[clangd] Be more explicit on testing the optional DefLoc in LocatedSymbol.

[hokein]

Summary

And also fix a bug where we may return a meaningless location.

[kadircet]

clang-tools-extra/clangd/XRefs.cpp

428–429

this is the 3rd time we are checking for Sym.Definition, what about moving the check on line 410 to down here? Then it would look something like this:

LocatedSymbol Located;
Located.PreferredDeclaration = DeclLoc;
if (Sym.Definition) {
      auto MaybeDefLoc = indexToLSPLocation(Sym.Definition, MainFilePath);
      if (!MaybeDefLoc) {
        log("locateSymbolNamedTextuallyAt: {0}", MaybeDefLoc.takeError());
        return;
      }
      Located.PreferredDeclaration = *MaybeDefLoc;
      Located.Definition = *MaybeDefLoc;
}
Located.Name = (Sym.Name + Sym.TemplateSpecializationArgs).str();

clang-tools-extra/clangd/unittests/XRefsTests.cpp

285

i am not sure if this change is aligned with the whole idea. we are trying to make the matcher more explicit, so if user wants to assert on the definition being equal to some range I think they should be explicitly specifying it. so I believe this should keep passing llvm::None to underlying matcher.

I know it is likely more work than this version, but otherwise we are not really making it explicit.

[hokein]

address comment.

[hokein]

clang-tools-extra/clangd/XRefs.cpp

428–429

good point.

clang-tools-extra/clangd/unittests/XRefsTests.cpp

285

yeah, it seems odd. I think this function is used as a syntax sugar to check LocatedSymbol has the *same* decl/def range, most callers have this assumptions.

options:

1. keeps it as is, and rename it to something like SymWithSameDeclDefRange (a better name is welcome);
2. remove it, and use the 3-arg matcher above, callers have to be more verbose (passing decl/def ranges explicitly, even they are the same), and we have 15 references;

1 is my preference, what do you think?

[kadircet]

clang-tools-extra/clangd/unittests/XRefsTests.cpp

285

yeah, it seems odd. I think this function is used as a syntax sugar to check LocatedSymbol has the *same* decl/def range, most callers have this assumptions.

my reading of the previous state was:

the real matcher treated llvm::None on the last parameter as a Dont care, it was basically ignoring the definition. hence the two parameter version was used in places where people didn't care about definition range (or even its existence). so this patch is changing the behaviour of this two parameter version from don't care to make sure they are equal, i am not saying that's a bad thing but it just feels like more implicit (which is against the idea of the patch).

keeps it as is, and rename it to something like SymWithSameDeclDefRange (a better name is welcome);

renaming would be one way of dealing with implicitness here. i am just not sure if it is really worth it though. I don't really think the existing call sites had the idea of make sure def and decl range are identical in mind. so I would opt for 2nd option you proposed if that's ok with you.

[hokein]

remove the 2-arg Sym matcher.

[kadircet]

thanks, lgtm!

clang-tools-extra/clangd/XRefs.cpp

if (Sym.SymInfo.Kind == index::SymbolKind::Constructor)
       return;
 
     auto MaybeDeclLoc =
         indexToLSPLocation(Sym.CanonicalDeclaration, MainFilePath);
     if (!MaybeDeclLoc) {
       log("locateSymbolNamedTextuallyAt: {0}", MaybeDeclLoc.takeError());
       return;
     }
-    Location DeclLoc = *MaybeDeclLoc;
-    Location DefLoc;
+    LocatedSymbol Located;
+    Located.PreferredDeclaration = *MaybeDeclLoc;
+    Located.Name = (Sym.Name + Sym.TemplateSpecializationArgs).str();
     if (Sym.Definition) {
       auto MaybeDefLoc = indexToLSPLocation(Sym.Definition, MainFilePath);
       if (!MaybeDefLoc) {
         log("locateSymbolNamedTextuallyAt: {0}", MaybeDefLoc.takeError());
         return;
       }
-      DefLoc = *MaybeDefLoc;
+      Located.PreferredDeclaration = *MaybeDefLoc;
+      Located.Definition = *MaybeDefLoc;
     }
 
     if (ScoredResults.size() >= 3) {
       // If we have more than 3 results, don't return anything,
       // as confidence is too low.
       // FIXME: Alternatively, try a stricter query?
       TooMany = true;
       return;
     }
 
