Canonical type nodes, or, comptypes considered harmful

[Gabriel Dos Reis]

"Doug Gregor" <doug.gregor@gmail.com> writes:

| On 11/7/06, Mike Stump <mrs@apple.com> wrote:
| > Anyway, in C++, the entire template mechanism was rife with building
| > up duplicates.  I'd propose that this problem can (and should be
| > addressed) and that we can do it incrementally.  Start with a hello
| > world, then in comptypes, check to see when it says yes, they are the
| > same, but the address equality checker says they might not be the
| > same, print a warning.  Fix the dup builders until no warnings.  Then
| > rebuild the world and repeat.  :-)  Work can be checked in, as dups
| > are eliminated.
| 
| It's a good plan.
| 
| Now, how much do we worry about the fact that we won't be printing
| typedef names when we combine duplicate nodes? If we don't care, our
| job is much easier. If we do care, then we need to introduce a system
| for equivalence classes to keep those typedef names, which will
| complicate matters a bit.

I believe we do care for good diagnostic purposes.

-- Gaby