# CMP0050

Warning

The `OLD` behavior of this policy was removed in CMake version 4.0. This policy must be set to `NEW` by a call to `cmake_minimum_required()` or `cmake_policy()`.

Disallow add_custom_command SOURCE signatures.

CMake 2.8.12 and lower allowed a signature for `add_custom_command()` which specified an input to a command. This was undocumented behavior. Modern use of CMake associates custom commands with their output, rather than their input.

The `OLD` behavior for this policy is to allow the use of `add_custom_command()` SOURCE signatures. The `NEW` behavior for this policy is to issue an error if such a signature is used.

This policy was introduced in CMake version 3.0. Prior to removal in CMake version 4.0, it could be set by `cmake_policy()` or `cmake_minimum_required()`. If it was not set, CMake warned, and used `OLD` behavior.