-    LocatedSymbol Located;
-    Located.Name = (Sym.Name + Sym.TemplateSpecializationArgs).str();
-    Located.PreferredDeclaration = bool(Sym.Definition) ? DefLoc : DeclLoc;
-    Located.Definition = DefLoc;
-
     SymbolQualitySignals Quality;
     Quality.merge(Sym);
     SymbolRelevanceSignals Relevance;
     Relevance.Name = Sym.Name;
     Relevance.Query = SymbolRelevanceSignals::Generic;
     Relevance.merge(Sym);
     auto Score =
         evaluateSymbolAndRelevance(Quality.evaluate(), Relevance.evaluate());
     dlog("locateSymbolNamedTextuallyAt: {0}{1} = {2}\n{3}{4}\n", Sym.Scope,

clang-tools-extra/clangd/unittests/XRefsTests.cpp

 namespace clang {
 namespace clangd {
 namespace {
 
 using ::testing::ElementsAre;
 using ::testing::Eq;
 using ::testing::IsEmpty;
 using ::testing::Matcher;
+using ::testing::UnorderedElementsAre;
 using ::testing::UnorderedElementsAreArray;
 
 MATCHER_P2(FileRange, File, Range, "") {
   return Location{URIForFile::canonicalize(File, testRoot()), Range} == arg;
 }
 
 // Extracts ranges from an annotated example, and constructs a matcher for a
 // highlight set. Ranges should be named $read/$write as appropriate.
if (Name != arg.Name) {
     *result_listener << "Name is " << arg.Name;
     return false;
   }
   if (Decl != arg.PreferredDeclaration.range) {
     *result_listener << "Declaration is "
                      << llvm::to_string(arg.PreferredDeclaration);
     return false;
   }
+  if (!Def && !arg.Definition)
+    return true;
   if (Def && !arg.Definition) {
     *result_listener << "Has no definition";
     return false;
   }
-  if (Def && arg.Definition->range != *Def) {
+  if (!Def && arg.Definition) {
+    *result_listener << "Definition is " << llvm::to_string(arg.Definition);
+    return false;
+  }
+  if (arg.Definition->range != *Def) {
     *result_listener << "Definition is " << llvm::to_string(arg.Definition);
     return false;
   }
   return true;
 }
 ::testing::Matcher<LocatedSymbol> Sym(std::string Name, Range Decl) {
-  return Sym(Name, Decl, llvm::None);
+  return Sym(Name, Decl, Decl);
 }
 MATCHER_P(Sym, Name, "") { return arg.Name == Name; }
 
