Pending further discussion, re-enable warnings for Objective C
covariant/contravariant overrides and implementations, but do so under
control of a new flag (-Wno-objc-covariant-overrides, which yes does cover
contravariance too).

*At least* the covariance cases will probably be enabled by default shortly,
but that's not totally uncontroversial.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117346 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed