Re: [musl] musl -- FFS get your shit together, please

[Joakim Sindholt <opensource@zhasha.com>]

On Mon, 17 Jul 2023 12:01:00 -0400, Jeffrey Walton <noloader@gmail.com> wrote:
> On Mon, Jul 17, 2023 at 11:21 AM Rich Felker <dalias@libc.org> wrote:
> >
> > On Mon, Jul 17, 2023 at 01:17:58AM -0500, Dave Blanchard wrote:
> > > There's a lot to like about musl, but damn, there's some absolutely ridiculous aspects also:
> > >
> > > 1) How in the hell are you going to make a MAJOR change like
> > > changing #ifdefs from defined(_LARGEFILE64_SOURCE) ||
> > > defined(_GNU_SOURCE) to just defined(_LARGEFILE64_SOURCE) in a PATCH
> > > level increment, from 1.2.3 to 1.2.4? What the hell is wrong with
> > > you? You just broke my entire build! Yet another patch had to be
> > > created on my end to UNDO this crazy change; the only alternative
> > > was patching half the packages on my system to fix their now-broken
> > > build! Do you know NOTHING about proper versioning???
> >
> > Our versioning system works like this: in x.y.z,
> >
> > - increment of x, likely to never happen, would indicate a completely
> >   different ABI
> >
> > - increment of y indicates a change whereby programs compiled for the
> >   new y, even without use of any new features added in new y, may not
> >   run with an older y. canonical example: time64.
> >
> > - increment of z indicates a change whereby programs built for the new
> >   z should still run on older z (modulo any bugs that might be present
> >   in the older version) as long as they're not using new interfaces
> >   introduced in the new z.
> >
> > All of these conditions are assuming the program used the public
> > interfaces and did not poke at unspecified internals, etc.; if it did,
> > all bets are off and any version change may be fully-breaking to the
> > program.
> >
> > Note that all of these deal with ABI compatibility, not compile-time
> > compatibility.
> 
> To play devil's advocate... If a symbol in Musl disappears, then
> shouldn't that be considered an ABI break? And then, shouldn't it
> require a major or 'x' bump?
> 
> It seems like Musl signed that contract when it first published a
> symbol under _LARGEFILE64_SOURCE or _GNU_SOURCE. When the symbol
> disappeared using one or the other define, then the contract was
> broken.

The symbols have only disappeared in the sense that you can't link new
binaries to them because they're not in the symbol table. The dynamic
linker resolves them at runtime as if the weak symbols still existed.
This way a link test will fail but an old binary will still load
properly.