Re: BZ #1190: stream behaviour on encountering an EOF

[Roland McGrath <roland at hack dot frob dot com>]

I don't think we want to have multiple modes for compilation.
The system is complex enough already.

Looking at the code, I note that _IO_wfile_underflow doesn't even have
the #if 0'd check.  The change needs to be made consistently between
regular and wide stream functions, and tests added for this issue should
cover the wide-char code paths.

This is not a bug per se but an intentional change in behavior.  Hence,
the conservative thing to do is to arrange that existing binaries don't
have their behavior changed.  Newly-compiled programs getting new
behavior unconditionally is much more acceptable.

The normal way to achieve that is by introducing new symbol versions for
affected symbols.  Old ones get old behavior and new ones get new
behavior.  For this issue, that could be a lot of work.  It affects
everything using stdio for input, so the naive approach would touch a
huge number of symbols.  Perhaps we can figure out a way to do it that
does not involve so much churn.  It needs some careful thought.  It's
straightforward to use an internal flag bit to control the behavior.
But then we need to figure out what all compat symbols we'd need to have
that arrange to set the flag.


Thanks,
Roland