1OPTIMIZE_DEPENDENCIES
2---------------------
3
4.. versionadded:: 3.19
5
6Activates dependency optimization of static and object libraries.
7
8When this property is set to true, some dependencies for a static or object
9library may be removed at generation time if they are not necessary to build
10the library, since static and object libraries don't actually link against
11anything.
12
13If a static or object library has dependency optimization enabled, it first
14discards all dependencies. Then, it looks through all of the direct and
15indirect dependencies that it initially had, and adds them back if they meet
16any of the following criteria:
17
18* The dependency was added to the library by :command:`add_dependencies`.
19* The dependency was added to the library through a source file in the library
20  generated by a custom command that uses the dependency.
21* The dependency has any ``PRE_BUILD``, ``PRE_LINK``, or ``POST_BUILD`` custom
22  commands associated with it.
23* The dependency contains any source files that were generated by a custom
24  command.
25* The dependency contains any languages which produce side effects that are
26  relevant to the library. Currently, all languages except C, C++, Objective-C,
27  Objective-C++, assembly, and CUDA are assumed to produce side effects.
28  However, side effects from one language are assumed not to be relevant to
29  another (for example, a Fortran library is assumed to not have any side
30  effects that are relevant for a Swift library.)
31
32As an example, assume you have a static Fortran library which depends on a
33static C library, which in turn depends on a static Fortran library. The
34top-level Fortran library has optimization enabled, but the middle C library
35does not. If you build the top Fortran library, the bottom Fortran library will
36also build, but not the middle C library, since the C library does not have any
37side effects that are relevant for the Fortran library. However, if you build
38the middle C library, the bottom Fortran library will also build, even though
39it does not have any side effects that are relevant to the C library, since the
40C library does not have optimization enabled.
41
42This property is initialized by the value of the
43:variable:`CMAKE_OPTIMIZE_DEPENDENCIES` variable when the target is created.
44