[libcxx] Remove installation rules on Darwin when it would overwrite the system installation.
Summary:
On Mac OS X overwriting `/usr/lib/libc++.dylib` can cause your computer to fail to boot. This patch tries to make it harder to do that accidentally.
If `CMAKE_SYSTEM_NAME` is `Darwin` and `CMAKE_INSTALL_PREFIX` is `/usr` don't generate installation rules unless the user explicitly provides `LIBCXX_OVERRIDE_DARWIN_INSTALL=ON`. Note that `CMAKE_INSTALL_PREFIX` is always absolute so we don't need to worry about things like `/usr/../usr`.
Reviewers: mclow.lists, beanz, jroelofs
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D12209
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@246070 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 872addd..fb9e2bf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -56,6 +56,7 @@
set(LIBCXX_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
"Define suffix of library directory name (32/64)")
option(LIBCXX_INSTALL_HEADERS "Install the libc++ headers." ON)
+option(LIBCXX_INSTALL_LIBRARY "Install the libc++ library." ON)
option(LIBCXX_INSTALL_SUPPORT_HEADERS "Install libc++ support headers." ON)
# ABI Library options ---------------------------------------------------------
@@ -95,6 +96,23 @@
set(LIBCXX_COVERAGE_LIBRARY "" CACHE STRING
"The Profile-rt library used to build with code coverage")
+# Don't allow a user to accidentally overwrite the system libc++ installation on Darwin.
+# If the user specifies -DCMAKE_INSTALL_PREFIX=/usr the install rules for libc++
+# will not be generated and a warning will be issued.
+option(LIBCXX_OVERRIDE_DARWIN_INSTALL "Enable overwriting darwins libc++ installation." OFF)
+mark_as_advanced(LIBCXX_OVERRIDE_DARWIN_INSTALL) # Don't show this option by default.
+
+if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" AND NOT LIBCXX_OVERRIDE_DARWIN_INSTALL)
+ if ("${CMAKE_INSTALL_PREFIX}" STREQUAL "/usr")
+ message(WARNING "Disabling libc++ install rules because installation would "
+ "overwrite the systems installation. Configure with "
+ "-DLIBCXX_OVERRIDE_DARWIN_INSTALL=ON to suppress this behaviour.")
+ mark_as_advanced(CLEAR LIBCXX_OVERRIDE_DARWIN_INSTALL) # Show the override option.
+ set(LIBCXX_INSTALL_HEADERS OFF)
+ set(LIBCXX_INSTALL_LIBRARY OFF)
+ endif()
+endif()
+
#===============================================================================
# Check option configurations
#===============================================================================