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

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2017-08-08 20:28, Andreas Arnez wrote:
> On Fri, Aug 04 2017, Yao Qi wrote:
> 
>> Andreas Arnez <arnez@linux.vnet.ibm.com> writes:
>> 
>> Hi Andreas,
>> 
>>> +    # Stop the compiler from producing colored output.
>>> +    setenv GCC_COLORS ""
>>> +
>> 
>> This doesn't work for remote host.
> 
> Hm, what scenario are you referring to?  It *does* work with
> "--target_board=native-gdbserver", at least on the system I've tested 
> it
> on.  And a cross-target config should work as well, right?

I believe Yao meant "host" in the build/host/target sense.  The debugger 
and compiler you are producing run on the host machine, doing some 
compiling/debugging about the target architecture. Let's say you're 
working on x86, cross-compiling a GDB that should run on ARM to debug 
native programs on ARM.  You have

build: x86
host: arm
target: arm

When you run the GDB testsuite, it's on your x86 machine, but the GDB 
you built has to run on an ARM board, therefore you will have a remote 
host.  You would then most likely specify the same host and target 
(though they could be different), with --host_board=my-arm-board 
--target_board=my-arm-board.  The compilation of test cases also happens 
on the host, which means it will also be remote.  And that's where 
unsetting the GCC_COLORS environment variable on the build machine 
doesn't help.

>> How about passing option -fno-color-diagnostics to compiler which
>> supports that option?  Both gcc (4.9 and later) and clang has this
>> option.
> 
> Actually, clang only, AFAIK.  And I don't know that there is a
> compatible option between GCC and clang for disabling colored
> diagnostics.  Clang's manual page (1) mentions
> 
>   -f[no-]color-diagnostics
> 
> whereas GCC has
> 
>   -fdiagnostics-color[=WHEN]
>   -fno-diagnostics-color
> 
> So unless I missed something, we have to handle clang and GCC
> separately.
> 
> See below for an alternative patch that tries the GCC option
> "-fdiagnostics-color=never".  We could possibly enrich this and try
> clang's "-fno-color-diagnostics" if that fails.

clang actually supports -fdiagnostics-color=never from what I saw, even 
though it may not be documented.  So we can rely on that.

> * (1) https://clang.llvm.org/docs/UsersManual.html
> 
> --
> Andreas
> 
> 
> Subject: [PATCH v2] GDB testsuite: Suppress GCC's colored output
> 
> 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.
> 
> gdb/testsuite/ChangeLog:
> 
> 	* lib/gdb.exp (universal_compile_options): New caching proc.
> 	(gdb_compile): Suppress GCC's coloring of messages.
> ---
>  gdb/testsuite/lib/gdb.exp | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> index 3d3eaab..51bf848 100644
> --- a/gdb/testsuite/lib/gdb.exp
> +++ b/gdb/testsuite/lib/gdb.exp
> @@ -3368,6 +3368,34 @@ proc gdb_wrapper_init { args } {
>      set gdb_wrapper_target [current_target_name]
>  }
> 
> +# Determine options that we always want to pass to the compiler.
> +gdb_caching_proc universal_compile_options {
> +    set me "universal_compile_options"
> +    set options {}
> +
> +    set src [standard_temp_file ccopts[pid].c]
> +    set obj [standard_temp_file ccopts[pid].o]
> +
> +    gdb_produce_source $src {
> +	int foo(void) { return 0; }
> +    }
> +
> +    # Try an option for disabling colored diagnostics.  Some compilers
> +    # yield colored diagnostics by default (when run from a tty) 
> unless
> +    # such an option is specified.
> +    set opt "additional_flags=-fdiagnostics-color=never"
> +    set lines [target_compile $src $obj object [list "quiet" $opt]]
> +    if [string match "" $lines] then {
> +	# Seems to have worked; use the option.
> +	lappend options $opt
> +    }
> +    file delete $src
> +    file delete $obj
> +
> +    verbose "$me:  returning $options" 2
> +    return $options
> +}
> +
>  # Some targets need to always link a special object in.  Save its path 
> here.
>  global gdb_saved_set_unbuffered_mode_obj
>  set gdb_saved_set_unbuffered_mode_obj ""
> @@ -3419,7 +3447,7 @@ proc gdb_compile {source dest type options} {
> 
>      # Add platform-specific options if a shared library was specified 
> using
>      # "shlib=librarypath" in OPTIONS.
> -    set new_options ""
> +    set new_options [universal_compile_options]
>      set shlib_found 0
>      set shlib_load 0
>      foreach opt $options {

I have not tried it yet, but at first glance it seems on the right path.

Thanks,

Simon