PING: Re: [PATCH] selftest: invoke "diff" when ASSERT_STREQ fails

[David Malcolm <dmalcolm@redhat.com>]

Ping.

This patch has actually been *very* helpful to me when debugging
selftest failures involving ASSERT_STREQ.

Thanks
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 <dmalcolm@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);
> +         }
>        }
>  }
>