Re: [PATCH] GDB testsuite: Suppress GCC's colored output

[Andreas Arnez <arnez at linux dot vnet dot ibm dot com>]

On Wed, Aug 02 2017, Simon Marchi wrote:

> On 2017-08-02 19:35, Andreas Arnez wrote:
>> Newer GCC versions yield colored diagnostic messages by default, which
>> may
>> be useful when executing GDB interactively from a terminal.  But when
>> run
>> from a GDB test case, the compiler output is written into gdb.log, where
>> such escape sequences are usually more inhibiting than helpful to the
>> evaluation of test results.  So this patch suppresses that.
>
> That's because you are not using the right viewer :).  Try "less -R 
> gdb.log", you should see the rainbow.

Right...  That's why I wrote "usually".  Such as when using "grep",
loading the file into an editor, pasting the error message into an
e-Mail, etc.

>
>>
>> gdb/testsuite/ChangeLog:
>>
>> 	* lib/gdb.exp (gdb_compile): Suppress GCC's coloring of messages.
>> ---
>>  gdb/testsuite/lib/gdb.exp | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
>> index 3d3eaab..9a5c27f 100644
>> --- a/gdb/testsuite/lib/gdb.exp
>> +++ b/gdb/testsuite/lib/gdb.exp
>> @@ -3552,6 +3552,9 @@ proc gdb_compile {source dest type options} {
>>  	}
>>      }
>>
>> +    # Stop the compiler from producing colored output.
>> +    setenv GCC_COLORS ""
>> +
>>      set result [target_compile $source $dest $type $options]
>>
>>      # Prune uninteresting compiler (and linker) output.
>
> I was wondering why GCC showed colors even though it's not invoked
> "interactively".  Dejagnu uses expect's spawn to spawn processes,
> including the compiler.  spawn allocates a tty for the subprocess, which
> is what GCC checks to determine whether or not to enable colors.

Right.  If spawn used a pipe instead of a pseudo-tty, then GCC wouldn't
show colors.

> You patch LGTM, but please leave the patch for review for a few days, then
> push it if nobody says anything.

OK.

--
Andreas