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diff --git a/Help/policy/CMP0113.rst b/Help/policy/CMP0113.rst new file mode 100644 index 000000000..6f56902d9 --- /dev/null +++ b/Help/policy/CMP0113.rst @@ -0,0 +1,43 @@ +CMP0113 +------- + +.. versionadded:: 3.19 + +:ref:`Makefile Generators` do not repeat custom commands from target +dependencies. + +Consider a chain of custom commands split across two dependent targets: + +.. code-block:: cmake + + 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 :prop_sf:`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 |release| does *not* warn when this policy is not set and +simply uses ``OLD`` behavior. + +.. include:: DEPRECATED.txt |