[clangd] Improve printing of Objective-C categories and methods

[dgoldman]

Summary

• Categories will now show up as MyClass(Category) instead of Category and MyCategory() instead of (anonymous) in document symbols
• Methods will now be shown as -selector: or +selector: instead of selector: to differentiate between instance and class methods in document symbols

[njames93]

I'm not an objc guy, but can you add a test case demonstrating class(?) methods showing as +name:?

clang-tools-extra/clangd/AST.cpp

224–226

nit: Can make these const auto * as the type is spelt in the initialisation.

[dgoldman]

• Add class method test case + swap to auto

[sammccall]

clang-tools-extra/clangd/AST.cpp

224

I'm not sure this fits with the contract of printName, which really is to print the name of the symbol rather than describe it.

Examples:

• the title of a hovercard for a method will be "instance-method -[foo]" instead of "instance-method foo", which is inconsistent with c/c++
• the title of a hovercard for a category will be "extension PotentiallyLongClassName(CatName)" instead of extension ClassName
• the documentSymbol response will include the extra details in the name field rather than the detail field

We don't actually populate detail in documentSymbol, so maybe we do need a separate function that gives that level of detail.
Though I wonder whether it should mosty just print the decl (e.g. class X{};, @implementation PotentiallyLongClassName(CatName) etc. WDYT?

See also https://github.com/clangd/clangd/issues/520 https://github.com/clangd/clangd/issues/601 though both appear to have stalled.

228

in the other patch this was with -[brackets]

[dgoldman]

clang-tools-extra/clangd/AST.cpp

224

Maybe instead this should be split somehow into a separate specialization for Document Symbols?

e.g.

Hovercards:
instance-method foo
extension (anonymous) (current) or class-extension BTNButtonModel or BTNButtonModel()

Document Symbols:
-method
ClassName(Ext)

Since I think for the case here we would prefer to keep them different. Maybe if the LSP spec differentiated between instance methods and class/static methods -method that wouldn't be necessary? I guess I could revert the Method change here and just keep a special case for categories/class extensions?

The detail work seems worth doing too, but I think we would similarly just put the type information in there (for methods), for categories/class extensions I feel like it would be odd since it would at the very least repeat the name

[dgoldman]

clang-tools-extra/clangd/AST.cpp

228

We don't want to put the full form (e.g. including the container name) here - that would repeat the class name in the document symbols when the methods are already nested under the class.

[dgoldman]

Limit changes to document symbols

[sammccall]

Great, thanks!

clang-tools-extra/clangd/FindSymbols.cpp

176 ↗

(On Diff #326719)

can we motivate this with a comment?
// print X rather than Y

[dgoldman]

Add comment and rebase

clang-tools-extra/clangd/AST.cpp

std::string printName(const ASTContext &Ctx, const NamedDecl &ND) {
   if (auto *UD = llvm::dyn_cast<UsingDirectiveDecl>(&ND)) {
     Out << "using namespace ";
     if (auto *Qual = UD->getQualifier())
       Qual->print(Out, PP);
     UD->getNominatedNamespaceAsWritten()->printName(Out);
     return Out.str();
   }
 
+  if (const ObjCContainerDecl *C = dyn_cast<ObjCContainerDecl>(&ND))
+    return printObjCContainer(*C);
+  if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(&ND)) {
+    Out << (Method->isInstanceMethod() ? '-' : '+');
+    Method->getSelector().print(Out);
+    return Out.str();
+  }
+
   if (isAnonymous(ND.getDeclName())) {
     // Come up with a presentation for an anonymous entity.
     if (isa<NamespaceDecl>(ND))
       return "(anonymous namespace)";
     if (auto *Cls = llvm::dyn_cast<RecordDecl>(&ND)) {
       if (Cls->isLambda())
         return "(lambda)";
       return ("(anonymous " + Cls->getKindName() + ")").str();

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

EXPECT_THAT(
                 Children(AllOf(WithName("Pointer"), WithKind(SymbolKind::Field),
                                SymRange(Main.range("structfield"))))),
           AllOf(WithName("StructDeclaration"), WithKind(SymbolKind::Struct),
                 SymRange(Main.range("forwardstruct"))),
           AllOf(WithName("forwardFunctionDecl"), WithKind(SymbolKind::Function),
                 SymRange(Main.range("forwardfunc")))));
 }
 
+TEST(DocumentSymbolsTest, ObjCCategoriesAndClassExtensions) {
+  TestTU TU;
+  TU.ExtraArgs = {"-xobjective-c++", "-Wno-objc-root-class"};
+  Annotations Main(R"cpp(
+      $Cat[[@interface Cat
+      @end]]
+      $SneakyCat[[@interface Cat (Sneaky)
+      - (id)sneak:(id)behavior;
+      @end]]
+
+      $MeowCat[[@interface Cat ()
+      - (void)meow;
+      @end]]
+      $PurCat[[@interface Cat ()
+      - (void)pur;
+      @end]]
+    )cpp");
+  TU.Code = Main.code().str();
+  EXPECT_THAT(
+      getSymbols(TU.build()),
+      ElementsAre(
+          AllOf(WithName("Cat"), SymRange(Main.range("Cat"))),
+          AllOf(WithName("Cat(Sneaky)"), SymRange(Main.range("SneakyCat")),
+                Children(
+                    AllOf(WithName("-sneak:"), WithKind(SymbolKind::Method)))),
+          AllOf(
+              WithName("Cat()"), SymRange(Main.range("MeowCat")),
+              Children(AllOf(WithName("-meow"), WithKind(SymbolKind::Method)))),
+          AllOf(WithName("Cat()"), SymRange(Main.range("PurCat")),
+                Children(
+                    AllOf(WithName("-pur"), WithKind(SymbolKind::Method))))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang