--- a/clang-tools-extra/clangd/FindTarget.cpp	Wed Jul 21 10:27:27 2021 +0900
+++ b/clang-tools-extra/clangd/FindTarget.cpp	Wed Nov 09 17:45:10 2022 +0900
@@ -31,15 +31,17 @@
 #include "clang/AST/TypeLocVisitor.h"
 #include "clang/AST/TypeVisitor.h"
 #include "clang/Basic/LangOptions.h"
-#include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <iterator>
+#include <string>
 #include <utility>
 #include <vector>
 
@@ -94,6 +96,16 @@
   return nullptr;
 }
 
+// Returns true if the `TypedefNameDecl` should not be reported.
+bool shouldSkipTypedef(const TypedefNameDecl *TD) {
+  // These should be treated as keywords rather than decls - the typedef is an
+  // odd implementation detail.
+  if (TD == TD->getASTContext().getObjCInstanceTypeDecl() ||
+      TD == TD->getASTContext().getObjCIdDecl())
+    return true;
+  return false;
+}
+
 // TargetFinder locates the entities that an AST node refers to.
 //
 // Typically this is (possibly) one declaration and (possibly) one type, but
@@ -115,11 +127,6 @@
 //      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.
-// We currently handle several dependent constructs, but some others remain to
-// be handled:
-//  - UnresolvedUsingTypenameDecl
 struct TargetFinder {
   using RelSet = DeclRelationSet;
   using Rel = DeclRelation;
@@ -182,8 +189,8 @@
         add(S->getUnderlyingDecl(), Flags);
       Flags |= Rel::Alias; // continue with the alias.
     } else if (const UsingEnumDecl *UED = dyn_cast<UsingEnumDecl>(D)) {
-      add(UED->getEnumDecl(), Flags);
-      Flags |= Rel::Alias; // continue with the alias.
+      // UsingEnumDecl is not an alias at all, just a reference.
+      D = UED->getEnumDecl();
     } else if (const auto *NAD = dyn_cast<NamespaceAliasDecl>(D)) {
       add(NAD->getUnderlyingDecl(), Flags | Rel::Underlying);
       Flags |= Rel::Alias; // continue with the alias
@@ -195,10 +202,17 @@
         }
       }
       Flags |= Rel::Alias; // continue with the alias
+    } else if (isa<UnresolvedUsingTypenameDecl>(D)) {
+      // FIXME: improve common dependent scope using name lookup in primary
+      // templates.
+      Flags |= Rel::Alias;
     } else if (const UsingShadowDecl *USD = dyn_cast<UsingShadowDecl>(D)) {
-      // Include the Introducing decl, but don't traverse it. This may end up
-      // including *all* shadows, which we don't want.
-      report(USD->getIntroducer(), Flags | Rel::Alias);
+      // Include the introducing UsingDecl, but don't traverse it. This may end
+      // up including *all* shadows, which we don't want.
+      // Don't apply this logic to UsingEnumDecl, which can't easily be
+      // conflated with the aliases it introduces.
+      if (llvm::isa<UsingDecl>(USD->getIntroducer()))
+        report(USD->getIntroducer(), Flags | Rel::Alias);
       // Shadow decls are synthetic and not themselves interesting.
       // Record the underlying decl instead, if allowed.
       D = USD->getTargetDecl();
@@ -354,6 +368,10 @@
         Outer.add(ET->desugar(), Flags);
       }
 
+      void VisitUsingType(const UsingType *ET) {
+        Outer.add(ET->getFoundDecl(), Flags);
+      }
+
       void VisitInjectedClassNameType(const InjectedClassNameType *ICNT) {
         Outer.add(ICNT->getDecl(), Flags);
       }
@@ -364,15 +382,21 @@
       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);
+        Outer.add(DT->getDeducedType(), Flags);
+      }
+      void VisitUnresolvedUsingType(const UnresolvedUsingType *UUT) {
+        Outer.add(UUT->getDecl(), Flags);
       }
       void VisitDeducedTemplateSpecializationType(
           const DeducedTemplateSpecializationType *DTST) {
+        if (const auto *USD = DTST->getTemplateName().getAsUsingShadowDecl())
+          Outer.add(USD, Flags);
+
         // FIXME: This is a workaround for https://llvm.org/PR42914,
         // which is causing DTST->getDeducedType() to be empty. We
         // fall back to the template pattern and miss the instantiation
         // even when it's known in principle. Once that bug is fixed,
-        // this method can be removed (the existing handling in
+        // the following code can be removed (the existing handling in
         // VisitDeducedType() is sufficient).
         if (auto *TD = DTST->getTemplateName().getAsTemplateDecl())
           Outer.add(TD->getTemplatedDecl(), Flags | Rel::TemplatePattern);
@@ -395,12 +419,17 @@
         }
       }
       void VisitTypedefType(const TypedefType *TT) {
+        if (shouldSkipTypedef(TT->getDecl()))
+          return;
         Outer.add(TT->getDecl(), Flags);
       }
       void
       VisitTemplateSpecializationType(const TemplateSpecializationType *TST) {
         // Have to handle these case-by-case.
 
