->getAs<PointerType>())
T = Ptr->getPointeeType();
else if (const ArrayType *Ptr = Context.getAsArrayType(T))
T = Ptr->getElementType();
else
break;
}
// -- If T is a fundamental type, its associated sets of
// namespaces and classes are both empty.
if (T->getAs<BuiltinType>())
return;
// -- If T is a class type (including unions), its associated
// classes are: the class itself; the class of which it is a
// member, if any; and its direct and indirect base
// classes. Its associated namespaces are the namespaces in
// which its associated classes are defined.
if (const RecordType *ClassType = T->getAs<RecordType>())
if (CXXRecordDecl *ClassDecl
= dyn_cast<CXXRecordDecl>(ClassType->getDecl())) {
addAssociatedClassesAndNamespaces(ClassDecl, Context,
AssociatedNamespaces,
AssociatedClasses);
return;
}
// -- If T is an enumeration type, its associated namespace is
// the namespace in which it is defined. If it is class
// member, its associated class is the member’s class; else
// it has no associated class.
if (const EnumType *EnumT = T->getAs<EnumType>()) {
EnumDecl *Enum = EnumT->getDecl();
DeclContext *Ctx = Enum->getDeclContext();
if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
AssociatedClasses.insert(EnclosingClass);
// Add the associated namespace for this class.
while (Ctx->isRecord())
Ctx = Ctx->getParent();
CollectNamespace(AssociatedNamespaces, Ctx);
return;
}
// -- If T is a function type, its associated namespaces and
// classes are those associated with the function parameter
// types and those associated with the return type.
if (const FunctionType *FnType = T->getAs<FunctionType>()) {
// Return type
addAssociatedClassesAndNamespaces(FnType->getResultType(),
Context,
AssociatedNamespaces, AssociatedClasses);
const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FnType);
if (!Proto)
return;
// Argument types
for (FunctionProtoType::arg_type_iterator Arg = Proto->arg_type_begin(),
ArgEnd = Proto->arg_type_end();
Arg != ArgEnd; ++Arg)
addAssociatedClassesAndNamespaces(*Arg, Context,
AssociatedNamespaces, AssociatedClasses);
return;
}
// -- If T is a pointer to a member function of a class X, its
// associated namespaces and classes are those associated
// with the function parameter types and return type,
// together with those associated with X.
//
// -- If T is a pointer to a data member of class X, its
// associated namespaces and classes are those associated
// with the member type together with those associated with
// X.
if (const MemberPointerType *MemberPtr = T->getAs<MemberPointerType>()) {
// Handle the type that the pointer to member points to.
addAssociatedClassesAndNamespaces(MemberPtr->getPointeeType(),
Context,
AssociatedNamespaces,
AssociatedClasses);
// Handle the class type into which this points.
if (const RecordType *Class = MemberPtr->getClass()->getAs<RecordType>())
addAssociatedClassesAndNamespaces(cast<CXXRecordDecl>(Class->getDecl()),
Context,
AssociatedNamespaces,
AssociatedClasses);
return;
}
// FIXME: What about block pointers?
// FIXME: What about Objective-C message sends?
}
/// \brief Find the associated classes and namespaces for
/// argument-dependent lookup for a call with the given set of
/// arguments.
///
/// This routine computes the sets of associated classes and associated
/// namespaces searched by argument-dependent lookup
/// (C++ [basic.lookup.argdep]) for a given set of arguments.
void
Sema::FindAssociatedClassesAndNamespaces(Expr **Args, unsigned NumArgs,
AssociatedNamespaceSet &AssociatedNamespaces,
AssociatedClassSet &AssociatedClasses) {
AssociatedNamespaces.clear();
AssociatedClasses.clear();
// C++ [basic.lookup.koenig]p2:
// For each argument type T in the function call, there is a set
// of zero or more associated namespaces and a set of zero or more
// associated classes to be considered. The sets of namespaces and
// classes is determined entirely by the types of the function
// arguments (and the namespace of any template template
// argument).
for (unsigned ArgIdx = 0; ArgIdx != NumArgs; ++ArgIdx) {
Expr *Arg = Args[ArgIdx];
if (Arg->getType() != Context.OverloadTy) {
addAssociatedClassesAndNamespaces(Arg->getType(), Context,
AssociatedNamespaces,
AssociatedClasses);
continue;
}
// [...] In addition, if the argument is the name or address of a
// set of overloaded functions and/or function templates, its
// associated classes and namespaces are the union of those
// associated with each of the members of the set: the namespace
// in which the function or function template is defined and the
// classes and namespaces associated with its (non-dependent)
// parameter types and return type.
