Sorry to mention aliasing again, but is the standard IN6_ARE_ADDR_EQUAL really wrong?

[Andreas Schwab]

Dave Korn <dave.korn.cygwin@googlemail.com> writes:

>   Is that really right?  The type of the pointer (in6->__s6_addr) that we're
> casting is unsigned char *, so shouldn't it already alias everything anyway
> and dereferencing it be allowed, like it is for the casted (a)?  I'll file a
> PR if so.  (I can't pretend I find the language in the spec easy to follow.)

IIUC both accesses are actually wrong, but in the case of a there is no
information about the actual target type, so the compiler cannot
optimize.  In both cases an object is accessed as type uint32_t, but the
effective type is different.  Aliasing is not symmetric, the aliasing
exception only applies to the case of accessing through a character
type, the effective type of the object does not matter.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."