Messages in this thread |  | | Date | Sun, 1 Sep 2002 14:39:03 +0200 | From | Tomas Szepe <> | Subject | Re: [PATCH] warnkill trivia 2/2 |
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> From: Tomas Szepe <szepe@pinerecords.com> > Date: Sun, 1 Sep 2002 14:10:53 +0200 > > > Let's keep the sparc atomic_read() how it is so more bugs > > like this can be found. > > I don't know, though... scratching my head here -- Is GCC actually > able to distinguish between 'const int *a' and 'int const *a'? > > No I don't mean this in a "C" sense, I mean conceptually that marking > an object const which has members which are volatile and updated > asynchronously makes zero sense.
True.
I've been playing a bit with how gcc handles the const qualifiers and made an interesting discovery:
Trying to compile
typedef int *p_int; void a(const p_int t) { *t = 0; } void b(const p_int t) { t = (int *) 0; } void c(const int *t) { *t = 0; } void d(const int *t) { t = (int *) 0; } void e(int const *t) { *t = 0; } void f(int const *t) { t = (int *) 0; }
will give 'assignment of read-only location' warnings for b(), c() and e(), i.e. it's impossible to have a constant pointer to a non-constant value w/o using a qualified typedef.
W/o a typedef, gcc seems unable to tell the difference between 'const int *' and 'int const *' altogether. In case one needs a constant pointer to a constant value, something like this should do:
typedef const int *p_int; void f(const p_int a);
Usable? I don't quite think so.
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