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 OBJC as the designator of the language, eg:

project(foo OBJC)

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

Co-Authored-By: Cristian Adam <cristian.adam@gmail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/Modules/CMakeOBJCCompilerABI.m b/Modules/CMakeOBJCCompilerABI.m
new file mode 100644
index 0000000..8fa8511
--- /dev/null
+++ b/Modules/CMakeOBJCCompilerABI.m
@@ -0,0 +1,20 @@
+#ifdef __cplusplus
+# error "A C++ compiler has been selected for Objective-C."
+#endif
+
+/*--------------------------------------------------------------------------*/
+
+#include "CMakeCompilerABI.h"
+
+/*--------------------------------------------------------------------------*/
+
+int main(int argc, char *argv[])
+{
+  int require = 0;
+  require += info_sizeof_dptr[argc];
+#if defined(ABI_ID)
+  require += info_abi[argc];
+#endif
+  (void)argv;
+  return require;
+}