Merge topic 'cross-compiling-toolchain-variables'

7cd65c9 Add CMAKE_SYSROOT variable to set --sysroot when cross compiling.
5096967 Allow toolchain files to specify an external toolchain.
76552d5 Add compiler target compile options.
f41ecd1 CMakeDetermineCompilerId: Look for internal file only on host

5 files changed, 48 insertions, 2 deletions

diff --git a/Help/command/FIND_XXX_ROOT.txt b/Help/command/FIND_XXX_ROOT.txt
index 407375a..7f80dcb 100644
--- a/Help/command/FIND_XXX_ROOT.txt
+++ b/Help/command/FIND_XXX_ROOT.txt
@@ -1,10 +1,17 @@
 The CMake variable CMAKE_FIND_ROOT_PATH specifies one or more
 directories to be prepended to all other search directories.  This
 effectively "re-roots" the entire search under given locations.  By
-default it is empty.  It is especially useful when cross-compiling to
+default it is empty.
+
+The :variable:`CMAKE_SYSROOT` variable can also be used to specify exactly one
+directory to use as a prefix.  Setting :variable:`CMAKE_SYSROOT` also has other
+effects.  See the documentation for that variable for more.
+
+These variables are especially useful when cross-compiling to
 point to the root directory of the target environment and CMake will
 search there too.  By default at first the directories listed in
-CMAKE_FIND_ROOT_PATH and then the non-rooted directories will be
+CMAKE_FIND_ROOT_PATH are searched, then the :variable:`CMAKE_SYSROOT` directory is
+searched, and then the non-rooted directories will be
 searched.  The default behavior can be adjusted by setting
 |CMAKE_FIND_ROOT_PATH_MODE_XXX|.  This behavior can be manually
 overridden on a per-call basis.  By using CMAKE_FIND_ROOT_PATH_BOTH
diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 59e8064..dd82b40 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -91,6 +91,7 @@ Variables that Change Behavior
    /variable/CMAKE_DISABLE_FIND_PACKAGE_PackageName
    /variable/CMAKE_ERROR_DEPRECATED
    /variable/CMAKE_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION
+   /variable/CMAKE_SYSROOT
    /variable/CMAKE_FIND_LIBRARY_PREFIXES
    /variable/CMAKE_FIND_LIBRARY_SUFFIXES
    /variable/CMAKE_FIND_PACKAGE_WARN_NO_MODULE
@@ -234,6 +235,8 @@ Variables for Languages
    /variable/CMAKE_LANG_COMPILER_ID
    /variable/CMAKE_LANG_COMPILER_LOADED
    /variable/CMAKE_LANG_COMPILER
+   /variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN
+   /variable/CMAKE_LANG_COMPILER_TARGET
    /variable/CMAKE_LANG_COMPILER_VERSION
    /variable/CMAKE_LANG_CREATE_SHARED_LIBRARY
    /variable/CMAKE_LANG_CREATE_SHARED_MODULE
diff --git a/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst b/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst
new file mode 100644
index 0000000..86c0b0e
--- /dev/null
+++ b/Help/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.rst
@@ -0,0 +1,13 @@
+CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAIN
+----------------------------------------
+
+The external toolchain for cross-compiling, if supported.
+
+Some compiler toolchains do not ship their own auxilliary 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 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
+the ``CMAKE_TOOLCHAIN_FILE`` variable.
diff --git a/Help/variable/CMAKE_LANG_COMPILER_TARGET.rst b/Help/variable/CMAKE_LANG_COMPILER_TARGET.rst
new file mode 100644
index 0000000..7c8efee
--- /dev/null
+++ b/Help/variable/CMAKE_LANG_COMPILER_TARGET.rst
@@ -0,0 +1,11 @@
+CMAKE_<LANG>_COMPILER_TARGET
+----------------------------
+
+The target for cross-compiling, if supported.
+
+Some compiler drivers are inherently cross-compilers, such as clang and
+QNX qcc. These compiler drivers support a command-line argument to specify
+the target to cross-compile for.
+
+This variable may only be set in a toolchain file specified by
+the ``CMAKE_TOOLCHAIN_FILE`` variable.
diff --git a/Help/variable/CMAKE_SYSROOT.rst b/Help/variable/CMAKE_SYSROOT.rst
new file mode 100644
index 0000000..e42e63a
--- /dev/null
+++ b/Help/variable/CMAKE_SYSROOT.rst
@@ -0,0 +1,12 @@
+CMAKE_SYSROOT
+-------------
+
+Path to pass to the compiler in the ``--sysroot`` flag.
+
+The ``CMAKE_SYSROOT`` content is passed to the compiler in the ``--sysroot``
+flag, if supported.  The path is also stripped from the RPATH/RUNPATH if
+necessary on installation.  The ``CMAKE_SYSROOT`` is also used to prefix
+paths searched by the ``find_*`` commands.
+
+This variable may only be set in a toolchain file specified by
+the ``CMAKE_TOOLCHAIN_FILE`` variable.