Go-to-definition / Find references for `meck` calls

[robertoaloi]

Context

ELP has support for go-to-definition and find-references for dynamic calls such as erlang:apply/X or erlang:spawn/X.

meck is a popular mocking library which also takes Erlang MFAs (module-function-arity or module-function-arguments) as parameters.

Problem

While it's possible to navigate and find references for certain dynamic calls, this is not possible for meck.

Solution

ELP already provides a mechanism to support dynamic calls in go-to-definition/find-reference. The details are described here.

Extend the list to support meck APIs which take a MFA as "argument".

Tests can be trivially implemented here.

[robertoaloi]

@eproxus in case you're looking for a tiny contribution to ELP. It should be a trivial thing to do and you'd get an idea of how to build/test in ELP. ;)

[eproxus]

@robertoaloi Thanks for the ping! I tried to the best of my ability to follow the steps in the CI job in order to build and test ELP locally but didn't succeed. Here are the steps I ran locally (on a M2 macOS machine):

$ mise use rust@stable erlang@28.1 java@17 graalvm scala sbt
$ git submodule update —init
# Having built EDB outside of the repo:
$ ln -s ../edb/_build/default/bin/edb .
$ cd eqwalizer/eqwalizer
eqwalizer/eqwalizer$ sbt assembly
eqwalizer/eqwalizer$ native-image -H:IncludeResources=application.conf --no-server --no-fallback -jar target/scala-3.6.4/eqwalizer.jar eqwalizer
eqwalizer/eqwalizer$ cd ../..
$ cargo test --no-default-features --workspace
   Compiling elp_eqwalizer v1.1.0 (/Users/alind/Developer/Code/erlang-language-platform/crates/eqwalizer)
   Compiling fd-lock v3.0.13
   Compiling termcolor v1.4.1
   Compiling vfs-notify v0.0.0 (https://github.com/rust-lang/rust-analyzer?rev=2025-03-04#02862f5d)
   Compiling elp v1.1.0 (/Users/alind/Developer/Code/erlang-language-platform/crates/elp)
   Compiling proc-macro-error v1.0.4
   Compiling tikv-jemallocator v0.5.4
   Compiling lsp-server v0.7.8
   Compiling serde_path_to_error v0.1.17
   Compiling url v2.5.4
   Compiling indicatif v0.17.11
   Compiling threadpool v1.8.1
   Compiling rustyline v11.0.0
   Compiling range-set v0.0.10
error: failed to run custom build command for `elp_eqwalizer v1.1.0 (/Users/alind/Developer/Code/erlang-language-platform/crates/eqwalizer)`

Caused by:
  process didn't exit successfully: `/Users/alind/Developer/Code/erlang-language-platform/target/debug/build/elp_eqwalizer-2dddfddc9d0e2d4d/build-script-build` (exit status: 101)
  --- stderr

  thread 'main' panicked at crates/eqwalizer/build.rs:31:35:
  Copying precompiled eqwalizer failed: Os { code: 20, kind: NotADirectory, message: "Not a directory" }
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...

[robertoaloi]

Hi @eproxus , glad you accepted the challenge :)

It's just a race condition between us adding eqwalizer as a submodule, you trying and us updating the docs. The updated version of the docs is up now:

https://whatsapp.github.io/erlang-language-platform/docs/get-started/install/#from-source

TL;DR; I think you just need to set the two environment variables above. EDB should not be relevant for this.

[robertoaloi]

Also, for faster builds, you don't need cargo build --release, since that step performs many optimizations that slow down compilation and you most likely don't need for local development

You can use the faster cargo build --profile release-thin. Will update the docs accordingly.