Re: type based aliasing again

[Joe Buck <jbuck at synopsys dot COM>]

Mark Mitchell writes:

> There is no way that we can guarantee the long-term viability of this
> variety of invalid code.  Seemingly minor changes to the compiler will
> change the set of programs which "work", with your proposal.  

My intent, which may be different from RMS's intent, is to help users
get rid of this variety of invalid code, not to perpetuate it.
I prefer what we called proposal A to proposal B because I think we
should do what the user means if we can tell, but we definitely
should let the user know that they are doing something very risky.

> Other
> compilers are already doing these optimizations.  Thus, portable code,
> including most GNU project code, simply must not contain these invalid
> constructs.

Agreed.  If not, within two years, I predict that it won't be possible to
build GNU tools with compilers other than gcc.  The Merced architecture in
particular will require very aggressive compilation techniques, with loads
of reordering of operations, to take full advantage of it.