def build(self, spec, prefix):
        """Build using the OpenFOAM Allwmake script, with a wrapper to source
        its environment first.
        Only build if the compiler is known to be supported.
        """
        self.foam_arch.has_rule(self.stage.source_path)
        self.foam_arch.create_rules(self.stage.source_path, self)

        args = []
        if self.parallel:  # Build in parallel? - pass via the environment
            os.environ['WM_NCOMPPROCS'] = str(make_jobs)
        builder = Executable(self.build_script)
        builder(*args)