Arg = Arg->IgnoreParens();
if (UnaryOperator *unaryOp = dyn_cast<UnaryOperator>(Arg))
if (unaryOp->getOpcode() == UnaryOperator::AddrOf)
Arg = unaryOp->getSubExpr();
// TODO: avoid the copies. This should be easy when the cases
// share a storage implementation.
llvm::SmallVector<NamedDecl*, 8> Functions;
if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(Arg))
Functions.append(ULE->decls_begin(), ULE->decls_end());
else
continue;
for (llvm::SmallVectorImpl<NamedDecl*>::iterator I = Functions.begin(),
E = Functions.end(); I != E; ++I) {
// Look through any using declarations to find the underlying function.
NamedDecl *Fn = (*I)->getUnderlyingDecl();
FunctionDecl *FDecl = dyn_cast<FunctionDecl>(Fn);
if (!FDecl)
FDecl = cast<FunctionTemplateDecl>(Fn)->getTemplatedDecl();
// Add the classes and namespaces associated with the parameter
// types and return type of this function.
addAssociatedClassesAndNamespaces(FDecl->getType(), Context,
AssociatedNamespaces,
AssociatedClasses);
}
}
}
/// IsAcceptableNonMemberOperatorCandidate - Determine whether Fn is
/// an acceptable non-member overloaded operator for a call whose
/// arguments have types T1 (and, if non-empty, T2). This routine
/// implements the check in C++ [over.match.oper]p3b2 concerning
/// enumeration types.
static bool
IsAcceptableNonMemberOperatorCandidate(FunctionDecl *Fn,
QualType T1, QualType T2,
ASTContext &Context) {
if (T1->isDependentType() || (!T2.isNull() && T2->isDependentType()))
return true;
if (T1->isRecordType() || (!T2.isNull() && T2->isRecordType()))
return true;
const FunctionProtoType *Proto = Fn->getType()->getAs<FunctionProtoType>();
if (Proto->getNumArgs() < 1)
return false;
if (T1->isEnumeralType()) {
QualType ArgType = Proto->getArgType(0).getNonReferenceType();
if (Context.hasSameUnqualifiedType(T1, ArgType))
return true;
}
if (Proto->getNumArgs() < 2)
return false;
if (!T2.isNull() && T2->isEnumeralType()) {
QualType ArgType = Proto->getArgType(1).getNonReferenceType();
if (Context.hasSameUnqualifiedType(T2, ArgType))
return true;
}
return false;
}
NamedDecl *Sema::LookupSingleName(Scope *S, DeclarationName Name,
LookupNameKind NameKind,
RedeclarationKind Redecl) {
LookupResult R(*this, Name, SourceLocation(), NameKind, Redecl);
LookupName(R, S);
return R.getAsSingle<NamedDecl>();
}
/// \brief Find the protocol with the given name, if any.
ObjCProtocolDecl *Sema::LookupProtocol(IdentifierInfo *II) {
Decl *D = LookupSingleName(TUScope, II, LookupObjCProtocolName);
return cast_or_null<ObjCProtocolDecl>(D);
}
void Sema::LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,
QualType T1, QualType T2,
FunctionSet &Functions) {
// C++ [over.match.oper]p3:
// -- The set of non-member candidates is the result of the
// unqualified lookup of operator@ in the context of the
// expression according to the usual rules for name lookup in
// unqualified function calls (3.4.2) except that all member
// functions are ignored. However, if no operand has a class
// type, only those non-member functions in the lookup set
// that have a first parameter of type T1 or "reference to
// (possibly cv-qualified) T1", when T1 is an enumeration
// type, or (if there is a right operand) a second parameter
// of type T2 or "reference to (possibly cv-qualified) T2",
// when T2 is an enumeration type, are candidate functions.
DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
LookupResult Operators(*this, OpName, SourceLocation(), LookupOperatorName);
LookupName(Operators, S);
assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
if (Operators.empty())
return;
for (LookupResult::iterator Op = Operators.begin(), OpEnd = Operators.end();
Op != OpEnd; ++Op) {
if (FunctionDecl *FD = dyn_cast<FunctionDecl>(*Op)) {
if (IsAcceptableNonMemberOperatorCandidate(FD, T1, T2, Context))
Functions.insert(FD); // FIXME: canonical FD
} else if (FunctionTemplateDecl *FunTmpl
= dyn_cast<FunctionTemplateDecl>(*Op)) {
// FIXME: friend operators?
// FIXME: do we need to check IsAcceptableNonMemberOperatorCandidate,
// later?
if (!FunTmpl->getDeclContext()->isRecord())
Functions.insert(FunTmpl);
}
}
}
static void CollectFunctionDecl(Sema::FunctionSet &Functions,
Decl *D) {
if (FunctionDecl *Func = dyn_cast<FunctionDecl>(D))
Functions.insert(Func);
else if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D))
Functions.insert(FunTmpl);
}
void Sema::ArgumentDependentLookup(DeclarationName Name, bool Operator,
Expr **Args, unsigned NumArgs,
FunctionSet &Functions) {
// Find all of the associated namespaces and classes based on the
// arguments we have.
AssociatedNamespaceSet AssociatedNamespaces;
AssociatedClassSet AssociatedClasses;
FindAssociatedClassesAndNamespaces(Args, NumArgs,
AssociatedNamespaces,
AssociatedClasses);
QualType T1, T2;
if (Operator) {
T1 = Args[0]->getType();
if (NumArgs >= 2)
T2 = Args[1]->getType();
}
// C++ [basic.lookup.argdep]p3:
// Let X be the lookup set produced by unqualified lookup (3.4.1)
// and let Y be the lookup set produced by argument dependent
// lookup (defined as follows). If X contains [...] then Y is
// empty. Otherwise Y is the set of declarations found in the
// namespaces associated with the argument types as described
// below. The set of declarations found by the lookup of the name
// is the union of X and Y.
//
// Here, we compute Y and add its members to the overloaded
// candidate set.
for (AssociatedNamespaceSet::iterator NS = AssociatedNamespaces.begin(),
NSEnd = AssociatedNamespaces.end();
NS != NSEnd; ++NS) {
// When considering an associated namespace, the lookup is the
// same as the lookup performed when the associated namespace is
// used as a qualifier (3.4.3.2) except that:
//
// -- Any using-directives in the associated namespace are
// ignored.
//
// -- Any namespace-scope friend functions declared in
// associated classes are visible within their respective
// namespaces even if they are not visible during an ordinary
// lookup (11.4).
DeclContext::lookup_iterator I, E;
for (llvm::tie(I, E) = (*NS)->lookup(Name); I != E; ++I) {
Decl *D = *I;
// If the only declaration here is an ordinary friend, consider
// it only if it was declared in an associated classes.
if (D->getIdentifierNamespace() == Decl::IDNS_OrdinaryFriend) {
DeclContext *LexDC = D->getLexicalDeclContext();
if (!AssociatedClasses.count(cast<CXXRecordDecl>(LexDC)))
continue;
}
FunctionDecl *Fn;
if (!Operator || !(Fn = dyn_cast<FunctionDecl>(D)) ||
IsAcceptableNonMemberOperatorCandidate(Fn, T1, T2, Context))
CollectFunctionDecl(Functions, D);
}
}
}
//----------------------------------------------------------------------------
// Search for all visible declarations.
