# CMP0113

New in version 3.19.

Makefile Generators do not repeat custom commands from target dependencies.

Consider a chain of custom commands split across two dependent targets:

    add_custom_command(OUTPUT output-not-created
      COMMAND ... DEPENDS ...)
    set_property(SOURCE output-not-created PROPERTY SYMBOLIC 1)
    add_custom_command(OUTPUT output-created
      COMMAND ... DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/output-not-created)
    add_custom_target(first DEPENDS output-not-created)
    add_custom_target(second DEPENDS output-created)
    add_dependencies(second first)

In CMake 3.18 and lower, the Makefile generators put a copy of both custom commands in the Makefile for target `second` even though its dependency on target `first` ensures that the first custom command runs before the second. Running `make second` would cause the first custom command to run once in the `first` target and then again in the `second` target.

CMake 3.19 and above prefer to not duplicate custom commands in a target that are already generated in other targets on which the target depends (directly or indirectly). This policy provides compatibility for projects that have not been updated to expect the new behavior. In particular, projects that relied on the duplicate execution or that did not properly set the `SYMBOLIC` source file property may be affected.

The `OLD` behavior for this policy is to duplicate custom commands in dependent targets. The `NEW` behavior of this policy is to not duplicate custom commands in dependent targets.

This policy was introduced in CMake version 3.19. Unlike many policies, CMake version 3.21.4 does not warn when this policy is not set and simply uses `OLD` behavior.

Note

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