From a826efc52f53edf59f639e62b6f5b1918fab547f Mon Sep 17 00:00:00 2001
From: Kefu Chai <kchai@redhat.com>
Date: Tue, 8 Oct 2019 16:04:45 +0800
Subject: [PATCH] cmake: detect linker support

check the linker support of `--version-script` and `--exclude-libs`
flags. and use them only if they are supported.

llvm-ld does not support `--version-script` at this moment. and it's
reported that old versions of llvm-ld do not support `--exclude-libs`
as well.

Signed-off-by: Kefu Chai <kchai@redhat.com>
---
 cmake/modules/CephCheck_link.c   |  2 ++
 cmake/modules/CephCheck_link.map |  1 +
 cmake/modules/CephChecks.cmake   | 11 +++++++++++
 src/librados/CMakeLists.txt      |  4 +++-
 4 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 cmake/modules/CephCheck_link.c
 create mode 100644 cmake/modules/CephCheck_link.map

diff --git a/cmake/modules/CephCheck_link.c b/cmake/modules/CephCheck_link.c
new file mode 100644
index 00000000000..0c87b37802d
--- /dev/null
+++ b/cmake/modules/CephCheck_link.c
@@ -0,0 +1,2 @@
+int main()
+{}
diff --git a/cmake/modules/CephCheck_link.map b/cmake/modules/CephCheck_link.map
new file mode 100644
index 00000000000..333a9b3c02f
--- /dev/null
+++ b/cmake/modules/CephCheck_link.map
@@ -0,0 +1 @@
+{};
\ No newline at end of file
diff --git a/cmake/modules/CephChecks.cmake b/cmake/modules/CephChecks.cmake
index 576971ed2a8..f5a77abc6e6 100644
--- a/cmake/modules/CephChecks.cmake
+++ b/cmake/modules/CephChecks.cmake
@@ -124,3 +124,14 @@ int main(int argc, char **argv)
 else(CMAKE_SYSTEM_PROCESSOR STREQUAL CMAKE_HOST_SYSTEM_PROCESSOR)
   message(STATUS "Assuming unaligned access is supported")
 endif(CMAKE_SYSTEM_PROCESSOR STREQUAL CMAKE_HOST_SYSTEM_PROCESSOR)
+
+# should use LINK_OPTIONS instead of LINK_LIBRARIES, if we can use cmake v3.14+
+try_compile(HAVE_LINK_VERSION_SCRIPT
+  ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_LIST_DIR}/CephCheck_link.c
+  LINK_LIBRARIES "-Wl,--version-script=${CMAKE_CURRENT_LIST_DIR}/CephCheck_link.map")
+
+try_compile(HAVE_LINK_EXCLUDE_LIBS
+  ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_LIST_DIR}/CephCheck_link.c
+  LINK_LIBRARIES "-Wl,--exclude-libs,ALL")
diff --git a/src/librados/CMakeLists.txt b/src/librados/CMakeLists.txt
index 6efed26bd8f..6335d0c5975 100644
--- a/src/librados/CMakeLists.txt
+++ b/src/librados/CMakeLists.txt
@@ -16,9 +16,11 @@ if(ENABLE_SHARED)
     VERSION 2.0.0
     SOVERSION 2
     VISIBILITY_INLINES_HIDDEN ON)
-  if(NOT APPLE)
+  if(HAVE_LINK_EXCLUDE_LIBS)
     set_property(TARGET librados APPEND_STRING PROPERTY
       LINK_FLAGS " -Wl,--exclude-libs,ALL")
+  endif()
+  if(HAVE_LINK_VERSION_SCRIPT)
     set_property(TARGET librados APPEND_STRING PROPERTY
       LINK_FLAGS " -Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/librados.map")
   endif()
-- 
2.39.5