------- Comment #2 from raeburn at raeburn dot org 2007-08-15 06:15 ------- Subject: Re: New: Warning when passing a pointer to a const array to a function that expects a pointer to a non-cast one
On Aug 14, 2007, at 23:45, martin dot ferrari at gmail dot com wrote: > Sorry if I'm misunderstanding something or this is a FAQ, but I > couldn't find > any reference, except for a unanswered mail with the same problem > from 2000 at > http://gcc.gnu.org/ml/gcc-bugs/2000-10/msg00337.html (and I don't > find it in > bugzilla either). The code looks semantically correct to me, the > function > declares that it won't touch the data and I'm passing a non-const > data. If the > typecast is not to an array, the warning goes away. > /home/martin/test.c:8: warning: passing argument 1 of foo from > incompatible > pointer type > typedef int caca[3]; > void foo (const caca* p); > void bar(caca *c) { > foo(c); > } I think this might be related to the bug report I filed in 31887 -- and I'm starting to think that we might both be wrong. Weird as it seems, my reading of the C spec, section 6.7.3 says that the qualifier (const, in both our cases, but it would apply to volatile as well) applies only to the array element type, and does *not* apply to the array type itself. So this isn't like assigning a "char *" value to a "const char *"; you're dealing with pointers to two different array types (which happen to have similar but differently-qualified element types). I'm not 100% sure I believe this interpretation, because it seems to needlessly prohibit perfectly reasonable code, and when I asked on comp.std.c a couple weeks back, I got some mixed feedback. But at the moment, that's my reading of the spec.... Ken -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33076
