<p dir="auto">If you look at the <code class="notranslate">iter</code> branch in the <code class="notranslate">nikomatsakis/rust</code> repo, you will find that it fails in stage0.  I debugged this a bit by building a vanilla compiler in another repoistory and managed to trace it as far as a failure in <code class="notranslate">make_mono_id()</code> because the call to <code class="notranslate">map2()</code> that is processing bounds and substs receives a bounds vec of length 1 and a substs vec of length 2.  This seems to occur with the call to <code class="notranslate">vec::flatmap()</code> that occurs in librustsyntax processing the attributes.  I tried to narrow down the test to a smaller test file but was unable to find anything that reproduced the error other than the full rustc.</p>
<p dir="auto"><a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/marijnh/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/marijnh">@marijnh</a> if you wouldn't mind taking a look and let me know if something jumps out at you, I would appreciate it.</p>
<p dir="auto">Compiling following source, rustc dumps core with error messages.</p>
<div class="highlight highlight-source-rust notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="import iter::*;

fn main() {
    let range = bind uint::range(0u, 1000u, _);
    let filt  = bind iter::filter(range, {|&amp;&amp;n: uint| n % 3u != 0u &amp;&amp; n % 5u != 0u }, _);
    let sum   = iter::foldl(filt, 0u) {|accum, &amp;&amp;n: uint| accum + n };

    io::println(#fmt(&quot;%u&quot;, sum));
}"><pre class="notranslate">import iter<span class="pl-kos">::</span><span class="pl-c1">*</span><span class="pl-kos">;</span>

<span class="pl-k">fn</span> <span class="pl-en">main</span><span class="pl-kos">(</span><span class="pl-kos">)</span> <span class="pl-kos">{</span>
    <span class="pl-k">let</span> range = bind uint<span class="pl-kos">::</span><span class="pl-en">range</span><span class="pl-kos">(</span><span class="pl-c1">0</span>u<span class="pl-kos">,</span> <span class="pl-c1">1000</span>u<span class="pl-kos">,</span> _<span class="pl-kos">)</span><span class="pl-kos">;</span>
    <span class="pl-k">let</span> filt  = bind iter<span class="pl-kos">::</span><span class="pl-en">filter</span><span class="pl-kos">(</span>range<span class="pl-kos">,</span> <span class="pl-kos">{</span>|<span class="pl-c1">&amp;</span><span class="pl-c1">&amp;</span>n<span class="pl-kos">:</span> <span class="pl-smi">uint</span>| n % <span class="pl-c1">3</span>u != <span class="pl-c1">0</span>u &amp;&amp; n % <span class="pl-c1">5</span>u != <span class="pl-c1">0</span>u <span class="pl-kos">}</span><span class="pl-kos">,</span> _<span class="pl-kos">)</span><span class="pl-kos">;</span>
    <span class="pl-k">let</span> sum   = iter<span class="pl-kos">::</span><span class="pl-en">foldl</span><span class="pl-kos">(</span>filt<span class="pl-kos">,</span> <span class="pl-c1">0</span>u<span class="pl-kos">)</span><span class="pl-kos"></span> <span class="pl-kos">{</span>|accum<span class="pl-kos">,</span> <span class="pl-c1">&amp;</span><span class="pl-c1">&amp;</span>n<span class="pl-kos">:</span> <span class="pl-smi">uint</span>| accum + n <span class="pl-kos">}</span><span class="pl-kos">;</span>

    io<span class="pl-kos">::</span><span class="pl-en">println</span><span class="pl-kos">(</span>#<span class="pl-en">fmt</span><span class="pl-kos">(</span><span class="pl-s">"%u"</span><span class="pl-kos">,</span> sum<span class="pl-kos">)</span><span class="pl-kos">)</span><span class="pl-kos">;</span>
<span class="pl-kos">}</span></pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ rustc foo.rs
error: internal compiler error unexpected failure
note: The compiler hit an unexpected failure path. This is a bug. Try running with RUST_LOG=rustc=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
leaked memory in rust main loop (1 objects)
Assertion failed: (false), function ~memory_region, file ../src/rt/memory_region.cpp, line 172.
zsh: abort (core dumped)  rustc foo.rs"><pre class="notranslate"><code class="notranslate">$ rustc foo.rs
error: internal compiler error unexpected failure
note: The compiler hit an unexpected failure path. This is a bug. Try running with RUST_LOG=rustc=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
leaked memory in rust main loop (1 objects)
Assertion failed: (false), function ~memory_region, file ../src/rt/memory_region.cpp, line 172.
