AIX: Add -pthread flag to enable std::thread with GCC

CMakeLists.txt

@@ -2,7 +2,11 @@
 # file Copyright.txt or https://cmake.org/licensing for details.
 
 cmake_minimum_required(VERSION 3.1 FATAL_ERROR)
+set(CMAKE_USER_MAKE_RULES_OVERRIDE_C ${CMAKE_CURRENT_SOURCE_DIR}/Source/Modules/OverrideC.cmake)
+set(CMAKE_USER_MAKE_RULES_OVERRIDE_CXX ${CMAKE_CURRENT_SOURCE_DIR}/Source/Modules/OverrideCXX.cmake)
 project(CMake)
+unset(CMAKE_USER_MAKE_RULES_OVERRIDE_CXX)
+unset(CMAKE_USER_MAKE_RULES_OVERRIDE_C)
 
 # Make sure we can find internal find_package modules only used for
 # building CMake and not for shipping externally

Source/Modules/OverrideC.cmake

@@ -0,0 +1,3 @@
+if("${CMAKE_SYSTEM_NAME};${CMAKE_C_COMPILER_ID}" STREQUAL "AIX;GNU")
+  string(APPEND CMAKE_C_FLAGS_INIT " -pthread")
+endif()

Source/Modules/OverrideCXX.cmake

@@ -0,0 +1,3 @@
+if("${CMAKE_SYSTEM_NAME};${CMAKE_CXX_COMPILER_ID}" STREQUAL "AIX;GNU")
+  string(APPEND CMAKE_CXX_FLAGS_INIT " -pthread")
+endif()

bootstrap

@@ -982,6 +982,9 @@ if [ -z "${CC}" -a -z "${CXX}" ]; then
 fi
 
 thread_flags=''
+case "${cmake_system}" in
+  *AIX*)   thread_flags='-pthread' ;;
+esac
 
 #-----------------------------------------------------------------------------
 # Test C compiler
@@ -1003,6 +1006,10 @@ echo '
 # error "The CMAKE_C_COMPILER is set to a C++ compiler"
 #endif
 
+#if defined(_AIX) && defined(__GNUC__) && !defined(_THREAD_SAFE)
+#error "On AIX with GNU we need the -pthread flag."
+#endif
+
 #if defined(__sun) && __STDC_VERSION__ < 199901L
 #error "On Solaris we need C99."
 #endif
@@ -1066,6 +1073,10 @@ echo '
 #error "Compiler is not in a mode aware of C++11."
 #endif
 
+#if defined(_AIX) && defined(__GNUC__) && !defined(_THREAD_SAFE)
+#error "On AIX with GNU we need the -pthread flag."
+#endif
+
 #if defined(__SUNPRO_CC) && __SUNPRO_CC < 0x5140
 #error "SunPro <= 5.13 mode not supported due to bug in move semantics."
 #endif
@@ -1326,7 +1337,7 @@ else
   uv_c_flags="${uv_c_flags} -DCMAKE_BOOTSTRAP"
   case "${cmake_system}" in
     *AIX*)
-      uv_c_flags="${uv_c_flags} -D_ALL_SOURCE -D_XOPEN_SOURCE=500 -D_LINUX_SOURCE_COMPAT -D_THREAD_SAFE"
+      uv_c_flags="${uv_c_flags} -D_ALL_SOURCE -D_XOPEN_SOURCE=500 -D_LINUX_SOURCE_COMPAT"
       libs="${libs} -lperfstat"
       ;;
     *Darwin*)