[PATCH weston] build: Define wayland prereq version

[Bryce Harrington]

On Thu, May 12, 2016 at 09:48:17AM +0100, Emil Velikov wrote:
> On 12 May 2016 at 09:13, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > On Thu, 12 May 2016 11:12:28 +1000
> > Peter Hutterer <peter.hutterer at who-t.net> wrote:
> >
> >> On Wed, May 11, 2016 at 01:18:59PM -0700, Bryce Harrington wrote:
> >> > Establishes a single variable for defining the libwayland version
> >> > requirements.  Enforces the same version dependency between
> >> > libwayland-client and libwayland-server, as recommended by pq in the
> >> > 1.11 release discussions.
> >> >
> >> > Signed-off-by: Bryce Harrington <bryce at osg.samsung.com>
> >> > ---
> >> >  configure.ac | 12 +++++++-----
> >> >  1 file changed, 7 insertions(+), 5 deletions(-)
> >> >
> >> > diff --git a/configure.ac b/configure.ac
> >> > index 2ca1f4e..0b23fc4 100644
> >> > --- a/configure.ac
> >> > +++ b/configure.ac
> >> > @@ -4,6 +4,8 @@ m4_define([weston_micro_version], [91])
> >> >  m4_define([weston_version],
> >> >            [weston_major_version.weston_minor_version.weston_micro_version])
> >> >
> >> > +m4_define([WAYLAND_PREREQ_VERSION], "1.10.0")
> >>
> >> how comes the line above uses [] and here you use ""? is that intentional?
> >> (I keep forgetting whether there's a difference between the two in m4)
> >
> > Yeah, I'm not that sure about using a m4 define. It is one way to do
> > it, but the quotes do look suspicious.
> >
> > FWIW, Mesa uses a big list of common dependency variables too, maybe
> > copy that approach?
> >
> > CC'ing Quentin and Emil, they probably know what's good.
> >
> In all honesty I don't know which one is better, so any
> info/references will be appreciated. For the time being (personally)
> I'd stick with the following as it reads a bit easier ;-)
> 
> WAYLAND_PREREQ_VERSION="1.10.0"

Alright, so I've tested several different variations.  I've tested both
using version 1.10.0 (which must pass), and 1.99.0 (which must fail)

                                               N=10  N=99
m4_define([WAYLAND_PREREQ_VERSION], "1.N.0")   PASS  FAIL  --> Okay
m4_define([WAYLAND_PREREQ_VERSION], [1.N.0])   PASS  FAIL  --> Okay
m4_define([WAYLAND_PREREQ_VERSION], 1.N.0)     PASS  FAIL  --> Okay

WAYLAND_PREREQ_VERSION="1.N.0"                 PASS  PASS  --> Incorrect
WAYLAND_PREREQ_VERSION=1.N.0                   PASS  PASS  --> Incorrect
WAYLAND_PREREQ_VERSION=[1.N.0]                 PASS  PASS  --> Incorrect

In all cases, I've referenced the variable as just
WAYLAND_PREREQ_VERSION in the code.  If I reference it as
$WAYLAND_PREREQ_VERSION then autogen.sh errors indicating a blank string
was substituted.  E.g.:

  configure: error: Package requirements (wayland-server >=  pixman-1 >= 0.25.2 xkbcommon >= 0.3.0) were not met:
  No package '>=' found
  No package '0.25.2' found

I'd tested a number of other variations prior to settling on the
m4_define() syntax, which is why I'm leaning that direction - I just
couldn't get anything else to work.  So if anyone feels m4_define() to
be the wrong way to do it, I'm happy to try another way but will need
more specific direction.

Regarding the quoting, it doesn't appear to matter what form to use.
I'll go ahead and resubmit the patch with the bracketed form since that
looks like it would be more consistent with the rest of the code, and
sounds like it would be more standard.

Bryce