Issue 1:
struct Foo<T>;
impl Foo<int> {
fn foo() {}
}
impl Foo<f64> {
fn foo() {}
}

t.rs:6:2: 6:13 error: duplicate definition of value `foo`
t.rs:6 fn foo() {}
^~~~~~~~~~~
t.rs:3:2: 3:13 note: first definition of value `foo` here
t.rs:3 fn foo() {}
^~~~~~~~~~~

This is frustrating.

Issue 2:
reduction2.rs:

use core::ops::{Add};

fn sum<T, U: Add<U, U>>(seq: &[T], mut u: U, f: &fn(&T) -> U) -> U {
for seq.each |x| { u += f(x); };
u
}

fn F(v: &[float]) -> float {
do sum(v, 0.) |x| { *x }
}

This is compiled with rust as pulled from master. Stack trace follows.

james@james-VirtualBox ~/r/rank> rustc --version; rust test reduction2.rs
rustc 0.6 (2d28d64 2013-05-17 15:52:25 -0700)
host: x86_64-unknown-linux-gnu
rust: task failed at 'assertion failed: !bcx.ccx().maps.moves_map.contains(&arg_expr.id)', /home/james/rust/src/librustc/middle/trans/callee.rs:745
/usr/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f65d031fdab]
/usr/bin/../lib/librustrt.so(+0x2ac49)[0x7f65d0330c49]
/usr/bin/../lib/librustrt.so(upcall_fail+0x1a8)[0x7f65d0321d78]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys13begin_unwind_16_615cb041c655a976_07preE+0x63)[0x7f65d2d8bdc3]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x125d52)[0x7f65d2d8bd52]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys14__extensions__9meth_91519fail_with17_ac9eb45dc42bd6906_07preE+0x6b)[0x7f65d2ccbceb]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee14trans_arg_expr16_d6bdcf6519b16136_07preE+0x2267)[0x7f65d125abd7]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee10trans_args16_c78fefe5617a1ec6_07preE+0x251)[0x7f65d1257071]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x23b11d)[0x7f65d125611d]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10with_scope17_22a7326c2e584f736_07preE+0x600)[0x7f65d1200ea0]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee16trans_call_inner15_1355cc84959a7b6_07preE+0x13e)[0x7f65d123c96e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x25dd47)[0x7f65d1278d47]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x25757b)[0x7f65d127257b]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x252d95)[0x7f65d126dd95]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr10trans_into15_c7c9f5adcc18a56_07preE+0xc4b)[0x7f65d11ae79b]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10trans_stmt17_91b18a57d4d993546_07preE+0x657)[0x7f65d11ad2d7]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans11controlflow11trans_block17_9854c08ac7b88ca86_07preE+0x1a4)[0x7f65d11aa974]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x259b0f)[0x7f65d1274b0f]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10with_scope17_22a7326c2e584f736_07preE+0x600)[0x7f65d1200ea0]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x24f762)[0x7f65d126a762]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr10trans_into15_c7c9f5adcc18a56_07preE+0xa85)[0x7f65d11ae5d5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans11controlflow11trans_block17_9854c08ac7b88ca86_07preE+0x340)[0x7f65d11aab10]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base13trans_closure17_582aa364a2bb51476_07preE+0xaad)[0x7f65d12e431d]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans7closure13trans_expr_fn16_a5888aeca87762e6_07preE+0x726)[0x7f65d125bff6]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x24f439)[0x7f65d126a439]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr14trans_to_datum16_2b8592f90405ae06_07preE+0x1127)[0x7f65d11b2977]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee14trans_arg_expr16_d6bdcf6519b16136_07preE+0xb35)[0x7f65d12594a5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee10trans_args16_c78fefe5617a1ec6_07preE+0x251)[0x7f65d1257071]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x23b11d)[0x7f65d125611d]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10with_scope17_22a7326c2e584f736_07preE+0x600)[0x7f65d1200ea0]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee16trans_call_inner15_1355cc84959a7b6_07preE+0x13e)[0x7f65d123c96e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee17trans_method_call17_d6baea2fbe907ff36_07preE+0x7d9)[0x7f65d123d2c9]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x24e4ba)[0x7f65d12694ba]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr10trans_into15_c7c9f5adcc18a56_07preE+0xa85)[0x7f65d11ae5d5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10trans_stmt17_91b18a57d4d993546_07preE+0x657)[0x7f65d11ad2d7]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans11controlflow11trans_block17_9854c08ac7b88ca86_07preE+0x1a4)[0x7f65d11aa974]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base13trans_closure17_582aa364a2bb51476_07preE+0xdae)[0x7f65d12e461e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base8trans_fn17_7349bdbfff909cc36_07preE+0x691)[0x7f65d115e681]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans12monomorphize14monomorphic_fn16_89a3ce4a93bdc826_07preE+0x4d68)[0x7f65d1163958]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee25trans_fn_ref_with_vtables16_ef718edcdd5474b6_07preE+0xe63)[0x7f65d123a353]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee12trans_fn_ref16_f864ba4eb76f2b16_07preE+0x87f)[0x7f65d12360af]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee5trans16_7a98d43af7ec57c6_07preE+0x78b)[0x7f65d123400b]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x221a88)[0x7f65d123ca88]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x23ab8f)[0x7f65d1255b8f]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10with_scope17_22a7326c2e584f736_07preE+0x600)[0x7f65d1200ea0]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee16trans_call_inner15_1355cc84959a7b6_07preE+0x13e)[0x7f65d123c96e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee10trans_call17_8f6836f7389cd68a6_07preE+0x39a)[0x7f65d123c53a]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x24e3c2)[0x7f65d12693c2]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr10trans_into15_c7c9f5adcc18a56_07preE+0xa85)[0x7f65d11ae5d5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans11controlflow11trans_block17_9854c08ac7b88ca86_07preE+0x340)[0x7f65d11aab10]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base13trans_closure17_582aa364a2bb51476_07preE+0xdae)[0x7f65d12e461e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base8trans_fn17_7349bdbfff909cc36_07preE+0x691)[0x7f65d115e681]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10trans_item17_cfa956d4cc97a5dc6_07preE+0xe03)[0x7f65d11545d3]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base9trans_mod17_f526fcf3681e9a666_07preE+0xb6)[0x7f65d12eaea6]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base11trans_crate16_3edbcbf2e01c2a26_07preE+0x344d)[0x7f65d130c56d]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_rest15_134f5496ff5de16_07preE+0x3bc9)[0x7f65d1a49939]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_upto17_747e21c0469b22f26_07preE+0x192)[0x7f65d1a4d442]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver13compile_input15_0b1e5b3afc4cd16_07preE+0x107)[0x7f65d1a4d8c7]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN12run_compiler17_63c0a0c62771367c6_07preE+0x2bcb)[0x7f65d1a7e0db]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa75dbe)[0x7f65d1a90dbe]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa736ac)[0x7f65d1a8e6ac]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa6d07c)[0x7f65d1a8807c]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa76098)[0x7f65d1a91098]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xeed05)[0x7f65d2d54d05]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x16b558)[0x7f65d2dd1558]
/usr/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f65d0320764]
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /home/james/rust/src/librustc/rustc.rc:355
/usr/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f65d031fdab]
/usr/bin/../lib/librustrt.so(+0x2ac49)[0x7f65d0330c49]
/usr/bin/../lib/librustrt.so(upcall_fail+0x1a8)[0x7f65d0321d78]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys13begin_unwind_16_615cb041c655a976_07preE+0x63)[0x7f65d2d8bdc3]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x125e72)[0x7f65d2d8be72]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x64144)[0x7f65d2cca144]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN7monitor17_67f3fc1a7e3ddd546_07preE+0x2415)[0x7f65d1a816d5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa76098)[0x7f65d1a91098]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN4main15_c4de63b748e03d6_07preE+0x69)[0x7f65d1a90cf9]
/usr/bin/../lib/librust-ff41319e20d2b87e-0.7-pre.so(+0x4208)[0x7f65d0559208]
/usr/bin/../lib/librust-ff41319e20d2b87e-0.7-pre.so(+0x2dfe)[0x7f65d0557dfe]
/usr/bin/../lib/librust-ff41319e20d2b87e-0.7-pre.so(+0x4c94)[0x7f65d0559c94]
/usr/bin/../lib/librust-ff41319e20d2b87e-0.7-pre.so(_ZN4main17_cafdd5fc92b0f2ec6_07preE+0x17c)[0x7f65d055977c]
rust(_rust_main+0x2e)[0x400e0e]
/usr/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f65d0320764]
rust: domain main @0x6ea440 root task failed