Languages: Add support for Objective-C++

Add entries in Modules and Modules/Platform to support
Objective-C++ compiler determination and identification.
Add Modules to check Objective-C++ compiler flags, source
compilations, program checks, etc...

Use OBJCXX as the designator of the language, eg:

project(foo OBJCXX)

Add various tests for Objective-C++ language features.  Add
tests to preserve C++ handling of .M and .mm files when
Objective-C++ is not a configured language.

Co-authored-by: Cristian Adam <cristian.adam@gmail.com>

1 files changed, 273 insertions, 0 deletions

diff --git a/Modules/CMakeOBJCXXInformation.cmake b/Modules/CMakeOBJCXXInformation.cmake
new file mode 100644
index 0000000..3f55b01
--- /dev/null
+++ b/Modules/CMakeOBJCXXInformation.cmake
@@ -0,0 +1,273 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+
+# This file sets the basic flags for the Objective-C++ language in CMake.
+# It also loads the available platform file for the system-compiler
+# if it exists.
+# It also loads a system - compiler - processor (or target hardware)
+# specific file, which is mainly useful for crosscompiling and embedded systems.
+
+include(CMakeLanguageInformation)
+
+# some compilers use different extensions (e.g. sdcc uses .rel)
+# so set the extension here first so it can be overridden by the compiler specific file
+set(CMAKE_OBJCXX_OUTPUT_EXTENSION .o)
+
+set(_INCLUDED_FILE 0)
+
+# Load compiler-specific information.
+if(CMAKE_OBJCXX_COMPILER_ID)
+  include(Compiler/${CMAKE_OBJCXX_COMPILER_ID}-OBJCXX OPTIONAL)
+endif()
+
+set(CMAKE_BASE_NAME)
+get_filename_component(CMAKE_BASE_NAME "${CMAKE_OBJCXX_COMPILER}" NAME_WE)
+# since the gnu compiler has several names force g++
+if(CMAKE_COMPILER_IS_GNUOBJCXX)
+  set(CMAKE_BASE_NAME g++)
+endif()
+
+
+# load a hardware specific file, mostly useful for embedded compilers
+if(CMAKE_SYSTEM_PROCESSOR)
+  if(CMAKE_OBJCXX_COMPILER_ID)
+    include(Platform/${CMAKE_EFFECTIVE_SYSTEM_NAME}-${CMAKE_OBJCXX_COMPILER_ID}-OBJCXX-${CMAKE_SYSTEM_PROCESSOR} OPTIONAL RESULT_VARIABLE _INCLUDED_FILE)
+  endif()
+  if (NOT _INCLUDED_FILE)
+    include(Platform/${CMAKE_EFFECTIVE_SYSTEM_NAME}-${CMAKE_BASE_NAME}-${CMAKE_SYSTEM_PROCESSOR} OPTIONAL)
+  endif ()
+endif()
+
+# load the system- and compiler specific files
+if(CMAKE_OBJCXX_COMPILER_ID)
+  include(Platform/${CMAKE_EFFECTIVE_SYSTEM_NAME}-${CMAKE_OBJCXX_COMPILER_ID}-OBJCXX OPTIONAL RESULT_VARIABLE _INCLUDED_FILE)
+endif()
+if (NOT _INCLUDED_FILE)
+  include(Platform/${CMAKE_EFFECTIVE_SYSTEM_NAME}-${CMAKE_BASE_NAME} OPTIONAL
+          RESULT_VARIABLE _INCLUDED_FILE)
+endif ()
+
+# load any compiler-wrapper specific information
+if (CMAKE_OBJCXX_COMPILER_WRAPPER)
+  __cmake_include_compiler_wrapper(OBJCXX)
