<p dir="auto">Versions:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ rustc --version
rustc 0.11.0-pre (11aa731 2014-05-23 14:56:24 -0700)
host: x86_64-unknown-linux-gnu
$ uname -a
Linux test 3.13-1-amd64 #1 SMP Debian 3.13.10-1 (2014-04-15) x86_64 GNU/Linux"><pre class="notranslate"><code class="notranslate">$ rustc --version
rustc 0.11.0-pre (11aa731 2014-05-23 14:56:24 -0700)
host: x86_64-unknown-linux-gnu
$ uname -a
Linux test 3.13-1-amd64 #1 SMP Debian 3.13.10-1 (2014-04-15) x86_64 GNU/Linux
</code></pre></div>
<p dir="auto">Code to reproduce the ICE:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="fn test(a: &amp;Vec&lt;u8&gt;) {
  print!(&quot;{}&quot;, a.len());
}

pub fn main() {
  let data = vec!();
  test(&amp;data);
}"><pre class="notranslate"><code class="notranslate">fn test(a: &amp;Vec&lt;u8&gt;) {
  print!("{}", a.len());
}

pub fn main() {
  let data = vec!();
  test(&amp;data);
}
</code></pre></div>
<p dir="auto">Compilation output (assuming code is in test.rs):</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ RUST_BACKTRACE=1 rustc -g test.rs 
test.rs:1:1: 1:1 error: internal compiler error: debuginfo::set_members_of_composite_type() - Already completed forward declaration re-encountered.
test.rs:1 fn test(a: &amp;Vec&lt;u8&gt;) {
          ^
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box&lt;Any&gt;', /tmp/rust/src/libsyntax/diagnostic.rs:106
stack backtrace:
   1:     0x7f6088d547b0 - rt::backtrace::imp::write::h91511e92fbebf61dJSy::v0.11.0.pre
   2:     0x7f6088cd4900 - rt::unwind::begin_unwind_inner::hc6a3eade6662bd0cRsy::v0.11.0.pre
   3:     0x7f60876d4cb0 - rt::unwind::begin_unwind::h14424584252031250192::v0.11.0.pre
   4:     0x7f60876d4be0 - diagnostic::SpanHandler::span_bug::hbb40ab336641d6bcoUb::v0.11.0.pre
   5:     0x7f6089823d00 - driver::session::Session::span_bug::hbc579a9c1652b4dcWQk::v0.11.0.pre
   6:     0x7f608992a540 - middle::trans::debuginfo::set_members_of_composite_type::ha39f45d6f9c0cb39stB::v0.11.0.pre
   7:     0x7f6089928e50 - middle::trans::debuginfo::RecursiveTypeDescription::finalize::h0fe21aef99d3e1c0I8A::v0.11.0.pre
   8:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
   9:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
  10:     0x7f6089932ee0 - middle::trans::debuginfo::vec_slice_metadata::h5b5525bc44b17f0dCKB::v0.11.0.pre
  11:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
  12:     0x7f6089921730 - middle::trans::debuginfo::declare_local::h3f3d7f3d971eec2bBLA::v0.11.0.pre
  13:     0x7f6089920a10 - middle::trans::debuginfo::create_local_var_metadata::closure.63979
  14:     0x7f6089d15cc0 - middle::pat_util::pat_bindings::closure.76254
  15:     0x7f608771bcd0 - ast_util::walk_pat::h73d09c5bbd81fc4aBNv::v0.11.0.pre
  16:     0x7f60897fbbd0 - middle::trans::controlflow::trans_stmt::hebe30cb187b2a930B2a::v0.11.0.pre
  17:     0x7f60897fdcb0 - middle::trans::controlflow::trans_block::hc64c9e56aa358790I7a::v0.11.0.pre
  18:     0x7f608983e730 - middle::trans::expr::trans_rvalue_dps_unadjusted::h9c3393158ea8f3e88hf::v0.11.0.pre
  19:     0x7f60897fd5a0 - middle::trans::expr::trans_into::h6b67f346e56d2aaagse::v0.11.0.pre
  20:     0x7f60898ee990 - middle::trans::_match::trans_match_inner::he680468c7e8edd8bk7s::v0.11.0.pre
  21:     0x7f608983e730 - middle::trans::expr::trans_rvalue_dps_unadjusted::h9c3393158ea8f3e88hf::v0.11.0.pre
  22:     0x7f60897fd5a0 - middle::trans::expr::trans_into::h6b67f346e56d2aaagse::v0.11.0.pre
  23:     0x7f60897fc780 - middle::trans::controlflow::trans_stmt_semi::h95ab3162fcdb8669P6a::v0.11.0.pre
  24:     0x7f60897fbbd0 - middle::trans::controlflow::trans_stmt::hebe30cb187b2a930B2a::v0.11.0.pre
  25:     0x7f60897fdcb0 - middle::trans::controlflow::trans_block::hc64c9e56aa358790I7a::v0.11.0.pre
  26:     0x7f60898bb6c0 - middle::trans::base::trans_closure::hd893efe09250c8a3Php::v0.11.0.pre
  27:     0x7f60897c6df0 - middle::trans::base::trans_fn::h02396ab03da5196a5pp::v0.11.0.pre
  28:     0x7f60897c1110 - middle::trans::base::trans_item::h4715e8b19ebc5b3eCBp::v0.11.0.pre
  29:     0x7f60898ca380 - middle::trans::base::trans_crate::h97a887f98edb0d3dpoq::v0.11.0.pre
  30:     0x7f608a0a1430 - driver::driver::phase_4_translate_to_llvm::h29f793bbb3691a0c01j::v0.11.0.pre
  31:     0x7f608a096b40 - driver::driver::compile_input::hf7a007097756b7ceBJj::v0.11.0.pre
  32:     0x7f608a160180 - driver::run_compiler::h6c18401fac048ee4umm::v0.11.0.pre
  33:     0x7f608a1600a0 - driver::main_args::closure.93487
  34:     0x7f608a174b50 - driver::monitor::closure.94559
  35:     0x7f608a170070 - task::TaskBuilder::try::closure.94322
  36:     0x7f608926c970 - task::spawn_opts::closure.7801
  37:     0x7f6088d4e6e0 - rt::task::Task::run::closure.25256
  38:     0x7f6088dadab0 - rust_try
  39:     0x7f6088d4e630 - rt::task::Task::run::h9a36fd2f34280279uhw::v0.11.0.pre
  40:     0x7f608926c720 - task::spawn_opts::closure.7774
  41:     0x7f6088d52b60 - rt::thread::thread_start::h057270a612f2c73020w::v0.11.0.pre
  42:     0x7f60867fdfa0 - start_thread
  43:     0x7f608899cbe9 - __clone
  44:                0x0 - &lt;unknown&gt;

