[CMake] Enable a bunch of Xcode build settings that correspond to war…

…nings that are for the most part enabled by default either by Clang or -Wall.

I personally build with these settings enabled all the time, and it
is clearer to see the actual warning flags (e.g., -Wuninitialized)
get passed by Xcode rather than seeing -Wno-uninitialized followed
by -Wall (the latter canceling out the former) and figuring out
what is going on.

Xcode will ignore build settings it doesn't understand, so this will
work on possibly older versions of Xcode that don't support all
of these settings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203760 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/modules/HandleLLVMOptions.cmake

@@ -173,6 +173,29 @@ if( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
   endif( LLVM_BUILD_32_BITS )
 endif( CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32 )
 
+if( XCODE )
+  # For Xcode enable several build settings that correspond to
+  # many warnings that are on by default in Clang but are
+  # not enabled for historical reasons.  For versions of Xcode
+  # that do not support these options they will simply
+  # be ignored.
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_ABOUT_RETURN_TYPE "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_ABOUT_MISSING_NEWLINE "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_UNUSED_VALUE "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_UNUSED_VARIABLE "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_SIGN_COMPARE "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_UNUSED_FUNCTION "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_INITIALIZER_NOT_FULLY_BRACKETED "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_HIDDEN_VIRTUAL_FUNCTIONS "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_UNINITIALIZED_AUTOS "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_CLANG_WARN_BOOL_CONVERSION "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_CLANG_WARN_EMPTY_BODY "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_CLANG_WARN_ENUM_CONVERSION "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_CLANG_WARN_INT_CONVERSION "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_CLANG_WARN_CONSTANT_CONVERSION "YES")
+  set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_NON_VIRTUAL_DESTRUCTOR "YES")
+endif()
+
 # On Win32 using MS tools, provide an option to set the number of parallel jobs
 # to use.
 if( MSVC_IDE )