Features: Record for historical Xcode clang versions.

Modules/Compiler/AppleClang-C-FeatureTests.cmake

@@ -1,5 +1,5 @@
 
-set(_cmake_oldestSupported "((__clang_major__ * 100) + __clang_minor__) >= 501")
+set(_cmake_oldestSupported "((__clang_major__ * 100) + __clang_minor__) >= 400")
 
 set(AppleClang_C11 "${_cmake_oldestSupported} && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L")
 set(_cmake_feature_test_c_static_assert "${AppleClang_C11}")

Modules/Compiler/AppleClang-C.cmake

@@ -19,7 +19,7 @@ macro(cmake_record_c_compile_features)
     record_compiler_features(C "${std_version}" ${list})
   endmacro()
 
-  if (UNIX AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.1)
+  if (UNIX AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
     _get_appleclang_features(${CMAKE_C11_STANDARD_COMPILE_OPTION} CMAKE_C11_COMPILE_FEATURES)
     if (_result EQUAL 0)
       _get_appleclang_features(${CMAKE_C99_STANDARD_COMPILE_OPTION} CMAKE_C99_COMPILE_FEATURES)

Modules/Compiler/AppleClang-CXX-FeatureTests.cmake

@@ -3,7 +3,28 @@
 # Generic reference: http://clang.llvm.org/cxx_status.html
 # http://clang.llvm.org/docs/LanguageExtensions.html
 
-set(_cmake_oldestSupported "((__clang_major__ * 100) + __clang_minor__) >= 501")
+# Note: CXX compiler in Xcode 4.3 does not set __apple_build_version__ and so is
+# not recognized as AppleClang.
+# Xcode_43 - Apple clang version 3.1 (tags/Apple/clang-318.0.61) (based on LLVM 3.1svn)
+# Xcode_44 - Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn)
+# Xcode_45 - Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
+# Xcode_46 - Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
+# Xcode_50 - Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
+# Xcode_51 - Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)
+# Xcode_60 - Apple LLVM version 6.0 (clang-600.0.51) (based on LLVM 3.5svn)
+# Xcode_61 - Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
+
+# There is some non-correspondance. __has_feature(cxx_user_literals) is
+# false for AppleClang 4.0 and 4.1, although it is reported as
+# supported in the reference link for Clang 3.1.  The compiler does not pass
+# the CompileFeatures/cxx_user_literals.cpp test.
+# cxx_attributes is listed as not supported until Clang 3.3. It works without
+# warning with AppleClang 5.0, but issues a gcc-compat warning for
+# AppleClang 4.0-4.2.
+# cxx_alignof and cxx_alignas tests work for early AppleClang versions, though
+# they are listed as supported for Clang 3.3 and later.
+
+set(_cmake_oldestSupported "((__clang_major__ * 100) + __clang_minor__) >= 400")
 
 include("${CMAKE_CURRENT_LIST_DIR}/Clang-CXX-TestableFeatures.cmake")
 
@@ -16,16 +37,16 @@ set(_cmake_feature_test_cxx_digit_separators "${AppleClang51_CXX14}")
 # http://llvm.org/bugs/show_bug.cgi?id=19674
 set(_cmake_feature_test_cxx_generic_lambdas "${AppleClang51_CXX14}")
 
-set(AppleClang51_CXX11 "${_cmake_oldestSupported} && __cplusplus >= 201103L")
-set(_cmake_feature_test_cxx_enum_forward_declarations "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_sizeof_member "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_extended_friend_declarations "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_extern_templates "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_func_identifier "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_inline_namespaces "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_long_long_type "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_right_angle_brackets "${AppleClang51_CXX11}")
-set(_cmake_feature_test_cxx_variadic_macros "${AppleClang51_CXX11}")
+set(AppleClang40_CXX11 "${_cmake_oldestSupported} && __cplusplus >= 201103L")
+set(_cmake_feature_test_cxx_enum_forward_declarations "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_sizeof_member "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_extended_friend_declarations "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_extern_templates "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_func_identifier "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_inline_namespaces "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_long_long_type "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_right_angle_brackets "${AppleClang40_CXX11}")
+set(_cmake_feature_test_cxx_variadic_macros "${AppleClang40_CXX11}")
 
 set(AppleClang_CXX98 "${_cmake_oldestSupported} && __cplusplus >= 199711L")
 set(_cmake_feature_test_cxx_template_template_parameters "${AppleClang_CXX98}")

Modules/Compiler/AppleClang-CXX.cmake

@@ -26,8 +26,11 @@ macro(cmake_record_cxx_compile_features)
     record_compiler_features(CXX "${std_version}" ${list})
   endmacro()
 
-  if (UNIX AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.1)
-    _get_appleclang_features(${CMAKE_CXX14_STANDARD_COMPILE_OPTION} CMAKE_CXX14_COMPILE_FEATURES)
+  if (UNIX AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.0)
+    set(_result 0)
+    if(CMAKE_CXX14_STANDARD_COMPILE_OPTION)
+      _get_appleclang_features(${CMAKE_CXX14_STANDARD_COMPILE_OPTION} CMAKE_CXX14_COMPILE_FEATURES)
+    endif()
     if (_result EQUAL 0)
       _get_appleclang_features(${CMAKE_CXX11_STANDARD_COMPILE_OPTION} CMAKE_CXX11_COMPILE_FEATURES)
     endif()

Tests/CompileFeatures/CMakeLists.txt

@@ -31,6 +31,26 @@ foreach(feature ${cxx_features})
   run_test(${feature} CXX)
 endforeach()
 
+if (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang"
+    AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.1)
+  # AppleClang prior to 5.1 does not set any preprocessor define to distinguish
+  # c++1y from c++11, so CMake does not support c++1y features before AppleClang 5.1.
+  list(REMOVE_ITEM CXX_non_features
+    cxx_attribute_deprecated
+    cxx_binary_literals
+  )
+endif()
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang"
+    AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.2)
+  # AppleClang prior to 4.1 reports false for __has_feature(cxx_local_type_template_args)
+  # and __has_feature(cxx_unrestricted_unions) but it happens to pass these tests.
+  list(REMOVE_ITEM CXX_non_features
+    cxx_local_type_template_args
+    cxx_unrestricted_unions
+  )
+endif()
+
 if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
     AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
   # The cxx_alignof feature happens to work (for *this* testcase) with