This fixes an error introduced in r228934 where None was converted to
an int instead of the int being converted to an Optional as intended.
We make that sort of mistake a compile error by changing NoneType into
a scoped enum.
Finally, provide a static NoneType called None to avoid forcing all
users to spell it NoneType::None.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229980 91177308-0d34-0410-b5e6-96231b3b80d8
This implementation of NoneType/None does have some holes but I haven't
found one that doesn't - open to improvement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175696 91177308-0d34-0410-b5e6-96231b3b80d8