zsh: abort (core dumped)  rustc foo.rs
</code></pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ RUST_LOG=rustc=0,::rt::backtrace rustc foo.rs
rust: upcall fail 'explicit failure', ../src/rustc/rustc.rc:1
0x802197914 &lt;_ZN9rust_task15call_on_c_stackEPvS0_+148&gt; at /usr/local/bin/../lib/librustrt.so                                                                                                                                                                                     @&amp;N0x8021986ed &lt;upcall_fail+141&gt; at /usr/local/bin/../lib/librustrt.so
�\0x8018dc7de &lt;_ZN6middle2ty16lookup_item_type17_f614ca4c755aeba7202E+846&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                              �0x8018dbde1 &lt;_ZN6middle5trans4base12make_mono_id17_f2ebd2e452b417a6202E+257&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018c7568 &lt;_ZN6middle5trans4base14monomorphic_fn17_77d7254b93f76bc2202E+472&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018ee718 &lt;_ZN6middle5trans4base20lval_static_fn_inner17_f1ee6671c5727412202E+488&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
��0x80193daf7 &lt;_ZN6middle5trans4impl26trans_monomorphized_callee17_397545b5c646b954202E+999&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0f06 &lt;_ZN6middle5trans4impl19trans_method_callee17_6b1587f014518324202E+470&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
@@�0x8018f61c4 &lt;_ZN6middle5trans4base12trans_callee17_ed5afa7c661e67af202E+484&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801901487 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+583&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190141c &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+476&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0c96 &lt;_ZN6middle5trans4base16trans_call_inner17_e4ab2a25f8e56a47202E+390&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                     @�0x8018fdf12 &lt;_ZN6middle5trans4base10trans_call17_f759ff632d924a7a202E+258&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d1c83 &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+3187&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190a00f &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1103&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d9fbf &lt;_ZN6middle5trans4base11trans_block17_5d538f556387313f202E+303&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190d9ed &lt;_ZN6middle5trans4base13trans_closure17_f68d7bace7a25795202E+1197&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018e636d &lt;_ZN6middle5trans4base8trans_fn17_30737349273ebd1b202E+461&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                0x8018c8122 &lt;_ZN6middle5trans4base14monomorphic_fn17_77d7254b93f76bc2202E+3474&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
@�0x8018ee718 &lt;_ZN6middle5trans4base20lval_static_fn_inner17_f1ee6671c5727412202E+488&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
��0x8018ee272 &lt;_ZN6middle5trans4base14lval_static_fn17_97c1e6b66444e182202E+418&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018f472d &lt;_ZN6middle5trans4base9trans_var17_7c5ea379277185b4202E+205&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                �0x8018f4556 &lt;_ZN6middle5trans4base10trans_path17_c674ef35f426c629202E+198&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018f608b &lt;_ZN6middle5trans4base12trans_callee17_ed5afa7c661e67af202E+171&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801901487 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+583&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8019012e7 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+167&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0c96 &lt;_ZN6middle5trans4base16trans_call_inner17_e4ab2a25f8e56a47202E+390&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                     @��0x8018fdf12 &lt;_ZN6middle5trans4base10trans_call17_f759ff632d924a7a202E+258&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d1c83 &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+3187&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d103c &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8019083ad &lt;_ZN6middle5trans4base10init_local17_17d57dd23a569e54202E+333&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x80190a1b5 &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1525&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190a0ab &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1259&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d9fbf &lt;_ZN6middle5trans4base11trans_block17_5d538f556387313f202E+303&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190d9ed &lt;_ZN6middle5trans4base13trans_closure17_f68d7bace7a25795202E+1197&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018e636d &lt;_ZN6middle5trans4base8trans_fn17_30737349273ebd1b202E+461&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                0x8018ec8bb &lt;_ZN6middle5trans4base10trans_item17_28e452dae21c3667202E+1883&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801911e94 &lt;_ZN6middle5trans4base9trans_mod17_384418731efae2e8202E+260&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                               �0x80191dc28 &lt;_ZN6middle5trans4base11trans_crate17_6616cfe44b3b9bb3202E+4600&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80191ca5c &lt;_ZN6middle5trans4base11trans_crate17_6616cfe44b3b9bb3202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b6182c &lt;_ZN6driver6driver12compile_upto17_40784acf6e567faf202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                               0x403f6a &lt;_init+8218&gt; at /usr/local/bin/rustc
