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Date: Tue, 29 Jan 2019 18:13:05 +0100
From: u-uy74@...ey.se
To: musl@...ts.openwall.com
Subject: Re: (OT?) Re: Symbol versioning approximation trips on
 compat symbols

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@...ey.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

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