# CMP0050

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. CMake version 3.16.0-rc2 warns when the policy is not set and uses `OLD` behavior. Use the `cmake_policy()` command to set it to `OLD` or `NEW` explicitly.

Note

The `OLD` behavior of a policy is `deprecated by definition` and may be removed in a future version of CMake.