[clang][CodeComplete] Do not suggest unqualified members in explicit-object member functions (#153760)

Fixes #141291

Author: MythreyaK

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

@@ -4473,6 +4473,65 @@ TEST(CompletionTest, SkipExplicitObjectParameter) {
                                   snippetSuffix(""))));
   }
 }
+
+TEST(CompletionTest, MemberAccessInExplicitObjMemfn) {
+  Annotations Code(R"cpp(
+    struct A {
+      int member {};
+      int memberFnA(int a);
+      int memberFnA(this A&, float a);
+
+      void foo(this A& self) {
+        // Should not offer any members here, since 
+        // it needs to be referenced through `self`.
+        mem$c1^;
+        // should offer all results
+        self.mem$c2^;
+
+        [&]() {
+          // should not offer any results
+          mem$c3^;
+        }();
+      }
+    };
+  )cpp");
+
+  auto TU = TestTU::withCode(Code.code());
+  TU.ExtraArgs = {"-std=c++23"};
+
+  auto Preamble = TU.preamble();
+  ASSERT_TRUE(Preamble);
+
+  CodeCompleteOptions Opts{};
+
+  MockFS FS;
+  auto Inputs = TU.inputs(FS);
+
+  {
+    auto Result = codeComplete(testPath(TU.Filename), Code.point("c1"),
+                               Preamble.get(), Inputs, Opts);
+
+    EXPECT_THAT(Result.Completions, ElementsAre());
+  }
+  {
+    auto Result = codeComplete(testPath(TU.Filename), Code.point("c2"),
+                               Preamble.get(), Inputs, Opts);
+
+    EXPECT_THAT(
+        Result.Completions,
+        UnorderedElementsAre(named("member"),
+                             AllOf(named("memberFnA"), signature("(int a)"),
+                                   snippetSuffix("(${1:int a})")),
+                             AllOf(named("memberFnA"), signature("(float a)"),
+                                   snippetSuffix("(${1:float a})"))));
+  }
+  {
+    auto Result = codeComplete(testPath(TU.Filename), Code.point("c3"),
+                               Preamble.get(), Inputs, Opts);
+
+    EXPECT_THAT(Result.Completions, ElementsAre());
+  }
+}
 } // namespace
 } // namespace clangd
 } // namespace clang

clang/lib/Sema/SemaCodeComplete.cpp

@@ -197,6 +197,9 @@ class ResultBuilder {
   /// Whether the \p ObjectTypeQualifiers field is active.
   bool HasObjectTypeQualifiers;
 
+  // Whether the member function is using an explicit object parameter
+  bool IsExplicitObjectMemberFunction;
+
   /// The selector that we prefer.
   Selector PreferredSelector;
 
@@ -218,8 +221,8 @@ class ResultBuilder {
                          LookupFilter Filter = nullptr)
       : SemaRef(SemaRef), Allocator(Allocator), CCTUInfo(CCTUInfo),
         Filter(Filter), AllowNestedNameSpecifiers(false),
-        HasObjectTypeQualifiers(false), CompletionContext(CompletionContext),
-        ObjCImplementation(nullptr) {
+        HasObjectTypeQualifiers(false), IsExplicitObjectMemberFunction(false),
+        CompletionContext(CompletionContext), ObjCImplementation(nullptr) {
     // If this is an Objective-C instance method definition, dig out the
     // corresponding implementation.
     switch (CompletionContext.getKind()) {
@@ -275,6 +278,10 @@ class ResultBuilder {
     HasObjectTypeQualifiers = true;
   }
 
+  void setExplicitObjectMemberFn(bool IsExplicitObjectFn) {
+    IsExplicitObjectMemberFunction = IsExplicitObjectFn;
+  }
+
   /// Set the preferred selector.
   ///
   /// When an Objective-C method declaration result is added, and that
@@ -1428,6 +1435,15 @@ void ResultBuilder::AddResult(Result R, DeclContext *CurContext,
 