+endif ()
+
+# We specify the compiler information in the system file for some
+# platforms, but this language may not have been enabled when the file
+# was first included.  Include it again to get the language info.
+# Remove this when all compiler info is removed from system files.
+if (NOT _INCLUDED_FILE)
+  include(Platform/${CMAKE_SYSTEM_NAME} OPTIONAL)
+endif ()
+
+if(CMAKE_OBJCXX_SIZEOF_DATA_PTR)
+  foreach(f ${CMAKE_OBJCXX_ABI_FILES})
+    include(${f})
+  endforeach()
+  unset(CMAKE_OBJCXX_ABI_FILES)
+endif()
+
+# This should be included before the _INIT variables are
+# used to initialize the cache.  Since the rule variables
+# have if blocks on them, users can still define them here.
+# But, it should still be after the platform file so changes can
+# be made to those values.
+
+if(CMAKE_USER_MAKE_RULES_OVERRIDE)
+  # Save the full path of the file so try_compile can use it.
+  include(${CMAKE_USER_MAKE_RULES_OVERRIDE} RESULT_VARIABLE _override)
+  set(CMAKE_USER_MAKE_RULES_OVERRIDE "${_override}")
+endif()
+
+if(CMAKE_USER_MAKE_RULES_OVERRIDE_OBJCXX)
+  # Save the full path of the file so try_compile can use it.
+  include(${CMAKE_USER_MAKE_RULES_OVERRIDE_OBJCXX} RESULT_VARIABLE _override)
+  set(CMAKE_USER_MAKE_RULES_OVERRIDE_OBJCXX "${_override}")
+endif()
+
+
+# Create a set of shared library variable specific to Objective-C++
+# For 90% of the systems, these are the same flags as the Objective-C versions
+# so if these are not set just copy the flags from the Objective-C version
+if(NOT CMAKE_SHARED_LIBRARY_CREATE_OBJCXX_FLAGS)
+  set(CMAKE_SHARED_LIBRARY_CREATE_OBJCXX_FLAGS ${CMAKE_SHARED_LIBRARY_CREATE_OBJC_FLAGS})
+endif()
+
+if(NOT CMAKE_OBJCXX_COMPILE_OPTIONS_PIC)
+  set(CMAKE_OBJCXX_COMPILE_OPTIONS_PIC ${CMAKE_OBJC_COMPILE_OPTIONS_PIC})
+endif()
+
+if(NOT CMAKE_OBJCXX_COMPILE_OPTIONS_PIE)
+  set(CMAKE_OBJCXX_COMPILE_OPTIONS_PIE ${CMAKE_OBJC_COMPILE_OPTIONS_PIE})
+endif()
+if(NOT CMAKE_OBJCXX_LINK_OPTIONS_PIE)
+  set(CMAKE_OBJCXX_LINK_OPTIONS_PIE ${CMAKE_OBJC_LINK_OPTIONS_PIE})
+endif()
+if(NOT CMAKE_OBJCXX_LINK_OPTIONS_NO_PIE)
+  set(CMAKE_OBJCXX_LINK_OPTIONS_NO_PIE ${CMAKE_OBJC_LINK_OPTIONS_NO_PIE})
+endif()
+
+if(NOT CMAKE_OBJCXX_COMPILE_OPTIONS_DLL)
+  set(CMAKE_OBJCXX_COMPILE_OPTIONS_DLL ${CMAKE_OBJC_COMPILE_OPTIONS_DLL})
+endif()
+
+if(NOT CMAKE_SHARED_LIBRARY_OBJCXX_FLAGS)
+  set(CMAKE_SHARED_LIBRARY_OBJCXX_FLAGS ${CMAKE_SHARED_LIBRARY_OBJC_FLAGS})
+endif()
+
+if(NOT DEFINED CMAKE_SHARED_LIBRARY_LINK_OBJCXX_FLAGS)
+  set(CMAKE_SHARED_LIBRARY_LINK_OBJCXX_FLAGS ${CMAKE_SHARED_LIBRARY_LINK_OBJC_FLAGS})
+endif()
+
+if(NOT CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG)
+  set(CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG ${CMAKE_SHARED_LIBRARY_RUNTIME_OBJC_FLAG})
