Looks good! Can you move your url_for_version function to just before install? We like to keep class methods at the end of the class. Actually, if you replace:

class Flex(Package):

with

class Flex(AutotoolsPackage):

you should be able to get rid of the install method altogether.

I've done this, but I'm getting the following error from the AutotoolsPackage:

==> Fetching https://github.com/westes/flex/archive/v2.6.2.tar.gz
######################################################################## 100.0%
==> Staging archive: /home/matthew/Software/NCSA/Vertical/spack/spack-dev-2/var/spack/stage/flex-2.6.2-73ae4w64tdnctwhhwkr26s772mpa7ypi/v2.6.2.tar.gz
==> Created stage in /home/matthew/Software/NCSA/Vertical/spack/spack-dev-2/var/spack/stage/flex-2.6.2-73ae4w64tdnctwhhwkr26s772mpa7ypi
==> Ran patch() for flex
==> Building flex [AutotoolsPackage]
==> Executing phase : 'autoreconf'
==> Error: RuntimeError: configure script not found in /tmp/matthew/spack-stage/spack-stage-LxdPUJ/flex-2.6.2
/home/matthew/Software/NCSA/Vertical/spack/spack-dev-2/lib/spack/spack/build_systems/autotools.py:137, in is_configure_or_die:
     131      @PackageBase.sanity_check('autoreconf')
     132      def is_configure_or_die(self):
     133          """Checks the presence of a `configure` file after the
     134          autoreconf phase"""
     135          if not os.path.exists('configure'):
     136              raise RuntimeError(
  >> 137                  'configure script not found in {0}'.format(os.getcwd()))

I've done this, but I'm getting the following error from the AutotoolsPackage:

strange. @alalazo any clues?

@davydden I'll try to have a look asap

The problem is that the latest tarball doesn't have a configure script in it. You'll have to generate one if you want to build from GitHub source. I don't think it's related to the switch to AutotoolsPackage.

@adamjstewart Well, in that case the error message is right:

Error: RuntimeError: configure script not found in /tmp/matthew/spack-stage/spack-stage-LxdPUJ/flex-2.6.2

@krafczyk see swiftsim for an example on how to override the autoreconf stage to actually do something. You need to depend_on autotools package, type=build.

@alalzo I've implemented the necessary changes and now flex builds properly. I'm a bit confused however why the AutotoolPackage doesn't try this type of autoreconf automatically. In my experience, almost all autotool packages which lack a configure do contain an autogen.sh script. You should be able to override this for the odd package or two, but I feel like a reasonable default action should be attempted.

@krafczyk The problem is adding on the fly build dependencies if configure is not found. autogen.sh will most likely do something like autoreconf -ivf and for that you need to:

depends_on('autotools',  type='build')

When we merged build system support the consensus was on minimizing dependencies over providing automation for this case.

An alternative would be to have autotools dependency coded in AutotoolsPackage even for packages that don't need it, but for that we lack support for having depends_on directives in base classes that reside in modules other than the package under install (check the directive module if you want to see the black-magic that powers directive).

@citibeth has also proposed always running autoreconf for Autotools packages. One of the reasons we don't currently do it is because it would mean every Autotools package would need to depend on autoconf/automake/libtool/m4.