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, 63 insertions, 0 deletions

diff --git a/Modules/CMakeOBJCCompilerId.m.in b/Modules/CMakeOBJCCompilerId.m.in
new file mode 100644
index 0000000..2b8aa30
--- /dev/null
+++ b/Modules/CMakeOBJCCompilerId.m.in
@@ -0,0 +1,63 @@
+#ifdef __cplusplus
+# error "An Objective-C++ compiler has been selected for Objective-C."
+#endif
+
+@CMAKE_OBJC_COMPILER_ID_CONTENT@
+
+/* Construct the string literal in pieces to prevent the source from
+   getting matched.  Store it in a pointer rather than an array
+   because some compilers will just produce instructions to fill the
+   array rather than assigning a pointer to a static array.  */
+char const* info_compiler = "INFO" ":" "compiler[" COMPILER_ID "]";
+#ifdef SIMULATE_ID
+char const* info_simulate = "INFO" ":" "simulate[" SIMULATE_ID "]";
+#endif
+
+#ifdef __QNXNTO__
+char const* qnxnto = "INFO" ":" "qnxnto[]";
+#endif
+
+@CMAKE_OBJC_COMPILER_ID_PLATFORM_CONTENT@
+@CMAKE_OBJC_COMPILER_ID_ERROR_FOR_TEST@
+
+#if !defined(__STDC__)
+# if (defined(_MSC_VER) && !defined(__clang__)) \
+  || (defined(__ibmxl__) || defined(__IBMC__))
+#  define C_DIALECT "90"
+# else
+#  define C_DIALECT
+# endif
+#elif __STDC_VERSION__ >= 201000L
+# define C_DIALECT "11"
+#elif __STDC_VERSION__ >= 199901L
+# define C_DIALECT "99"
+#else
+# define C_DIALECT "90"
+#endif
+const char* info_language_dialect_default =
+  "INFO" ":" "dialect_default[" C_DIALECT "]";
+
+/*--------------------------------------------------------------------------*/
+
+int main(int argc, char* argv[])
+{
+  int require = 0;
+  require += info_compiler[argc];
+  require += info_platform[argc];
+  require += info_arch[argc];
+#ifdef COMPILER_VERSION_MAJOR
+  require += info_version[argc];
+#endif
+#ifdef COMPILER_VERSION_INTERNAL
+  require += info_version_internal[argc];
+#endif
+#ifdef SIMULATE_ID
+  require += info_simulate[argc];
+#endif
+#ifdef SIMULATE_VERSION_MAJOR
+  require += info_simulate_version[argc];
+#endif
+  require += info_language_dialect_default[argc];
+  (void)argv;
+  return require;
+}