+endif()
+
+if(NOT CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG_SEP)
+  set(CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG_SEP ${CMAKE_SHARED_LIBRARY_RUNTIME_OBJC_FLAG_SEP})
+endif()
+
+if(NOT CMAKE_SHARED_LIBRARY_RPATH_LINK_OBJCXX_FLAG)
+  set(CMAKE_SHARED_LIBRARY_RPATH_LINK_OBJCXX_FLAG ${CMAKE_SHARED_LIBRARY_RPATH_LINK_OBJC_FLAG})
+endif()
+
+if(NOT DEFINED CMAKE_EXE_EXPORTS_OBJCXX_FLAG)
+  set(CMAKE_EXE_EXPORTS_OBJCXX_FLAG ${CMAKE_EXE_EXPORTS_OBJC_FLAG})
+endif()
+
+if(NOT DEFINED CMAKE_SHARED_LIBRARY_SONAME_OBJCXX_FLAG)
+  set(CMAKE_SHARED_LIBRARY_SONAME_OBJCXX_FLAG ${CMAKE_SHARED_LIBRARY_SONAME_OBJC_FLAG})
+endif()
+
+if(NOT CMAKE_EXECUTABLE_RUNTIME_OBJCXX_FLAG)
+  set(CMAKE_EXECUTABLE_RUNTIME_OBJCXX_FLAG ${CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG})
+endif()
+
+if(NOT CMAKE_EXECUTABLE_RUNTIME_OBJCXX_FLAG_SEP)
+  set(CMAKE_EXECUTABLE_RUNTIME_OBJCXX_FLAG_SEP ${CMAKE_SHARED_LIBRARY_RUNTIME_OBJCXX_FLAG_SEP})
+endif()
+
+if(NOT CMAKE_EXECUTABLE_RPATH_LINK_OBJCXX_FLAG)
+  set(CMAKE_EXECUTABLE_RPATH_LINK_OBJCXX_FLAG ${CMAKE_SHARED_LIBRARY_RPATH_LINK_OBJCXX_FLAG})
+endif()
+
+if(NOT DEFINED CMAKE_SHARED_LIBRARY_LINK_OBJCXX_WITH_RUNTIME_PATH)
+  set(CMAKE_SHARED_LIBRARY_LINK_OBJCXX_WITH_RUNTIME_PATH ${CMAKE_SHARED_LIBRARY_LINK_OBJC_WITH_RUNTIME_PATH})
+endif()
+
+if(NOT CMAKE_INCLUDE_FLAG_OBJCXX)
+  set(CMAKE_INCLUDE_FLAG_OBJCXX ${CMAKE_INCLUDE_FLAG_C})
+endif()
+
+# for most systems a module is the same as a shared library
+# so unless the variable CMAKE_MODULE_EXISTS is set just
+# copy the values from the LIBRARY variables
+if(NOT CMAKE_MODULE_EXISTS)
+  set(CMAKE_SHARED_MODULE_OBJCXX_FLAGS ${CMAKE_SHARED_LIBRARY_OBJCXX_FLAGS})
+  set(CMAKE_SHARED_MODULE_CREATE_OBJCXX_FLAGS ${CMAKE_SHARED_LIBRARY_CREATE_OBJCXX_FLAGS})
+endif()
+
+# repeat for modules
+if(NOT CMAKE_SHARED_MODULE_CREATE_OBJCXX_FLAGS)
+  set(CMAKE_SHARED_MODULE_CREATE_OBJCXX_FLAGS ${CMAKE_SHARED_MODULE_CREATE_OBJC_FLAGS})
+endif()
+
+if(NOT CMAKE_SHARED_MODULE_OBJCXX_FLAGS)
+  set(CMAKE_SHARED_MODULE_OBJCXX_FLAGS ${CMAKE_SHARED_MODULE_OBJC_FLAGS})
+endif()
+
+# Initialize OBJCXX link type selection flags from OBJC versions.
+foreach(type SHARED_LIBRARY SHARED_MODULE EXE)
+  if(NOT CMAKE_${type}_LINK_STATIC_OBJCXX_FLAGS)
+    set(CMAKE_${type}_LINK_STATIC_OBJCXX_FLAGS
+      ${CMAKE_${type}_LINK_STATIC_OBJC_FLAGS})
+  endif()
+  if(NOT CMAKE_${type}_LINK_DYNAMIC_OBJCXX_FLAGS)
+    set(CMAKE_${type}_LINK_DYNAMIC_OBJCXX_FLAGS
+      ${CMAKE_${type}_LINK_DYNAMIC_OBJC_FLAGS})
+  endif()
+endforeach()
+
+# add the flags to the cache based
+# on the initial values computed in the platform/*.cmake files
+# use _INIT variables so that this only happens the first time
