strict alias analysis question

[Manfred Spraul <manfred at colorfullife dot com>]

Hi,

the latest gcc versions generate warnings about potentially dangerous 
pointer casts if strict alias analysis is enabled.
Right now two groups of  warnings are generated: several from the 
inlined MemSet macros:

#define MemSetLoop(start, val, len) \
       do \
       { \
               int32 * _start = (int32 *) (start); \
               int32 * _stop = (int32 *) ((char *) \
                           _start + (Size) (len)); \
       \
               while (_start < _stop) \
                       *_start++ = 0; \
       } while (0)

And a few from structures with common headers:

struct hdr {
   ...;
}
struct b {
   struct hdr info;
   ...
};

void handler(struct hdr* parm)
{
   struct b* ptr = (struct b*)parm;
}

Does MemSet break the rules for strict alias analysis? And what about 
manual base classes? The actual use it a bit longer (the cast to (Node 
*) in src/backend/commands/tablecmds.c generates the warning).

--
   Manfred