 MATCHER_P(RangeIs, R, "") { return arg.range == R; }
 
 TEST(LocateSymbol, WithIndex) {
   Annotations SymbolHeader(R"cpp(
         class $forward[[Forward]];
TEST(LocateSymbol, Ambiguous) {
   EXPECT_THAT(locateSymbolAt(AST, T.point("6")), ElementsAre(Sym("str")));
   // FIXME: Target the constructor as well.
   EXPECT_THAT(locateSymbolAt(AST, T.point("7")), ElementsAre(Sym("abc")));
   // FIXME: Target the constructor as well.
   EXPECT_THAT(locateSymbolAt(AST, T.point("8")), ElementsAre(Sym("abcd")));
   // FIXME: Target the constructor as well.
   EXPECT_THAT(locateSymbolAt(AST, T.point("9")), ElementsAre(Sym("Foo")));
   EXPECT_THAT(locateSymbolAt(AST, T.point("10")),
-              ElementsAre(Sym("Foo", T.range("ConstructorLoc"))));
+              ElementsAre(Sym("Foo", T.range("ConstructorLoc"), llvm::None)));
   EXPECT_THAT(locateSymbolAt(AST, T.point("11")),
-              ElementsAre(Sym("Foo", T.range("ConstructorLoc"))));
+              ElementsAre(Sym("Foo", T.range("ConstructorLoc"), llvm::None)));
   // These assertions are unordered because the order comes from
   // CXXRecordDecl::lookupDependentName() which doesn't appear to provide
   // an order guarantee.
   EXPECT_THAT(locateSymbolAt(AST, T.point("12")),
-              UnorderedElementsAre(Sym("bar", T.range("NonstaticOverload1")),
-                                   Sym("bar", T.range("NonstaticOverload2"))));
-  EXPECT_THAT(locateSymbolAt(AST, T.point("13")),
-              UnorderedElementsAre(Sym("baz", T.range("StaticOverload1")),
-                                   Sym("baz", T.range("StaticOverload2"))));
+              UnorderedElementsAre(
+                  Sym("bar", T.range("NonstaticOverload1"), llvm::None),
+                  Sym("bar", T.range("NonstaticOverload2"), llvm::None)));
+  EXPECT_THAT(
+      locateSymbolAt(AST, T.point("13")),
+      UnorderedElementsAre(Sym("baz", T.range("StaticOverload1"), llvm::None),
+                           Sym("baz", T.range("StaticOverload2"), llvm::None)));
 }
 
 TEST(LocateSymbol, TextualDependent) {
   // Put the declarations in the header to make sure we are
   // finding them via the index heuristic and not the
   // nearby-ident heuristic.
   Annotations Header(R"cpp(
         struct Foo {
TEST(LocateSymbol, TextualDependent) {
   TU.Code = std::string(Source.code());
   TU.HeaderCode = std::string(Header.code());
   auto AST = TU.build();
   auto Index = TU.index();
   // Need to use locateSymbolAt() since we are testing an
   // interaction between locateASTReferent() and
   // locateSymbolNamedTextuallyAt().
   auto Results = locateSymbolAt(AST, Source.point(), Index.get());
-  EXPECT_THAT(Results, UnorderedElementsAre(
-                           Sym("uniqueMethodName", Header.range("FooLoc")),
-                           Sym("uniqueMethodName", Header.range("BarLoc"))));
+  EXPECT_THAT(Results,
+              UnorderedElementsAre(
+                  Sym("uniqueMethodName", Header.range("FooLoc"), llvm::None),
+                  Sym("uniqueMethodName", Header.range("BarLoc"), llvm::None)));
 }
 
 TEST(LocateSymbol, TemplateTypedefs) {
   auto T = Annotations(R"cpp(
     template <class T> struct function {};
     template <class T> using callback = function<T()>;
 
     c^allback<int> foo;
TEST(LocateSymbol, WithPreamble) {
 
   // Only preamble is built, and no AST is built in this request.
   Server.addDocument(FooCpp, FooWithoutHeader.code(), "null",
                      WantDiagnostics::No);
   // We build AST here, and it should use the latest preamble rather than the
   // stale one.
   EXPECT_THAT(
       cantFail(runLocateSymbolAt(Server, FooCpp, FooWithoutHeader.point())),
-      ElementsAre(Sym("foo", FooWithoutHeader.range())));
+      ElementsAre(Sym("foo", FooWithoutHeader.range(), llvm::None)));
 
   // Reset test environment.
   runAddDocument(Server, FooCpp, FooWithHeader.code());
   // Both preamble and AST are built in this request.
   Server.addDocument(FooCpp, FooWithoutHeader.code(), "null",
                      WantDiagnostics::Yes);
   // Use the AST being built in above request.
   EXPECT_THAT(
       cantFail(runLocateSymbolAt(Server, FooCpp, FooWithoutHeader.point())),
-      ElementsAre(Sym("foo", FooWithoutHeader.range())));
+      ElementsAre(Sym("foo", FooWithoutHeader.range(), llvm::None)));
 }
 
 TEST(LocateSymbol, NearbyTokenSmoke) {
   auto T = Annotations(R"cpp(
     // prints e^rr and crashes
     void die(const char* [[err]]);
   )cpp");
   auto AST = TestTU::withCode(T.code()).build();