$ "><pre class="notranslate"><code class="notranslate">$ RUST_BACKTRACE=1 rustc -g test.rs 
test.rs:1:1: 1:1 error: internal compiler error: debuginfo::set_members_of_composite_type() - Already completed forward declaration re-encountered.
test.rs:1 fn test(a: &amp;Vec&lt;u8&gt;) {
          ^
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box&lt;Any&gt;', /tmp/rust/src/libsyntax/diagnostic.rs:106
stack backtrace:
   1:     0x7f6088d547b0 - rt::backtrace::imp::write::h91511e92fbebf61dJSy::v0.11.0.pre
   2:     0x7f6088cd4900 - rt::unwind::begin_unwind_inner::hc6a3eade6662bd0cRsy::v0.11.0.pre
   3:     0x7f60876d4cb0 - rt::unwind::begin_unwind::h14424584252031250192::v0.11.0.pre
   4:     0x7f60876d4be0 - diagnostic::SpanHandler::span_bug::hbb40ab336641d6bcoUb::v0.11.0.pre
   5:     0x7f6089823d00 - driver::session::Session::span_bug::hbc579a9c1652b4dcWQk::v0.11.0.pre
   6:     0x7f608992a540 - middle::trans::debuginfo::set_members_of_composite_type::ha39f45d6f9c0cb39stB::v0.11.0.pre
   7:     0x7f6089928e50 - middle::trans::debuginfo::RecursiveTypeDescription::finalize::h0fe21aef99d3e1c0I8A::v0.11.0.pre
   8:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
   9:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
  10:     0x7f6089932ee0 - middle::trans::debuginfo::vec_slice_metadata::h5b5525bc44b17f0dCKB::v0.11.0.pre
  11:     0x7f608991d440 - middle::trans::debuginfo::type_metadata::h98963d42bb116c2fCVB::v0.11.0.pre
  12:     0x7f6089921730 - middle::trans::debuginfo::declare_local::h3f3d7f3d971eec2bBLA::v0.11.0.pre
  13:     0x7f6089920a10 - middle::trans::debuginfo::create_local_var_metadata::closure.63979
  14:     0x7f6089d15cc0 - middle::pat_util::pat_bindings::closure.76254
  15:     0x7f608771bcd0 - ast_util::walk_pat::h73d09c5bbd81fc4aBNv::v0.11.0.pre
  16:     0x7f60897fbbd0 - middle::trans::controlflow::trans_stmt::hebe30cb187b2a930B2a::v0.11.0.pre
  17:     0x7f60897fdcb0 - middle::trans::controlflow::trans_block::hc64c9e56aa358790I7a::v0.11.0.pre
  18:     0x7f608983e730 - middle::trans::expr::trans_rvalue_dps_unadjusted::h9c3393158ea8f3e88hf::v0.11.0.pre
  19:     0x7f60897fd5a0 - middle::trans::expr::trans_into::h6b67f346e56d2aaagse::v0.11.0.pre
  20:     0x7f60898ee990 - middle::trans::_match::trans_match_inner::he680468c7e8edd8bk7s::v0.11.0.pre
  21:     0x7f608983e730 - middle::trans::expr::trans_rvalue_dps_unadjusted::h9c3393158ea8f3e88hf::v0.11.0.pre
  22:     0x7f60897fd5a0 - middle::trans::expr::trans_into::h6b67f346e56d2aaagse::v0.11.0.pre
  23:     0x7f60897fc780 - middle::trans::controlflow::trans_stmt_semi::h95ab3162fcdb8669P6a::v0.11.0.pre
  24:     0x7f60897fbbd0 - middle::trans::controlflow::trans_stmt::hebe30cb187b2a930B2a::v0.11.0.pre
  25:     0x7f60897fdcb0 - middle::trans::controlflow::trans_block::hc64c9e56aa358790I7a::v0.11.0.pre
  26:     0x7f60898bb6c0 - middle::trans::base::trans_closure::hd893efe09250c8a3Php::v0.11.0.pre
  27:     0x7f60897c6df0 - middle::trans::base::trans_fn::h02396ab03da5196a5pp::v0.11.0.pre
  28:     0x7f60897c1110 - middle::trans::base::trans_item::h4715e8b19ebc5b3eCBp::v0.11.0.pre
  29:     0x7f60898ca380 - middle::trans::base::trans_crate::h97a887f98edb0d3dpoq::v0.11.0.pre
  30:     0x7f608a0a1430 - driver::driver::phase_4_translate_to_llvm::h29f793bbb3691a0c01j::v0.11.0.pre
  31:     0x7f608a096b40 - driver::driver::compile_input::hf7a007097756b7ceBJj::v0.11.0.pre
  32:     0x7f608a160180 - driver::run_compiler::h6c18401fac048ee4umm::v0.11.0.pre
  33:     0x7f608a1600a0 - driver::main_args::closure.93487
  34:     0x7f608a174b50 - driver::monitor::closure.94559
  35:     0x7f608a170070 - task::TaskBuilder::try::closure.94322
  36:     0x7f608926c970 - task::spawn_opts::closure.7801
  37:     0x7f6088d4e6e0 - rt::task::Task::run::closure.25256
  38:     0x7f6088dadab0 - rust_try
  39:     0x7f6088d4e630 - rt::task::Task::run::h9a36fd2f34280279uhw::v0.11.0.pre
  40:     0x7f608926c720 - task::spawn_opts::closure.7774
  41:     0x7f6088d52b60 - rt::thread::thread_start::h057270a612f2c73020w::v0.11.0.pre
  42:     0x7f60867fdfa0 - start_thread
  43:     0x7f608899cbe9 - __clone
  44:                0x0 - &lt;unknown&gt;

