Performs cross reference checks between modules.

Xref modes

The xref task expects a mode as first argument:

mix xref MODE

All available modes are discussed below.

warnings

Prints warnings for violated cross reference checks:

mix xref warnings

This is the mode used by Mix during compilation.

unreachable

Prints all unreachable “file:line: module.function/arity” entries:

mix xref unreachable

The “file:line” represents the file and line a call to an unknown “module.function/arity” is made.

callers CALLEE

Prints all callers of the given CALLEE, which can be one of: Module, Module.function, or Module.function/arity. Examples:

mix xref callers MyMod
mix xref callers MyMod.fun
mix xref callers MyMod.fun/3

graph

Prints a file dependency graph where an edge from A to B indicates that A depends on B.

mix xref graph --format dot

The following options are accepted:

• --exclude - paths to exclude

• --source - displays all files that the given source file references (directly or indirectly)

• --sink - displays all files that reference the given file (directly or indirectly)

• --format - can be set to one of:

  • pretty - uses Unicode codepoints for formatting the graph. This is the default except on Windows

  • plain - does not use Unicode codepoints for formatting the graph. This is the default on Windows

  • dot - produces a DOT graph description in xref_graph.dot in the current directory. Warning: this will override any previously generated file

The --source and --sink options are particularly useful when trying to understand how the modules in a particular file interact with the whole system.

Shared options

Those options are shared across all modes:

• --no-compile - does not compile even if files require compilation

• --no-deps-check - does not check dependencies

• --no-archives-check - does not check archives

• --no-elixir-version-check - does not check the Elixir version from mix.exs

Configuration

All configuration for Xref should be placed under the key :xref.

• :exclude - a list of modules and {module, function, arity} tuples to ignore when checking cross references. For example: [MissingModule, {MissingModule2, :missing_func, 2}]