//----------------------------------------------------------------------------
VisibleDeclConsumer::~VisibleDeclConsumer() { }
namespace {
class ShadowContextRAII;
class VisibleDeclsRecord {
public:
/// \brief An entry in the shadow map, which is optimized to store a
/// single declaration (the common case) but can also store a list
/// of declarations.
class ShadowMapEntry {
typedef llvm::SmallVector<NamedDecl *, 4> DeclVector;
/// \brief Contains either the solitary NamedDecl * or a vector
/// of declarations.
llvm::PointerUnion<NamedDecl *, DeclVector*> DeclOrVector;
public:
ShadowMapEntry() : DeclOrVector() { }
void Add(NamedDecl *ND);
void Destroy();
// Iteration.
typedef NamedDecl **iterator;
iterator begin();
iterator end();
};
private:
/// \brief A mapping from declaration names to the declarations that have
/// this name within a particular scope.
typedef llvm::DenseMap<DeclarationName, ShadowMapEntry> ShadowMap;
/// \brief A list of shadow maps, which is used to model name hiding.
std::list<ShadowMap> ShadowMaps;
/// \brief The declaration contexts we have already visited.
llvm::SmallPtrSet<DeclContext *, 8> VisitedContexts;
friend class ShadowContextRAII;
public:
/// \brief Determine whether we have already visited this context
/// (and, if not, note that we are going to visit that context now).
bool visitedContext(DeclContext *Ctx) {
return !VisitedContexts.insert(Ctx);
}
/// \brief Determine whether the given declaration is hidden in the
/// current scope.
///
/// \returns the declaration that hides the given declaration, or
/// NULL if no such declaration exists.
NamedDecl *checkHidden(NamedDecl *ND);
/// \brief Add a declaration to the current shadow map.
void add(NamedDecl *ND) { ShadowMaps.back()[ND->getDeclName()].Add(ND); }
};
/// \brief RAII object that records when we've entered a shadow context.
class ShadowContextRAII {
VisibleDeclsRecord &Visible;
typedef VisibleDeclsRecord::ShadowMap ShadowMap;
public:
ShadowContextRAII(VisibleDeclsRecord &Visible) : Visible(Visible) {
Visible.ShadowMaps.push_back(ShadowMap());
}
~ShadowContextRAII() {
for (ShadowMap::iterator E = Visible.ShadowMaps.back().begin(),
EEnd = Visible.ShadowMaps.back().end();
E != EEnd;
++E)
E->second.Destroy();
Visible.ShadowMaps.pop_back();
}
};
} // end anonymous namespace
void VisibleDeclsRecord::ShadowMapEntry::Add(NamedDecl *ND) {
if (DeclOrVector.isNull()) {
// 0 - > 1 elements: just set the single element information.
DeclOrVector = ND;
return;
}
if (NamedDecl *PrevND = DeclOrVector.dyn_cast<NamedDecl *>()) {
// 1 -> 2 elements: create the vector of results and push in the
// existing declaration.
DeclVector *Vec = new DeclVector;
Vec->push_back(PrevND);
DeclOrVector = Vec;
}
// Add the new element to the end of the vector.
DeclOrVector.get<DeclVector*>()->push_back(ND);
}
void VisibleDeclsRecord::ShadowMapEntry::Destroy() {
if (DeclVector *Vec = DeclOrVector.dyn_cast<DeclVector *>()) {
delete Vec;
DeclOrVector = ((NamedDecl *)0);
}
}
VisibleDeclsRecord::ShadowMapEntry::iterator
VisibleDeclsRecord::ShadowMapEntry::begin() {
if (DeclOrVector.isNull())
return 0;
if (DeclOrVector.dyn_cast<NamedDecl *>())
return &reinterpret_cast<NamedDecl*&>(DeclOrVector);
return DeclOrVector.get<DeclVector *>()->begin();
}
VisibleDeclsRecord::ShadowMapEntry::iterator
VisibleDeclsRecord::ShadowMapEntry::end() {
if (DeclOrVector.isNull())
return 0;
if (DeclOrVector.dyn_cast<NamedDecl *>())
return &reinterpret_cast<NamedDecl*&>(DeclOrVector) + 1;
return DeclOrVector.get<DeclVector *>()->end();
}
NamedDecl *VisibleDeclsRecord::checkHidden(NamedDecl *ND) {
unsigned IDNS = ND->getIdentifierNamespace();
std::list<ShadowMap>::reverse_iterator SM = ShadowMaps.rbegin();
for (std::list<ShadowMap>::reverse_iterator SMEnd = ShadowMaps.rend();
SM != SMEnd; ++SM) {
ShadowMap::iterator Pos = SM->find(ND->getDeclName());
if (Pos == SM->end())
continue;
for (ShadowMapEntry::iterator I = Pos->second.begin(),
IEnd = Pos->second.end();
I != IEnd; ++I) {
// A tag declaration does not hide a non-tag declaration.
