[CodeComplete] Add code completion after function equals

Summary:
Provide `default` and `delete` completion after the function equals.

Reviewers: kadircet, sammccall

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82548

Author: lh123

clang/include/clang/Sema/Sema.h

@@ -11996,6 +11996,7 @@ class Sema final {
 
   void CodeCompleteLambdaIntroducer(Scope *S, LambdaIntroducer &Intro,
                                     bool AfterAmpersand);
+  void CodeCompleteAfterFunctionEquals(Declarator &D);
 
   void CodeCompleteObjCAtDirective(Scope *S);
   void CodeCompleteObjCAtVisibility(Scope *S);

clang/lib/Parse/ParseDecl.cpp

@@ -1898,46 +1898,52 @@ Parser::DeclGroupPtrTy Parser::ParseDeclGroup(ParsingDeclSpec &DS,
   }
 
   // Check to see if we have a function *definition* which must have a body.
-  if (D.isFunctionDeclarator() &&
-      // Look at the next token to make sure that this isn't a function
-      // declaration.  We have to check this because __attribute__ might be the
-      // start of a function definition in GCC-extended K&R C.
-      !isDeclarationAfterDeclarator()) {
-
-    // Function definitions are only allowed at file scope and in C++ classes.
-    // The C++ inline method definition case is handled elsewhere, so we only
-    // need to handle the file scope definition case.
-    if (Context == DeclaratorContext::FileContext) {
-      if (isStartOfFunctionDefinition(D)) {
-        if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
-          Diag(Tok, diag::err_function_declared_typedef);
-
-          // Recover by treating the 'typedef' as spurious.
-          DS.ClearStorageClassSpecs();
-        }
+  if (D.isFunctionDeclarator()) {
+    if (Tok.is(tok::equal) && NextToken().is(tok::code_completion)) {
+      Actions.CodeCompleteAfterFunctionEquals(D);
+      cutOffParsing();
+      return nullptr;
+    }
+    // Look at the next token to make sure that this isn't a function
+    // declaration.  We have to check this because __attribute__ might be the
+    // start of a function definition in GCC-extended K&R C.
+    if (!isDeclarationAfterDeclarator()) {
+
+      // Function definitions are only allowed at file scope and in C++ classes.
+      // The C++ inline method definition case is handled elsewhere, so we only
+      // need to handle the file scope definition case.
+      if (Context == DeclaratorContext::FileContext) {
+        if (isStartOfFunctionDefinition(D)) {
+          if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
+            Diag(Tok, diag::err_function_declared_typedef);
+
+            // Recover by treating the 'typedef' as spurious.
+            DS.ClearStorageClassSpecs();
+          }
 
-        Decl *TheDecl =
-          ParseFunctionDefinition(D, ParsedTemplateInfo(), &LateParsedAttrs);
-        return Actions.ConvertDeclToDeclGroup(TheDecl);
-      }
+          Decl *TheDecl = ParseFunctionDefinition(D, ParsedTemplateInfo(),
+                                                  &LateParsedAttrs);
+          return Actions.ConvertDeclToDeclGroup(TheDecl);
+        }
 
-      if (isDeclarationSpecifier()) {
-        // If there is an invalid declaration specifier right after the
-        // function prototype, then we must be in a missing semicolon case
-        // where this isn't actually a body.  Just fall through into the code
-        // that handles it as a prototype, and let the top-level code handle
-        // the erroneous declspec where it would otherwise expect a comma or
-        // semicolon.
+        if (isDeclarationSpecifier()) {
+          // If there is an invalid declaration specifier right after the
+          // function prototype, then we must be in a missing semicolon case
+          // where this isn't actually a body.  Just fall through into the code
+          // that handles it as a prototype, and let the top-level code handle
+          // the erroneous declspec where it would otherwise expect a comma or
+          // semicolon.
+        } else {
+          Diag(Tok, diag::err_expected_fn_body);
+          SkipUntil(tok::semi);
+          return nullptr;
+        }
       } else {
-        Diag(Tok, diag::err_expected_fn_body);
-        SkipUntil(tok::semi);
-        return nullptr;
-      }
-    } else {
-      if (Tok.is(tok::l_brace)) {
-        Diag(Tok, diag::err_function_definition_not_allowed);
-        SkipMalformedDecl();
-        return nullptr;
+        if (Tok.is(tok::l_brace)) {
+          Diag(Tok, diag::err_function_definition_not_allowed);
+          SkipMalformedDecl();
+          return nullptr;
+        }
       }
     }
   }

clang/lib/Parse/ParseDeclCXX.cpp

@@ -2713,6 +2713,11 @@ Parser::ParseCXXClassMemberDeclaration(AccessSpecifier AS,
           DefinitionKind = FDK_Defaulted;
         else if (KW.is(tok::kw_delete))
           DefinitionKind = FDK_Deleted;
+        else if (KW.is(tok::code_completion)) {
+          Actions.CodeCompleteAfterFunctionEquals(DeclaratorInfo);
+          cutOffParsing();
+          return nullptr;
+        }
       }
     }
     DeclaratorInfo.setFunctionDefinitionKind(DefinitionKind);

clang/lib/Sema/SemaCodeComplete.cpp

@@ -24,11 +24,13 @@
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/CharInfo.h"
+#include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
+#include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/Designator.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Overload.h"
@@ -6266,6 +6268,53 @@ void Sema::CodeCompleteLambdaIntroducer(Scope *S, LambdaIntroducer &Intro,
                             Results.data(), Results.size());
 }
 
