CMake: Split out Objective-C++ flags on macOS to fix crash

This now requires CMake 3.16

This is a similar fix as 987f2f036b7d5b0e02a7ed8a2ff0f1029ae0d048 but for CMake

CMakeLists.txt

@@ -24,6 +24,9 @@ endif()
 
 # Set defaults for macOS, must be before project().
 if(APPLE)
+  # Needed for enable_language(OBJCXX)
+  cmake_minimum_required(VERSION 3.16)
+
   set(CMAKE_OSX_DEPLOYMENT_TARGET "10.9" CACHE STRING "Minimum macOS version to target")
   set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
 
@@ -46,6 +49,11 @@ project(Panda3D VERSION ${_version})
 unset(_version)
 unset(_s)
 
+if(APPLE)
+  # Allows separating out C++ flags from ObjC++ flags
+  enable_language(OBJCXX)
+endif()
+
 # Determine the possible build types.  Must be *after* calling project().
 set(_configs Standard Release RelWithDebInfo Debug MinSizeRel)
 if(CMAKE_CXX_COMPILER_ID MATCHES "(AppleClang|Clang|GCC)")

dtool/CompilerFlags.cmake

@@ -16,6 +16,7 @@ if(MSVC)
 else()
   set(CMAKE_C_FLAGS_STANDARD "-O3")
   set(CMAKE_CXX_FLAGS_STANDARD "-O3")
+  set(CMAKE_OBJCXX_FLAGS_STANDARD "-O3")
 endif()
 set(CMAKE_SHARED_LINKER_FLAGS_STANDARD "")
 set(CMAKE_MODULE_LINKER_FLAGS_STANDARD "")
@@ -27,6 +28,8 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "(AppleClang|Clang)")
     "${CMAKE_C_FLAGS_DEBUG} -fprofile-instr-generate -fcoverage-mapping")
   set(CMAKE_CXX_FLAGS_COVERAGE
     "${CMAKE_CXX_FLAGS_DEBUG} -fprofile-instr-generate -fcoverage-mapping")
+  set(CMAKE_OBJCXX_FLAGS_COVERAGE
+    "${CMAKE_OBJCXX_FLAGS_DEBUG} -fprofile-instr-generate -fcoverage-mapping")
 
   set(CMAKE_SHARED_LINKER_FLAGS_COVERAGE
     "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} -fprofile-instr-generate")
@@ -106,6 +109,9 @@ if(MSVC)
 else()
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
+  if(APPLE)
+    set(CMAKE_OBJCXX_FLAGS "${CMAKE_OBJCXX_FLAGS} -Wall")
+  endif()
 
 endif()
 
@@ -133,6 +139,14 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "(GNU|Clang)")
   set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_CXX_FLAGS_MINSIZEREL} ${release_flags}")
   set(CMAKE_CXX_FLAGS_STANDARD "${CMAKE_CXX_FLAGS_STANDARD} ${standard_flags}")
 
+  if(APPLE)
+    set(CMAKE_OBJCXX_FLAGS "${CMAKE_OBJCXX_FLAGS} ${global_flags}")
+    set(CMAKE_OBJCXX_FLAGS_RELEASE "${CMAKE_OBJCXX_FLAGS_RELEASE} ${global_flags}")
+    set(CMAKE_OBJCXX_FLAGS_RELWITHDEBINFO "${CMAKE_OBJCXX_FLAGS_RELWITHDEBINFO} ${global_flags}")
+    set(CMAKE_OBJCXX_FLAGS_MINSIZEREL "${CMAKE_OBJCXX_FLAGS_MINSIZEREL} ${global_flags}")
+    set(CMAKE_OBJCXX_FLAGS_STANDARD "${CMAKE_OBJCXX_FLAGS_STANDARD} ${global_flags}")
+  endif()
+
   if(MSVC)
     # Clang behaving as MSVC
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-command-line-argument")
@@ -151,6 +165,7 @@ endif()
 # and stops us from identifying cases where ENABLE_EXPORTS is needed.
 set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
 set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "")
+set(CMAKE_SHARED_LIBRARY_LINK_OBJCXX_FLAGS "")
 
 # As long as we're figuring out compiler flags, figure out the flags for
 # turning C++ exception support on and off