Re: [gpsd-dev] ✘scons 3.0.5

[Fred Wright]

On Thu, 28 Mar 2019, Gary E. Miller wrote:
> On Thu, 28 Mar 2019 12:48:02 -0700 (PDT)
> Fred Wright <address@hidden> wrote:
>
> > On Thu, 28 Mar 2019, Gary E. Miller wrote:
> > > On Thu, 28 Mar 2019 13:29:19 -0300
> > > Lisandro Dami?n Nicanor P?rez Meyer <address@hidden> wrote:
> > >
> > > > > I have qtnetwork 5.12.2 installed.    There is no file
> > > > > QtNetwork.pc
> > > > It should be Qt5Network.pc. QtNetwork.pc is the Qt 4 version.
> >
> > Ah, yes.  I'd forgotten about that issue.  That's why I added the
> > qt_versioned option.
>
> Options are OK, autodetect is best.

Autodetect *alone* is a bad idea, since opportunistic configuration leads 
to nonreproducible builds.  One shouldn't have to remove a dependency just 
to turn off a feature.

It's not unreasonable to use the environment to set the *default value* of 
options, but it should always be possible to specify the desired 
configuration explicitly, and have the build fail if the requested 
configuration doesn't work.

And in the particular case of Qt, one might have both versions installed 
(which was the whole point of the name change in the first place), so 
there may be no single "correct" value of qt_versioned.

Fred Wright