Introduce CMAKE_STAGING_PREFIX variable.

This variable can be useful in cross-compiling contexts where the
sysroot is read-only or where the sysroot should otherwise remain
pristine.

If the new CMAKE_STAGING_PREFIX variable is set, it is used instead
of CMAKE_INSTALL_PREFIX when generating the installation rules in
cmake_install.cmake.

This way, the CMAKE_INSTALL_PREFIX variable
always refers to the installation prefix on the target device, regardless
of whether host==target.

If any -rpath paths passed to the linker contain the CMAKE_STAGING_PREFIX,
the matching path fragments are replaced with the CMAKE_INSTALL_PREFIX.
Matching paths in the -rpath-link are not transformed.

The cross-prefix usr-move workaround is assumed not to require extension
regarding CMAKE_STAGING_PREFIX. The staging area is a single prefix, so
there is no scope for cross-prefix symlinks. The CMAKE_INSTALL_PREFIX
is still used to determine the workaround path, and that variable
remains the relevant one even if CMAKE_STAGING_PREFIX is used. If the
generated export files are deployed to the target, the workaround
will still be in place, and still be employed if required.

1 files changed, 10 insertions, 0 deletions

diff --git a/Tests/StagingPrefix/Producer/bar.h b/Tests/StagingPrefix/Producer/bar.h
new file mode 100644
index 0000000000..acd1fae023
--- /dev/null
+++ b/Tests/StagingPrefix/Producer/bar.h
@@ -0,0 +1,10 @@
+
+class
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+Bar
+{
+public:
+  int bar();
+};