if ((*I)->getIdentifierNamespace() == Decl::IDNS_Tag &&
(IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary |
Decl::IDNS_ObjCProtocol)))
continue;
// Protocols are in distinct namespaces from everything else.
if ((((*I)->getIdentifierNamespace() & Decl::IDNS_ObjCProtocol)
|| (IDNS & Decl::IDNS_ObjCProtocol)) &&
(*I)->getIdentifierNamespace() != IDNS)
continue;
// We've found a declaration that hides this one.
return *I;
}
}
return 0;
}
static void LookupVisibleDecls(DeclContext *Ctx, LookupResult &Result,
bool QualifiedNameLookup,
VisibleDeclConsumer &Consumer,
VisibleDeclsRecord &Visited) {
// Make sure we don't visit the same context twice.
if (Visited.visitedContext(Ctx->getPrimaryContext()))
return;
// Enumerate all of the results in this context.
for (DeclContext *CurCtx = Ctx->getPrimaryContext(); CurCtx;
CurCtx = CurCtx->getNextContext()) {
for (DeclContext::decl_iterator D = CurCtx->decls_begin(),
DEnd = CurCtx->decls_end();
D != DEnd; ++D) {
if (NamedDecl *ND = dyn_cast<NamedDecl>(*D))
if (Result.isAcceptableDecl(ND)) {
Consumer.FoundDecl(ND, Visited.checkHidden(ND));
Visited.add(ND);
}
// Visit transparent contexts inside this context.
if (DeclContext *InnerCtx = dyn_cast<DeclContext>(*D)) {
if (InnerCtx->isTransparentContext())
LookupVisibleDecls(InnerCtx, Result, QualifiedNameLookup,
Consumer, Visited);
}
}
}
// Traverse using directives for qualified name lookup.
if (QualifiedNameLookup) {
ShadowContextRAII Shadow(Visited);
DeclContext::udir_iterator I, E;
for (llvm::tie(I, E) = Ctx->getUsingDirectives(); I != E; ++I) {
LookupVisibleDecls((*I)->getNominatedNamespace(), Result,
QualifiedNameLookup, Consumer, Visited);
}
}
// Traverse the contexts of inherited classes.
if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx)) {
for (CXXRecordDecl::base_class_iterator B = Record->bases_begin(),
BEnd = Record->bases_end();
B != BEnd; ++B) {
QualType BaseType = B->getType();
// Don't look into dependent bases, because name lookup can't look
// there anyway.
if (BaseType->isDependentType())
continue;
const RecordType *Record = BaseType->getAs<RecordType>();
if (!Record)
continue;
// FIXME: It would be nice to be able to determine whether referencing
// a particular member would be ambiguous. For example, given
//
// struct A { int member; };
// struct B { int member; };
// struct C : A, B { };
//
// void f(C *c) { c->### }
//
// accessing 'member' would result in an ambiguity. However, we
// could be smart enough to qualify the member with the base
// class, e.g.,
//
// c->B::member
//
// or
//
// c->A::member
// Find results in this base class (and its bases).
ShadowContextRAII Shadow(Visited);
LookupVisibleDecls(Record->getDecl(), Result, QualifiedNameLookup,
Consumer, Visited);
}
}
// FIXME: Look into base classes in Objective-C!
}
static void LookupVisibleDecls(Scope *S, LookupResult &Result,
UnqualUsingDirectiveSet &UDirs,
VisibleDeclConsumer &Consumer,
VisibleDeclsRecord &Visited) {
if (!S)
return;
DeclContext *Entity = 0;
if (S->getEntity() &&
!((DeclContext *)S->getEntity())->isFunctionOrMethod()) {
// Look into this scope's declaration context, along with any of its
// parent lookup contexts (e.g., enclosing classes), up to the point
// where we hit the context stored in the next outer scope.
