gleam-lang/gleam

Improve error message for invalid dependency

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#4925 opened on Sep 3, 2025

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 (3 comments) (0 reactions) (0 assignees)Rust (21,417 stars) (960 forks)batch import
help wanted

Description

Right now if I try and use a git dependency and mess up one of the fields the error I get looks like this:

error: File IO failure

An error occurred while trying to parse this file:

    /Users/giacomocavalieri/Documents/progetti/giacomocavalieri.me/gleam.toml

The error message from the file IO library was:

    TOML parse error at line 6, column 7
  |
6 | jot = { a = "58499d73c0a980f4d6cfb04b7cbfab9198238b76" }
  |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
data did not match any variant of untagged enum Requirement

That big underline is not all that useful and is talking about compiler internals, I think it would be nice if it provided a better error message here. Not sure what it would look like!

Contributor guide

Tech stack
rust
Domain
developer experiencetooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with RustUnderstanding of Gleam project structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Look at the Gleam compiler source code, specifically the TOML parsing and error handling in the `gleam config` module. Check how errors from the `toml` crate are currently displayed and consider providing a more user friendly error message that explains which field is invalid instead of showing the internal `untagged enum Requirement` message. Review the issue comments for any additional context or suggestions.