Install cmt along with packages for merlin jump-to-definition

Recently, I tried to setup development environment with ocamlbuild + merlin for a project that depends on external packages, e.g. ocamlgraph.

What I noticed is that I was not able to jump to definitions of functions or types defined in Graph.

My guess is that opam install doesn’t download *.cmt file by default, so I need to somehow locate those to right location.

Are there any options that I can download *.cmt files along with opam packages? Or simply how I can get those bit-annot files for opam packages?

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A possible solution to this problem is to manually add the _build folder to the .merlin file in your project root directory. You will need to keep the build files of the external dependencies by doing opam install -b --deps-only first, however.

See How to get merlin to do a good job on project dependencies? How to get dune to generate better .merlin files? for more details.

Hi,
In the case of ocamlgraph, this is not an opam issue, this is a build system issue. To expand a bit, it’s up to each build system to tell opam what to install: mli files, cma files, cmt files, etc. A build system like dune will do the right thing by default and install cmt/cmti files, but older packages like ocamlgraph deal with their installation by hand using a Makefile.

There’s a dune port (that should install cmt files) at https://github.com/dune-universe/ocamlgraph/tree/duniverse-v1.8.8. You can also try to patch the Makefile, but in the long run I think it’s better to adapt the build system so that this is taken care of automatically.

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