   AdjustResultPriorityForDecl(R);
 
+  if (IsExplicitObjectMemberFunction &&
+      R.Kind == CodeCompletionResult::RK_Declaration &&
+      (isa<CXXMethodDecl>(R.Declaration) || isa<FieldDecl>(R.Declaration))) {
+    // If result is a member in the context of an explicit-object member
+    // function, drop it because it must be accessed through the object
+    // parameter
+    return;
+  }
+
   if (HasObjectTypeQualifiers)
     if (const auto *Method = dyn_cast<CXXMethodDecl>(R.Declaration))
       if (Method->isInstance()) {
@@ -4636,12 +4652,19 @@ void SemaCodeCompletion::CodeCompleteOrdinaryName(
     break;
   }
 
-  // If we are in a C++ non-static member function, check the qualifiers on
-  // the member function to filter/prioritize the results list.
   auto ThisType = SemaRef.getCurrentThisType();
-  if (!ThisType.isNull())
+  if (ThisType.isNull()) {
+    // check if function scope is an explicit object function
+    if (auto *MethodDecl = llvm::dyn_cast_if_present<CXXMethodDecl>(
+            SemaRef.getCurFunctionDecl()))
+      Results.setExplicitObjectMemberFn(
+          MethodDecl->isExplicitObjectMemberFunction());
+  } else {
+    // If we are in a C++ non-static member function, check the qualifiers on
+    // the member function to filter/prioritize the results list.
     Results.setObjectTypeQualifiers(ThisType->getPointeeType().getQualifiers(),
                                     VK_LValue);
+  }
 
   CodeCompletionDeclConsumer Consumer(Results, SemaRef.CurContext);
   SemaRef.LookupVisibleDecls(S, SemaRef.LookupOrdinaryName, Consumer,

clang/test/CodeCompletion/skip-explicit-object-parameter.cpp renamed to clang/test/CodeCompletion/cpp23-explicit-object.cpp

@@ -42,7 +42,42 @@ int func3() {
 
 int func4() {
   // TODO (&A::foo)(
-  (&A::bar)(
+  (&A::bar)()
 }
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-2):13 -std=c++23 %s | FileCheck -check-prefix=CHECK-CC5 %s
 // CHECK-CC5: OVERLOAD: [#void#](<#A#>, int)
+
+struct C {
+  int member {};
+  int memberFnA(int a);
+  int memberFnA(this C&, float a);
+
+  void foo(this C& self) {
+    // Should not offer any members here, since 
+    // it needs to be referenced through `self`.
+    mem
+    // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-1):8 -std=c++23 %s | FileCheck --allow-empty %s
+    // CHECK-NOT: COMPLETION: member : [#int#]member
+    // CHECK-NOT: COMPLETION: memberFnA : [#int#]memberFnA(<#int a#>)
+    // CHECK-NOT: COMPLETION: memberFnA : [#int#]memberFnA(<#float a#>)
+  }
+  void bar(this C& self) {
+    // should offer all results
+    self.mem
+    // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-1):13 -std=c++23 %s | FileCheck -check-prefix=CHECK-CC6 %s
+    // CHECK-CC6: COMPLETION: member : [#int#]member
+    // CHECK-CC6: COMPLETION: memberFnA : [#int#]memberFnA(<#int a#>)
+    // CHECK-CC6: COMPLETION: memberFnA : [#int#]memberFnA(<#float a#>)
+  }
+  void baz(this C& self) {
+    [&]() {
+      // Should not offer any results
+      mem
+      // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-1):10 -std=c++23 %s | FileCheck --allow-empty %s
+      // CHECK-NOT: COMPLETION: member : [#int#]member
+      // CHECK-NOT: COMPLETION: memberFnA : [#int#]memberFnA(<#int a#>)
+      // CHECK-NOT: COMPLETION: memberFnA : [#int#]memberFnA(<#float a#>)
+    }();
+  }
+};
+