C++: const_iterator not comparable to iterator for map<>s

[Benjamin Kosnik]

> > No problem (I hope), I'll try to do that.
> > Is a modification of the test 23_containers/map_operators.cc
> > acceptable ? Or should I create a different test ?
> 
> Shouldn't this stuff go into the main GCC testsuite?

no this is a library bug. we need a library regression test for it

> Unless I am mistaken, libstdc++-v3/testsuite is not executed by
> `make  check` and thus regressions won't be caught?

run `make check-target-libstdc++-v3`

-benjamin