+# and you can set these flags in the cmake cache
+set(CMAKE_OBJCXX_FLAGS_INIT "$ENV{OBJCXXFLAGS} ${CMAKE_OBJCXX_FLAGS_INIT}")
+
+cmake_initialize_per_config_variable(CMAKE_OBJCXX_FLAGS "Flags used by the Objective-C++ compiler")
+
+if(CMAKE_OBJCXX_STANDARD_LIBRARIES_INIT)
+  set(CMAKE_OBJCXX_STANDARD_LIBRARIES "${CMAKE_OBJCXX_STANDARD_LIBRARIES_INIT}"
+    CACHE STRING "Libraries linked by default with all Objective-C++ applications.")
+  mark_as_advanced(CMAKE_OBJCXX_STANDARD_LIBRARIES)
+endif()
+
+include(CMakeCommonLanguageInclude)
+
+# now define the following rules:
+# CMAKE_OBJCXX_CREATE_SHARED_LIBRARY
+# CMAKE_OBJCXX_CREATE_SHARED_MODULE
+# CMAKE_OBJCXX_COMPILE_OBJECT
+# CMAKE_OBJCXX_LINK_EXECUTABLE
+
+# variables supplied by the generator at use time
+# <TARGET>
+# <TARGET_BASE> the target without the suffix
+# <OBJECTS>
+# <OBJECT>
+# <LINK_LIBRARIES>
+# <FLAGS>
+# <LINK_FLAGS>
+
+# Objective-C++ compiler information
+# <CMAKE_OBJCXX_COMPILER>
+# <CMAKE_SHARED_LIBRARY_CREATE_OBJCXX_FLAGS>
+# <CMAKE_OBJCXX_SHARED_MODULE_CREATE_FLAGS>
+# <CMAKE_OBJCXX_LINK_FLAGS>
+
+# Static library tools
+# <CMAKE_AR>
+# <CMAKE_RANLIB>
+
+
+# create a shared Objective-C++ library
+if(NOT CMAKE_OBJCXX_CREATE_SHARED_LIBRARY)
+  set(CMAKE_OBJCXX_CREATE_SHARED_LIBRARY
+      "<CMAKE_OBJCXX_COMPILER> <CMAKE_SHARED_LIBRARY_OBJCXX_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_OBJCXX_FLAGS> <SONAME_FLAG><TARGET_SONAME> -o <TARGET> <OBJECTS> <LINK_LIBRARIES>")
+endif()
+
+# create an Objective-C++ shared module copy the shared library rule by default
+if(NOT CMAKE_OBJCXX_CREATE_SHARED_MODULE)
+  set(CMAKE_OBJCXX_CREATE_SHARED_MODULE ${CMAKE_OBJCXX_CREATE_SHARED_LIBRARY})
+endif()
+
+
+# Create a static archive incrementally for large object file counts.
+# If CMAKE_OBJCXX_CREATE_STATIC_LIBRARY is set it will override these.
+if(NOT DEFINED CMAKE_OBJCXX_ARCHIVE_CREATE)
+  set(CMAKE_OBJCXX_ARCHIVE_CREATE "<CMAKE_AR> qc <TARGET> <LINK_FLAGS> <OBJECTS>")
+endif()
+if(NOT DEFINED CMAKE_OBJCXX_ARCHIVE_APPEND)
+  set(CMAKE_OBJCXX_ARCHIVE_APPEND "<CMAKE_AR> q  <TARGET> <LINK_FLAGS> <OBJECTS>")
+endif()
+if(NOT DEFINED CMAKE_OBJCXX_ARCHIVE_FINISH)
+  set(CMAKE_OBJCXX_ARCHIVE_FINISH "<CMAKE_RANLIB> <TARGET>")
+endif()
+
+# compile an Objective-C++ file into an object file
+if(NOT CMAKE_OBJCXX_COMPILE_OBJECT)
+  set(CMAKE_OBJCXX_COMPILE_OBJECT
+    "<CMAKE_OBJCXX_COMPILER>  <DEFINES> <INCLUDES> <FLAGS> -o <OBJECT> -c <SOURCE>")
+endif()
+
+if(NOT CMAKE_OBJCXX_LINK_EXECUTABLE)
+  set(CMAKE_OBJCXX_LINK_EXECUTABLE
+    "<CMAKE_OBJCXX_COMPILER>  <FLAGS> <CMAKE_OBJCXX_LINK_FLAGS> <LINK_FLAGS> <OBJECTS>  -o <TARGET> <LINK_LIBRARIES>")
+endif()
+
+mark_as_advanced(
+CMAKE_VERBOSE_MAKEFILE
+)
+
+set(CMAKE_OBJCXX_INFORMATION_LOADED 1)