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>

2 files changed, 20 insertions, 0 deletions

diff --git a/Tests/Objective-C++/objcxx-file-extension-test/CMakeLists.txt b/Tests/Objective-C++/objcxx-file-extension-test/CMakeLists.txt
new file mode 100644
index 0000000..eda7bba
--- /dev/null
+++ b/Tests/Objective-C++/objcxx-file-extension-test/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.15)
+
+project(objcxx-file-extension-test OBJCXX CXX)
+
+add_executable(objcxx-file-extension-test main.mm)
+target_link_libraries(objcxx-file-extension-test "-framework Foundation")
diff --git a/Tests/Objective-C++/objcxx-file-extension-test/main.mm b/Tests/Objective-C++/objcxx-file-extension-test/main.mm
new file mode 100644
index 0000000..d4aa1bb
--- /dev/null
+++ b/Tests/Objective-C++/objcxx-file-extension-test/main.mm
@@ -0,0 +1,14 @@
+#ifndef __OBJC__
+#  error "Compiler is not an Objective-C compiler."
+#endif
+
+#import <Foundation/Foundation.h>
+#include <iostream>
+
+int main()
+{
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+  std::cout << "Hello World" << std::endl;
+  [pool release];
+  return 0;
+}