[PATCH] D47623: [clangd] Avoid indexing decls associated with friend decls.

[Eric Liu via Phabricator via cfe-commits]

ioeric updated this revision to Diff 149526.
ioeric added a comment.

- Make canonical decls determinstic.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D47623

Files:
  clangd/index/SymbolCollector.cpp
  clangd/index/SymbolCollector.h
  unittests/clangd/SymbolCollectorTests.cpp


Index: unittests/clangd/SymbolCollectorTests.cpp
===================================================================
--- unittests/clangd/SymbolCollectorTests.cpp
+++ unittests/clangd/SymbolCollectorTests.cpp
@@ -812,6 +812,50 @@
                                    QName("nx::Kind"), QName("nx::Kind_Fine")));
 }
 
+TEST_F(SymbolCollectorTest, DoNotIndexSymbolsInFriendDecl) {
+  Annotations Header(R"(
+    namespace nx {
+      class $z[[Z]] {};
+      class X {
+        friend class Y;
+        friend class Z;
+        friend void foo();
+        friend void $bar[[bar]]() {}
+      };
+      class $y[[Y]] {};
+      void $foo[[foo]]();
+    }
+  )");
+  runSymbolCollector(Header.code(), /*Main=*/"");
+
+  EXPECT_THAT(Symbols,
+              UnorderedElementsAre(
+                  QName("nx"), QName("nx::X"),
+                  AllOf(QName("nx::Y"), DeclRange(Header.range("y"))),
+                  AllOf(QName("nx::Z"), DeclRange(Header.range("z"))),
+                  AllOf(QName("nx::foo"), DeclRange(Header.range("foo"))),
+                  AllOf(QName("nx::bar"), DeclRange(Header.range("bar")))));
+}
+
+TEST_F(SymbolCollectorTest, ReferencesInFriendDecl) {
+  const std::string Header = R"(
+    class X;
+    class Y;
+  )";
+  const std::string Main = R"(
+    class C {
+      friend ::X;
+      friend class Y;
+    };
+  )";
+  CollectorOpts.CountReferences = true;
+  runSymbolCollector(Header, Main);
+  for (const auto &Sym : Symbols)
+    llvm::errs() << Sym.Name << ":   " << Sym.References << "\n";
+  EXPECT_THAT(Symbols, UnorderedElementsAre(AllOf(QName("X"), Refs(1)),
+                                            AllOf(QName("Y"), Refs(1))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang
Index: clangd/index/SymbolCollector.h
===================================================================
--- clangd/index/SymbolCollector.h
+++ clangd/index/SymbolCollector.h
@@ -80,6 +80,12 @@
   Options Opts;
   // Decls referenced from the current TU, flushed on finish().
   llvm::DenseSet<const NamedDecl *> ReferencedDecls;
+  // Maps canonical declaration provided by clang to canonical declaration for
+  // an index symbol, if clangd prefers a different declaration than that
+  // provided by clang. For example, friend declaration might be considered
+  // canonical by clang but should not be considered canonical in the index
+  // unless it's a definition.
+  llvm::DenseMap<const Decl *, const Decl *> CanonicalDecls;
 };
 
 } // namespace clangd
Index: clangd/index/SymbolCollector.cpp
===================================================================
--- clangd/index/SymbolCollector.cpp
+++ clangd/index/SymbolCollector.cpp
@@ -290,6 +290,23 @@
     index::IndexDataConsumer::ASTNodeInfo ASTNode) {
   assert(ASTCtx && PP.get() && "ASTContext and Preprocessor must be set.");
   assert(CompletionAllocator && CompletionTUInfo);
+  assert(ASTNode.OrigD);
+  // If OrigD is an declaration associated with a friend declaration and it's
+  // not a definition, skip it. Note that OrigD is the occurrence that the
+  // collector is currently visiting.
+  if ((ASTNode.OrigD->getFriendObjectKind() !=
+       Decl::FriendObjectKind::FOK_None) &&
+      !(Roles & static_cast<unsigned>(index::SymbolRole::Definition)))
+    return true;
+  // A declaration created for a friend declaration should not be used as the
+  // canonical declaration in the index. If D is a defintion and is not OrigD,
+  // D would have been picked as the canonical declaration, if it has been
+  // visited, or OrigD, which could only be a non-friend declaration as multiple
+  // definitons are not possible, will be preferred.
+  if (D->getFriendObjectKind() != Decl::FriendObjectKind::FOK_None)
+    // Either use a OrigD or a previous recorded canonical declaration as the
+    // canonical declaration.
+    D = CanonicalDecls.try_emplace(D, ASTNode.OrigD).first->second;
   const NamedDecl *ND = llvm::dyn_cast<NamedDecl>(D);
   if (!ND)
     return true;


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