# CMP0037

Target names should not be reserved and should match a validity pattern.

CMake 2.8.12 and lower allowed creating targets using `add_library()`, `add_executable()` and `add_custom_target()` with unrestricted choice for the target name. Newer cmake features such as `cmake-generator-expressions(7)` and some diagnostics expect target names to match a restricted pattern.

Target names may contain upper and lower case letters, numbers, the underscore character (`_`), dot(`.`), plus(`+`) and minus(`-`). As a special case, `ALIAS` and `IMPORTED` targets may contain two consecutive colons.

Target names reserved by one or more CMake generators are not allowed. Among others these include `all`, `clean`, `help`, and `install`.

Target names associated with optional features, such as `test` and `package`, may also be reserved. CMake 3.10 and below always reserve them. CMake 3.11 and above reserve them only when the corresponding feature is enabled (e.g. by including the `CTest` or `CPack` modules).

The `OLD` behavior for this policy is to allow creating targets with reserved names or which do not match the validity pattern. The `NEW` behavior for this policy is to report an error if an add_* command is used with an invalid target name.

This policy was introduced in CMake version 3.0. CMake version 3.19.0-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.