[Bug middle-end/109224] Wmismatched-new-delete false positive with a templated operator new (common with coroutines)

[arsen at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109224

Arsen Arsenović <arsen at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Wmismatched-new-delete      |Wmismatched-new-delete
                   |false positive with         |false positive with a
                   |coroutines                  |templated operator new
                   |                            |(common with coroutines)
           Keywords|                            |c++-coroutines

--- Comment #4 from Arsen Arsenović <arsen at gcc dot gnu.org> ---
non-coroutine reproducer:

  #include <new>
  #include <concepts>
  struct foo
  {
    template<typename... Args>
    requires (sizeof...(Args) == 0)
    void* operator new (std::size_t sz, Args&&...)
    { return ::operator new (sz); }

    void operator delete (void* x)
    { ::operator delete (x); }
  };

  void
  f ()
  {
    delete (new foo);
  }

this fails because the mangled name of operator new contains template
parameters whereas operator delete does not, so the code in
new_delete_mismatch_p (const demangle_component&, const demangle_component&)
that handles checking for mismatched operator names decides that they are
different.

I think that a class-specific operator delete can be called correctly for any
class-specific operator new, so perhaps we ought to consider all operator new
matching (ditto for class-specific new[]/delete[]).  it should also be valid to
call any sized operator delete for any operator new (ditto for new[]/delete[]
again), I think.  I'll try teaching new_delete_mismatch_p to throw away
template arguments to the allocation fn as a start