[Mesa-dev] WebGL WG interested in 1.0.1 conformance test results on real drivers

[Eric Anholt]

On Mon, 23 Apr 2012 10:30:41 -0700 (PDT), Benoit Jacob <bjacob at mozilla.com> wrote:
> 
> 
> ----- Original Message -----
> > On Sat, 21 Apr 2012 08:09:33 -0700 (PDT), Benoit Jacob
> > <bjacob at mozilla.com> wrote:
> > > > > conformance/programs/program-test.html: 1 tests failed
> > > > 
> > > > > PASS linking should fail with in-use formerly good program,
> > > > > with
> > > > > new bad shader attached
> > > > > FAIL getError expected: NO_ERROR. Was INVALID_OPERATION :
> > > > > drawing
> > > > > with a
> > > > > valid program shouldn't generate a GL error
> > > > 
> > > > This sounded like it was going to be a Mesa bug, but this
> > > > testcase
> > > > passes:
> > > 
> > > This is indeed Mesa's bug: on failure, glLinkProgram should leave a
> > > previously-successfully-linked program intact. The testcase in
> > > your email doesn't seem to be re-linking the program with the bad
> > > shader, which would explain why it doesn't reproduce this issue.
> > 
> > It should?  I read the opposite in this quote from the GL 3.0 spec:
> > 
> >     "Linking will also fail if one or more of the shader objects,
> >      attached to program are not compiled successfully, or if more
> >      active uniform or active sampler variables are used in program
> >      than
> >      allowed (see section 2.20.3). If LinkProgram failed, any
> >      information about a previous link of that program object is
> >      lost. Thus, a failed link does not restore the old state of
> >      program."
> 
> Thanks, I hadn't questioned that the test might be wrong, but now I agree with you. Also, the same phrasing is found in the OpenGL ES 2.0.25 spec page 30:
> 
> "If LinkProgram failed, any information about a previous link of that program object is lost. Thus, a failed link does not restore the old state of program."
> 
> Reporting this to the WebGL mailing list.

I did find this gem later:

    "If that program object that is in use is re-linked unsuccessfully,
     the link status will be set to FALSE, but existing executable and
     associated state will remain part of the current rendering state
     until a subsequent call to UseProgram removes it from use."

Maybe they're testing that.  I wonder what possible use was imagined for
forcing that sort of complexity on driver developers.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20120423/d9317393/attachment.pgp>