On Mon, Jan 02, 2017 at 03:51:14PM -0700, Martin Sebor wrote:
> On 01/02/2017 12:36 PM, Jakub Jelinek wrote:
> > Hi!
> >
> > Even when we know the exact return value of a snprintf call with 0 length
> > (i.e. one that doesn't write anything into a buffer), there can be %n
> > directives in the format string that have side-effects that shouldn't be
> > discarded.
> >
> > The following patch avoids the replacement of the snprintf call
> > with just the constant if there is any %n directive.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> Thanks. The fix looks good to me. I would suggest to also update
> the comment above the nowrite member to say something like this:
>
> /* True for bounded functions like snprintf that specify a zero-size
> buffer as a request to compute the size of output without actually
> writing any. NOWRITE is cleared in response to the %n directive
> which has side-effects similar to writing output. */
LGTM, thanks. I'll adjust the comment if it is approved.
> > 2017-01-02 Jakub Jelinek <ja...@redhat.com>
> >
> > PR tree-optimization/78965
> > * gimple-ssa-sprintf.c (pass_sprintf_length::compute_format_length):
> > Change first argument from const call_info & to call_info &. For %n
> > set info.nowrite to false.
> >
> > * gcc.dg/pr78965.c: New test.
Jakub
