The recent commit 5777e9944b broke code such as
(*it++).foo(), where the result of dereferencing would be convertible to
the value type but did not provide the members of the value type. To mitigate
this, return a reference to the value instead of a proxy object. This will only
work for non-writable iterators (and it didn't work for writable iterators
before either) because in that case a proxy is needed to be able to intercept
operator=.
Also fix a similar issue with (it++)->foo() by adding operator-> overloads
to the post-increment result proxies.
Added tests for the fixes.
7c9b4296a1