Should basic_*stream::is_open() be const?

[Gabriel Dos Reis]

Paolo Carlini <pcarlini@suse.de> writes:

| Andreas Kohn wrote:
| 
| >So, if I read this correctly, "Note that implementers can make this
| >change in a binary compatible way by providing both overloads; this
| >would be a conforming extension." overloads could be added to libstdc++
| >without violating the standard?
| >
| >Is anything like that planned?
| >
| Ok, I'm going to apply the below to mainline (would be 3.5.0 or 4.0), not to
| the release branch, however, since we want complete backward and forward
| compatibility.

Still, I find the need to this addition very dubious.

-- Gaby