Entity = (DeclContext *)S->getEntity();
DeclContext *OuterCtx = findOuterContext(S);
for (DeclContext *Ctx = Entity; Ctx && Ctx->getPrimaryContext() != OuterCtx;
Ctx = Ctx->getLookupParent()) {
if (Ctx->isFunctionOrMethod())
continue;
LookupVisibleDecls(Ctx, Result, /*QualifiedNameLookup=*/false,
Consumer, Visited);
}
} else if (!S->getParent()) {
// Look into the translation unit scope. We walk through the translation
// unit's declaration context, because the Scope itself won't have all of
// the declarations if we loaded a precompiled header.
// FIXME: We would like the translation unit's Scope object to point to the
// translation unit, so we don't need this special "if" branch. However,
// doing so would force the normal C++ name-lookup code to look into the
// translation unit decl when the IdentifierInfo chains would suffice.
// Once we fix that problem (which is part of a more general "don't look
// in DeclContexts unless we have to" optimization), we can eliminate the
// TranslationUnit parameter entirely.
Entity = Result.getSema().Context.getTranslationUnitDecl();
LookupVisibleDecls(Entity, Result, /*QualifiedNameLookup=*/false,
Consumer, Visited);
} else {
// Walk through the declarations in this Scope.
for (Scope::decl_iterator D = S->decl_begin(), DEnd = S->decl_end();
D != DEnd; ++D) {
if (NamedDecl *ND = dyn_cast<NamedDecl>((Decl *)((*D).get())))
if (Result.isAcceptableDecl(ND)) {
Consumer.FoundDecl(ND, Visited.checkHidden(ND));
Visited.add(ND);
}
}
}
if (Entity) {
// Lookup visible declarations in any namespaces found by using
// directives.
UnqualUsingDirectiveSet::const_iterator UI, UEnd;
llvm::tie(UI, UEnd) = UDirs.getNamespacesFor(Entity);
for (; UI != UEnd; ++UI)
LookupVisibleDecls(const_cast<DeclContext *>(UI->getNominatedNamespace()),
Result, /*QualifiedNameLookup=*/false, Consumer,
Visited);
}
// Lookup names in the parent scope.
ShadowContextRAII Shadow(Visited);
LookupVisibleDecls(S->getParent(), Result, UDirs, Consumer, Visited);
}
void Sema::LookupVisibleDecls(Scope *S, LookupNameKind Kind,
VisibleDeclConsumer &Consumer) {
// Determine the set of using directives available during
// unqualified name lookup.
Scope *Initial = S;
UnqualUsingDirectiveSet UDirs;
if (getLangOptions().CPlusPlus) {
// Find the first namespace or translation-unit scope.
while (S && !isNamespaceOrTranslationUnitScope(S))
S = S->getParent();
UDirs.visitScopeChain(Initial, S);
}
UDirs.done();
// Look for visible declarations.
LookupResult Result(*this, DeclarationName(), SourceLocation(), Kind);
VisibleDeclsRecord Visited;
ShadowContextRAII Shadow(Visited);
::LookupVisibleDecls(Initial, Result, UDirs, Consumer, Visited);
}
void Sema::LookupVisibleDecls(DeclContext *Ctx, LookupNameKind Kind,
VisibleDeclConsumer &Consumer) {
LookupResult Result(*this, DeclarationName(), SourceLocation(), Kind);
VisibleDeclsRecord Visited;
ShadowContextRAII Shadow(Visited);
::LookupVisibleDecls(Ctx, Result, /*QualifiedNameLookup=*/true, Consumer,
Visited);
}
//----------------------------------------------------------------------------
// Typo correction
//----------------------------------------------------------------------------
namespace {
class TypoCorrectionConsumer : public VisibleDeclConsumer {
/// \brief The name written that is a typo in the source.
llvm::StringRef Typo;
/// \brief The results found that have the smallest edit distance
/// found (so far) with the typo name.
llvm::SmallVector<NamedDecl *, 4> BestResults;
/// \brief The best edit distance found so far.
