merlin-locate 3.0.5 doesn't work with Base/Core/Async etc

[yminsky]

Cross-linking to this issue:

janestreet/base#36

Given that it's a problem that came up with 3.0.5, it seems like there's a decent chance that it's a Merlin side issue.

[hhugo]

The issue does not exist with 3.0.4 because reading the cmts was broken with 4.06.
Merlin was instead jumping to the interface.

Because merlin.3.0.5 can now read cmts, it tries to locate the implementation and fails
because the implementation is not installed. (see ocaml/dune#500)

[trefis]

More precisely: an exception is generated (and caught) when the .cmt doesn't match the version we know how to read. In which case we decide to use the location stored in the environment (there is one by default since 4.06.0, there wasn't any before), and that location always points to the interface, so we jump there.

Merlin should probably just report that the .cmt doesn't match the expected version.

[copy]

A related issue, is the following fixable with the extra information available from cmt files?

Several source files in your path have the same name, and merlin doesn't know which is the right one: /home/fabian/.opam/4.06.0+flambda/lib/ocaml/queue.ml, /home/fabian/.opam/4.06.0+flambda/lib/core_kernel/queue.ml

Also, a MerlinLocateInterface command might be useful.

[trefis]

Also, a MerlinLocateInterface command might be useful.

You can define one, have a look at g:merlin_locate_preference.