RFC: Document unexpected behaviour of --fatal-warnings

[H.J. Lu]

On Tue, Jan 23, 2024 at 4:39 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 23.01.2024 13:28, Nick Clifton wrote:
> > Hi Guys,
> >
> >   It was recently pointed out to me that the bfd linker's
> >   --fatal-warnings option can behave in an unexpected manner.  For
> >   example:
> >
> >     $ ld.bfd -z bad-option --fatal-warnings -e 0/dev/null
> >     ld.bfd: warning: -z bad-option ignored
> >     $ echo $?
> >     0
> >
> >   ie the warning about the ignored option is not being treated as an
> >   error.  This happens because the --fatal-warnings option only takes
> >   affect after it has been processed, and we process the options in a
> >   linear order.  So the following works:
> >
> >     $ ld.bfd --fatal-warnings -z bad-option -e 0 /dev/null
> >     ld.bfd: warning: -z bad-option ignored
> >     $ echo $?
> >     1
> >
> >   This behaviour differs from gold and lld, both of which honour
> >   --fatal-warnings no matter where it occurs on the command line.
> >
> >   So we could fix the linker, create a two pass argument scan and the
> >   problem would be solved.  But a) I am lazy and b) we already have a
> >   precedent for options on the command line only affecting options that
> >   come after it.  (I am thinking of the -L option here, although there
> >   are probably several others).  So instead I am considering documenting
> >   the current behaviour as expected.  (See the patch below).
> >
> >   What do people think ?
>
> I'd be fine either way, and I agree documenting is cheaper and sufficient.
>
> Jan

We should give a warning or an error if --fatal-warnings isn't the first
command-line option.

-- 
H.J.