<p dir="auto">The compiler appears to crash when fed this invalid syntax.</p>
<p dir="auto">I tried this code:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="fn main() {
    let a = [];
}"><pre class="notranslate"><code class="notranslate">fn main() {
    let a = [];
}
</code></pre></div>
<p dir="auto">I expected to see a syntax error, but instead I got this trace:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="e0309.rs:2:13: 2:15 error: internal compiler error: cat_expr Errd
e0309.rs:2     let a = [];
                       ^~
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&lt;Any&gt;', /home/rustbuild/src/rust-buildbot/slave/beta-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:130
"><pre class="notranslate"><code class="notranslate">e0309.rs:2:13: 2:15 error: internal compiler error: cat_expr Errd
e0309.rs:2     let a = [];
                       ^~
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&lt;Any&gt;', /home/rustbuild/src/rust-buildbot/slave/beta-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:130

</code></pre></div>
<p dir="auto">Backtrace is this:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="stack backtrace:
   1:     0x7efbf74743c8 - sys::backtrace::write::h179e141147f9ee14IJC
   2:     0x7efbf749f770 - panicking::on_panic::h6aa569d33389f0cfsXI
   3:     0x7efbf73d74a3 - rt::unwind::begin_unwind_inner::h082f07869f4b9731ACI
   4:     0x7efbf479d04d - rt::unwind::begin_unwind::h13428428822164950735
   5:     0x7efbf479cff3 - diagnostic::SpanHandler::span_bug::he82cb6427e6a50a8jnB
   6:     0x7efbf503eb63 - session::Session::span_bug::h460607360e8bf7cc5Xq
   7:     0x7efbf6100d0d - check::regionck::visit_expr::hfc7cf3e25c050a92PJd
   8:     0x7efbf610183a - check::regionck::visit_local::h3c0931e616562244UGd
   9:     0x7efbf60fbd05 - check::regionck::Rcx&lt;'a, 'tcx&gt;::visit_fn_body::hd4da730c0cf65ac9amd
  10:     0x7efbf6196b91 - check::check_bare_fn::hb43e600383cf2ee2UQn
  11:     0x7efbf6190674 - check::check_item::h77d9b4d4612f23cfF9n
  12:     0x7efbf6268a96 - check_crate::closure.36300
  13:     0x7efbf6262e73 - check_crate::h4b0848761f18a2bcbwC
  14:     0x7efbf7af35cd - driver::phase_3_run_analysis_passes::hf7cad4098b28ceb1gGa
  15:     0x7efbf7ad7425 - driver::compile_input::h7c62c2870ff901f6Qba
  16:     0x7efbf7b8ea25 - run_compiler::hc815b49ce638c28eV4b
  17:     0x7efbf7b8c33d - boxed::F.FnBox&lt;A&gt;::call_box::h4290333406520961126
  18:     0x7efbf7b8b879 - rt::unwind::try::try_fn::h13999576404798567721
  19:     0x7efbf751bc68 - rust_try_inner
  20:     0x7efbf751bc55 - rust_try
  21:     0x7efbf7b8bb4b - boxed::F.FnBox&lt;A&gt;::call_box::h14489442628055152240
  22:     0x7efbf748a781 - sys::thread::create::thread_start::h02b7da32b4d7a4aaExH
  23:     0x7efbf127b373 - start_thread
  24:     0x7efbf704a27c - __clone
  25:                0x0 - &lt;unknown&gt;
"><pre class="notranslate"><code class="notranslate">stack backtrace:
   1:     0x7efbf74743c8 - sys::backtrace::write::h179e141147f9ee14IJC
   2:     0x7efbf749f770 - panicking::on_panic::h6aa569d33389f0cfsXI
   3:     0x7efbf73d74a3 - rt::unwind::begin_unwind_inner::h082f07869f4b9731ACI
   4:     0x7efbf479d04d - rt::unwind::begin_unwind::h13428428822164950735
   5:     0x7efbf479cff3 - diagnostic::SpanHandler::span_bug::he82cb6427e6a50a8jnB
   6:     0x7efbf503eb63 - session::Session::span_bug::h460607360e8bf7cc5Xq
   7:     0x7efbf6100d0d - check::regionck::visit_expr::hfc7cf3e25c050a92PJd
   8:     0x7efbf610183a - check::regionck::visit_local::h3c0931e616562244UGd
   9:     0x7efbf60fbd05 - check::regionck::Rcx&lt;'a, 'tcx&gt;::visit_fn_body::hd4da730c0cf65ac9amd
  10:     0x7efbf6196b91 - check::check_bare_fn::hb43e600383cf2ee2UQn
  11:     0x7efbf6190674 - check::check_item::h77d9b4d4612f23cfF9n
  12:     0x7efbf6268a96 - check_crate::closure.36300
  13:     0x7efbf6262e73 - check_crate::h4b0848761f18a2bcbwC
  14:     0x7efbf7af35cd - driver::phase_3_run_analysis_passes::hf7cad4098b28ceb1gGa
