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Re: Fix may be uninitialized warnings in libgfortran
- From: Paul Brook <paul at codesourcery dot com>
- To: fortran at gcc dot gnu dot org
- Cc: Steven Bosscher <stevenb at suse dot de>,Andreas Jaeger <aj at suse dot de>,gcc-patches at gcc dot gnu dot org
- Date: Sun, 15 May 2005 16:26:38 +0100
- Subject: Re: Fix may be uninitialized warnings in libgfortran
- References: <email@example.com> <firstname.lastname@example.org>
On Sunday 15 May 2005 16:19, Steven Bosscher wrote:
> On Sunday 15 May 2005 14:40, Andreas Jaeger wrote:
> > We get a number of these warnings in libgfortran:
> > /cvs/gcc/libgfortran/generated/eoshift1_4.c:73: warning: âlenâ may be
> > used uninitialized in this function
> > All of them look like false positives but the algorithm is written in
> > a way that the compiler cannot catch it. I propose to initialize the
> > warnings - this is AFAIK the same way we do in the rest of the
> > compiler.
> It's IMHO a bad thing to do. Can't we just write that loop differently,
> e.g. something like the following?
> Index: m4/eoshift1.m4
> RCS file: /cvs/gcc/gcc/libgfortran/m4/eoshift1.m4,v
> retrieving revision 1.7
> diff -u -3 -p -r1.7 eoshift1.m4
> --- m4/eoshift1.m4 4 May 2005 21:38:15 -0000 1.7
> +++ m4/eoshift1.m4 15 May 2005 15:19:02 -0000
> @@ -91,7 +91,8 @@ eoshift1_`'atype_kind (const gfc_array_c
> count = 0;
> size = GFC_DESCRIPTOR_SIZE (array);
> n = 0;
> - for (dim = 0; dim < GFC_DESCRIPTOR_RANK (array); dim++)
> + dim = 0;
> + do
> if (dim == which)
This wouldn't help. The warning is technically correct.
The compiler has no way of proving 0 <= which < rank(array).