Adds a self-contained 'unused' Mix compiler task that finds public
functions in this project no caller in the project ever invokes:
- MixUnused.Analyzer: enumerates public functions across the project's
compiled BEAM files (filtered by app), walks the abstract code in
each BEAM via :beam_lib to collect every remote {Module, fun, arity}
call observed at compile time, and subtracts the call set from the
def set. Exposes :exclude (modules or MFA triples), :compile_path,
and :app options. Behaviour callbacks (@impl true and any listed
in behaviour_info(:callbacks)) and well-known entry points
(start_link, child_spec, mount, render, GenServer callbacks,
__info__, module_info, etc.) are excluded automatically.
- Mix.Tasks.Compile.Unused: a Mix.Task.Compiler that compiles the
project then asks the analyzer for unused defs. Severity is
configurable via the :unused project key; per-file exclusion of
test/ paths is on by default.
Inspired by https://github.com/hauleth/mix_unused — uses BEAM
introspection rather than a compilation tracer to avoid the
chicken-and-egg problem of recompiling the tracer module itself
during analysis.
Graham McIntire
5fb653bf05