Revert "Add macro to suppress -Wunnecessary-virtual-specifier (#139614)"

This reverts commit 0954c9d487e7cb30673df9f0ac125f71320d2936.

It breaks the build when built with gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04).

clang/include/clang/AST/Decl.h

@@ -173,7 +173,7 @@ class PragmaCommentDecl final
                     PragmaMSCommentKind CommentKind)
       : Decl(PragmaComment, TU, CommentLoc), CommentKind(CommentKind) {}
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   static PragmaCommentDecl *Create(const ASTContext &C, TranslationUnitDecl *DC,
@@ -207,7 +207,7 @@ class PragmaDetectMismatchDecl final
                            size_t ValueStart)
       : Decl(PragmaDetectMismatch, TU, Loc), ValueStart(ValueStart) {}
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   static PragmaDetectMismatchDecl *Create(const ASTContext &C,
@@ -5024,7 +5024,7 @@ public:
 ///   export void foo();
 /// \endcode
 class ExportDecl final : public Decl, public DeclContext {
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 private:
   friend class ASTDeclReader;

clang/include/clang/AST/DeclCXX.h

@@ -3297,7 +3297,7 @@ class LifetimeExtendedTemporaryDecl final
 
   mutable APValue *Value = nullptr;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   LifetimeExtendedTemporaryDecl(Expr *Temp, ValueDecl *EDecl, unsigned Mangling)
       : Decl(Decl::LifetimeExtendedTemporary, EDecl->getDeclContext(),

clang/include/clang/AST/DeclFriend.h

@@ -52,7 +52,7 @@ class ASTContext;
 class FriendDecl final
     : public Decl,
       private llvm::TrailingObjects<FriendDecl, TemplateParameterList *> {
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   using FriendUnion = llvm::PointerUnion<NamedDecl *, TypeSourceInfo *>;

clang/include/clang/AST/DeclOpenMP.h

@@ -110,7 +110,7 @@ public:
 class OMPThreadPrivateDecl final : public OMPDeclarativeDirective<Decl> {
   friend class OMPDeclarativeDirective<Decl>;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   OMPThreadPrivateDecl(DeclContext *DC = nullptr,
                        SourceLocation L = SourceLocation())
@@ -418,7 +418,7 @@ class OMPRequiresDecl final : public OMPDeclarativeDirective<Decl> {
   friend class OMPDeclarativeDirective<Decl>;
   friend class ASTDeclReader;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   OMPRequiresDecl(DeclContext *DC, SourceLocation L)
       : OMPDeclarativeDirective<Decl>(OMPRequires, DC, L) {}
@@ -475,7 +475,7 @@ class OMPAllocateDecl final : public OMPDeclarativeDirective<Decl> {
   friend class OMPDeclarativeDirective<Decl>;
   friend class ASTDeclReader;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   OMPAllocateDecl(DeclContext *DC, SourceLocation L)
       : OMPDeclarativeDirective<Decl>(OMPAllocate, DC, L) {}

clang/include/clang/Driver/Action.h

@@ -267,7 +267,7 @@ public:
 /// programming model implementation needs and propagates the offloading kind to
 /// its dependences.
 class OffloadAction final : public Action {
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   /// Type used to communicate device actions. It associates bound architecture,

clang/include/clang/Sema/Sema.h

@@ -895,7 +895,7 @@ public:
   /// with a vtable when the vtable is emitted. Sema is final and not
   /// polymorphic, but the debug info size savings are so significant that it is
   /// worth adding a vtable just to take advantage of this optimization.
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   const LangOptions &getLangOpts() const { return LangOpts; }
   OpenCLOptions &getOpenCLOptions() { return OpenCLFeatures; }

clang/lib/AST/ByteCode/InterpFrame.h

@@ -119,7 +119,7 @@ public:
   CodePtr getRetPC() const { return RetPC; }
 
   /// Map a location to a source.
-  SourceInfo getSource(CodePtr PC) const;
+  virtual SourceInfo getSource(CodePtr PC) const;
   const Expr *getExpr(CodePtr PC) const;
   SourceLocation getLocation(CodePtr PC) const;
   SourceRange getRange(CodePtr PC) const;

clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp

@@ -323,7 +323,7 @@ public:
   CheckVarsEscapingDeclContext(CodeGenFunction &CGF,
                                ArrayRef<const ValueDecl *> TeamsReductions)
       : CGF(CGF), EscapedDecls(llvm::from_range, TeamsReductions) {}
-  ~CheckVarsEscapingDeclContext() = default;
+  virtual ~CheckVarsEscapingDeclContext() = default;
   void VisitDeclStmt(const DeclStmt *S) {
     if (!S)
       return;

clang/lib/CodeGen/CGStmtOpenMP.cpp

@@ -4783,7 +4783,7 @@ class CheckVarsEscapingUntiedTaskDeclContext final
 
 public:
   explicit CheckVarsEscapingUntiedTaskDeclContext() = default;
-  ~CheckVarsEscapingUntiedTaskDeclContext() = default;
+  virtual ~CheckVarsEscapingUntiedTaskDeclContext() = default;
   void VisitDeclStmt(const DeclStmt *S) {
     if (!S)
       return;

clang/lib/Driver/ToolChains/Hexagon.h

@@ -42,8 +42,8 @@ public:
   bool hasIntegratedCPP() const override { return false; }
   bool isLinkJob() const override { return true; }
 
