[libcxx-commits] [libcxx] r359755 - [libcxx] cmake - guard list remove

[Brian Cain via libcxx-commits]

Author: bcain
Date: Wed May  1 20:49:50 2019
New Revision: 359755

URL: http://llvm.org/viewvc/llvm-project?rev=359755&view=rev
Log:
[libcxx] cmake - guard list remove

REMOVE_ITEM fails if CMAKE_REQUIRED_LIBRARIES is empty on some
versions of cmake.

Modified:
    libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake

Modified: libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake?rev=359755&r1=359754&r2=359755&view=diff
==============================================================================
--- libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake (original)
+++ libcxx/trunk/cmake/Modules/CheckLibcxxAtomic.cmake Wed May  1 20:49:50 2019
@@ -34,10 +34,12 @@ endfunction(check_cxx_atomics)
 # Perform the check for 64bit atomics without libatomic. It may have been
 # added to the required libraries during in the configuration of LLVM, which
 # would cause the check for CXX atomics without libatomic to incorrectly pass.
-set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
-list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "atomic")
-check_cxx_atomics(LIBCXX_HAVE_CXX_ATOMICS_WITHOUT_LIB)
-set(CMAKE_REQUIRED_LIBRARIES ${OLD_CMAKE_REQUIRED_LIBRARIES})
+if (CMAKE_REQUIRED_LIBRARIES)
+  set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
+  list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "atomic")
+  check_cxx_atomics(LIBCXX_HAVE_CXX_ATOMICS_WITHOUT_LIB)
+  set(CMAKE_REQUIRED_LIBRARIES ${OLD_CMAKE_REQUIRED_LIBRARIES})
+endif()
 
 check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
 # If not, check if the library exists, and atomics work with it.