Hey Ludovic,
Thanks for the comments!

> “Nowadays” we’d use gexps, like so:
>  #~(cons* #$extra-flags #$list-of-flags)
Noted, I will follow this in the updated patch.

> This seems to be pasted from somewhere else; we might want to factorize
it (not your fault of course, but something to keep in mind.)
It was indeed copied over from the with-patches segment, as I thought it
would be useful to check if a configure-flag is being passed again. I think
it is not particularly necessary as we assume that the user knows what they
are doing when they are using transforms, so I will omit it in the updated
patch.

> In general, the ‘name’ field of build systems is purely informational and
I would suggest not relying on it.
Yes, and I've factored that in in the current patch- I have obtained the
actual 'name' parameters of each of the given build systems through
grepping. However, I agree with you in thinking that it might not be
necessary at all- I wrote this as a 'stopgap' of sorts anyways. I would
like to update it with a sophisticated checking mechanism at a later date
that actually checks if the build system supports configure-flags if
necessary.

> Have you been able to test it on actual packages? (I haven’t taken the
time yet.)
This is the part where I've been having the most trouble actually; I
haven't been able to find suitable methods for testing this, so for now
I've used two methods for testing if it works:
1) printing the arguments of the rewritten package record with display
2) comparing the hashes of patches built with and without configure-flags
Both tests seem to agree that it is working, however I would really
appreciate more rigorous testing by someone else or suggestions on how to
test it more rigorously.
For one, I have been unable to actually check if a feature is getting
added/removed by adding configure-flags because I haven't been able to find
a suitable package to test it with.
If possible, that would be a very clear indication of it working.

> What we’d like to have, in addition to this, is two things:
> ...
> Could you give it a try?
Sure, I will include these changes with the updated patch.

I will try to submit it in about a week, as I would like to test it more
rigorously first.

Happy hacking!
Sarthak (cel7t)