+void Sema::CodeCompleteAfterFunctionEquals(Declarator &D) {
+  if (!LangOpts.CPlusPlus11)
+    return;
+  ResultBuilder Results(*this, CodeCompleter->getAllocator(),
+                        CodeCompleter->getCodeCompletionTUInfo(),
+                        CodeCompletionContext::CCC_Other);
+  auto ShouldAddDefault = [&D, this]() {
+    if (!D.isFunctionDeclarator())
+      return false;
+    auto &Id = D.getName();
+    if (Id.getKind() == UnqualifiedIdKind::IK_DestructorName)
+      return true;
+    // FIXME(liuhui): Ideally, we should check the constructor parameter list to
+    // verify that it is the default, copy or move constructor?
+    if (Id.getKind() == UnqualifiedIdKind::IK_ConstructorName &&
+        D.getFunctionTypeInfo().NumParams <= 1)
+      return true;
+    if (Id.getKind() == UnqualifiedIdKind::IK_OperatorFunctionId) {
+      auto Op = Id.OperatorFunctionId.Operator;
+      // FIXME(liuhui): Ideally, we should check the function parameter list to
+      // verify that it is the copy or move assignment?
+      if (Op == OverloadedOperatorKind::OO_Equal)
+        return true;
+      if (LangOpts.CPlusPlus20 &&
+          (Op == OverloadedOperatorKind::OO_EqualEqual ||
+           Op == OverloadedOperatorKind::OO_ExclaimEqual ||
+           Op == OverloadedOperatorKind::OO_Less ||
+           Op == OverloadedOperatorKind::OO_LessEqual ||
+           Op == OverloadedOperatorKind::OO_Greater ||
+           Op == OverloadedOperatorKind::OO_GreaterEqual ||
+           Op == OverloadedOperatorKind::OO_Spaceship))
+        return true;
+    }
+    return false;
+  };
+
+  Results.EnterNewScope();
+  if (ShouldAddDefault())
+    Results.AddResult("default");
+  // FIXME(liuhui): Ideally, we should only provide `delete` completion for the
+  // first function declaration.
+  Results.AddResult("delete");
+  Results.ExitScope();
+  HandleCodeCompleteResults(this, CodeCompleter, Results.getCompletionContext(),
+                            Results.data(), Results.size());
+}
+
 /// Macro that optionally prepends an "@" to the string literal passed in via
 /// Keyword, depending on whether NeedAt is true or false.
 #define OBJC_AT_KEYWORD_NAME(NeedAt, Keyword) ((NeedAt) ? "@" Keyword : Keyword)

clang/test/CodeCompletion/after-function-equals.cpp

@@ -0,0 +1,47 @@
+struct A {
+  A() = default;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:2:9 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
+  // CHECK-CC1: COMPLETION: default
+  // CHECK-CC1-NEXT: COMPLETION: delete
+
+  A(const A &) = default;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:7:18 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC2 %s
+  // CHECK-CC2: COMPLETION: default
+  // CHECK-CC2-NEXT: COMPLETION: delete
+
+  A(const A &, int) = delete;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:12:23 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC3 %s
+  // CHECK-CC3-NOT: COMPLETION: default
+  // CHECK-CC3: COMPLETION: delete
+
+  A(A &&);
+
+  A &operator=(const A &) = default;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:19:29 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC4 %s
+  // CHECK-CC4: COMPLETION: default
+  // CHECK-CC4-NEXT: COMPLETION: delete
+
+  bool operator==(const A &) const = delete;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:24:38 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC5 %s
+  // CHECK-CC5-NOT: COMPLETION: default
+  // CHECK-CC5: COMPLETION: delete
+
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:24:38 -std=gnu++20 %s -o - | FileCheck -check-prefix=CHECK-CC6 %s
+  // CHECK-CC6: COMPLETION: default
+  // CHECK-CC6-NEXT: COMPLETION: delete
+
+  void test() = delete;
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:33:17 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC7 %s
+  // CHECK-CC7-NOT: COMPLETION: default
+  // CHECK-CC7: COMPLETION: delete
+};
+
+A::A(A &&) = default;
+// RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:39:14 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC8 %s
+// CHECK-CC8: COMPLETION: default
+// CHECK-CC8-NEXT: COMPLETION: delete
+
+void test() = delete;
+// RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:44:15 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+// CHECK-CC9-NOT: COMPLETION: default
+// CHECK-CC9: COMPLETION: delete