Tools or approaches for structured compile-time warnings/errors output in Mix

Questions / Help
1

Hi everyone,

I’m looking for a way to capture compile-time warnings and errors from mix compile in a structured format (e.g., JSON) for use in tooling/CI pipelines.

What I’m trying to achieve

I want to turn compiler output into structured logs like:

[
  {
    "file": "lib/foo.ex",
    "line": 12,
    "severity": "warning",
    "message": "variable \"x\" is unused"
  }
]

What I’ve tried so far

Using Code.with_diagnostics/1

{status, diagnostics} =
  Code.with_diagnostics(fn ->
    Mix.Task.run("compile.elixir", [])
  end)

However, diagnostics is empty even when there are visible warnings during compilation.

My questions

  • Are there existing tools or libraries that provide structured compile-time diagnostics for Elixir/Mix?

  • Is there a more official or robust way to access compiler warnings/errors programmatically?

  • How do tools like Credo or other linters approach this problem?

Context

I’m building tooling around compilation for a no code platform project, so having reliable structured diagnostics would be very helpful.

Thanks in advance for any pointers!

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