[clangd] Prefer the definition of a TagDecl (e.g. class) as CanonicalDeclaration.

[ioeric]

Summary

Currently, we pick the first declaration of a symbol in a TU, which is considered
canonical in the clangIndex, as the canonical declaration in clangd. This causes
forward declarations that might appear in a random header to be used as a
canonical declaration, which is not desirable for features like go-to-declaration
or include insertion.

For example, for class X, we would consider the forward declaration in fwd.h to
be the canonical declaration, while the preferred canonical declaration should
be the actual definition in x.h.

// fwd.h
class X;  // forward decl

// x.h
class X {};

This patch fixes the issue by making symbol collector favor the actual definition of
a TagDecl (i.e. class/struct/enum/union) found in a header file over the first seen
declarations in a TU. Other symbol types like functions are not handled because
using the first seen declarations as canonical declarations is usually a good
heuristic for them.

The patch also removes the IncludeMainFile option from SymbolCollector because no user of SymbolCollector collects symbols in main files.

[sammccall]

clangd/index/FileIndex.cpp

23 ↗

(On Diff #136085)

this comment doesn't make sense here anymore. I think it's ok just to remove, otherwise add to the documentation of symbolcollector I guess.

clangd/index/SymbolCollector.cpp

260 ↗

(On Diff #136085)

This is a bit subtle and I think comment-worthy.
We're doing a bunch of duplicated work, but at most once because we expect to see only one preferred declaration per TU, because in practice they're definitions?

An alternative would be to have addDeclaration loop through the redecls to try to find a preferred one (and use the passed in one if none is found). This would avoid any duplicated work. Up to you.

289 ↗

(On Diff #136085)

You're addressing this fixme. (I expected it to be done inside addDeclaration, which is why the fixme is here - may still be a good idea as noted above).

unittests/clangd/SymbolCollectorTests.cpp

218 ↗

(On Diff #136085)

please keep this and verify it's not indexed.

222 ↗

(On Diff #136085)

i'm not sure it's necessary to assert the file - it's inconsistent (i don't think there's anything special about this one?) and would add a lot of noise to do consistently.

There's not much risk of an actual collision, right? up to you though

[ioeric]

• Addressed review comments.

clangd/index/SymbolCollector.cpp

260 ↗

(On Diff #136085)

The reason why I am a bit hesitant to use redecls is that we wouldn't know whether all re-declarations would have been indexed (e.g. there might be implicit decls that were dropped by the index library) and passed the filters we had (e.g. shouldFilterDecl). And you are right, the duplicated work should usually be little. I added a comment to clarify the duplicated work.

clang-tools-extra/trunk/clangd/index/FileIndex.cpp

 namespace clangd {
 namespace {
 
 /// Retrieves namespace and class level symbols in \p Decls.
 std::unique_ptr<SymbolSlab> indexAST(ASTContext &Ctx,
                                      std::shared_ptr<Preprocessor> PP,
                                      llvm::ArrayRef<const Decl *> Decls) {
   SymbolCollector::Options CollectorOpts;
-  // Although we do not index symbols in main files (e.g. cpp file), information
-  // in main files like definition locations of class declarations will still be
-  // collected; thus, the index works for go-to-definition.
-  // FIXME(ioeric): get rid of `IndexMainFiles` as this is always set to false.
-  CollectorOpts.IndexMainFiles = false;
   // FIXME(ioeric): we might also want to collect include headers. We would need
   // to make sure all includes are canonicalized (with CanonicalIncludes), which
   // is not trivial given the current way of collecting symbols: we only have
   // AST at this point, but we also need preprocessor callbacks (e.g.
   // CommentHandler for IWYU pragma) to canonicalize includes.
   CollectorOpts.CollectIncludePath = false;
 
   auto Collector = std::make_shared<SymbolCollector>(std::move(CollectorOpts));

clang-tools-extra/trunk/clangd/index/SymbolCollector.h

 #include "clang/Index/IndexSymbol.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
 
