bug#60974: 30.0.50; byte-compile-preprocess mutates self evaluating forms in expanded macro bodies

[Stefan Monnier]

> Alternatively, we could define a macro, store its expanded form in a
> variable and run it through `cconv-closure-convert`, checking
> afterwards whether the original value changed or not. It feels a little
> more reliable, but writing it might be a little tricky.

I was thinking of doing something like:

    (let ((f '(lambda () (interactive ...) ...)))
      (should (equal f
                     (let ((fc (copy-tree f)))
                       (byte-compile fc)
                       fc))))


-- Stefan