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>

4 files changed, 47 insertions, 1 deletions

diff --git a/Tests/CMakeOnly/CMakeLists.txt b/Tests/CMakeOnly/CMakeLists.txt
index 19f3f79..1a25469 100644
--- a/Tests/CMakeOnly/CMakeLists.txt
+++ b/Tests/CMakeOnly/CMakeLists.txt
@@ -30,6 +30,12 @@ add_CMakeOnly_test(CheckStructHasMember)
 
 add_CMakeOnly_test(CompilerIdC)
 add_CMakeOnly_test(CompilerIdCXX)
+
+if(CMAKE_OBJC_COMPILER)
+  add_CMakeOnly_test(CompilerIdOBJC)
+  add_CMakeOnly_test(CheckOBJCCompilerFlag)
+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 ca4becb..e9bdf6a 100644
--- a/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt
+++ b/Tests/CMakeOnly/CheckLanguage/CMakeLists.txt
@@ -5,10 +5,19 @@ include(CheckLanguage)
 set(langs )
 set(expect_C 1)
 set(expect_CXX 1)
+if(APPLE)
+  set(expect_OBJC 1)
+endif()
 unset(expect_Fortran)
 set(expect_NoSuchLanguage 0)
 
-foreach(lang C CXX Fortran CUDA NoSuchLanguage)
+set(LANGUAGES C CXX Fortran CUDA NoSuchLanguage)
+
+if(APPLE)
+  list(APPEND LANGUAGES OBJC)
+endif()
+
+foreach(lang ${LANGUAGES})
   check_language(${lang})
   if(NOT DEFINED CMAKE_${lang}_COMPILER)
     message(FATAL_ERROR "check_language(${lang}) did not set result")
diff --git a/Tests/CMakeOnly/CheckOBJCCompilerFlag/CMakeLists.txt b/Tests/CMakeOnly/CheckOBJCCompilerFlag/CMakeLists.txt
new file mode 100644
index 0000000..a9a96ee
--- /dev/null
+++ b/Tests/CMakeOnly/CheckOBJCCompilerFlag/CMakeLists.txt
@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 2.8.12)
+
+project(CheckOBJCCompilerFlag)
+
+include(CheckOBJCCompilerFlag)
+
+if(CMAKE_COMPILER_IS_GNUOBJC)
+  set(COMPILER_FLAG -fobjc-direct-dispatch)
+else()
+  set(COMPILER_FLAG -fobjc-gc)
+endif()
+
+CHECK_OBJC_COMPILER_FLAGS(${COMPILER_FLAG} HAS_COMPILER_FLAG)
+
+if(NOT HAS_COMPILER_FLAG)
+  message(SEND_ERROR "Test fail: HAS_COMPILER_FLAG: ${COMPILER_FLAG}")
+endif
diff --git a/Tests/CMakeOnly/CompilerIdOBJC/CMakeLists.txt b/Tests/CMakeOnly/CompilerIdOBJC/CMakeLists.txt
new file mode 100644
index 0000000..8f13787
--- /dev/null
+++ b/Tests/CMakeOnly/CompilerIdOBJC/CMakeLists.txt
@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 2.8.12)
+project(CompilerIdOBJC OBJC)
+
+foreach(v
+    CMAKE_OBJC_COMPILER
+    CMAKE_OBJC_COMPILER_ID
+    CMAKE_OBJC_COMPILER_VERSION
+    )
+  if(${v})
+    message(STATUS "${v}=[${${v}}]")
+  else()
+    message(SEND_ERROR "${v} not set!")
+  endif()
+endforeach()