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Re: [Bug c++/25845] want optional warning for non-constant declarations that could be constant
- From: Andrew Pinski <pinskia at physics dot uc dot edu>
- To: gcc-bugzilla at gcc dot gnu dot org
- Cc: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 18 Jan 2006 11:23:48 -0500
- Subject: Re: [Bug c++/25845] want optional warning for non-constant declarations that could be constant
- References: <bug-25845-315@http.gcc.gnu.org/bugzilla/> <20060118161927.7673.qmail@sourceware.org>
On Jan 18, 2006, at 11:19 AM, pcarlini at suse dot de wrote:
------- Comment #4 from pcarlini at suse dot de 2006-01-18 16:19
-------
(In reply to comment #3)
const does nothing when it comes to local variables except for not
letting you
touch it in other expressions. It does nothing for optimizations or
anything
else.
This last point is not obvious at all, in my opinion. Why not? In
principle,
certainly const-ness *can* help optimizers one way or the other. Is
this just a
current limitation? A design choice? Anything in the standard making
that
tricky? I would like to know more.
int f(const int *a, int *b)
{
*b = 1;
return *a;
}
a and b can alias and there is no way around that at all because that is
what the C++ standard says.
-- Pinski