Convert error propagation to monadic style for Ppxlib 0.28, 0.29 compatibility

[aantron]

@pitag-ha, now that Bisect passes errors around using the With_errors monad, is it worth converting Bisect to also report errors using it? I assume the answer is yes.

For example, here and in other places:

bisect_ppx/src/ppx/instrument.ml

Lines 78 to 79 in df530ff

	| _ ->
	Location.raise_errorf ~loc:attr_loc "Bad payload in coverage attribute."

Fixes #410.

[pitag-ha]

Hi @aantron,

Sorry for missing this!

About mondically propagating all errors in order to later embed them, including the ones that are currently raised: Yes, that would indeed be great! Btw, in case you'd like to read about embedding errors vs raising errors just out of interest: we now have a section about that in our manual (it doesn't cover the With_error style, though).

Also, btw, about your change: I don't understand the test file changes, but the instrument.ml changes look good.

[pitag-ha]

Hello @aantron,

Let me know if you have more questions about this. We're now in the OCaml 5.1.0 support phase. If bisect_ppx can get compatible with the latest ppxlib versions, it will also become compatible with OCaml 5.1.0; and it will form part of the next PPX universe and therefore will be taken into account wrt future breaking changes and patches.

[aantron]

Hi @aantron,

Sorry for missing this!

About mondically propagating all errors in order to later embed them, including the ones that are currently raised: Yes, that would indeed be great! Btw, in case you'd like to read about embedding errors vs raising errors just out of interest: we now have a section about that in our manual (it doesn't cover the With_error style, though).

Also, btw, about your change: I don't understand the test file changes, but the instrument.ml changes look good.

The response at this link is 404. I'm merging this as it is -- we can change the error generation later.

[pitag-ha]

The response at this link is 404.

Oh, there seems to be a problem with ocaml-doc-ci generating the documentation of our last release. Let me give the link for a fixed version as opposed to latest: https://ocaml.org/p/ppxlib/0.29.1/doc/good-practices.html#handling_errors

I'm merging this as it is -- we can change the error generation later.

Sounds good. Thanks!