unsigned BestEditDistance;
public:
explicit TypoCorrectionConsumer(IdentifierInfo *Typo)
: Typo(Typo->getName()) { }
virtual void FoundDecl(NamedDecl *ND, NamedDecl *Hiding);
typedef llvm::SmallVector<NamedDecl *, 4>::const_iterator iterator;
iterator begin() const { return BestResults.begin(); }
iterator end() const { return BestResults.end(); }
bool empty() const { return BestResults.empty(); }
unsigned getBestEditDistance() const { return BestEditDistance; }
};
}
void TypoCorrectionConsumer::FoundDecl(NamedDecl *ND, NamedDecl *Hiding) {
// Don't consider hidden names for typo correction.
if (Hiding)
return;
// Only consider entities with identifiers for names, ignoring
// special names (constructors, overloaded operators, selectors,
// etc.).
IdentifierInfo *Name = ND->getIdentifier();
if (!Name)
return;
// Compute the edit distance between the typo and the name of this
// entity. If this edit distance is not worse than the best edit
// distance we've seen so far, add it to the list of results.
unsigned ED = Typo.edit_distance(Name->getName());
if (!BestResults.empty()) {
if (ED < BestEditDistance) {
// This result is better than any we've seen before; clear out
// the previous results.
BestResults.clear();
BestEditDistance = ED;
} else if (ED > BestEditDistance) {
// This result is worse than the best results we've seen so far;
// ignore it.
return;
}
} else
BestEditDistance = ED;
BestResults.push_back(ND);
}
/// \brief Try to "correct" a typo in the source code by finding
/// visible declarations whose names are similar to the name that was
/// present in the source code.
///
/// \param Res the \c LookupResult structure that contains the name
/// that was present in the source code along with the name-lookup
/// criteria used to search for the name. On success, this structure
/// will contain the results of name lookup.
///
/// \param S the scope in which name lookup occurs.
///
/// \param SS the nested-name-specifier that precedes the name we're
/// looking for, if present.
///
/// \returns true if the typo was corrected, in which case the \p Res
/// structure will contain the results of name lookup for the
/// corrected name. Otherwise, returns false.
bool Sema::CorrectTypo(LookupResult &Res, Scope *S, const CXXScopeSpec *SS,
bool AllowBuiltinCreation, bool EnteringContext) {
// We only attempt to correct typos for identifiers.
IdentifierInfo *Typo = Res.getLookupName().getAsIdentifierInfo();
if (!Typo)
return false;
// If the scope specifier itself was invalid, don't try to correct
// typos.
if (SS && SS->isInvalid())
return false;
// Never try to correct typos during template deduction or
// instantiation.
if (!ActiveTemplateInstantiations.empty())
return false;
TypoCorrectionConsumer Consumer(Typo);
if (SS && SS->isSet()) {
DeclContext *DC = computeDeclContext(*SS, EnteringContext);
if (!DC)
return false;
LookupVisibleDecls(DC, Res.getLookupKind(), Consumer);
} else {
LookupVisibleDecls(S, Res.getLookupKind(), Consumer);
}
if (Consumer.empty())
return false;
// Only allow a single, closest name in the result set (it's okay to
// have overloads of that name, though).
TypoCorrectionConsumer::iterator I = Consumer.begin();
DeclarationName BestName = (*I)->getDeclName();
++I;
for(TypoCorrectionConsumer::iterator IEnd = Consumer.end(); I != IEnd; ++I) {
if (BestName != (*I)->getDeclName())
return false;
}
// BestName is the closest viable name to what the user
// typed. However, to make sure that we don't pick something that's
// way off, make sure that the user typed at least 3 characters for
// each correction.
unsigned ED = Consumer.getBestEditDistance();
if (ED == 0 || (BestName.getAsIdentifierInfo()->getName().size() / ED) < 3)
return false;
// Perform name lookup again with the name we chose, and declare
// success if we found something that was not ambiguous.
Res.clear();
Res.setLookupName(BestName);
LookupParsedName(Res, S, SS, AllowBuiltinCreation, EnteringContext);
return Res.getResultKind() != LookupResult::NotFound && !Res.isAmbiguous();
}