Issue 1:
Hi, I used vec! the wrong way, and the compiler panicked.

rustc -V -> rustc 1.0.0-dev (built 2015-05-17)

Sorry, if this is a dup, I looked but did not see a report of this.

fn main() {
vec!([]);
println!("Hello, world!");
}

produces

~/code/rust/panic/ § RUST_BACKTRACE=1 rustc src/main.rs (master*) [18:07:43]
<std macros>:3:1: 3:76 error: internal compiler error: cat_expr Errd
<std macros>:3 < [ _ ] > :: into_vec ( $ crate:: boxed:: Box:: new ( [ $ ( $ x ) , * ] ) ) )
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<std macros>:1:1: 4:58 note: in expansion of vec!
src/main.rs:2:5: 2:14 note: expansion site
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /build/rust/src/rustc-1.0.0/src/libsyntax/diagnostic.rs:149

stack backtrace:
1: 0x7ff56b5d5189 - sys::backtrace::write::h85e36588f6ec519ed4r
2: 0x7ff56b5dce96 - panicking::on_panic::h6e154bbd20295560jrw
3: 0x7ff56b5a01a2 - rt::unwind::begin_unwind_inner::h58d8677c31c147e6t6v
4: 0x7ff568b94a0d - rt::unwind::begin_unwind::h17109019831519213513
5: 0x7ff568b949a2 - diagnostic::SpanHandler::span_bug::he871130351e8da9fEqB
6: 0x7ff56942f163 - session::Session::span_bug::hf5507d592e7c6099PDq
7: 0x7ff56a3d1a5d - check::regionck::visit_expr::h55b582b9adf67231Yhd
8: 0x7ff56a3ce9d0 - check::regionck::Rcx<'a, 'tcx>::visit_fn_body::h894f2218ba6ba28epUc
9: 0x7ff56a448546 - check::check_bare_fn::h16e5c54944c58ce3twn
10: 0x7ff56a4463a2 - check::CheckItemBodiesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::h960d90c3a6588469wtn
11: 0x7ff56a50a34a - check_crate::closure.38028
12: 0x7ff56a5056e0 - check_crate::h16da0c29bfd97789XcC
13: 0x7ff56bb0fa08 - driver::phase_3_run_analysis_passes::h7268293564f4d974nGa
14: 0x7ff56baf0b05 - driver::compile_input::hf89ed7761a9a5930Qba
15: 0x7ff56bbb1fd1 - run_compiler::h61cd16b138828888z4b
16: 0x7ff56bbafc22 - boxed::F.FnBox<A>::call_box::h3676213088059194772
17: 0x7ff56bbaf159 - rt::unwind::try::try_fn::h2238843044414567073
18: 0x7ff56b646b28 - rust_try_inner
19: 0x7ff56b646b15 - rust_try
20: 0x7ff56bbaf408 - boxed::F.FnBox<A>::call_box::h6492341214887270608
21: 0x7ff56b5dbd81 - sys::thread::create::thread_start::ha66925ca4f47d19baqv
22: 0x7ff566067353 - start_thread
23: 0x7ff56b235bfc - __clone
24: 0x0 - <unknown>

Issue 2:
Test case:

fn main() { []; }

Output:

$ RUST_BACKTRACE=1 rustc test.rs
test.rs:1:13: 1:15 error: internal compiler error: cat_expr Errd
test.rs:1 fn main() { []; }
^~
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:129

stack backtrace:
1: 0xcc029720 - sys::backtrace::write::h66f3f2784d0f6c5ddgA
2: 0xcc051b80 - panicking::on_panic::h6fdde9e4e9166fe6jaJ
3: 0xcbf91c30 - rt::unwind::begin_unwind_inner::hba10c536ef2aae75MQI
4: 0xc92a10c0 - rt::unwind::begin_unwind::h11287547919384241778
5: 0xc92a1050 - diagnostic::SpanHandler::span_bug::h551f703868554ecfUBD
6: 0xc9e32fe0 - session::Session::span_bug::h10f6b5fdbea6485fbjp
7: 0xcb6c5920 - check::regionck::visit_expr::hc78138689559ecf8Yrd
8: 0xcb6c35c0 - check::regionck::Rcx<'a, 'tcx>::visit_fn_body::h75e2fac33dc50b43a4c
9: 0xcb75ee50 - check::check_bare_fn::hf42e5aabaa5cb880Oan
10: 0xcb756f40 - check::check_item::hdbe569c101f96905stn
11: 0xcb822f10 - check_crate::closure.36015
12: 0xcb81d9c0 - check_crate::h9d44bf3fde687089EXB
13: 0xcc6a38c0 - driver::phase_3_run_analysis_passes::h36c633d41f11ca74wFa
14: 0xcc689ec0 - driver::compile_input::h0de317319ab5c701Hba
15: 0xcc754e20 - run_compiler::hffa0c0711e361de8E5b
16: 0xcc753720 - thunk::F.Invoke<A, R>::invoke::h12673221910893163557
17: 0xcc752610 - rt::unwind::try::try_fn::h15130568597725528481
18: 0xcc0bd740 - rust_try_inner
19: 0xcc0bd730 - rust_try
20: 0xcc752910 - thunk::F.Invoke<A, R>::invoke::h3924406537784056782
21: 0xcc03d990 - sys::thread::thread_start::h3734be2229bd3edegEE
22: 0xc5f650c0 - start_thread
23: 0xcbc0a449 - __clone
24: 0x0 - <unknown>

Compiler version:

rustc 1.0.0-nightly (b47aebe3f 2015-02-26) (built 2015-02-27)
binary: rustc
commit-hash: b47aebe3fc2da06c760fd8ea19f84cbc41d34831
commit-date: 2015-02-26
build-date: 2015-02-27
host: x86_64-unknown-linux-gnu
release: 1.0.0-nightly

I modified the test case in #22894 by moving the &*"" into fn main(), and I saw the same ICE. I then changed the "" to the similar &[], and I saw an ICE with a different error message and a different stack trace (e.g. phase 3 instead of phase 4). The & and * are unnecessary.

I also see the cat_expr Errd message in #22037, but there are differences -- this issue happens in phase 3 rather than 4, and there is no "fictitious type" message.