From 0a6e715d56149a51b977259b1d08ef4c11b77ab7 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 20 Jan 2015 21:23:15 +0000
Subject: [PATCH] Use -Wl,defs when linking.

ELF linkers by default allow shared libraries to contain undefined references
and it is up to the dynamic linker to look for them.

On COFF and MachO, that is not the case.

This creates a situation where a .so might build on an ELF system, but the build
of the corresponding .dylib or .dll will fail.

This patch changes the cmake build to use -Wl,-z,defs when linking and updates
the dependencies so that -DBUILD_SHARED_LIBS=ON build still works.

llvm-svn: 226611
---
 cmake/modules/HandleLLVMOptions.cmake |  7 +++++++
 utils/unittest/CMakeLists.txt         | 13 +++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 2ee0dd5b1b7..e60018e6a0d 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -104,6 +104,13 @@ if(APPLE)
   set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -Wl,-flat_namespace -Wl,-undefined -Wl,suppress")
 endif()
 
+# Pass -Wl,-z,defs. This makes sure all symbols are defined. Otherwise a DSO
+# build might work on ELF but fail on MachO/COFF.
+if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" OR WIN32))
+  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,defs")
+endif()
+
+
 function(append value)
   foreach(variable ${ARGN})
     set(${variable} "${${variable}} ${value}" PARENT_SCOPE)
diff --git a/utils/unittest/CMakeLists.txt b/utils/unittest/CMakeLists.txt
index b6d2d6d9e0e..7ac894dff14 100644
--- a/utils/unittest/CMakeLists.txt
+++ b/utils/unittest/CMakeLists.txt
@@ -38,11 +38,20 @@ if(MSVC AND MSVC_VERSION EQUAL 1700)
   add_definitions(-D_VARIADIC_MAX=10)
 endif ()
 
+set(LIBS
+  LLVMSupport # Depends on llvm::raw_ostream
+)
+
+find_library(PTHREAD_LIBRARY_PATH pthread)
+if (PTHREAD_LIBRARY_PATH)
+  list(APPEND LIBS pthread)
+endif()
+
 add_llvm_library(gtest
   googletest/src/gtest-all.cc
 
   LINK_LIBS
-  LLVMSupport # Depends on llvm::raw_ostream
-  )
+  ${LIBS}
+)
 
 add_subdirectory(UnitTestMain)