[clangd] Dont index ObjCCategoryDecls for completion

They are already provided by Sema, deserializing from preamble if need
be. Moreover category names are meaningless outside interface/implementation
context, hence they were only causing noise.

Differential Revision: https://reviews.llvm.org/D104540

clang-tools-extra/clangd/CodeComplete.cpp

@@ -62,6 +62,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Error.h"
@@ -1910,6 +1911,13 @@ bool isIndexedForCodeCompletion(const NamedDecl &ND, ASTContext &ASTCtx) {
   if (isExplicitTemplateSpecialization(&ND))
     return false;
 
+  // Category decls are not useful on their own outside the interface or
+  // implementation blocks. Moreover, sema already provides completion for
+  // these, even if it requires preamble deserialization. So by excluding them
+  // from the index, we reduce the noise in all the other completion scopes.
+  if (llvm::isa<ObjCCategoryDecl>(&ND) || llvm::isa<ObjCCategoryImplDecl>(&ND))
+    return false;
+
   if (InTopLevelScope(ND))
     return true;
 

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

@@ -3221,6 +3221,45 @@ TEST(CompletionTest, NoCrashDueToMacroOrdering) {
               UnorderedElementsAre(Labeled("ECHO(X)"), Labeled("ECHO2(X)")));
 }
 
+TEST(CompletionTest, ObjCCategoryDecls) {
+  TestTU TU;
+  TU.ExtraArgs.push_back("-xobjective-c");
+  TU.HeaderCode = R"objc(
+  @interface Foo
+  @end
+
+  @interface Foo (FooExt1)
+  @end
+
+  @interface Foo (FooExt2)
+  @end
+
+  @interface Bar
+  @end
+
+  @interface Bar (BarExt)
+  @end)objc";
+
+  {
+    Annotations Test(R"objc(
+  @implementation Foo (^)
+  @end
+  )objc");
+    TU.Code = Test.code().str();
+    auto Results = completions(TU, Test.point());
+    EXPECT_THAT(Results.Completions,
+                UnorderedElementsAre(Labeled("FooExt1"), Labeled("FooExt2")));
+  }
+  {
+    Annotations Test(R"objc(
+  @interface Foo (^)
+  @end
+  )objc");
+    TU.Code = Test.code().str();
+    auto Results = completions(TU, Test.point());
+    EXPECT_THAT(Results.Completions, UnorderedElementsAre(Labeled("BarExt")));
+  }
+}
 } // namespace
 } // namespace clangd
 } // namespace clang

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

@@ -552,8 +552,9 @@ TEST_F(SymbolCollectorTest, ObjCSymbols) {
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(
                   QName("Person"), QName("Person::someMethodName:lastName:"),
-                  QName("MyCategory"), QName("Person::someMethodName2:"),
-                  QName("MyProtocol"), QName("MyProtocol::someMethodName3:")));
+                  AllOf(QName("MyCategory"), ForCodeCompletion(false)),
+                  QName("Person::someMethodName2:"), QName("MyProtocol"),
+                  QName("MyProtocol::someMethodName3:")));
 }
 
 TEST_F(SymbolCollectorTest, ObjCPropertyImpl) {