Re: (OT?) Re: [musl] Symbol versioning approximation trips on compat symbols

[u-uy74@aetey.se]

On Mon, Jan 28, 2019 at 10:29:12AM -0500, Rich Felker wrote:
> On Mon, Jan 28, 2019 at 02:08:13PM +0100, u-uy74@aetey.se wrote:
> > If there is a feature which is hard or impossible to test for, like
> > symbol versioning, it means that the applications may _have_ to rely on
> > an explicit build flag telling whether to use it.

> It wouldn't be hard to test for if toolchains had been consistent with
> musl capabilities all along. They have not been. So we have a
> situation where the valid build-time tests indicate support, but
> runtime silently lacks it. I don't think this is a good situation to

What is the value (the "validity"?) of a build-time test if it
does not help to distinguish how to build a usable binary?
This seems to be testing for A when we want to know B.

> Fortunately, it mostly doesn't matter since the main intended usage
> for versioning is to link to the current/default version symbols,
> assuming your apps are all up-to-date with respect to your libs (and
> libs wrt each other). But I still think honoring version bindings in
> ldso is the right course of action.

I assume you'll find a good balance between the cost/complexity and
usefulness.

(Musl is by far the best libc I ever worked with on Linux, among others
omitting a number of regrettably popular misfeatures. Kudos.)

Rune