diff options
Diffstat (limited to 'Help/variable')
| -rw-r--r-- | Help/variable/CMAKE_CROSSCOMPILING.rst | 26 | ||||
| -rw-r--r-- | Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst | 2 |
2 files changed, 23 insertions, 5 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. diff --git a/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst b/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst index 5be935b..cbe3544 100644 --- a/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst +++ b/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst @@ -6,7 +6,7 @@ The external toolchain for cross-compiling, if supported. Some compiler toolchains do not ship their own auxiliary utilities such as archivers and linkers. The compiler driver may support a command-line argument to specify the location of such tools. -``CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAIN`` may be set to a path to a path to +``CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAIN`` may be set to a path to the external toolchain and will be passed to the compiler driver if supported. This variable may only be set in a toolchain file specified by |