 namespace clang {
 namespace clangd {
 
 /// \brief Collect top-level symbols from an AST. These are symbols defined
 /// immediately inside a namespace or a translation unit scope. For example,
-/// symbols in classes or functions are not collected.
+/// symbols in classes or functions are not collected. Note that this only
+/// collects symbols that declared in at least one file that is not a main
+/// file (i.e. the source file corresponding to a TU). These are symbols that
+/// can be imported by other files by including the file where symbols are
+/// declared.
 ///
 /// Clients (e.g. clangd) can use SymbolCollector together with
 /// index::indexTopLevelDecls to retrieve all symbols when the source file is
 /// changed.
 class SymbolCollector : public index::IndexDataConsumer {
 public:
   struct Options {
-    /// Whether to collect symbols in main files (e.g. the source file
-    /// corresponding to a TU).
-    bool IndexMainFiles = false;
     /// When symbol paths cannot be resolved to absolute paths (e.g. files in
     /// VFS that does not have absolute path), combine the fallback directory
     /// with symbols' paths to get absolute paths. This must be an absolute
     /// path.
     std::string FallbackDir;
     /// Specifies URI schemes that can be used to generate URIs for file paths
     /// in symbols. The list of schemes will be tried in order until a working
     /// scheme is found. If no scheme works, symbol location will be dropped.

clang-tools-extra/trunk/clangd/index/SymbolCollector.cpp

if (ND->isInAnonymousNamespace())
     return true;
 
   // We only want:
   //   * symbols in namespaces or translation unit scopes (e.g. no class
   //     members)
   //   * enum constants in unscoped enum decl (e.g. "red" in "enum {red};")
   auto InTopLevelScope = hasDeclContext(
       anyOf(namespaceDecl(), translationUnitDecl(), linkageSpecDecl()));
-  if (match(decl(allOf(Opts.IndexMainFiles
-                           ? decl()
-                           : decl(unless(isExpansionInMainFile())),
+  if (match(decl(allOf(unless(isExpansionInMainFile()),
                        anyOf(InTopLevelScope,
                              hasDeclContext(enumDecl(InTopLevelScope,
                                                      unless(isScoped())))))),
             *ND, *ASTCtx)
           .empty())
     return true;
 
   return false;
getIncludeHeader(const SourceManager &SM, SourceLocation Loc,
   return toURI(SM, SM.getFilename(Loc), Opts);
 }
 
 // Return the symbol location of the given declaration `D`.
 //
 // For symbols defined inside macros:
 //   * use expansion location, if the symbol is formed via macro concatenation.
 //   * use spelling location, otherwise.
-llvm::Optional<SymbolLocation>
-getSymbolLocation(const NamedDecl &D, SourceManager &SM,
-                  const SymbolCollector::Options &Opts,
-                  const clang::LangOptions& LangOpts,
-                  std::string &FileURIStorage) {
+llvm::Optional<SymbolLocation> getSymbolLocation(
+    const NamedDecl &D, SourceManager &SM, const SymbolCollector::Options &Opts,
+    const clang::LangOptions &LangOpts, std::string &FileURIStorage) {
   SourceLocation SpellingLoc = SM.getSpellingLoc(D.getLocation());
   if (D.getLocation().isMacroID()) {
     std::string PrintLoc = SpellingLoc.printToString(SM);
     if (llvm::StringRef(PrintLoc).startswith("<scratch") ||
         llvm::StringRef(PrintLoc).startswith("<command line>")) {
       // We use the expansion location for the following symbols, as spelling
       // locations of these symbols are not interesting to us:
       //   * symbols formed via macro concatenation, the spelling location will
llvm::Optional<SymbolLocation> getSymbolLocation(
   SymbolLocation Result;
   Result.FileURI = FileURIStorage;
   Result.StartOffset = SM.getFileOffset(SpellingLoc);
   Result.EndOffset = Result.StartOffset + clang::Lexer::MeasureTokenLength(
                                               SpellingLoc, SM, LangOpts);
   return std::move(Result);
 }
 
+// Checks whether \p ND is a definition of a TagDecl (class/struct/enum/union)
+// in a header file, in which case clangd would prefer to use ND as a canonical
+// declaration.
+// FIXME: handle symbol types that are not TagDecl (e.g. functions), if using
+// the the first seen declaration as canonical declaration is not a good enough
+// heuristic.
+bool isPreferredDeclaration(const NamedDecl &ND, index::SymbolRoleSet Roles) {
+  using namespace clang::ast_matchers;
+  return (Roles & static_cast<unsigned>(index::SymbolRole::Definition)) &&
+         llvm::isa<TagDecl>(&ND) &&
+         match(decl(isExpansionInMainFile()), ND, ND.getASTContext()).empty();
+}
+
 } // namespace
 
