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>

4 files changed, 39 insertions, 2 deletions

diff --git a/Tests/CMakeOnly/CMakeLists.txt b/Tests/CMakeOnly/CMakeLists.txt
index 1a25469..03babd2 100644
--- a/Tests/CMakeOnly/CMakeLists.txt
+++ b/Tests/CMakeOnly/CMakeLists.txt
@@ -36,6 +36,11 @@ if(CMAKE_OBJC_COMPILER)
   add_CMakeOnly_test(CheckOBJCCompilerFlag)
 endif()
 
+if(CMAKE_OBJCXX_COMPILER)
+  add_CMakeOnly_test(CompilerIdOBJCXX)
+  add_CMakeOnly_test(CheckOBJCXXCompilerFlag)
+endif()
+
 if(CMAKE_Fortran_COMPILER)
   add_CMakeOnly_test(CompilerIdFortran)
 endif()
diff --git a/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt b/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt
index e9bdf6a..90aa921 100644
--- a/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt
+++ b/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt
@@ -5,16 +5,17 @@ include(CheckLanguage)
 set(langs )
 set(expect_C 1)
 set(expect_CXX 1)
+
 if(APPLE)
   set(expect_OBJC 1)
+  set(expect_OBJCXX 1)
 endif()
 unset(expect_Fortran)
 set(expect_NoSuchLanguage 0)
 
 set(LANGUAGES C CXX Fortran CUDA NoSuchLanguage)
-
 if(APPLE)
-  list(APPEND LANGUAGES OBJC)
+  list(APPEND LANGUAGES OBJC OBJCXX)
 endif()
 
 foreach(lang ${LANGUAGES})
diff --git a/Tests/CMakeOnly/CheckOBJCXXCompilerFlag/CMakeLists.txt b/Tests/CMakeOnly/CheckOBJCXXCompilerFlag/CMakeLists.txt
new file mode 100644
index 0000000..f83b738
--- /dev/null
+++ b/Tests/CMakeOnly/CheckOBJCXXCompilerFlag/CMakeLists.txt
@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 2.8.12)
+
+project(CheckOBJCXXCompilerFlag)
+
+include(CheckOBJCXXCompilerFlag)
+
+if(CMAKE_COMPILER_IS_GNUOBJCXX)
+  set(COMPILER_FLAG -fobjc-direct-dispatch)
+else()
+  set(COMPILER_FLAG -fobjc-gc)
+endif()
+
+CHECK_OBJCXX_COMPILER_FLAGS(${COMPILER_FLAG} HAS_COMPILER_FLAG)
+
+if(NOT HAS_COMPILER_FLAG)
+  message(SEND_ERROR "Test fail: HAS_COMPILER_FLAG: ${COMPILER_FLAG}")
+endif()
diff --git a/Tests/CMakeOnly/CompilerIdOBJCXX/CMakeLists.txt b/Tests/CMakeOnly/CompilerIdOBJCXX/CMakeLists.txt
new file mode 100644
index 0000000..8f41db0
--- /dev/null
+++ b/Tests/CMakeOnly/CompilerIdOBJCXX/CMakeLists.txt
@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 2.8.12)
+project(CompilerIdOBJCXX OBJCXX)
+
+foreach(v
+    CMAKE_OBJCXX_COMPILER
+    CMAKE_OBJCXX_COMPILER_ID
+    CMAKE_OBJCXX_COMPILER_VERSION
+    )
+  if(${v})
+    message(STATUS "${v}=[${${v}}]")
+  else()
+    message(SEND_ERROR "${v} not set!")
+  endif()
+endforeach()