Cast alignment warnings

[Russ Allbery]

Julien ÉLIE <julien at trigofacile.com> writes:

> On a Debian sparc64 server (TI UltraSparc IIe Hummingbird), I encounter
> cast alignment errors:

> /home/iulius/autobuild/bin/gcc-core-4.6.1/bin/gcc -g -O2 -DDEBUG=1 -Wall -W -Wendif-labels -Wpointer-arith -Wbad-function-cast -Wcast-align -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Werror -g -O2 -I../include  -c network.c
> network.c: In function ‘network_sockaddr_sprint’:
> network.c:611:15: error: cast increases required alignment of target type [-Werror=cast-align]

http://comments.gmane.org/gmane.comp.gcc.help/29997

Basically, it's an unhelpful warning, since there isn't really anything
that you can do to fix it.  You have to make sure you don't create a
struct of type sockaddr on the stack, since it may not be aligned
properly, but as long as you create a sockaddr_in, sockaddr_in6, or
sockaddr_storage and are only casting to and from sockaddr, there isn't
any actual problem.

I've stopped using -Wcast-align because it seems to only produce these
false positives in the sort of code I usually work on.  People who use the
warning paper around it by casting to void * first, which doesn't actually
fix anything, just hides the issue from the compiler and makes the code
more complicated.  That's the mark of a useless warning to me.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>

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