possible bug on PPC/ GNU/LINUX

[Mike Stump]

> Date: Tue, 15 Jun 1999 12:26:43 -0400
> From: Daniel Jacobowitz <drow@false.org>

> If I am not mistaken, he should not have a compatibility problem if
> he uses a register which is normally saved by function calls.

Almost, but see the below.

> Although, come to think about it, this would NOT be callback safe.

Bingo.  Unfortunately, C allows pointers to functions, and sometimes
people use them.  gcc typically can't claim to work without them.
Though, an application can promise not to do that.  Though the problem
will just come later, when someone adds a callback to do something,
they don't realize what the previous programmer promised, and they
expect it to work, then they file a bug report, we read it, and after
a little while we say, that's not supposed to work.  :-(