Implement reasonable conversion ranking for Objective-C pointer
conversions (<rdar://problem/8592139>) for overload resolution. The
conversion ranking mirrors C++'s conversion ranking fairly closely,
except that we use a same pseudo-subtyping relationship employed by
Objective-C pointer assignment rather than simple checking
derived-to-base conversions. This change covers:
- Conversions to pointers to a specific object type are better than
conversions to 'id', 'Class', qualified 'id', or qualified 'Class'
(note: GCC doesn't perform this ranking, but it matches C++'s rules
for ranking conversions to void*).
- Conversions to qualified 'id' or qualified 'Class' are better than
conversions to 'id' or 'Class', respectively.
- When two conversion sequences convert to the same type, rank the
conversions based on the relationship between the types we're
converting from.
- When two conversion sequences convert from the same non-id,
non-Class type, rank the conversions based on the relationship of
the types we're converting to. (note: GCC allows this ranking even
when converting from 'id', which is extremeley dangerous).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124591 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed