Changes to base class does not change package hash

[iarspider]

Steps to reproduce

$ spack create -n cmsroot -t cmake https://github.com/cms-sw/root/
$ cat var/spack/repos/builtin/packages/cmsroot/package.py
from spack.pkg.builtin.root import Root as BuiltinRoot


class Cmsroot(BuiltinRoot):
    __doc__ = BuiltinRoot.__doc__

    git      = "https://github.com/cms-sw/root.git"

    version('1.2.3', '0123456789abcdef0123456789abcdef')

    def cmake_args(self):
        args = []
        replace_args = ('builtin_ftgl', 'builtin_gl2ps', 'builtin_glew')
        for arg in super().cmake_args():
            for rarg in replace_args:
                if arg.startswith('-D' + rarg):
                    args.append(self.define(rarg, True))
                    break
            else:
                args.append(arg)

        return args
$ spack spec --format '{hash}' cmsroot
idkrysrzi72lmyiah6ne2gyswrduzhy5
$ sed -i -e "s/return options/options.append(define('FOO', 'BAR'))\n        return options"
$ spack spec --format '{hash}' cmsroot
idkrysrzi72lmyiah6ne2gyswrduzhy5

Error message

Hash should be different

Information on your system

• Spack: 0.18.0.dev0 (c775c32)
• Python: 3.10.4
• Platform: linux-fedora36-skylake
• Concretizer: clingo

General information

• I have run spack debug report and reported the version of Spack/Python/Platform
• I have searched the issues of this repo and believe this is not a duplicate
• I have run the failing commands in debug mode and reported the output

[iarspider]

A bit of context: in CMS, we modify many recipes to match our setup (e.g. we drop documentation and static libraries to reduce the image size). In order not to copy and patch the upstream recipe every time it updates, we decided to use inheritance. However, it was discovered that if upstream package changes we may miss the changes in our build since the hash of the package will not change.

[becker33]

@tgamblin how feasible is it to fix this for the release? I think we can do the static version of this (canonicalize all modules in class hierarchy between package and PackageBase) and not worry about whether those changes would be masked out by an overriding method the inheriting class.