 SymbolCollector::SymbolCollector(Options Opts) : Opts(std::move(Opts)) {}
 
 void SymbolCollector::initialize(ASTContext &Ctx) {
   ASTCtx = &Ctx;
   CompletionAllocator = std::make_shared<GlobalCodeCompletionAllocator>();
   CompletionTUInfo =
bool SymbolCollector::handleDeclOccurence(
 
   if (const NamedDecl *ND = llvm::dyn_cast<NamedDecl>(D)) {
     if (shouldFilterDecl(ND, ASTCtx, Opts))
       return true;
     llvm::SmallString<128> USR;
     if (index::generateUSRForDecl(ND, USR))
       return true;
 
+    const NamedDecl &OriginalDecl = *cast<NamedDecl>(ASTNode.OrigD);
     auto ID = SymbolID(USR);
-    const Symbol* BasicSymbol = Symbols.find(ID);
+    const Symbol *BasicSymbol = Symbols.find(ID);
     if (!BasicSymbol) // Regardless of role, ND is the canonical declaration.
       BasicSymbol = addDeclaration(*ND, std::move(ID));
+    else if (isPreferredDeclaration(OriginalDecl, Roles))
+      // If OriginalDecl is preferred, replace the existing canonical
+      // declaration (e.g. a class forward declaration). There should be at most
+      // one duplicate as we expect to see only one preferred declaration per
+      // TU, because in practice they are definitions.
+      BasicSymbol = addDeclaration(OriginalDecl, std::move(ID));
+
     if (Roles & static_cast<unsigned>(index::SymbolRole::Definition))
-      addDefinition(*cast<NamedDecl>(ASTNode.OrigD), *BasicSymbol);
+      addDefinition(OriginalDecl, *BasicSymbol);
   }
   return true;
 }
 
 const Symbol *SymbolCollector::addDeclaration(const NamedDecl &ND,
                                               SymbolID ID) {
   auto &SM = ND.getASTContext().getSourceManager();
 
   std::string QName;
   llvm::raw_string_ostream OS(QName);
   PrintingPolicy Policy(ASTCtx->getLangOpts());
   // Note that inline namespaces are treated as transparent scopes. This
   // reflects the way they're most commonly used for lookup. Ideally we'd
   // include them, but at query time it's hard to find all the inline
   // namespaces to query: the preamble doesn't have a dedicated list.
   Policy.SuppressUnwrittenScope = true;
   ND.printQualifiedName(OS, Policy);
   OS.flush();
 
   Symbol S;
   S.ID = std::move(ID);
   std::tie(S.Scope, S.Name) = splitQualifiedName(QName);
   S.SymInfo = index::getSymbolInfo(&ND);
   std::string FileURI;
-  // FIXME: we may want a different "canonical" heuristic than clang chooses.
-  // Clang seems to choose the first, which may not have the most information.
   if (auto DeclLoc =
           getSymbolLocation(ND, SM, Opts, ASTCtx->getLangOpts(), FileURI))
     S.CanonicalDeclaration = *DeclLoc;
 
   // Add completion info.
   // FIXME: we may want to choose a different redecl, or combine from several.
   assert(ASTCtx && PP.get() && "ASTContext and Preprocessor must be set.");
   CodeCompletionResult SymbolCompletion(&ND, 0);

clang-tools-extra/trunk/unittests/clangd/SymbolCollectorTests.cpp

 }
 MATCHER_P(Doc, D, "") { return arg.Detail && arg.Detail->Documentation == D; }
 MATCHER_P(Plain, Text, "") { return arg.CompletionPlainInsertText == Text; }
 MATCHER_P(Snippet, S, "") {
   return arg.CompletionSnippetInsertText == S;
 }
 MATCHER_P(QName, Name, "") { return (arg.Scope + arg.Name).str() == Name; }
 MATCHER_P(DeclURI, P, "") { return arg.CanonicalDeclaration.FileURI == P; }
+MATCHER_P(DefURI, P, "") { return arg.Definition.FileURI == P; }
 MATCHER_P(IncludeHeader, P, "") {
   return arg.Detail && arg.Detail->IncludeHeader == P;
 }
 MATCHER_P(DeclRange, Offsets, "") {
   return arg.CanonicalDeclaration.StartOffset == Offsets.first &&
       arg.CanonicalDeclaration.EndOffset == Offsets.second;
 }
 MATCHER_P(DefRange, Offsets, "") {
protected:
   std::string TestFileName;
   std::string TestFileURI;
   SymbolSlab Symbols;
   SymbolCollector::Options CollectorOpts;
   std::unique_ptr<CommentHandler> PragmaHandler;
 };
 
