Re: Signal 11

Linus Torvalds
2000-12-15T00:22:58Z

On Thu, 14 Dec 2000, Jakub Jelinek wrote:

> On Thu, Dec 14, 2000 at 11:11:28AM -0800, Linus Torvalds wrote:
> > user applications and (b) gcc-2.96 is so broken that it requires special
> > libraries for C++ vtable chunks handling that is different, so the
> > _working_ gcc can only be used with programs that do not need such
> > library support.
>
> Every major g++ release had incompatible libstdc++, even g++ 2.95.2 if
> bootstrapped under glibc 2.1.x is binary incompatible with g++ 2.95.2
> bootstrapped under glibc 2.2.x (libstdc++ uses different soname then;
> even if we used g++ 2.95.2 we would not have C++ binary compatible with
> other distributions).

Yes.

And I realize that somebody inside RedHat really wanted to use a snapshot
in order to get some C++ code to compile right.

But it at the same time threw C stability out the window, by using a
not-very-widely-tested snapshot for a major new release.

Are you seriously saying that you think it was a good trade-off? Or are
you just ashamed of admitting that RH did something stupid?

> > compiler to something that works better RSN. It apparently has problems
> > compiling stuff like the CVS snapshots of X etc too (and obviously,
> > anything you compile under gcc-2.96 is not likely to work anywhere else
> > except with the broken libraries).
>
> Can you point to things in X which were actually miscompiled because of bugs
> in gcc 2.96?

I have a report from a Sony VAIO user that couldn't compile the CVS X at
all on his picturebook (and you need to compile the CVS tree in order to
get required fixes for the ATI Rage Mobility in that machine). I don't
know the details, but they were apparently due to RH 7 issues.

> So far I was aware about X bugs (already fixed in X CVS) which
> were triggered with -fstrict-aliasing which is now the default while
> gcc 2.95.2 had -fstrict-aliasing disabled by default.

I hope that's another thing that the gcc people fix by the time they do a
_real_ release. Anobody who thinks that "-fstrict-aliasing" being on by
default is a good idea is probably a compiler person who hasn't seen real
code.

> That is not to say there were not bugs in the gcc we shipped, but the bugs
> which were reported against it have been fixed already.

That's good.

It's even better if you don't play quite as fast-and-lose with your
shipping compiler.

Linus