[m-rev.] for post-commit review and request for tryout: simplify a test

[Julien Fischer]

On Sun, 15 Feb 2026 at 14:43, Zoltan Somogyi <zoltan.somogyi at runbox.com> wrote:
>
> For review by anyone.
>
> I would request everyone to install a compiler containing diff,
> and use it for the next few days. If you tickle one of the new exceptions,
> please report it to me. If nothing like that happens during your tryouts,
> then I can delete the old version of the test.

Using the latest commit for mercury-json
(<https://github.com/juliensf/mercury-json>)
and adding to --warn-unused-args  to MCFLAGS in src/Mercury.options and then
running 'make' in the src directory gives me one of the new exceptions.:

Making Mercury/asm_fast.gc/x86_64-pc-linux-gnu/Mercury/opts/json.opt
Making Mercury/asm_fast.gc/x86_64-pc-linux-gnu/Mercury/cs/json.c
Uncaught Mercury exception:
Software Error: predicate
`transform_hlds.unused_args.may_gather_warning_pragma_for_pred'/3:
Unexpected: old succeeds, new fails
Stack dump not available in this grade.
** Error making `Mercury/asm_fast.gc/x86_64-pc-linux-gnu/Mercury/cs/json.c'.
make: *** [Makefile:5: default] Error 1

Julien.