 TEST_F(SymbolCollectorTest, CollectSymbols) {
-  CollectorOpts.IndexMainFiles = true;
   const std::string Header = R"(
     class Foo {
       void f();
     };
     void f1();
     inline void f2() {}
     static const int KInt = 2;
     const char* kStr = "123";
-  )";
-  const std::string Main = R"(
+
     namespace {
     void ff() {} // ignore
     }
 
     void f1() {}
 
     namespace foo {
     // Type alias
const std::string Header = R"(
     namespace baz = bar;
 
     // FIXME: using declaration is not supported as the IndexAction will ignore
     // implicit declarations (the implicit using shadow declaration) by default,
     // and there is no way to customize this behavior at the moment.
     using bar::v2;
     } // namespace foo
   )";
-  runSymbolCollector(Header, Main);
+  runSymbolCollector(Header, /*Main=*/"");
   EXPECT_THAT(Symbols,
               UnorderedElementsAreArray(
                   {QName("Foo"), QName("f1"), QName("f2"), QName("KInt"),
                    QName("kStr"), QName("foo"), QName("foo::bar"),
                    QName("foo::int32"), QName("foo::int32_t"), QName("foo::v1"),
                    QName("foo::bar::v2"), QName("foo::baz")}));
 }
 
 TEST_F(SymbolCollectorTest, Locations) {
-  CollectorOpts.IndexMainFiles = true;
   Annotations Header(R"cpp(
     // Declared in header, defined in main.
     extern int $xdecl[[X]];
     class $clsdecl[[Cls]];
     void $printdecl[[print]]();
 
     // Declared in header, defined nowhere.
     extern int $zdecl[[Z]];
   )cpp");
   Annotations Main(R"cpp(
     int $xdef[[X]] = 42;
     class $clsdef[[Cls]] {};
     void $printdef[[print]]() {}
 
     // Declared/defined in main only.
-    int $y[[Y]];
+    int Y;
   )cpp");
   runSymbolCollector(Header.code(), Main.code());
   EXPECT_THAT(
       Symbols,
       UnorderedElementsAre(
           AllOf(QName("X"), DeclRange(Header.offsetRange("xdecl")),
                 DefRange(Main.offsetRange("xdef"))),
           AllOf(QName("Cls"), DeclRange(Header.offsetRange("clsdecl")),
                 DefRange(Main.offsetRange("clsdef"))),
           AllOf(QName("print"), DeclRange(Header.offsetRange("printdecl")),
                 DefRange(Main.offsetRange("printdef"))),
-          AllOf(QName("Z"), DeclRange(Header.offsetRange("zdecl"))),
-          AllOf(QName("Y"), DeclRange(Main.offsetRange("y")),
-                DefRange(Main.offsetRange("y")))));
+          AllOf(QName("Z"), DeclRange(Header.offsetRange("zdecl")))));
 }
 
 TEST_F(SymbolCollectorTest, SymbolRelativeNoFallback) {
-  CollectorOpts.IndexMainFiles = false;
   runSymbolCollector("class Foo {};", /*Main=*/"");
-  EXPECT_THAT(Symbols,
-              UnorderedElementsAre(AllOf(QName("Foo"), DeclURI(TestHeaderURI))));
+  EXPECT_THAT(Symbols, UnorderedElementsAre(
+                           AllOf(QName("Foo"), DeclURI(TestHeaderURI))));
 }
 
 TEST_F(SymbolCollectorTest, SymbolRelativeWithFallback) {
-  CollectorOpts.IndexMainFiles = false;
   TestHeaderName = "x.h";
   TestFileName = "x.cpp";
   TestHeaderURI = URI::createFile(testPath(TestHeaderName)).toString();
   CollectorOpts.FallbackDir = testRoot();
   runSymbolCollector("class Foo {};", /*Main=*/"");
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(AllOf(QName("Foo"), DeclURI(TestHeaderURI))));
 }
 
