[LyX/master] Make it possible to select C++ standard with autoconf

[Pavel Sanda]

On Tue, Nov 03, 2020 at 04:12:16PM +0100, Pavel Sanda wrote:
> On Tue, Nov 03, 2020 at 02:44:43PM +0100, Jean-Marc Lasgouttes wrote:
> > commit ce526607ff4ae33834dabe64e0072530eca16183
> > Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
> > Date:   Mon Nov 2 17:40:29 2020 +0100
> > 
> >     Make it possible to select C++ standard with autoconf
> >     
> >     Introduce new configure option --enable-cxx-mode=MODE, which allows to
> >     force a C++ version. The default is {14,11}, which means that C++14 is
> >     chosen if it is supported, and C++11 will be selected as a fallback.
> >     
> >     Using --enable-cxx-mode=11 ensures that LyX compiles correctly
> >     with an older C++11 compiler.
> 
> Is this supposed to work by default on old compilers or do I need to 
> pass cxx-mode now?
> 
> checking for a good C++ mode... none
> configure: error: Cannot find suitable mode for compiler g++
> make: *** [Makefile:502: config.status] Error 1

looking at the log I see:
g++: error: unrecognized command line option '-std=gnu++14,11'
Seems like wrong argument? 

> Pavel