1CMP0116
2-------
3
4.. versionadded:: 3.20
5
6Ninja generators transform ``DEPFILE`` s from :command:`add_custom_command`.
7
8In CMake 3.19 and below, files given to the ``DEPFILE`` argument of
9:command:`add_custom_command` were passed directly to Ninja's ``depfile``
10variable without any path resolution. This meant that if
11:command:`add_custom_command` was called from a subdirectory (created by
12:command:`add_subdirectory`), the ``DEPFILE`` argument would have to be either
13an absolute path or a path relative to :variable:`CMAKE_BINARY_DIR`, rather
14than :variable:`CMAKE_CURRENT_BINARY_DIR`. In addition, no transformation was
15done on the file listed in ``DEPFILE``, which meant that the paths within the
16``DEPFILE`` had the same restrictions.
17
18Starting with CMake 3.20, the ``DEPFILE`` argument is relative to
19:variable:`CMAKE_CURRENT_BINARY_DIR` (unless it is absolute), and the paths in
20the ``DEPFILE`` are also relative to :variable:`CMAKE_CURRENT_BINARY_DIR`.
21CMake automatically transforms the paths in the ``DEPFILE`` (unless they are
22absolute) after the custom command is run. The file listed in ``DEPFILE`` is
23not modified in any way. Instead, CMake writes the transformation to its own
24internal file, and passes this internal file to Ninja's ``depfile`` variable.
25This transformation happens regardless of whether or not ``DEPFILE`` is
26relative, and regardless of whether or not :command:`add_custom_command` is
27called from a subdirectory.
28
29The ``OLD`` behavior for this policy is to pass the ``DEPFILE`` to Ninja
30unaltered. The ``NEW`` behavior for this policy is to transform the ``DEPFILE``
31after running the custom command. The status of ``CMP0116`` is recorded at the
32time of the custom command's creation, and you can have custom commands in the
33same directory with different values for ``CMP0116`` by setting the policy
34before each custom command.
35
36This policy was introduced in CMake version 3.20.  Unlike most policies,
37CMake version |release| does *not* warn by default when this policy is not set
38(unless ``DEPFILE`` is used in a subdirectory) and simply uses ``OLD``
39behavior.  See documentation of the
40:variable:`CMAKE_POLICY_WARNING_CMP0116 <CMAKE_POLICY_WARNING_CMP<NNNN>>`
41variable to control the warning.
42