  15:     0x7efbf7ad7425 - driver::compile_input::h7c62c2870ff901f6Qba
  16:     0x7efbf7b8ea25 - run_compiler::hc815b49ce638c28eV4b
  17:     0x7efbf7b8c33d - boxed::F.FnBox&lt;A&gt;::call_box::h4290333406520961126
  18:     0x7efbf7b8b879 - rt::unwind::try::try_fn::h13999576404798567721
  19:     0x7efbf751bc68 - rust_try_inner
  20:     0x7efbf751bc55 - rust_try
  21:     0x7efbf7b8bb4b - boxed::F.FnBox&lt;A&gt;::call_box::h14489442628055152240
  22:     0x7efbf748a781 - sys::thread::create::thread_start::h02b7da32b4d7a4aaExH
  23:     0x7efbf127b373 - start_thread
  24:     0x7efbf704a27c - __clone
  25:                0x0 - &lt;unknown&gt;

</code></pre></div>
<p dir="auto">Test case:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="fn main() { []; }"><pre class="notranslate"><code class="notranslate">fn main() { []; }
</code></pre></div>
<p dir="auto">Output:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ 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&lt;Any&gt;', /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&lt;'a, 'tcx&gt;::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&lt;A, R&gt;::invoke::h12673221910893163557
  17:         0xcc752610 - rt::unwind::try::try_fn::h15130568597725528481
  18:         0xcc0bd740 - rust_try_inner
  19:         0xcc0bd730 - rust_try
  20:         0xcc752910 - thunk::F.Invoke&lt;A, R&gt;::invoke::h3924406537784056782
  21:         0xcc03d990 - sys::thread::thread_start::h3734be2229bd3edegEE
  22:         0xc5f650c0 - start_thread
  23:         0xcbc0a449 - __clone
  24:                0x0 - &lt;unknown&gt;"><pre class="notranslate"><code class="notranslate">$ 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&lt;Any&gt;', /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&lt;'a, 'tcx&gt;::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&lt;A, R&gt;::invoke::h12673221910893163557
  17:         0xcc752610 - rt::unwind::try::try_fn::h15130568597725528481
  18:         0xcc0bd740 - rust_try_inner
  19:         0xcc0bd730 - rust_try
  20:         0xcc752910 - thunk::F.Invoke&lt;A, R&gt;::invoke::h3924406537784056782
  21:         0xcc03d990 - sys::thread::thread_start::h3734be2229bd3edegEE
  22:         0xc5f650c0 - start_thread
  23:         0xcbc0a449 - __clone
  24:                0x0 - &lt;unknown&gt;
</code></pre></div>
<p dir="auto">Compiler version:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="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"><pre class="notranslate"><code class="notranslate">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
</code></pre></div>
<p dir="auto">I modified the test case in <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="59341575" data-permission-text="Title is private" data-url="https://github.com/rust-lang/rust/issues/22894" data-hovercard-type="issue" data-hovercard-url="/rust-lang/rust/issues/22894/hovercard" href="https://github.com/rust-lang/rust/issues/22894">#22894</a> by moving the <code class="notranslate">&amp;*""</code> into <code class="notranslate">fn main()</code>, and I saw the same ICE.  I then changed the <code class="notranslate">""</code> to the similar <code class="notranslate">&amp;[]</code>, and I saw an ICE with a different error message and a different stack trace (e.g. phase 3 instead of phase 4).  The <code class="notranslate">&amp;</code> and <code class="notranslate">*</code> are unnecessary.</p>
<p dir="auto">I also see the <code class="notranslate">cat_expr Errd</code> message in <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="56894364" data-permission-text="Title is private" data-url="https://github.com/rust-lang/rust/issues/22037" data-hovercard-type="issue" data-hovercard-url="/rust-lang/rust/issues/22037/hovercard" href="https://github.com/rust-lang/rust/issues/22037">#22037</a>, but there are differences -- this issue happens in phase 3 rather than 4, and there is no "fictitious type" message.</p>