 #ifndef LLVM_ON_WIN32
 TEST_F(SymbolCollectorTest, CustomURIScheme) {
-  CollectorOpts.IndexMainFiles = false;
   // Use test URI scheme from URITests.cpp
   CollectorOpts.URISchemes.insert(CollectorOpts.URISchemes.begin(), "unittest");
   TestHeaderName = testPath("test-root/x.h");
   TestFileName = testPath("test-root/x.cpp");
   runSymbolCollector("class Foo {};", /*Main=*/"");
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(AllOf(QName("Foo"), DeclURI("unittest:x.h"))));
 }
 #endif
 
 TEST_F(SymbolCollectorTest, InvalidURIScheme) {
-  CollectorOpts.IndexMainFiles = false;
   // Use test URI scheme from URITests.cpp
   CollectorOpts.URISchemes = {"invalid"};
   runSymbolCollector("class Foo {};", /*Main=*/"");
   EXPECT_THAT(Symbols, UnorderedElementsAre(AllOf(QName("Foo"), DeclURI(""))));
 }
 
 TEST_F(SymbolCollectorTest, FallbackToFileURI) {
-  CollectorOpts.IndexMainFiles = false;
   // Use test URI scheme from URITests.cpp
   CollectorOpts.URISchemes = {"invalid", "file"};
   runSymbolCollector("class Foo {};", /*Main=*/"");
   EXPECT_THAT(Symbols, UnorderedElementsAre(
                            AllOf(QName("Foo"), DeclURI(TestHeaderURI))));
 }
 
 TEST_F(SymbolCollectorTest, IncludeEnums) {
-  CollectorOpts.IndexMainFiles = false;
   const std::string Header = R"(
     enum {
       Red
     };
     enum Color {
       Green
     };
     enum class Color2 {
       Yellow // ignore
     };
     namespace ns {
     enum {
       Black
     };
     }
   )";
   runSymbolCollector(Header, /*Main=*/"");
   EXPECT_THAT(Symbols, UnorderedElementsAre(QName("Red"), QName("Color"),
                                             QName("Green"), QName("Color2"),
                                             QName("ns"), QName("ns::Black")));
 }
 
 TEST_F(SymbolCollectorTest, IgnoreNamelessSymbols) {
-  CollectorOpts.IndexMainFiles = false;
   const std::string Header = R"(
     struct {
       int a;
     } Foo;
   )";
   runSymbolCollector(Header, /*Main=*/"");
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(QName("Foo")));
 }
 
 TEST_F(SymbolCollectorTest, SymbolFormedFromMacro) {
-  CollectorOpts.IndexMainFiles = false;
 
   Annotations Header(R"(
     #define FF(name) \
       class name##_Test {};
 
     $expansion[[FF]](abc);
 
     #define FF2() \
       class $spelling[[Test]] {};
 
     FF2();
   )");
 
   runSymbolCollector(Header.code(), /*Main=*/"");
   EXPECT_THAT(
       Symbols,
       UnorderedElementsAre(
           AllOf(QName("abc_Test"), DeclRange(Header.offsetRange("expansion")),
                 DeclURI(TestHeaderURI)),
           AllOf(QName("Test"), DeclRange(Header.offsetRange("spelling")),
                 DeclURI(TestHeaderURI))));
 }
 
-TEST_F(SymbolCollectorTest, SymbolFormedFromMacroInMainFile) {
-  CollectorOpts.IndexMainFiles = true;
-
-  Annotations Main(R"(
-    #define FF(name) \
-      class name##_Test {};
-
-    $expansion[[FF]](abc);
-
-    #define FF2() \
-      class $spelling[[Test]] {};
-
-    FF2();
-  )");
-  runSymbolCollector(/*Header=*/"", Main.code());
-  EXPECT_THAT(
-      Symbols,
-      UnorderedElementsAre(
-          AllOf(QName("abc_Test"), DeclRange(Main.offsetRange("expansion")),
-                DeclURI(TestFileURI)),
-          AllOf(QName("Test"), DeclRange(Main.offsetRange("spelling")),
-                DeclURI(TestFileURI))));
-}
-
 TEST_F(SymbolCollectorTest, SymbolFormedByCLI) {
-  CollectorOpts.IndexMainFiles = false;
-
   Annotations Header(R"(
     #ifdef NAME
     class $expansion[[NAME]] {};
     #endif
   )");
 
   runSymbolCollector(Header.code(), /*Main=*/"",
                      /*ExtraArgs=*/{"-DNAME=name"});
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(AllOf(
                   QName("name"), DeclRange(Header.offsetRange("expansion")),
                   DeclURI(TestHeaderURI))));
 }
 
