[PATCH wayland] wayland-egl: Ignore underscored symbols in ABI check

[Daniel Stone]

Hi Emil,

On 20 March 2018 at 11:30, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 20 March 2018 at 11:01, Daniel Stone <daniels at collabora.com> wrote:
>> Rather than a hard-coded list of platform symbols, just ignore anything
>> prefaced with an underscore. This fixes breakage on ARM, which declares
>> several slightly different platform symbols to x86.
>
> FWIW I've explicitly opted against this kind of heuristics for a few reasons:
>
>  - projects use single/double underscored symbols for internal API
>  - other projects have been using such symbols knowingly that it's internal API
> Last but not least
>  - the symbols exposed by the C runtime should stay stable
>
> In other words - prevents others from going silly things, only the
> list might need 1-2 updates.
> If the latter turns out to be false we can nuke it.

Sure. As on IRC though, we definitely need to add at least _ftext for
MIPS anyway:
https://gitlab.gnome.org/GNOME/glib/commit/ad12142943e0f20ed9583c9d6bf50f6262110c74

And probably some more for ARM toolchains using other linkers:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0474k/pge1362066045758.html

Doing a quick check across all the architectures on Debian shows that
your updated list is also missing _fbss, _fdata, and _ftext. So we'd
need to respin for those as well, but I think at this point the
inconvenience of maintaining a list of every linker's implementation
detail on every platform, outweighs the risk of an exported
underscore-prefixed symbol slipping through review.

Cheers,
Daniel