[m-rev.] for review: improve var/functor type mismatch diagnostics

[Julien Fischer]

On Tue, 14 Oct 2025 at 16:12, Zoltan Somogyi <zoltan.somogyi at runbox.com> wrote:

> Better diagnostics for var/functor type mismatches.
>
> compiler/typecheck_error_unify.m:
>     As above.
>
> compiler/hlds_error_util.m:
> compiler/typecheck_error_util.m:
>     Export operations that are now needed by typecheck_error_unify.m.
>     To make this possible, carve some of those operations out of
>     other operations.
>
> tests/invalid/ho_type_arity_bug.err_exp:
> tests/invalid/missing_closure_arg.err_exp:
> tests/invalid/nullary_ho_func_error.err_exp:
> tests/invalid_nodepend/errors_2.err_exp:
> tests/invalid_purity/impure_func_t5.err_exp:
> tests/invalid_purity/impure_pred_t1.err_exp:
>     Expect the updated diagnostics.

That's fine.

Julien.