[m-rev.] for post-commit review: document an issue with tuple_cons cons_ids

[Zoltan Somogyi]

2021-02-27 12:30 GMT+11:00 "Peter Wang" <novalazy at gmail.com>:
> Do you know the reason for using tuple_cons(Arity) instead of
> cons(unqualified("{}"), Arity, ...)?

The log message of the commit in which I introduced tuple_cons,
d69ba1a1f0596e7f740b1a788350b5dcb343c276, says:

    This diff also separates tuples out from user-defined types, since in many
    respects they are different (they don't have a single type_ctor, for starters).

That was in 2009. The fact that the problem described in my diff yesterday
hasn't caused any issues in eleven years shows that the problem affects
*probably* only small parts of the compiler. This definitely includes mode
analysis, but it would be nice to know what other parts of the compiler,
if any, are also affected.

Zoltan.