phx:trace

To trace function calls in an Elixir Phoenix application, generate recursive call trees from defined entry points to visualize invocation paths and analyze argument patterns for diagnosing runtime issues.

To find where a nil value was introduced in Elixir code, trace data flow back from the point of failure to identify the origin using argument pattern analysis and call trees.

Yes, mix xref works for generating recursive call trees in Phoenix by leveraging call site identification and AST parsing to accurately trace function invocation paths.

The best way to plan function signature modifications in Elixir is to analyze argument patterns and call trees to understand how data is passed between functions before making changes.

Yes, you can trace data flow from a specific entry point like MyApp.Accounts.update_user/2 by building a recursive call tree to map its function invocation paths.

AST parsing is needed for debugging data flow in Elixir because it enables accurate call site and argument origin identification within complex recursive call trees.