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| author | Craig Scott <craig.scott@crascit.com> | 2018-01-18 21:30:53 (GMT) |
|---|---|---|
| committer | Craig Scott <craig.scott@crascit.com> | 2018-01-18 21:31:34 (GMT) |
| commit | 60febda45541c65e0ca7fb4535c629c77c17e13a (patch) | |
| tree | 4558c35025e73e4bd489aaf132823f1d8750f1ad /Help | |
| parent | cbe7314bb0f0ce5dbc7a5a9d71f3688c810cf731 (diff) | |
| download | CMake-60febda45541c65e0ca7fb4535c629c77c17e13a.zip CMake-60febda45541c65e0ca7fb4535c629c77c17e13a.tar.gz CMake-60febda45541c65e0ca7fb4535c629c77c17e13a.tar.bz2 | |
Help: Explain meaning and limitations of CMAKE_CROSSCOMPILING
Fixes: #17653
Diffstat (limited to 'Help')
| -rw-r--r-- | Help/variable/CMAKE_CROSSCOMPILING.rst | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/Help/variable/CMAKE_CROSSCOMPILING.rst b/Help/variable/CMAKE_CROSSCOMPILING.rst index cf9865b..9e96769 100644 --- a/Help/variable/CMAKE_CROSSCOMPILING.rst +++ b/Help/variable/CMAKE_CROSSCOMPILING.rst @@ -1,8 +1,26 @@ CMAKE_CROSSCOMPILING -------------------- -Is CMake currently cross compiling. +Intended to indicate whether CMake is cross compiling, but note limitations +discussed below. -This variable will be set to true by CMake if CMake is cross -compiling. Specifically if the build platform is different from the -target platform. +This variable will be set to true by CMake if the :variable:`CMAKE_SYSTEM_NAME` +variable has been set manually (i.e. in a toolchain file or as a cache entry +from the :manual:`cmake <cmake(1)>` command line). In most cases, manually +setting :variable:`CMAKE_SYSTEM_NAME` will only be done when cross compiling, +since it will otherwise be given the same value as +:variable:`CMAKE_HOST_SYSTEM_NAME` if not manually set, which is correct for +the non-cross-compiling case. In the event that :variable:`CMAKE_SYSTEM_NAME` +is manually set to the same value as :variable:`CMAKE_HOST_SYSTEM_NAME`, then +``CMAKE_CROSSCOMPILING`` will still be set to true. + +Another case to be aware of is that builds targeting Apple platforms other than +macOS are handled differently to other cross compiling scenarios. Rather than +relying on :variable:`CMAKE_SYSTEM_NAME` to select the target platform, Apple +device builds use :variable:`CMAKE_OSX_SYSROOT` to select the appropriate SDK, +which indirectly determines the target platform. Furthermore, when using the +Xcode generator, developers can switch between device and simulator builds at +build time rather than having a single choice at configure time, so the concept +of whether the build is cross compiling or not is more complex. Therefore, the +use of ``CMAKE_CROSSCOMPILING`` is not recommended for projects targeting Apple +devices. |