From cb274c0c4724c65b8c9cef32e431cf6152b0410e 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
---
 llvm/cmake/modules/HandleLLVMOptions.cmake |  7 +++++++
 llvm/utils/unittest/CMakeLists.txt         | 13 +++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 2ee0dd5b1b73..e60018e6a0dc 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/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/llvm/utils/unittest/CMakeLists.txt b/llvm/utils/unittest/CMakeLists.txt
index b6d2d6d9e0e9..7ac894dff14f 100644
--- a/llvm/utils/unittest/CMakeLists.txt
+++ b/llvm/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)