$ 
</code></pre></div>
<p dir="auto">This might be related to issue <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="34216777" data-permission-text="Title is private" data-url="https://github.com/rust-lang/rust/issues/14385" data-hovercard-type="issue" data-hovercard-url="/rust-lang/rust/issues/14385/hovercard" href="https://github.com/rust-lang/rust/issues/14385">#14385</a>.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="servo/src/support/glfw/glfw-rs/src/lib/lib.rs:1:1: 1:1 error: internal compiler error: debuginfo::set_members_of_composite_type() - Already completed forward declaration re-encountered.
...
task 'rustc' failed at 'Box&lt;Any&gt;', /home/travis/build/Manishearth/rust/src/libsyntax/diagnostic.rs:99
"><pre class="notranslate"><code class="notranslate">servo/src/support/glfw/glfw-rs/src/lib/lib.rs:1:1: 1:1 error: internal compiler error: debuginfo::set_members_of_composite_type() - Already completed forward declaration re-encountered.
...
task 'rustc' failed at 'Box&lt;Any&gt;', /home/travis/build/Manishearth/rust/src/libsyntax/diagnostic.rs:99

</code></pre></div>
<p dir="auto">This seems similar to the already-fixed issue <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="24602641" data-permission-text="Title is private" data-url="https://github.com/rust-lang/rust/issues/11083" data-hovercard-type="issue" data-hovercard-url="/rust-lang/rust/issues/11083/hovercard" href="https://github.com/rust-lang/rust/issues/11083">#11083</a></p>
<p dir="auto">Note: I'm using a Rust snapshot that I generated on a different system (with the same DEFAULT_TARGET as mine)</p>
<p dir="auto">cc <a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/michaelwoerister/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/michaelwoerister">@michaelwoerister</a></p>