[clangd] Do not query index for new name completions.

[sammccall]

(This looks good, of course the Sema patch needs to land first!)

clangd/CodeComplete.cpp

651

consider Recovery, NaturalLanguage there too? and maybe Other?

[ilya-biryukov]

A drive-by NIT ;-)

clangd/CodeComplete.cpp

651

NIT: use FIXME to be consistent with the rest of clangd

[kadircet]

• Rebase and take in new changes.

[kadircet]

• Address comments.

[kadircet]

• Use new enum types.

[sammccall]

unittests/clangd/CodeCompleteTests.cpp

2180

Any need to actually enable this option, or just copied from above test?

(If not, no need to pass opts at all, it'll be defaulted).

[kadircet]

• Change symbols name to get a match from index.

unittests/clangd/CodeCompleteTests.cpp

2180

Actually it was needed to check we don't add suggest items from cross namespaces, but I had an error in symbols name, changing that to start with "n" as well.

clangd/CodeComplete.cpp

bool contextAllowsIndex(enum CodeCompletionContext::Kind K) {
   case CodeCompletionContext::CCC_Expression:
   case CodeCompletionContext::CCC_ObjCMessageReceiver:
   case CodeCompletionContext::CCC_EnumTag:
   case CodeCompletionContext::CCC_UnionTag:
   case CodeCompletionContext::CCC_ClassOrStructTag:
   case CodeCompletionContext::CCC_ObjCProtocolName:
   case CodeCompletionContext::CCC_Namespace:
   case CodeCompletionContext::CCC_Type:
-  case CodeCompletionContext::CCC_Name: // FIXME: why does ns::^ give this?
-  case CodeCompletionContext::CCC_PotentiallyQualifiedName:
   case CodeCompletionContext::CCC_ParenthesizedExpression:
   case CodeCompletionContext::CCC_ObjCInterfaceName:
   case CodeCompletionContext::CCC_ObjCCategoryName:
+  case CodeCompletionContext::CCC_ExistingName:
+  case CodeCompletionContext::CCC_PotentiallyQualifiedExistingName:
     return true;
-  case CodeCompletionContext::CCC_Other: // Be conservative.
   case CodeCompletionContext::CCC_OtherWithMacros:
   case CodeCompletionContext::CCC_DotMemberAccess:
   case CodeCompletionContext::CCC_ArrowMemberAccess:
   case CodeCompletionContext::CCC_ObjCPropertyAccess:
   case CodeCompletionContext::CCC_MacroName:
   case CodeCompletionContext::CCC_MacroNameUse:
   case CodeCompletionContext::CCC_PreprocessorExpression:
   case CodeCompletionContext::CCC_PreprocessorDirective:
-  case CodeCompletionContext::CCC_NaturalLanguage:
   case CodeCompletionContext::CCC_SelectorName:
   case CodeCompletionContext::CCC_TypeQualifiers:
   case CodeCompletionContext::CCC_ObjCInstanceMessage:
   case CodeCompletionContext::CCC_ObjCClassMessage:
   case CodeCompletionContext::CCC_IncludedFile:
+  // FIXME: Provide identifier based completions for the following contexts:
+  case CodeCompletionContext::CCC_Other: // Be conservative.
+  case CodeCompletionContext::CCC_NaturalLanguage:
   case CodeCompletionContext::CCC_Recovery:
+  case CodeCompletionContext::CCC_NewName:
+  case CodeCompletionContext::CCC_PotentiallyQualifiedNewName:
     return false;
   }
   llvm_unreachable("unknown code completion context");
 }
 
 // Some member calls are blacklisted because they're so rarely useful.
 static bool isBlacklistedMember(const NamedDecl &D) {
   // Destructor completion is rarely useful, and works inconsistently.

clangd/index/SymbolCollector.cpp

if (auto DeclLoc = getTokenLocation(findNameLoc(&ND), SM, Opts,
     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.");
   // We use the primary template, as clang does during code completion.
   CodeCompletionResult SymbolCompletion(&getTemplateOrThis(ND), 0);
   const auto *CCS = SymbolCompletion.CreateCodeCompletionString(
-      *ASTCtx, *PP, CodeCompletionContext::CCC_Name, *CompletionAllocator,
-      *CompletionTUInfo,
+      *ASTCtx, *PP, CodeCompletionContext::CCC_ExistingName,
+      *CompletionAllocator, *CompletionTUInfo,
       /*IncludeBriefComments*/ false);
   std::string Signature;
   std::string SnippetSuffix;
   getSignature(*CCS, &Signature, &SnippetSuffix);
   std::string Documentation =
       formatDocumentation(*CCS, getDocComment(Ctx, SymbolCompletion,
                                               /*CommentsFromHeaders=*/true));
   std::string ReturnType = getReturnType(*CCS);

unittests/clangd/CodeCompleteTests.cpp

)cpp",
                              {cls("nx::Clangd1"), cls("nx::Clangd2")}, Opts);
   // Although Clangd1 is from another namespace, Sema tells us it's in-scope and
   // needs no qualifier.
   EXPECT_THAT(Results.Completions,
               UnorderedElementsAre(AllOf(Qualifier(""), Named("Clangd1")),
                                    AllOf(Qualifier("nx::"), Named("Clangd2"))));
 }
 
+TEST(CompletionTest, NoCompletionsForNewNames) {
+  clangd::CodeCompleteOptions Opts;
+  Opts.AllScopes = true;
+  auto Results = completions(R"cpp(
+      void f() { int n^ }
+    )cpp",
+                             {cls("naber"), cls("nx::foo")}, Opts);
+  EXPECT_THAT(Results.Completions, UnorderedElementsAre());
+}
 } // namespace
 } // namespace clangd
 } // namespace clang