+        if (const auto *UTN = TST->getTemplateName().getAsUsingShadowDecl())
+          Outer.add(UTN, Flags);
+
         // 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
@@ -428,21 +457,16 @@
             Outer.add(TD->getTemplatedDecl(), Flags | Rel::TemplatePattern);
         }
       }
+      void
+      VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *STTPT) {
+        Outer.add(STTPT->getReplacementType(), Flags);
+      }
       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) {
-        // Make all of the protocols targets since there's no child nodes for
-        // protocols. This isn't needed for the base type, which *does* have a
-        // child `ObjCInterfaceTypeLoc`. This structure is a hack, but it works
-        // well for go-to-definition.
-        unsigned NumProtocols = OOT->getNumProtocols();
-        for (unsigned I = 0; I < NumProtocols; I++)
-          Outer.add(OOT->getProtocol(I), Flags);
-      }
     };
     Visitor(*this, Flags).Visit(T.getTypePtr());
   }
@@ -495,9 +519,13 @@
     // DeclRefExpr).
     if (Arg.getKind() == TemplateArgument::Template ||
         Arg.getKind() == TemplateArgument::TemplateExpansion) {
-      if (TemplateDecl *TD = Arg.getAsTemplate().getAsTemplateDecl()) {
+      if (TemplateDecl *TD =
+              Arg.getAsTemplateOrTemplatePattern().getAsTemplateDecl()) {
         report(TD, Flags);
       }
+      if (const auto *USD =
+              Arg.getAsTemplateOrTemplatePattern().getAsUsingShadowDecl())
+        add(USD, Flags);
     }
   }
 };
@@ -527,6 +555,8 @@
     Finder.add(TAL->getArgument(), Flags);
   else if (const CXXBaseSpecifier *CBS = N.get<CXXBaseSpecifier>())
     Finder.add(CBS->getTypeSourceInfo()->getType(), Flags);
+  else if (const ObjCProtocolLoc *PL = N.get<ObjCProtocolLoc>())
+    Finder.add(PL->getProtocol(), Flags);
   return Finder.takeDecls();
 }
 
@@ -599,6 +629,12 @@
                                    DeclRelation::Underlying, Resolver)});
     }
 
+    void VisitUsingEnumDecl(const UsingEnumDecl *D) {
+      // "using enum ns::E" is a non-declaration reference.
+      // The reference is covered by the embedded typeloc.
+      // Don't use the default VisitNamedDecl, which would report a declaration.
+    }
+
     void VisitNamespaceAliasDecl(const NamespaceAliasDecl *D) {
       // For namespace alias, "namespace Foo = Target;", we add two references.
       // Add a declaration reference for Foo.
@@ -649,25 +685,7 @@
                                   {OMD}});
     }
 
-    void visitProtocolList(
-        llvm::iterator_range<ObjCProtocolList::iterator> Protocols,
-        llvm::iterator_range<const SourceLocation *> Locations) {
-      for (const auto &P : llvm::zip(Protocols, Locations)) {
-        Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
-                                    std::get<1>(P),
-                                    /*IsDecl=*/false,
-                                    {std::get<0>(P)}});
-      }
-    }
-
-    void VisitObjCInterfaceDecl(const ObjCInterfaceDecl *OID) {
-      if (OID->isThisDeclarationADefinition())
-        visitProtocolList(OID->protocols(), OID->protocol_locs());
-      Base::VisitObjCInterfaceDecl(OID); // Visit the interface's name.
-    }
-
     void VisitObjCCategoryDecl(const ObjCCategoryDecl *OCD) {
-      visitProtocolList(OCD->protocols(), OCD->protocol_locs());
       // getLocation is the extended class's location, not the category's.
       Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
                                   OCD->getLocation(),
@@ -689,12 +707,6 @@
                                   /*IsDecl=*/true,
                                   {OCID->getCategoryDecl()}});
     }
-
-    void VisitObjCProtocolDecl(const ObjCProtocolDecl *OPD) {
-      if (OPD->isThisDeclarationADefinition())
-        visitProtocolList(OPD->protocols(), OPD->protocol_locs());
-      Base::VisitObjCProtocolDecl(OPD); // Visit the protocol's name.
-    }
   };
 
