[clang] Do not diagnose unused deleted operator delete[] (#134357)

For vector deleting dtors support we now also search and save operator
delete[]. Avoid diagnosing deleted operator delete[] when doing that
because vector deleting dtors are only called when delete[] is present
and whenever delete[] is present in the TU it will be diagnosed
correctly.

Fixes llvm/llvm-project#134265

Author: Fznamznon

clang/include/clang/AST/DeclCXX.h

@@ -2886,7 +2886,7 @@ class CXXDestructorDecl : public CXXMethodDecl {
   static CXXDestructorDecl *CreateDeserialized(ASTContext &C, GlobalDeclID ID);
 
   void setOperatorDelete(FunctionDecl *OD, Expr *ThisArg);
-  void setOperatorArrayDelete(FunctionDecl *OD, Expr *ThisArg);
+  void setOperatorArrayDelete(FunctionDecl *OD);
 
   const FunctionDecl *getOperatorDelete() const {
     return getCanonicalDecl()->OperatorDelete;

clang/include/clang/Sema/Sema.h

@@ -8254,7 +8254,8 @@ class Sema final : public SemaBase {
                                               DeclarationName Name);
   FunctionDecl *FindDeallocationFunctionForDestructor(SourceLocation StartLoc,
                                                       CXXRecordDecl *RD,
-                                                      DeclarationName Name);
+                                                      DeclarationName Name,
+                                                      bool Diagnose = true);
 
   /// ActOnCXXDelete - Parsed a C++ 'delete' expression (C++ 5.3.5), as in:
   /// @code ::delete ptr; @endcode

clang/lib/AST/DeclCXX.cpp

@@ -3014,8 +3014,7 @@ void CXXDestructorDecl::setOperatorDelete(FunctionDecl *OD, Expr *ThisArg) {
   }
 }
 
-void CXXDestructorDecl::setOperatorArrayDelete(FunctionDecl *OD,
-                                               Expr *ThisArg) {
+void CXXDestructorDecl::setOperatorArrayDelete(FunctionDecl *OD) {
   auto *First = cast<CXXDestructorDecl>(getFirstDecl());
   if (OD && !First->OperatorArrayDelete)
     First->OperatorArrayDelete = OD;

clang/lib/Sema/SemaDeclCXX.cpp

@@ -11015,12 +11015,12 @@ bool Sema::CheckDestructor(CXXDestructorDecl *Destructor) {
       // Lookup delete[] too in case we have to emit a vector deleting dtor;
       DeclarationName VDeleteName =
           Context.DeclarationNames.getCXXOperatorName(OO_Array_Delete);
-      FunctionDecl *ArrOperatorDelete =
-          FindDeallocationFunctionForDestructor(Loc, RD, VDeleteName);
+      FunctionDecl *ArrOperatorDelete = FindDeallocationFunctionForDestructor(
+          Loc, RD, VDeleteName, /*Diagnose=*/false);
       // delete[] in the TU will make sure the operator is referenced and its
       // uses diagnosed, otherwise vector deleting dtor won't be called anyway,
       // so just record it in the destructor.
-      Destructor->setOperatorArrayDelete(ArrOperatorDelete, ThisArg);
+      Destructor->setOperatorArrayDelete(ArrOperatorDelete);
     }
   }
 

clang/lib/Sema/SemaExprCXX.cpp

@@ -3295,11 +3295,13 @@ FunctionDecl *Sema::FindUsualDeallocationFunction(SourceLocation StartLoc,
   return Result.FD;
 }
 
-FunctionDecl *Sema::FindDeallocationFunctionForDestructor(
-    SourceLocation Loc, CXXRecordDecl *RD, DeclarationName Name) {
+FunctionDecl *Sema::FindDeallocationFunctionForDestructor(SourceLocation Loc,
+                                                          CXXRecordDecl *RD,
+                                                          DeclarationName Name,
+                                                          bool Diagnose) {
 
   FunctionDecl *OperatorDelete = nullptr;
-  if (FindDeallocationFunction(Loc, RD, Name, OperatorDelete))
+  if (FindDeallocationFunction(Loc, RD, Name, OperatorDelete, Diagnose))
     return nullptr;
   if (OperatorDelete)
     return OperatorDelete;

clang/test/SemaCXX/gh134265.cpp

@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+struct Foo {
+  virtual ~Foo() {} // expected-error {{attempt to use a deleted function}}
+  static void operator delete(void* ptr) = delete; // expected-note {{explicitly marked deleted here}}
+};
+
+
+struct Bar {
+  virtual ~Bar() {}
+  static void operator delete[](void* ptr) = delete;
+};
+
+struct Baz {
+  virtual ~Baz() {}
+  static void operator delete[](void* ptr) = delete; // expected-note {{explicitly marked deleted here}}
+};
+
+void foobar() {
+  Baz *B = new Baz[10]();
+  delete [] B; // expected-error {{attempt to use a deleted function}}
+}