In clang++ v21, the following code correctly raises the diagnostic below:

  struct base
  {
      virtual ~base() = default;
      virtual void foo() {}
  };

  struct derived final : public base
  {
      void foo() override {}

      virtual void bar() {} // raise error due to this.
  };




Diagnostic

  <source>:11:18: error: virtual method 'bar' is inside a 'final' class and can never be overridden [-Werror,-Wunnecessary-virtual-specifier]
     11 |     virtual void bar() {}


Where the arguments are:

-pedantic-errors -Wall -Wextra -Werror  -Wcast-align -Wcast-qual -Wctor-dtor-privacy -Wint-in-bool-context -Wmissing-declarations -Wredundant-decls -Wundef -Wunused-function -Wnon-virtual-dtor -Woverloaded-virtual -Wno-missing-template-arg-list-after-template-kw


However afaict, G++ does not provide such a diagnostic - unless I'm possibly missing the appropriate option.

It should be noted that the -Wunnecessary-virtual-specifier seems to, for now, be clang++ specific.


https://godbolt.org/z/rPG6r8EPa