support alloca

[thestinger]

It's probably going to be tricky to get this working with the segmented stack implementation.

[pcwalton]

I think it's impossible to get that working.

[pcwalton]

Well, I'll reopen in case there is some way I hadn't thought of.

[brson]

The full gcc __morestack implementation does allow for dynamically sized frames. It inserts calls to yet another __morestack function before alloca-ing. I don't particularly want to support it though.

[pnkfelix]

Visiting for bug triage, email from 2013-08-12.

Nothing to add (wish list tag seems appropriate for now).

[thestinger]

There are no more segmented stacks, so supporting this seems very feasible. It could be implemented with a wrapper function performing a stack overflow check inside.

[steveklabnik]

I'm pulling a massive triage effort to get us ready for 1.0. As part of this, I'm moving stuff that's wishlist-like to the RFCs repo, as that's where major new things should get discussed/prioritized.

This issue has been moved to the RFCs repo: rust-lang/rfcs#618