[PATCH] Do not abort compilation when dump file is /dev/*

[Richard Biener]

On Fri, 19 Nov 2021, Alexandre Oliva wrote:

> On Nov 18, 2021, Richard Biener <rguenther@suse.de> wrote:
> 
> > IMHO a more reasonable thing to do would be to not treat
> > -o /dev/null as a source for -dumpdir and friends.  Alex?
> 
> +1
> 
> I think we already have some special-casing for /dev/null somewhere.

Grepping finds me the following in system.h which is already checked
for in gcc.c in a few places indeed.

/* Provide a default for the HOST_BIT_BUCKET.
   This suffices for POSIX-like hosts.  */

#ifndef HOST_BIT_BUCKET
#define HOST_BIT_BUCKET "/dev/null"
#endif


> > You did the last re-org, where'd we put such special casing?
> 
> I think we're missing something like this, to avoid messing with dumpdir
> with -o /dev/null.  We already use the same function when computing
> outbase just below this.

Ah yeah, not_actual_file_p should do the trick indeed.  Giuliano, can
you update the patch like below?  I think we should still adjust
documentation as you did.

> diff --git a/gcc/gcc.c b/gcc/gcc.c
> index 506c2acc282d6..a986728fb91d6 100644
> --- a/gcc/gcc.c
> +++ b/gcc/gcc.c
> @@ -5098,7 +5098,8 @@ process_command (unsigned int decoded_options_count,
>  
>    bool explicit_dumpdir = dumpdir;
>  
> -  if (!save_temps_overrides_dumpdir && explicit_dumpdir)
> +  if ((!save_temps_overrides_dumpdir && explicit_dumpdir)
> +      || (output_file != NULL && not_actual_file_p (output_file)))
>      {
>        /* Do nothing.  */
>      }
>