On Wed, May 29, 2024 at 5:06 PM David Malcolm <dmalc...@redhat.com> wrote:
>
> On Wed, 2024-05-29 at 16:35 -0400, Eric Gallager wrote:
> > On Tue, May 28, 2024 at 1:21 PM David Malcolm <dmalc...@redhat.com>
> > wrote:
> > >
> > > Ping.
> > >
> > > This patch has actually been *very* helpful to me when debugging
> > > selftest failures involving ASSERT_STREQ.
> > >
> > > Thanks
> > > Dave
> > >
> >
> > Currently `diff` is only listed under the "Tools/packages necessary
> > for modifying GCC" section of install/prerequisites.html:
> > https://gcc.gnu.org/install/prerequisites.html
> > If it's going to become a dependency for actually running GCC, too,
> > it
> > should get moved to be documented elsewhere, IMO.
>
> All this is selftest code, and is turned off in a release configuration
> of GCC. The code path that invokes "diff" is when a selftest is
> failing, which is immediately before a hard failure of the *build* of
> GCC. So arguably this is just a build-time thing for people
> packaging/hacking on GCC, and thus not a new dependency for end-usage.
>
Well to be clear, I'm just asking for a documentation update here, so
if you want to use wording that reflects all of that, I think that'd
be fine. It seems like a useful idea overall, so don't let my
documentation request hold you up from proceeding with it.
> BTW I'm a bit hazy on the details of how "pex" is meant to work, so
> hopefully someone more knowledgable than me can comment on that aspect
> of the patch. It seems to work though.
>
I'm not too clear on it either; maybe one of the libiberty maintainers
can chime in? Or wait, looks like there's just the one currently
(Ian); cc-ing...
> Dave
>
> >
> > > On Fri, 2024-05-17 at 15:51 -0400, David Malcolm wrote:
> > > > Currently when ASSERT_STREQ or ASSERT_STREQ_AT fail we print
> > > > both strings to stderr. However it can be hard to figure out
> > > > the problem (e.g. for 1-character differences in long strings).
> > > >
> > > > Extend the output by writing out the strings to tempfiles and
> > > > invoking "diff -up" on them when we have such a selftest failure,
> > > > to (I hope) simplify debugging.
> > > >
> > > > Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
> > > >
> > > > OK for trunk?
> > > >
> > > > gcc/ChangeLog:
> > > > * selftest.cc (selftest::print_diff): New function.
> > > > (selftest::assert_streq): Call it when we have non-equal
> > > > non-null strings.
> > > >
> > > > Signed-off-by: David Malcolm <dmalc...@redhat.com>
> > > > ---
> > > > gcc/selftest.cc | 28 ++++++++++++++++++++++++++--
> > > > 1 file changed, 26 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/gcc/selftest.cc b/gcc/selftest.cc
> > > > index 6438d86a6aa0..f58c0631908e 100644
> > > > --- a/gcc/selftest.cc
> > > > +++ b/gcc/selftest.cc
> > > > @@ -63,6 +63,26 @@ fail_formatted (const location &loc, const
> > > > char
> > > > *fmt, ...)
> > > > abort ();
> > > > }
> > > >
> > > > +/* Invoke "diff" to print the difference between VAL1 and VAL2
> > > > + on stdout. */
> > > > +
> > > > +static void
> > > > +print_diff (const location &loc, const char *val1, const char
> > > > *val2)
> > > > +{
> > > > + temp_source_file tmpfile1 (loc, ".txt", val1);
> > > > + temp_source_file tmpfile2 (loc, ".txt", val2);
> > > > + const char *args[] = {"diff",
> > > > + "-up",
> > > > + tmpfile1.get_filename (),
> > > > + tmpfile2.get_filename (),
> > > > + NULL};
> > > > + int exit_status = 0;
> > > > + int err = 0;
> > > > + pex_one (PEX_SEARCH | PEX_LAST,
> > > > + args[0], CONST_CAST (char **, args),
> > > > + NULL, NULL, NULL, &exit_status, &err);
> > > > +}
> > > > +
> > > > /* Implementation detail of ASSERT_STREQ.
> > > > Compare val1 and val2 with strcmp. They ought
> > > > to be non-NULL; fail gracefully if either or both are NULL.
> > > > */
> > > > @@ -89,8 +109,12 @@ assert_streq (const location &loc,
> > > > if (strcmp (val1, val2) == 0)
> > > > pass (loc, "ASSERT_STREQ");
> > > > else
> > > > - fail_formatted (loc, "ASSERT_STREQ (%s, %s)\n
> > > > val1=\"%s\"\n
> > > > val2=\"%s\"\n",
> > > > - desc_val1, desc_val2, val1, val2);
> > > > + {
> > > > + print_diff (loc, val1, val2);
> > > > + fail_formatted
> > > > + (loc, "ASSERT_STREQ (%s, %s)\n val1=\"%s\"\n
> > > > val2=\"%s\"\n",
> > > > + desc_val1, desc_val2, val1, val2);
> > > > + }
> > > > }
> > > > }
> > > >
> > >
> >
>
