Re: Minimal Qt version for the default branch

[John W. Eaton]

On 3/12/19 12:51 PM, Mike Miller wrote:

> > What does the output for the list of tests above look like for Qt 5.5?
>
> I'll try to find that out, maybe for a handful of different Qt 5
> versions for comparison.

OK.  BTW, for 5.12, the only ones that fail for me are:

checking QGLWidget usability... no
checking QGLWidget presence... no
checking for QGLWidget... no
checking QGLFunctions_1_1 usability... no
checking QGLFunctions_1_1 presence... no
checking for QGLFunctions_1_1... no

but I think that's because these tests are done without the Qt5OpenGL 
module.  So that's another error in the current configure tests that we 
could eliminate more easily if we could simplify things.

> Yeah, the existence of one enum in QStandardPaths is something we can
> easily work around.
>
> As you saw in bug #55883, the logic around QtOpenGL vs QOpenGLWidget is
> getting very confusing.

Yes, definitely.  And the more confusing, the more time wasted and the 
more fragile these checks tend to become.  After this experience, I'm 
leaning much more toward dropping support for Qt4.

> This only affects libgui/graphics, but how about
> making QOpenGLWidget and QOffscreenSurface hard requirements and
> dropping support for deprecated QtOpenGL as a first simplification?

Are you saying still support Qt4 for the main GUI but if QOpenGLWidget 
and QOffscreenSurface are not available, then disable the Qt plotting 
widget?

jwe