-  void RenderExtraToolArgs(const JobAction &JA,
+  virtual void RenderExtraToolArgs(const JobAction &JA,
-                           llvm::opt::ArgStringList &CmdArgs) const;
+                                   llvm::opt::ArgStringList &CmdArgs) const;
   void ConstructJob(Compilation &C, const JobAction &JA,
                     const InputInfo &Output, const InputInfoList &Inputs,
                     const llvm::opt::ArgList &TCArgs,

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -882,6 +882,11 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
   # The LLVM libraries have no stable C++ API, so -Wnoexcept-type is not useful.
   append("-Wno-noexcept-type" CMAKE_CXX_FLAGS)
 
+  # LLVM has a policy of including virtual "anchor" functions to control
+  # where the vtable is emitted. In `final` classes, these are exactly what
+  # this warning detects: unnecessary virtual methods.
+  add_flag_if_supported("-Wno-unnecessary-virtual-specifier" CXX_SUPPORTS_UNNECESSARY_VIRTUAL_FLAG)
+
   if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     append("-Wnon-virtual-dtor" CMAKE_CXX_FLAGS)
   endif()

llvm/include/llvm/Analysis/InstSimplifyFolder.h

@@ -36,7 +36,7 @@ class InstSimplifyFolder final : public IRBuilderFolder {
   TargetFolder ConstFolder;
   SimplifyQuery SQ;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   explicit InstSimplifyFolder(const DataLayout &DL) : ConstFolder(DL), SQ(DL) {}

llvm/include/llvm/Analysis/TargetFolder.h

@@ -39,7 +39,7 @@ class TargetFolder final : public IRBuilderFolder {
     return ConstantFoldConstant(C, DL);
   }
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   explicit TargetFolder(const DataLayout &DL) : DL(DL) {}

llvm/include/llvm/IR/ConstantFolder.h

@@ -28,7 +28,7 @@ namespace llvm {
 
 /// ConstantFolder - Create constants with minimum, target independent, folding.
 class ConstantFolder final : public IRBuilderFolder {
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   explicit ConstantFolder() = default;

llvm/include/llvm/IR/NoFolder.h

@@ -33,7 +33,7 @@ namespace llvm {
 
 /// NoFolder - Create "constants" (actually, instructions) with no folding.
 class NoFolder final : public IRBuilderFolder {
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
 public:
   explicit NoFolder() = default;

llvm/include/llvm/Support/Compiler.h

@@ -710,22 +710,4 @@ void AnnotateIgnoreWritesEnd(const char *file, int line);
 #define LLVM_PREFERRED_TYPE(T)
 #endif
 
-/// \macro LLVM_VIRTUAL_ANCHOR_FUNCTION
-/// This macro is used to adhere to LLVM's policy that each class with a vtable
-/// must have at least one out-of-line virtual function. This macro allows us
-/// to declare such a function in `final` classes without triggering a warning.
-// clang-format off
-// Autoformatting makes this look awful.
-#if defined(__clang__) && __has_warning("-Wunnecessary-virtual-specifier")
-#define LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION()                            \
-  _Pragma("clang diagnostic push")                                        \
-  _Pragma("clang diagnostic ignored \"-Wunnecessary-virtual-specifier\"") \
-  virtual void anchor()                                                   \
-  _Pragma("clang diagnostic pop")
-#else
-#define LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION()                            \
-  virtual void anchor()
-#endif
-// clang-format on
-
 #endif

llvm/include/llvm/Transforms/Scalar/GVNExpression.h

@@ -452,7 +452,7 @@ public:
     IntOperands[NumIntOperands++] = IntOperand;
   }
 
-  void allocateIntOperands(BumpPtrAllocator &Allocator) {
+  virtual void allocateIntOperands(BumpPtrAllocator &Allocator) {
     assert(!IntOperands && "Operands already allocated");
     IntOperands = Allocator.Allocate<unsigned>(MaxIntOperands);
   }

llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp

@@ -1212,7 +1212,7 @@ public:
                           ValueToValueMapTy &UnderlyingMap)
       : TypeMap(TypeMap),
         InternalMapper(UnderlyingMap, RF_None, TypeMap, this) {}
-  ~FatPtrConstMaterializer() = default;
+  virtual ~FatPtrConstMaterializer() = default;
 
   Value *materialize(Value *V) override;
 };

llvm/lib/Target/X86/X86InstrInfo.h

@@ -225,7 +225,7 @@ class X86InstrInfo final : public X86GenInstrInfo {
   X86Subtarget &Subtarget;
   const X86RegisterInfo RI;
 
-  LLVM_DECLARE_VIRTUAL_ANCHOR_FUNCTION();
+  virtual void anchor();
 
   bool analyzeBranchImpl(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                          MachineBasicBlock *&FBB,