Issue 1:
The following snippet:

macro_rules! getarg {
(x => $e:expr) => (println! ("x = {}", $e));
$b:block => $b;
}

fn main() {
getarg! (x => 1 + 2);
getarg! {
}
}

gives the following error:

src/main.rs:3:1: 4:2 error: internal compiler error: wrong-structured lhs for follow check (didn't find a TtDelimited or TtSequence)

This is the backtrace:

stack backtrace:
1: 0x104fe5da3 - sys::backtrace::write::h36da3fb1e07e78da0nC
2: 0x105013da5 - panicking::on_panic::haade6d6d86433bf5HOL
3: 0x104f3d5d8 - rt::unwind::begin_unwind_inner::h00317caea0131299UvL
4: 0x1045efb5f - rt::unwind::begin_unwind::h15168281961459128075
5: 0x1045efb0c - diagnostic::SpanHandler::span_bug::hbfe227f81d0cd8devYE
6: 0x104741719 - ext::base::ExtCtxt<'a>::span_bug::hdb7ec5648176a7f89y7
7: 0x104740ed5 - ext::tt::macro_rules::compile::ha9fc6d551176d0ddx5i
8: 0x104740265 - ext::base::ExtCtxt<'a>::insert_macro::h91b42296cf30a29dSw7
9: 0x1047b49f0 - ext::expand::expand_item_mac::hb9eabd9a17097c78v5d
10: 0x1047a0227 - ext::expand::expand_annotatable::hb2c7b6cf1688383b0ze
11: 0x10479c230 - ext::expand::expand_item::h82a19f3ce454f84daZd
12: 0x1047ab7a2 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h7f85720548281771dSe
13: 0x1047ab578 - fold::noop_fold_mod::closure.58932
14: 0x1047ab316 - iter::FlatMap<I, U, F>.Iterator::next::h10055531995118448306
15: 0x1047aaf60 - vec::Vec<T>.FromIterator<T>::from_iter::h8228182012818297599
16: 0x1047aab9f - fold::noop_fold_mod::h3115526397988167409
17: 0x1047a6a7c - ext::expand::expand_item_underscore::h52c4b03ceb86d01b02d
18: 0x10480f552 - fold::Folder::fold_item_simple::h4379758381320372925
19: 0x10480ecd3 - ptr::P<T>::map::h1390305908052494351
20: 0x1047a1b95 - ext::expand::expand_annotatable::hb2c7b6cf1688383b0ze
21: 0x10479c230 - ext::expand::expand_item::h82a19f3ce454f84daZd
22: 0x1047ab7a2 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h7f85720548281771dSe
23: 0x10481be94 - ext::expand::expand_crate::h8ce8d9aec4e20430IYe
24: 0x1016c70d4 - driver::phase_2_configure_and_expand::closure.20378
25: 0x10167a90b - driver::phase_2_configure_and_expand::h7df30fbfe33501e73ta
26: 0x10166a436 - driver::compile_input::h1408964d65bdd4c4Gba
27: 0x101743bf7 - run_compiler::hc234a0e393bd73edZbc
28: 0x101741071 - thunk::F.Invoke<A, R>::invoke::h15756873051927943851
29: 0x10173fcd0 - rt::unwind::try::try_fn::h4998921728403241693
30: 0x10508ae09 - rust_try_inner
31: 0x10508adf6 - rust_try
32: 0x101740435 - thunk::F.Invoke<A, R>::invoke::h14944404643238507248
33: 0x104ffcc83 - sys::thread::thread_start::h384864084e567330e4G
34: 0x7fff8e031268 - _pthread_body
35: 0x7fff8e0311e5 - _pthread_body

Issue 2:
A simple malformed macro makes the compiler crash.

Code:

macro_rules! code_block {
$c:block => $c
}

Playpen error:

<anon>:1:1: 3:2 error: internal compiler error: wrong-structured lhs for follow check (didn't find a TtDelimited or TtSequence)
<anon>:1 macro_rules! code_block {
<anon>:2 $c:block => $c
<anon>:3 }
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:130

Playpen: http://is.gd/COoZe7