@0�0x407818 &lt;_rust_main+1464&gt; at /usr/local/bin/rustc                                                                                                                                                                                                                             �0x402f1c &lt;_init+4044&gt; at /usr/local/bin/rustc
@��0x406878 &lt;_init+18728&gt; at /usr/local/bin/rustc
@�0x80089e675 &lt;_ZN4task11get_task_id17_42c92e624d84fbbc202E+149&gt; at /usr/local/bin/../lib/libcore-d27e4777a53c3e50-0.2.so
�0x802196735 &lt;_Z18task_start_wrapperP10spawn_args+37&gt; at /usr/local/bin/../lib/librustrt.so
@`�error: internal compiler error unexpected failure
note: The compiler hit an unexpected failure path. This is a bug. Try running with RUST_LOG=rustc=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: upcall fail 'explicit failure', ../src/rustc/driver/rustc.rs:187
0x802197914 &lt;_ZN9rust_task15call_on_c_stackEPvS0_+148&gt; at /usr/local/bin/../lib/librustrt.so                                                                                                                                                                                     @cM0x8021986ed &lt;upcall_fail+141&gt; at /usr/local/bin/../lib/librustrt.so
�\0x406388 &lt;_init+17464&gt; at /usr/local/bin/rustc
�F0x407818 &lt;_rust_main+1464&gt; at /usr/local/bin/rustc                                                                                                                                                                                                                              �0x405cdc &lt;_init+15756&gt; at /usr/local/bin/rustc
�E0x802196735 &lt;_Z18task_start_wrapperP10spawn_args+37&gt; at /usr/local/bin/../lib/librustrt.so
@�Erust: domain main @0x80443a810 root task failed
leaked memory in rust main loop (1 objects)
Assertion failed: (false), function ~memory_region, file ../src/rt/memory_region.cpp, line 172.
zsh: abort (core dumped)  RUST_LOG=rustc=0,::rt::backtrace rustc foo.rs"><pre class="notranslate"><code class="notranslate">$ RUST_LOG=rustc=0,::rt::backtrace rustc foo.rs
rust: upcall fail 'explicit failure', ../src/rustc/rustc.rc:1
0x802197914 &lt;_ZN9rust_task15call_on_c_stackEPvS0_+148&gt; at /usr/local/bin/../lib/librustrt.so                                                                                                                                                                                     @&amp;N0x8021986ed &lt;upcall_fail+141&gt; at /usr/local/bin/../lib/librustrt.so
�\0x8018dc7de &lt;_ZN6middle2ty16lookup_item_type17_f614ca4c755aeba7202E+846&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                              �0x8018dbde1 &lt;_ZN6middle5trans4base12make_mono_id17_f2ebd2e452b417a6202E+257&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018c7568 &lt;_ZN6middle5trans4base14monomorphic_fn17_77d7254b93f76bc2202E+472&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018ee718 &lt;_ZN6middle5trans4base20lval_static_fn_inner17_f1ee6671c5727412202E+488&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
��0x80193daf7 &lt;_ZN6middle5trans4impl26trans_monomorphized_callee17_397545b5c646b954202E+999&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0f06 &lt;_ZN6middle5trans4impl19trans_method_callee17_6b1587f014518324202E+470&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
@@�0x8018f61c4 &lt;_ZN6middle5trans4base12trans_callee17_ed5afa7c661e67af202E+484&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801901487 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+583&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190141c &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+476&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0c96 &lt;_ZN6middle5trans4base16trans_call_inner17_e4ab2a25f8e56a47202E+390&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                     @�0x8018fdf12 &lt;_ZN6middle5trans4base10trans_call17_f759ff632d924a7a202E+258&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d1c83 &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+3187&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190a00f &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1103&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d9fbf &lt;_ZN6middle5trans4base11trans_block17_5d538f556387313f202E+303&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190d9ed &lt;_ZN6middle5trans4base13trans_closure17_f68d7bace7a25795202E+1197&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018e636d &lt;_ZN6middle5trans4base8trans_fn17_30737349273ebd1b202E+461&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                0x8018c8122 &lt;_ZN6middle5trans4base14monomorphic_fn17_77d7254b93f76bc2202E+3474&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
