[clang][Index] Visit UsingDecls and generate USRs for them

Summary:
Add indexing of UsingDecl itself.
Also enable generation of USRs for UsingDecls, using the qualified name of the
decl.

Reviewers: ilya-biryukov, akyrtzi

Subscribers: arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58340

llvm-svn: 354878

clang/lib/Index/IndexDecl.cpp

@@ -580,9 +580,10 @@ public:
   }
 
   bool VisitUsingDecl(const UsingDecl *D) {
+    IndexCtx.handleDecl(D);
+
     const DeclContext *DC = D->getDeclContext()->getRedeclContext();
     const NamedDecl *Parent = dyn_cast<NamedDecl>(DC);
-
     IndexCtx.indexNestedNameSpecifierLoc(D->getQualifierLoc(), Parent,
                                          D->getLexicalDeclContext());
     for (const auto *I : D->shadows())

clang/lib/Index/IndexSymbol.cpp

@@ -316,6 +316,10 @@ SymbolInfo index::getSymbolInfo(const Decl *D) {
       Info.Lang = SymbolLanguage::CXX;
       Info.Properties |= (SymbolPropertySet)SymbolProperty::Generic;
       break;
+    case Decl::Using:
+      Info.Kind = SymbolKind::Using;
+      Info.Lang = SymbolLanguage::CXX;
+      break;
     case Decl::Binding:
       Info.Kind = SymbolKind::Variable;
       Info.Lang = SymbolLanguage::CXX;

clang/lib/Index/USRGeneration.cpp

@@ -111,7 +111,12 @@ public:
   }
 
   void VisitUsingDecl(const UsingDecl *D) {
-    IgnoreResults = true;
+    VisitDeclContext(D->getDeclContext());
+    Out << "@UD@";
+
+    bool EmittedDeclName = !EmitDeclName(D);
+    assert(EmittedDeclName && "EmitDeclName can not fail for UsingDecls");
+    (void)EmittedDeclName;
   }
 
   bool ShouldGenerateLocation(const NamedDecl *D);

clang/test/Index/usrs.cpp

@@ -158,7 +158,7 @@ __m128 vectorOverload(__m128 f);
 // CHECK: usrs.cpp c:@NA@foo_alias
 // CHECK-NOT: foo
 // CHECK: usrs.cpp c:@NA@foo_alias2
-// CHECK-NOT: ClsB
+// CHECK: usrs.cpp c:@UD@ClsB Extent=[64:1 - 64:16]
 // CHECK: usrs.cpp c:@NA@foo_alias3
 // CHECK: usrs.cpp c:@aN Extent=[68:1 - 73:2]
 // CHECK: usrs.cpp c:usrs.cpp@aN@S@RDar9371763_Foo Extent=[69:1 - 72:2]

clang/unittests/Index/IndexTests.cpp

@@ -57,6 +57,7 @@ struct TestSymbol {
   std::string QName;
   Position WrittenPos;
   Position DeclPos;
+  SymbolInfo SymInfo;
   // FIXME: add more information.
 };
 
@@ -78,6 +79,7 @@ public:
     if (!ND)
       return true;
     TestSymbol S;
+    S.SymInfo = getSymbolInfo(D);
     S.QName = ND->getQualifiedNameAsString();
     S.WrittenPos = Position::fromSourceLocation(Loc, AST->getSourceManager());
     S.DeclPos =
@@ -140,6 +142,7 @@ using testing::UnorderedElementsAre;
 MATCHER_P(QName, Name, "") { return arg.QName == Name; }
 MATCHER_P(WrittenAt, Pos, "") { return arg.WrittenPos == Pos; }
 MATCHER_P(DeclAt, Pos, "") { return arg.DeclPos == Pos; }
+MATCHER_P(Kind, SymKind, "") { return arg.SymInfo.Kind == SymKind; }
 
 TEST(IndexTest, Simple) {
   auto Index = std::make_shared<Indexer>();
@@ -240,6 +243,20 @@ TEST(IndexTest, IndexTypeParmDecls) {
                     Contains(QName("Foo::C")), Contains(QName("Foo::NoRef"))));
 }
 
+TEST(IndexTest, UsingDecls) {
+  std::string Code = R"cpp(
+    void foo(int bar);
+    namespace std {
+      using ::foo;
+    }
+  )cpp";
+  auto Index = std::make_shared<Indexer>();
+  IndexingOptions Opts;
+  tooling::runToolOnCode(new IndexAction(Index, Opts), Code);
+  EXPECT_THAT(Index->Symbols,
+              Contains(AllOf(QName("std::foo"), Kind(SymbolKind::Using))));
+}
+
 } // namespace
 } // namespace index
 } // namespace clang