Re: New type-based pool allocator code miscompiled due to aliasing issue?

[Marc Glisse]

On Mon, 15 Jun 2015, Martin Liška wrote:

Ah, I overlooked that it's not a placement new, but just static casting.
Anyway, if I added:

cselib_val () {}

to struct cselib_val and changed the cast to placement new:
 char *ptr = (char *) header;
 return new (ptr) T ();

I got following compilation error:

In file included from ../../gcc/alias.c:46:0:
../../gcc/alloc-pool.h: In instantiation of ‘T* pool_allocator<T>::allocate() 
[with T = cselib_val]’:
../../gcc/cselib.h:51:27:   required from here
../../gcc/alloc-pool.h:416:23: error: no matching function for call to 
‘cselib_val::operator new(sizetype, char*&)’
  return new (ptr) T ();
                      ^
In file included from ../../gcc/alias.c:47:0:
../../gcc/cselib.h:49:16: note: candidate: static void* cselib_val::operator 
new(size_t)
  inline void *operator new (size_t)
               ^
../../gcc/cselib.h:49:16: note:   candidate expects 1 argument, 2 provided

#include <new>

--
Marc Glisse