bug#50975: 28.0.60; mh-utils-tests fail with native compilation

[Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Stephen Gildea <stepheng+emacs@gildea.com> writes:

> Thank you, Andrea, for the native-trampolines patch to mh-utils-tests.el.
> In this patch, the test explicitly compiles trampolines before redefining
> two functions that are defined in C.
>
> Is it necessary to provide trampolines at all for these short-lived test
> functions?  The following works for me:
>
>     (mapc (lambda (x) (add-to-list 'native-comp-never-optimize-functions x))
>           '(call-process file-directory-p))

Yes disabling the trampoline generation is another option.

> Before redefining the functions, the test could create a dynamic local
> binding for native-comp-never-optimize-functions and add to it as above.
>
> If that is a reasonable approach, can we go further?  Can the
> native-compile code detect that this is a test and automatically
> suppress trying to compile a trampoline, without the test having
> to be aware of native-compile?

I don't think so.  The Emacs implementation has the right to use
`call-process' to function and in general I think we really want to test
the full implementation including trampolines as much as possible in all
running tests we can.

If we find it useful we could add a knob to disable all trampoline
generation for special cases like this.

Best Regards

  Andrea