 TEST_F(SymbolCollectorTest, IgnoreSymbolsInMainFile) {
-  CollectorOpts.IndexMainFiles = false;
   const std::string Header = R"(
     class Foo {};
     void f1();
     inline void f2() {}
   )";
   const std::string Main = R"(
     namespace {
     void ff() {} // ignore
     }
     void main_f() {} // ignore
     void f1() {}
   )";
   runSymbolCollector(Header, Main);
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(QName("Foo"), QName("f1"), QName("f2")));
 }
 
-TEST_F(SymbolCollectorTest, IncludeSymbolsInMainFile) {
-  CollectorOpts.IndexMainFiles = true;
-  const std::string Header = R"(
-    class Foo {};
-    void f1();
-    inline void f2() {}
-  )";
-  const std::string Main = R"(
-    namespace {
-    void ff() {} // ignore
-    }
-    void main_f() {}
-    void f1() {}
-  )";
-  runSymbolCollector(Header, Main);
-  EXPECT_THAT(Symbols, UnorderedElementsAre(QName("Foo"), QName("f1"),
-                                            QName("f2"), QName("main_f")));
-}
-
 TEST_F(SymbolCollectorTest, IgnoreClassMembers) {
   const std::string Header = R"(
     class Foo {
       void f() {}
       void g();
       static void sf() {}
       static void ssf();
       static int x;
const std::string Header = R"(
     class Foo {};
   )";
   runSymbolCollector(Header, /*Main=*/"");
   EXPECT_THAT(Symbols, UnorderedElementsAre(
                            AllOf(QName("Foo"), DeclURI(TestHeaderURI),
                                  IncludeHeader("\"the/good/header.h\""))));
 }
 
+TEST_F(SymbolCollectorTest, AvoidUsingFwdDeclsAsCanonicalDecls) {
+  CollectorOpts.CollectIncludePath = true;
+  Annotations Header(R"(
+    // Forward declarations of TagDecls.
+    class C;
+    struct S;
+    union U;
+
+    // Canonical declarations.
+    class $cdecl[[C]] {};
+    struct $sdecl[[S]] {};
+    union $udecl[[U]] {int x; bool y;};
+  )");
+  runSymbolCollector(Header.code(), /*Main=*/"");
+  EXPECT_THAT(Symbols,
+              UnorderedElementsAre(
+                  AllOf(QName("C"), DeclURI(TestHeaderURI),
+                        DeclRange(Header.offsetRange("cdecl")),
+                        IncludeHeader(TestHeaderURI), DefURI(TestHeaderURI),
+                        DefRange(Header.offsetRange("cdecl"))),
+                  AllOf(QName("S"), DeclURI(TestHeaderURI),
+                        DeclRange(Header.offsetRange("sdecl")),
+                        IncludeHeader(TestHeaderURI), DefURI(TestHeaderURI),
+                        DefRange(Header.offsetRange("sdecl"))),
+                  AllOf(QName("U"), DeclURI(TestHeaderURI),
+                        DeclRange(Header.offsetRange("udecl")),
+                        IncludeHeader(TestHeaderURI), DefURI(TestHeaderURI),
+                        DefRange(Header.offsetRange("udecl")))));
+}
+
+TEST_F(SymbolCollectorTest, ClassForwardDeclarationIsCanonical) {
+  CollectorOpts.CollectIncludePath = true;
+  runSymbolCollector(/*Header=*/"class X;", /*Main=*/"class X {};");
+  EXPECT_THAT(Symbols, UnorderedElementsAre(AllOf(
+                           QName("X"), DeclURI(TestHeaderURI),
+                           IncludeHeader(TestHeaderURI), DefURI(TestFileURI))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang