Windows: Flag to disable PPX evaluation?

[bryphe]

This is related to #714 , which is a blocking issue to having merlin+PPX evaluation work correctly on Windows.

Because the PPX evaluation does not work correctly, whenever I use on Windows ocamlmerlin single with a file that uses PPX - I end up with an error message prior to getting the response.

File "<command-line>", line 1:
Error: I/O error: .\camlppxf639ce: No such file or directory
{"class":"return","value":[],"notifications":[],"timing":{"clock":112,"cpu":16,"query":0,"pp":0,"reader":0,"ppx":0,"typer":16,"error":0}}

(I also end up with lots of camlppx files around).

A few questions:

• Is it a bug that this error message is occurring on stdout vs stderr - or the intended behavior?
• Is there a way to disable the creation of camlppx files and the corresponding warning?

The best case for Windows would be to fix #714 so we can get merlin working correctly with PPXes on that platform - but it seems like it will require a fix for both merlin and dune (for dune - we need to adjust the way it sends flags to the .merlin file).

So I'm trying to see if there is a way to at least workaround this in the meantime. Thanks for the help!

[bryphe]

The root issue is that I end up accumulating a massive amount of camlppx files: