Argus.Analyses.UnsafeTask (Panoptes v0.13.0)

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Unsafe task usage detection.

Detects two patterns that commonly cause production issues:

  1. Leaked async tasks — Task.async or Task.Supervisor.async_nolink calls in functions that never await/yield the result, directly or transitively through the call graph.

  2. Unchecked start_child — Task.Supervisor.start_child calls where the result is discarded without error handling. The call is not in tail position and no branch instruction follows it, indicating the {:ok, pid} / {:error, reason} result is ignored.

Suppresses leaked_async_task for process modules with message-receiving callbacks (GenServer, LiveView, LiveComponent, gen_statem) that consume task results through their mailbox rather than explicit await/yield. Also recognizes Task.shutdown/1,2 as a valid way to consume a task.

Requires the OTP extractor for implements_behaviour facts.

Output relations

  • leaked_async_task(func, id) — async task created but never awaited.
  • unchecked_start_child(func, id) — start_child result not checked.

Finding severities

Both relations are :warning: leaked tasks crash their caller or pile up unread result messages; unchecked starts make failed launches look like success. Neither is a guaranteed failure on every execution.