ICE with cross-crate resources and channels

[eholk]

Here's a test program:

import comm::{port, chan, methods};
use std;
import std::arc;

enum e<T: send> { e2, e(chan<arc::arc<T>>) }

resource r<T: send>(x : comm::chan<e<T>>) {
    x.send(e2);
}

fn foo<T: send const>(-x : T) -> r<T> {
    fail
}

fn main() {
    foo([some(1)]);
}

This gives an internal compiler error. The problem is that type variable leaks into trans. If I define a resource like arc::arc in the same file and use that instead, the program compiles successfully. Here is some of the log from compiling this:

rust: "cleanup_and_leave: leaving [block 389]"
rust: "new insn_ctxt: cleanup_and_Br"
rust: "new insn_ctxt: cleanup_and_leave"
rust: "cleanup_and_leave: leaving [block 7fb923853d50]"
rust: "cleanup_and_leave: leaving [block 391]"
rust: "new insn_ctxt: finish_fn"
rust: "new insn_ctxt: tie_up_header_blocks"
rust: "new insn_ctxt: trans_args"
rust: "new insn_ctxt: alloc_ty"
rust: upcall fail 'Assertion !ty::type_has_params(t) failed', /Users/eholk/Documents/projects/mozilla/rust/src/rustc/middle/trans/base.rs:4233

The uninstantiated type variable is the data field in the arc.

[nikomatsakis]

@eholk and I tracked this down. The problem is how we handle shape tables for generic enums. We still generate one table for the 'Generic enum' and then encode the values of the type parameters. This is pre-monomorphization thinking. We need to rewrite that code.

[eholk]

Here's a simpler test case:

use std;
import std::arc;

enum e<T: const> { e(arc::arc<T>) }

resource r(x : e<int>) {
}

fn foo() -> r {fail;}

fn main() {
    let x = foo();
}

[eholk]

Here's an even simpler test. It's not a cross-crate issue at all.

resource r<T> (x: T) { fail }

enum e<T: const> { e(r<T>) }

fn foo() -> e<int> {fail;}

fn main() {
    let x = foo();
}

[nikomatsakis]

I believe this to be fixed now.

[eholk]

I just verified that this fixes the program that originally caused this problem.