Issue 1:
I would have expected this to work, but it does not:

#[feature(macro_rules)];

macro_rules! test {
() => {
fn foo();
}
}

trait Foo {
test!()
}

Currently fails with this error:

test.rs:10:4: 10:8 error: unexpected token: `test`
test.rs:10 test!()
^~~~
task 'rustc' failed at 'explicit failure', /Users/mitsuhiko/Development/rust/src/libsyntax/diagnostic.rs:76
task '<main>' failed at 'explicit failure', /Users/mitsuhiko/Development/rust/src/librustc/lib.rs:441

Issue 2:
The following code produces an ICE (using the latest nightly)

macro_rules! width(
($this:expr) => {
$this.width.unwrap()
}
);

struct HasInfo {
width: Option<usize>
}

impl HasInfo {
fn get_size(&mut self, n: usize) -> usize {
n
}

fn get_other(&mut self) -> usize {
self.get_size(width!(self))
}
}

fn main() {
println!("hello?");
}

Backtrace:

$ RUST_BACKTRACE=1 rustc test.rs
test.rs:17:30: 3:20 error: cannot use `self.width` because it was mutably borrowed
error: internal compiler error: unexpected panic
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 'capacity overflow', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libcore/option.rs:330

stack backtrace:
1: 0x10834491f - sys::backtrace::write::hbd92b2f3b9d1f59bh7r
2: 0x10834cf80 - panicking::on_panic::hdc2c5977e67a233aUlw
3: 0x108308105 - rt::unwind::begin_unwind_inner::h01673f860cb84cd8D3v
4: 0x108308f3c - rt::unwind::begin_unwind_fmt::h9151fe47c4b99bcdJ2v
5: 0x10834cadc - rust_begin_unwind
6: 0x10839c7f5 - panicking::panic_fmt::he085f3b18c15d040hJy
7: 0x107ab1183 - codemap::CodeMap::span_to_lines::hb2f0d1a92c447e1btLA
8: 0x107af89eb - diagnostic::emit::h0cb83e197668e62aspC
9: 0x107af631c - diagnostic::EmitterWriter.Emitter::emit::h514d00ff1c0c52feamC
10: 0x107aa7969 - diagnostic::SpanHandler::span_err::h2e7e4e702a3c83e0gSB
11: 0x1054c5c43 - session::Session::span_err::hb309dbdc83438db3WGq
12: 0x104f015f4 - borrowck::check_loans::CheckLoanCtxt<'a, 'tcx>::consume_common::h37627587e5d63ecfQWa
13: 0x104f00fd1 - borrowck::check_loans::CheckLoanCtxt<'a, 'tcx>.euv..Delegate<'tcx>::consume::h70f8cd9f17ba9508Bea
14: 0x104f1530a - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'tcx, TYPER>::consume_expr::h15185387293697103588
15: 0x104f11f2e - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'tcx, TYPER>::walk_expr::h15228336715392409603
16: 0x104f1531e - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'tcx, TYPER>::consume_expr::h15185387293697103588
17: 0x104f11f2e - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'tcx, TYPER>::walk_expr::h15228336715392409603
18: 0x104f1531e - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'tcx, TYPER>::consume_expr::h15185387293697103588
19: 0x104f30aef - borrowck::borrowck_fn::h4c8fd678dfdeee49NOe
20: 0x104f300dc - borrowck::BorrowckCtxt<'a, 'tcx>.Visitor<'v>::visit_fn::h55da20bf55e34495bGe
21: 0x104f32ab4 - visit::walk_impl_item::h12505514548441264404
22: 0x104f3378a - visit::walk_item::h2754692921043539544
23: 0x104f32c08 - borrowck::check_crate::h3db16b6efa27d8adQIe
24: 0x104a9b880 - driver::phase_3_run_analysis_passes::hba2077d3401024fbtGa
25: 0x104a7bd5c - driver::compile_input::hddc4eab8e7fc8420Qba
26: 0x104b3ac83 - run_compiler::hf4a5110b6d35543565b
27: 0x104b383ea - boxed::F.FnBox<A>::call_box::h8166354692369242215
28: 0x104b37947 - rt::unwind::try::try_fn::h645230996156021718
29: 0x1083cf488 - rust_try_inner
30: 0x1083cf475 - rust_try
31: 0x104b37c1d - boxed::F.FnBox<A>::call_box::h7235942386744103169
32: 0x10834b97d - sys::thread::Thread::new::thread_start::h7bede09625198736Cov
33: 0x7fff8b475267 - _pthread_body
34: 0x7fff8b4751e4 - _pthread_start

Probably an duplicate of #25353 or #24761. I opened a new bug since I was able to reduce it to a minimal example. This is not related to the borrow checker as it also crashes if I change $this.width to $this.undefined.