   Visitor V{Resolver};
@@ -842,6 +854,13 @@
       }
     }
 
+    void VisitUsingTypeLoc(UsingTypeLoc L) {
+      Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
+                                  L.getLocalSourceRange().getBegin(),
+                                  /*IsDecl=*/false,
+                                  {L.getFoundDecl()}});
+    }
+
     void VisitTagTypeLoc(TagTypeLoc L) {
       Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
                                   L.getNameLoc(),
@@ -903,6 +922,8 @@
     }
 
     void VisitTypedefTypeLoc(TypedefTypeLoc L) {
+      if (shouldSkipTypedef(L.getTypedefNameDecl()))
+        return;
       Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
                                   L.getNameLoc(),
                                   /*IsDecl=*/false,
@@ -915,16 +936,6 @@
                                   /*IsDecl=*/false,
                                   {L.getIFaceDecl()}});
     }
-
-    void VisitObjCObjectTypeLoc(ObjCObjectTypeLoc L) {
-      unsigned NumProtocols = L.getNumProtocols();
-      for (unsigned I = 0; I < NumProtocols; I++) {
-        Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
-                                    L.getProtocolLoc(I),
-                                    /*IsDecl=*/false,
-                                    {L.getProtocol(I)}});
-      }
-    }
   };
 
   Visitor V{Resolver};
@@ -952,7 +963,10 @@
     // ElaboratedTypeLoc will reports information for its inner type loc.
     // Otherwise we loose information about inner types loc's qualifier.
     TypeLoc Inner = L.getNamedTypeLoc().getUnqualifiedLoc();
-    TypeLocsToSkip.insert(Inner.getBeginLoc());
+    if (L.getBeginLoc() == Inner.getBeginLoc())
+      return RecursiveASTVisitor::TraverseTypeLoc(Inner);
+    else
+      TypeLocsToSkip.insert(Inner.getBeginLoc());
     return RecursiveASTVisitor::TraverseElaboratedTypeLoc(L);
   }
 
@@ -1020,6 +1034,11 @@
     return RecursiveASTVisitor::TraverseNestedNameSpecifierLoc(L);
   }
 
+  bool TraverseObjCProtocolLoc(ObjCProtocolLoc ProtocolLoc) {
+    visitNode(DynTypedNode::create(ProtocolLoc));
+    return true;
+  }
+
   bool TraverseConstructorInitializer(CXXCtorInitializer *Init) {
     visitNode(DynTypedNode::create(*Init));
     return RecursiveASTVisitor::TraverseConstructorInitializer(Init);
@@ -1065,6 +1084,12 @@
                              {CCI->getAnyMember()}}};
       }
     }
+    if (const ObjCProtocolLoc *PL = N.get<ObjCProtocolLoc>())
+      return {ReferenceLoc{NestedNameSpecifierLoc(),
+                           PL->getLocation(),
+                           /*IsDecl=*/false,
+                           {PL->getProtocol()}}};
+
     // We do not have location information for other nodes (QualType, etc)
     return {};
   }
@@ -1143,14 +1168,13 @@
 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, ReferenceLoc R) {
   // note we cannot print R.NameLoc without a source manager.
   OS << "targets = {";
-  bool First = true;
+  llvm::SmallVector<std::string> Targets;
   for (const NamedDecl *T : R.Targets) {
-    if (!First)
-      OS << ", ";
-    else
-      First = false;
-    OS << printQualifiedName(*T) << printTemplateSpecializationArgs(*T);
+    llvm::raw_string_ostream Target(Targets.emplace_back());
+    Target << printQualifiedName(*T) << printTemplateSpecializationArgs(*T);
   }
+  llvm::sort(Targets);
+  OS << llvm::join(Targets, ", ");
   OS << "}";
   if (R.Qualifier) {
     OS << ", qualifier = '";