Bug in std::fs:File read_to_string

[maksimsco]

I tried this code:

use std::io::prelude::{Read};
use std::fs::File;


fn main() {
  let mut file = File::open("").unwrap();
  let mut temp = Vec::new();
  file.read_to_string(&mut temp).unwrap();
}

https://is.gd/g8Qo3H

I expected to see this happen:

Mismatched type error, stating that expected type is &mut std::string::String, found type &mut std::vec::Vec<_>

Instead, this happened:

error: internal compiler error: unexpected panic
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
thread 'rustc' panicked at 'index out of bounds: the len is 11 but the index is 13', ../src/libcollections/vec.rs:1167

Meta

rustc 1.10.0-nightly (267cde259 2016-05-25)
binary: rustc
commit-hash: 267cde2598db3b858730cc1f700f740964343828
commit-date: 2016-05-25
host: x86_64-unknown-linux-gnu
release: 1.10.0-nightly

Backtrace:

   1:     0x7f0c3a63f300 - std::sys::backtrace::tracing::imp::write::h9fb600083204ae7f
   2:     0x7f0c3a64cefb - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hca543c34f11229ac
   3:     0x7f0c3a64ca9c - std::panicking::default_hook::hc2c969e7453d080c
   4:     0x7f0c3a612508 - std::panicking::rust_panic_with_hook::hfe203e3083c2b544
   5:     0x7f0c3a64d141 - std::panicking::begin_panic::h4889569716505182
   6:     0x7f0c3a6145aa - std::panicking::begin_panic_fmt::h484cd47786497f03
   7:     0x7f0c3a64d0de - rust_begin_unwind
   8:     0x7f0c3a696c0f - core::panicking::panic_fmt::h257ceb0aa351d801
   9:     0x7f0c3a696df2 - core::panicking::panic_bounds_check::h3956fdcea61ff421
  10:     0x7f0c36d5f04d - _<rustc_data_structures..unify..UnificationTable<K>>::get::h8ff555081abcc760
  11:     0x7f0c36d000c0 - rustc::infer::InferCtxt::shallow_resolve::hff438d8ff8173683
  12:     0x7f0c36e67c6b - _<traits..fulfill..FulfillProcessor<'a, 'b, 'gcx, 'tcx> as rustc_data_structures..obligation_forest..ObligationProcessor>::process_obligation::h97a6c04480fde384
  13:     0x7f0c36e671d7 - _<rustc_data_structures..obligation_forest..ObligationForest<O>>::process_obligations::h66b78b3df852f4c4
  14:     0x7f0c36e5f77f - rustc::traits::fulfill::FulfillmentContext::select_where_possible::h8b194aeaf688996f
  15:     0x7f0c393ac995 - rustc_typeck::check::FnCtxt::select_obligations_where_possible::h4d863d3c82f83fa7
  16:     0x7f0c393c0c07 - rustc_typeck::check::FnCtxt::resolve_type_vars_with_obligations::he5b46c6af8ba8c04
  17:     0x7f0c393d5cbe - rustc_typeck::check::demand::_<impl check..FnCtxt<'a, 'gcx, 'tcx>>::demand_coerce::h09ff47efa702d716
  18:     0x7f0c393d36ca - rustc_typeck::check::FnCtxt::check_argument_types::ha1363bf21548e22e
  19:     0x7f0c393d25f7 - rustc_typeck::check::FnCtxt::check_method_argument_types::h2c2345d254cd8031
  20:     0x7f0c393d87a3 - rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref::hf7a336bf3f6d489c
  21:     0x7f0c393d6880 - rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref::hf7a336bf3f6d489c
  22:     0x7f0c3940dc18 - rustc_typeck::check::FnCtxt::check_stmt::h631e2149cd32c75c
  23:     0x7f0c393b2a73 - rustc_typeck::check::FnCtxt::check_block_with_expected::hb3119871f6a1bbfa
  24:     0x7f0c393a9aa8 - rustc_typeck::check::check_fn::h4bb517663c83e412
  25:     0x7f0c393a62de - rustc_typeck::check::check_bare_fn::ha3f2d22e33abb8cf
  26:     0x7f0c393a1d72 - rustc_typeck::check::check_item_body::h7ffec660fc242796
  27:     0x7f0c39398779 - rustc_typeck::check::check_item_bodies::ha729008a2e67410e
  28:     0x7f0c393916b6 - rustc_typeck::check_crate::hab54f1dbb6479f2b
  29:     0x7f0c3ab9b83c - rustc_driver::driver::phase_3_run_analysis_passes::_$u7b$$u7b$closure$u7d$$u7d$::he8e0792bce031dff
  30:     0x7f0c3ab9987b - rustc::ty::context::TyCtxt::create_and_enter::h9e0841510a9ae184
  31:     0x7f0c3ab614ec - rustc_driver::driver::compile_input::h0629572e6f316b31
  32:     0x7f0c3ab4c704 - rustc_driver::run_compiler::h8902aebf8b1849a8
  33:     0x7f0c3ab497de - std::panicking::try::call::hb9e578062982aefa
  34:     0x7f0c3a65b69b - __rust_try
  35:     0x7f0c3a65b63e - __rust_maybe_catch_panic
  36:     0x7f0c3ab4a2c4 - _<F as std..boxed..FnBox<A>>::call_box::h27f542a39f1d61ef
  37:     0x7f0c3a64b004 - std::sys::thread::Thread::new::thread_start::h6f266e069bf4ec2b
  38:     0x7f0c32316473 - start_thread
  39:     0x7f0c3a2a2acc - clone
  40:                0x0 - <unknown>

[apasel422]

Duplicate of #31964.