ICE with some sort of lifetimes

[o11c]

#![crate_type="lib"]
use std::io::BufReader;
use std::io::BufferedReader;
use std::io::File;
use std::io::IoResult;

struct Lexer<R: Reader>
{
    reader: BufferedReader<R>,
}

impl<R: Reader> Lexer<R>
{
    pub fn new_from_reader(r: R) -> Lexer<R>
    {
        Lexer{reader: BufferedReader::new(r)}
    }

    pub fn new_from_file(p: Path) -> IoResult<Lexer<File>>
    {
        Ok(Lexer::new_from_reader(try!(File::open(&p))))
    }

    pub fn new_from_str<'a>(s: &'a str) -> Lexer<BufReader<'a>>
    {
        Lexer::new_from_reader(BufReader::new(s.as_bytes()))
    }
}

Backtrace with PPA package 201409090406325808atrusty

bug.rs:24:5: 27:6 error: internal compiler error: cannot relate bound region: ReLateBound(70, BrNamed(syntax::ast::DefId{krate: 0u32, node: 71u32}, 'a)) <= ReInfer(0)
bug.rs:24     pub fn new_from_str<'a>(s: &'a str) -> Lexer<BufReader<'a>>
bug.rs:25     {
bug.rs:26         Lexer::new_from_reader(BufReader::new(s.as_bytes()))
bug.rs:27     }
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<Any>', /build/buildd/rust-nightly-201409090406~325808a~trusty/src/libsyntax/ast_util.rs:776

stack backtrace:
   1:     0x7f65fac5be80 - rt::backtrace::imp::write::h533ddb797a731700F8q
   2:     0x7f65fac5f020 - <unknown>
   3:     0x7f65fb43ccf0 - unwind::begin_unwind_inner::hc34a69a089e2120362d
   4:     0x7f65f96b30a0 - <unknown>
   5:     0x7f65f96b2ff0 - diagnostic::SpanHandler::span_bug::h09f788e188c9de8eYaF
   6:     0x7f65fb9f6be0 - driver::session::Session::span_bug::h42560c2b6afa10c21IE
   7:     0x7f65fbf21230 - middle::typeck::infer::region_inference::RegionVarBindings<'a, 'tcx>::make_subregion::h5078aeae044bd102jUc
   8:     0x7f65fbedbb20 - middle::typeck::infer::region_inference::RegionVarBindings<'a, 'tcx>::make_eqregion::h38d6d0176e9c74d8ITc
   9:     0x7f65fbedb790 - middle::typeck::infer::equate::Equate<'f, 'tcx>.Combine<'tcx>::regions::h36b30ff408e85c192s8
  10:     0x7f65fbedece0 - <unknown>
  11:     0x7f65fbed7ea0 - middle::typeck::infer::equate::Equate<'f, 'tcx>.Combine<'tcx>::tys::h7c47bfb33ed92bc5cB8
  12:     0x7f65fbf3d070 - <unknown>
  13:     0x7f65fbf3bd30 - <unknown>
  14:     0x7f65fc215770 - <unknown>
  15:     0x7f65fbed1f90 - <unknown>
  16:     0x7f65fbdc6f00 - middle::typeck::infer::mk_eqty::h5e3021312e17de70j9h
  17:     0x7f65fbdc1c40 - <unknown>
  18:     0x7f65fbdbf1b0 - <unknown>
  19:     0x7f65fbd8bcf0 - middle::ty::each_bound_trait_and_supertraits::h0936baf25c23be8cAYK
  20:     0x7f65fbdbeb10 - <unknown>
  21:     0x7f65fbdbc990 - <unknown>
  22:     0x7f65fbb095a0 - middle::typeck::check::vtable::check_param_bounds::h0c5aea9dc65452e4exP
  23:     0x7f65fbb09290 - <unknown>
  24:     0x7f65fbd87e00 - <unknown>
  25:     0x7f65fbaf04f0 - middle::ty::maybe_walk_ty::h8639be883bfdfd23jcH
  26:     0x7f65fbaf04f0 - middle::ty::maybe_walk_ty::h8639be883bfdfd23jcH
  27:     0x7f65fbb01550 - <unknown>
  28:     0x7f65fbaf8220 - <unknown>
  29:     0x7f65fbb01e30 - <unknown>
  30:     0x7f65fbaf9500 - <unknown>
  31:     0x7f65fbafd220 - middle::kind::check_crate::h6d1f43c98c1bfceb4ex
  32:     0x7f65fb844140 - <unknown>
  33:     0x7f65fc107280 - driver::driver::phase_3_run_analysis_passes::hff23c66244c4d7416YD
  34:     0x7f65fc102760 - driver::driver::compile_input::h8d4e8c34e761a31dJKD
  35:     0x7f65fc1946c0 - <unknown>
  36:     0x7f65fc1945b0 - <unknown>
  37:     0x7f65fb85cf60 - <unknown>
  38:     0x7f65fb85cd60 - <unknown>
  39:     0x7f65fcc51c60 - <unknown>
  40:     0x7f65fb492630 - <unknown>
  41:     0x7f65fb492620 - rust_try
  42:     0x7f65fb43a3c0 - unwind::try::hd631851c05a82863gRd
  43:     0x7f65fb43a220 - task::Task::run::h5647ca4a975adbf692c
  44:     0x7f65fcc519d0 - <unknown>
  45:     0x7f65fb43bda0 - <unknown>
  46:     0x7f65fa70ffe0 - start_thread
  47:     0x7f65fb10dbf9 - __clone
  48:                0x0 - <unknown>