[analyzer] Improve misleading RetainCountChcker diagnostic under ARC
Under automated reference counting the analyzer treats a methods -- even those
starting with 'copy' and friends -- as returning an unowned value. This is
because ownership of CoreFoundation objects must be transferred to ARC
with __bridge_transfer or CFBridgingRelease() before being returned as
ARC-managed bridged objects.
Unfortunately this could lead to a poor diagnostic inside copy methods under
ARC where the analyzer would complain about a leak of a returned CF value inside
a method "whose name does not start with 'copy'" -- even though the name did
start with 'copy'.
This commit improves the diagnostic under ARC to say inside a method "returned
from a method managed by Automated Reference Counting".
rdar://problem/
28849667
llvm-svn: 286694