Add options for separate compile and link sysroots

Add `CMAKE_SYSROOT_COMPILE` and `CMAKE_SYSROOT_LINK` variables to as
operation-specific alternatives to `CMAKE_SYSROOT`.  This will be useful
for Android NDKs that compile and link with different sysroot values
(e.g. `r14` with unified headers).

Co-Author: Florent Castelli <florent.castelli@gmail.com>

5 files changed, 28 insertions, 0 deletions

diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 4317f67..6ee4257 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -171,6 +171,8 @@ Variables that Change Behavior
    /variable/CMAKE_SUBLIME_TEXT_2_ENV_SETTINGS
    /variable/CMAKE_SUBLIME_TEXT_2_EXCLUDE_BUILD_TREE
    /variable/CMAKE_SYSROOT
+   /variable/CMAKE_SYSROOT_COMPILE
+   /variable/CMAKE_SYSROOT_LINK
    /variable/CMAKE_SYSTEM_APPBUNDLE_PATH
    /variable/CMAKE_SYSTEM_FRAMEWORK_PATH
    /variable/CMAKE_SYSTEM_IGNORE_PATH
diff --git a/Help/release/dev/split-sysroot.rst b/Help/release/dev/split-sysroot.rst
new file mode 100644
index 0000000..8144e3f
--- /dev/null
+++ b/Help/release/dev/split-sysroot.rst
@@ -0,0 +1,5 @@
+split-sysroot
+-------------
+
+* The :variable:`CMAKE_SYSROOT_COMPILE` and :variable:`CMAKE_SYSROOT_LINK`
+  variables were added to use separate sysroots for compiling and linking.
diff --git a/Help/variable/CMAKE_SYSROOT.rst b/Help/variable/CMAKE_SYSROOT.rst
index 7aa0450..64f81bb 100644
--- a/Help/variable/CMAKE_SYSROOT.rst
+++ b/Help/variable/CMAKE_SYSROOT.rst
@@ -10,3 +10,6 @@ paths searched by the ``find_*`` commands.
 
 This variable may only be set in a toolchain file specified by
 the :variable:`CMAKE_TOOLCHAIN_FILE` variable.
+
+See also the :variable:`CMAKE_SYSROOT_COMPILE` and
+:variable:`CMAKE_SYSROOT_LINK` variables.
diff --git a/Help/variable/CMAKE_SYSROOT_COMPILE.rst b/Help/variable/CMAKE_SYSROOT_COMPILE.rst
new file mode 100644
index 0000000..e96c62b
--- /dev/null
+++ b/Help/variable/CMAKE_SYSROOT_COMPILE.rst
@@ -0,0 +1,9 @@
+CMAKE_SYSROOT_COMPILE
+---------------------
+
+Path to pass to the compiler in the ``--sysroot`` flag when compiling source
+files.  This is the same as :variable:`CMAKE_SYSROOT` but is used only for
+compiling sources and not linking.
+
+This variable may only be set in a toolchain file specified by
+the :variable:`CMAKE_TOOLCHAIN_FILE` variable.
diff --git a/Help/variable/CMAKE_SYSROOT_LINK.rst b/Help/variable/CMAKE_SYSROOT_LINK.rst
new file mode 100644
index 0000000..88b48ef
--- /dev/null
+++ b/Help/variable/CMAKE_SYSROOT_LINK.rst
@@ -0,0 +1,9 @@
+CMAKE_SYSROOT_LINK
+------------------
+
+Path to pass to the compiler in the ``--sysroot`` flag when linking.  This is
+the same as :variable:`CMAKE_SYSROOT` but is used only for linking and not
+compiling sources.
+
+This variable may only be set in a toolchain file specified by
+the :variable:`CMAKE_TOOLCHAIN_FILE` variable.