Support the NO_COLOR environment variable

I ran across this site:

    https://no-color.org/

... which lobbies for tools to recognize the NO_COLOR environment
variable and disable any terminal styling when it is seen.

This patch implements this for gdb.

Regression tested on x86-64 Fedora 38.

Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
Reviewed-by: Kevin Buettner <kevinb@redhat.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Andrew Burgess <aburgess@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/gdb/main.c b/gdb/main.c
index cf46f6a..97e04f5 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -654,6 +654,10 @@ captured_main_1 (struct captured_main_args *context)
   int save_auto_load;
   int ret = 1;
 
+  const char *no_color = getenv ("NO_COLOR");
+  if (no_color != nullptr && *no_color != '\0')
+    cli_styling = false;
+
 #ifdef HAVE_USEFUL_SBRK
   /* Set this before constructing scoped_command_stats.  */
   lim_at_start = (char *) sbrk (0);