GLProfile fails to select default core profiles when no compat profiles are available.
This is what is left from Bug 1382:
Compat profiles being disabled via GLRendererQuirks.GLNonCompliant
and GLProfile fails to use the highest core profile available as default.
Fixed as described in the git logs.
First patches clean-up the affected code-path w/o semantic change,
where the subsequent patches clean up semantics and fix the issue.
GLRendererQuirks.GLNonCompliant -> GLRendererQuirks.GL3CompatNonCompliant
Notable is Bug 1385, i.e. GL3CompatNonCompliant is now more required
for Mesa >= 18.2.0 ;-)
However, this cleanup & fix was worth its time.
Tighten version/profile qualification: fail if: requested compat profile && has core profile
On Mesa, if requesting a 3.1 compat profile, we receive a 4.5 core profile.
This is natural due to constraints within glXCreateContextAttribsARB,
i.e. GLX_CONTEXT_PROFILE_MASK_ARB is only a available for versions >= 3.2
and these are not available on Mesa.
Tested with Mesa 18.3.6 of Debian 10 Buster,
which also confirms Bug 1385 fix of limitating GL3CompatNonCompliant
to Mesa < 18.2.0
(In reply to Sven Gothel from comment #1)
> Notable is Bug 1385, i.e. GL3CompatNonCompliant is now more required
> for Mesa >= 18.2.0 ;-)
You meant "no more" of course.