@�0x8018ee718 &lt;_ZN6middle5trans4base20lval_static_fn_inner17_f1ee6671c5727412202E+488&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
��0x8018ee272 &lt;_ZN6middle5trans4base14lval_static_fn17_97c1e6b66444e182202E+418&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018f472d &lt;_ZN6middle5trans4base9trans_var17_7c5ea379277185b4202E+205&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                �0x8018f4556 &lt;_ZN6middle5trans4base10trans_path17_c674ef35f426c629202E+198&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018f608b &lt;_ZN6middle5trans4base12trans_callee17_ed5afa7c661e67af202E+171&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801901487 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+583&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8019012e7 &lt;_ZN6middle5trans4base10with_scope17_13d2b9fa8bfa3e3f202E+167&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d0c96 &lt;_ZN6middle5trans4base16trans_call_inner17_e4ab2a25f8e56a47202E+390&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                     @��0x8018fdf12 &lt;_ZN6middle5trans4base10trans_call17_f759ff632d924a7a202E+258&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8018d1c83 &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+3187&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d103c &lt;_ZN6middle5trans4base10trans_expr17_2f49fb6e59efc0cc202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x8019083ad &lt;_ZN6middle5trans4base10init_local17_17d57dd23a569e54202E+333&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x80190a1b5 &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1525&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190a0ab &lt;_ZN6middle5trans4base10trans_stmt17_dda29e9b5a06725d202E+1259&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x8018d9fbf &lt;_ZN6middle5trans4base11trans_block17_5d538f556387313f202E+303&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80190d9ed &lt;_ZN6middle5trans4base13trans_closure17_f68d7bace7a25795202E+1197&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
0x8018e636d &lt;_ZN6middle5trans4base8trans_fn17_30737349273ebd1b202E+461&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                                0x8018ec8bb &lt;_ZN6middle5trans4base10trans_item17_28e452dae21c3667202E+1883&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801911e94 &lt;_ZN6middle5trans4base9trans_mod17_384418731efae2e8202E+260&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                               �0x80191dc28 &lt;_ZN6middle5trans4base11trans_crate17_6616cfe44b3b9bb3202E+4600&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x80191ca5c &lt;_ZN6middle5trans4base11trans_crate17_6616cfe44b3b9bb3202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�\0x801b7e11c &lt;_ZN3lib4llvm16section_iter_res4dtor17_3815581a5148d851202E+396&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so
�0x801b6182c &lt;_ZN6driver6driver12compile_upto17_40784acf6e567faf202E+44&gt; at /usr/local/bin/../lib/librustc-688fa7810161fd45-0.2.so                                                                                                                                               0x403f6a &lt;_init+8218&gt; at /usr/local/bin/rustc
@0�0x407818 &lt;_rust_main+1464&gt; at /usr/local/bin/rustc                                                                                                                                                                                                                             �0x402f1c &lt;_init+4044&gt; at /usr/local/bin/rustc
@��0x406878 &lt;_init+18728&gt; at /usr/local/bin/rustc
@�0x80089e675 &lt;_ZN4task11get_task_id17_42c92e624d84fbbc202E+149&gt; at /usr/local/bin/../lib/libcore-d27e4777a53c3e50-0.2.so
�0x802196735 &lt;_Z18task_start_wrapperP10spawn_args+37&gt; at /usr/local/bin/../lib/librustrt.so
@`�error: internal compiler error unexpected failure
note: The compiler hit an unexpected failure path. This is a bug. Try running with RUST_LOG=rustc=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: upcall fail 'explicit failure', ../src/rustc/driver/rustc.rs:187
0x802197914 &lt;_ZN9rust_task15call_on_c_stackEPvS0_+148&gt; at /usr/local/bin/../lib/librustrt.so                                                                                                                                                                                     @cM0x8021986ed &lt;upcall_fail+141&gt; at /usr/local/bin/../lib/librustrt.so
�\0x406388 &lt;_init+17464&gt; at /usr/local/bin/rustc
�F0x407818 &lt;_rust_main+1464&gt; at /usr/local/bin/rustc                                                                                                                                                                                                                              �0x405cdc &lt;_init+15756&gt; at /usr/local/bin/rustc
�E0x802196735 &lt;_Z18task_start_wrapperP10spawn_args+37&gt; at /usr/local/bin/../lib/librustrt.so
@�Erust: domain main @0x80443a810 root task failed
leaked memory in rust main loop (1 objects)
Assertion failed: (false), function ~memory_region, file ../src/rt/memory_region.cpp, line 172.
zsh: abort (core dumped)  RUST_LOG=rustc=0,::rt::backtrace rustc foo.rs
</code></pre></div>