[CodeComplete] Set preferred type for qualified-id

[kadircet]

thanks, lgtm.

one irrelevant question though, it looks like most of the calls to ResultBuilder::setPreferredType performs a !isNull check before hand. should we perform this check implicitly and make the setPreferredType no-op in case of a null type?

[ilya-biryukov]

In D62514#1518941, @kadircet wrote:

thanks, lgtm.

one irrelevant question though, it looks like most of the calls to ResultBuilder::setPreferredType performs a !isNull check before hand. should we perform this check implicitly and make the setPreferredType no-op in case of a null type?

I don't see any reason why not, that could save some typing.
Better yet, we might be able to remove it altogether. Preferred type is also stored in completion context and I'm not sure whether it's ever different from the one in ResultBuilder.

clang/include/clang/Sema/Sema.h

QualType ProduceCtorInitMemberSignatureHelp(Scope *S, Decl *ConstructorDecl,
                                               CXXScopeSpec SS,
                                               ParsedType TemplateTypeTy,
                                               ArrayRef<Expr *> ArgExprs,
                                               IdentifierInfo *II,
                                               SourceLocation OpenParLoc);
   void CodeCompleteInitializer(Scope *S, Decl *D);
   void CodeCompleteAfterIf(Scope *S);
 
-  void CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
-                               bool EnteringContext, QualType BaseType);
+  void CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS, bool EnteringContext,
+                               QualType BaseType, QualType PreferredType);
   void CodeCompleteUsing(Scope *S);
   void CodeCompleteUsingDirective(Scope *S);
   void CodeCompleteNamespaceDecl(Scope *S);
   void CodeCompleteNamespaceAliasDecl(Scope *S);
   void CodeCompleteOperatorName(Scope *S);
   void CodeCompleteConstructorInitializer(
                                 Decl *Constructor,
                                 ArrayRef<CXXCtorInitializer *> Initializers);

clang/lib/Parse/ParseExprCXX.cpp

bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
   }
 
   while (true) {
     if (HasScopeSpecifier) {
       if (Tok.is(tok::code_completion)) {
         // Code completion for a nested-name-specifier, where the code
         // completion token follows the '::'.
         Actions.CodeCompleteQualifiedId(getCurScope(), SS, EnteringContext,
-                                        ObjectType.get());
+                                        ObjectType.get(),
+                                        PreferredType.get(SS.getBeginLoc()));
         // Include code completion token into the range of the scope otherwise
         // when we try to annotate the scope tokens the dangling code completion
         // token will cause assertion in
         // Preprocessor::AnnotatePreviousCachedTokens.
         SS.setEndLoc(Tok.getLocation());
         cutOffParsing();
         return true;
       }

clang/lib/Sema/SemaCodeComplete.cpp

void Sema::CodeCompleteAfterIf(Scope *S) {
   if (CodeCompleter->includeMacros())
     AddMacroResults(PP, Results, CodeCompleter->loadExternal(), false);
 
   HandleCodeCompleteResults(this, CodeCompleter, Results.getCompletionContext(),
                             Results.data(), Results.size());
 }
 
 void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
-                                   bool EnteringContext, QualType BaseType) {
+                                   bool EnteringContext, QualType BaseType,
+                                   QualType PreferredType) {
   if (SS.isEmpty() || !CodeCompleter)
     return;
 
   // We want to keep the scope specifier even if it's invalid (e.g. the scope
   // "a::b::" is not corresponding to any context/namespace in the AST), since
   // it can be useful for global code completion which have information about
   // contexts/symbols that are not in the AST.
   if (SS.isInvalid()) {
-    CodeCompletionContext CC(CodeCompletionContext::CCC_Symbol);
+    CodeCompletionContext CC(CodeCompletionContext::CCC_Symbol, PreferredType);
     CC.setCXXScopeSpecifier(SS);
     // As SS is invalid, we try to collect accessible contexts from the current
     // scope with a dummy lookup so that the completion consumer can try to
     // guess what the specified scope is.
     ResultBuilder DummyResults(*this, CodeCompleter->getAllocator(),
                                CodeCompleter->getCodeCompletionTUInfo(), CC);
+    if (!PreferredType.isNull())
+      DummyResults.setPreferredType(PreferredType);
     if (S->getEntity()) {
       CodeCompletionDeclConsumer Consumer(DummyResults, S->getEntity(),
                                           BaseType);
       LookupVisibleDecls(S, LookupOrdinaryName, Consumer,
                          /*IncludeGlobalScope=*/false,
                          /*LoadExternal=*/false);
     }
     HandleCodeCompleteResults(this, CodeCompleter,
                               DummyResults.getCompletionContext(), nullptr, 0);
     return;
   }
   // Always pretend to enter a context to ensure that a dependent type
   // resolves to a dependent record.
   DeclContext *Ctx = computeDeclContext(SS, /*EnteringContext=*/true);
   if (!Ctx)
     return;
 
   // Try to instantiate any non-dependent declaration contexts before
   // we look in them.
   if (!isDependentScopeSpecifier(SS) && RequireCompleteDeclContext(SS, Ctx))
     return;
 
-  ResultBuilder Results(*this, CodeCompleter->getAllocator(),
-                        CodeCompleter->getCodeCompletionTUInfo(),
-                        CodeCompletionContext::CCC_Symbol);
+  ResultBuilder Results(
+      *this, CodeCompleter->getAllocator(),
+      CodeCompletionContext(CodeCompletionContext::CCC_Symbol, PreferredType));
+  if (!PreferredType.isNull())
+    Results.setPreferredType(PreferredType);
   Results.EnterNewScope();
 
   // The "template" keyword can follow "::" in the grammar, but only
   // put it into the grammar if the nested-name-specifier is dependent.
   NestedNameSpecifier *NNS = SS.getScopeRep();
   if (!Results.empty() && NNS->isDependent())
     Results.AddResult("template");
 

clang/unittests/Sema/CodeCompleteTest.cpp

struct class_members {
       void bar(int, volatile double *, int, int);
     };
     void test() {
       bar(10, ^(^(^(^vec^tor^().^da^ta^()))));
       class_members().bar(10, ^(^(^(^vec^tor^().^da^ta^()))));
     }
   )cpp";
   EXPECT_THAT(collectPreferredTypes(Code), Each("volatile double *"));
+
+  Code = R"cpp(
+    namespace ns {
+      struct vector {
+      };
+    }
+    void accepts_vector(ns::vector);
+
+    void test() {
+      accepts_vector(^::^ns::^vector());
+    }
+  )cpp";
+  EXPECT_THAT(collectPreferredTypes(Code), Each("ns::vector"));
 }
 } // namespace