Internal compiler error on mutable stable slice

[EPashkin]

Internal compiler error on
rustc 1.22.1 (05e2e1c 2017-11-22) running on x86_64-pc-windows-gnu
rustc 1.24.0-nightly (0a2e9ad 2017-11-29) running on x86_64-pc-windows-gnu
also on playground
rustc 1.22.1 (05e2e1c 2017-11-22) running on x86_64-unknown-linux-gnu
rustc 1.23.0-beta.2 (c9107ee 2017-12-08) running on x86_64-unknown-linux-gnu
rustc 1.24.0-nightly (ad3543d 2017-12-08) running on x86_64-unknown-linux-gnu

I tried this code in empty lib crate:

static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];

fn tst() {
    unsafe {
        write(&buf);
        buf[0]=2;
    }
}

fn write<T: AsRef<[u8]>/* + Send*/>(buffer: T) { }

I expected see only message "statics require immutable values".
Instead I see

error[E0017]: references in statics may only refer to immutable values
 --> lib.rs:1:25
  |
1 | static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];
  |                         ^^^^^^^^^^^^^^^^^^^^ statics require immutable values

error[E0017]: references in statics may only refer to immutable values
 --> lib.rs:1:25
  |
1 | static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];
  |                         ^^^^^^^^^^^^^^^^^^^^ statics require immutable values

error: internal compiler error: src\librustc_borrowck\borrowck\mod.rs:1050: aliasability violation for static `cannot assign to data`
 --> lib.rs:6:9
  |
6 |         buf[0]=2;
  |         ^^^^^^^^

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: rustc 1.22.1 (05e2e1c41 2017-11-22) running on x86_64-pc-windows-gnu

note: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:439:8
stack backtrace:
   0: mingw_set_invalid_parameter_handler
   1: mingw_set_invalid_parameter_handler
   2: mingw_set_invalid_parameter_handler
   3: mingw_set_invalid_parameter_handler
   4: mingw_set_invalid_parameter_handler
   5: mingw_set_invalid_parameter_handler
   6: mingw_set_invalid_parameter_handler
   7: mingw_set_invalid_parameter_handler
   8: mingw_set_invalid_parameter_handler
   9: mingw_set_invalid_parameter_handler
  10: mingw_set_invalid_parameter_handler
  11: mingw_set_invalid_parameter_handler
  12: mingw_set_invalid_parameter_handler
  13: mingw_set_invalid_parameter_handler
  14: mingw_set_invalid_parameter_handler
  15: mingw_set_invalid_parameter_handler
  16: mingw_set_invalid_parameter_handler
  17: mingw_set_invalid_parameter_handler
  18: mingw_set_invalid_parameter_handler
  19: mingw_set_invalid_parameter_handler
  20: mingw_set_invalid_parameter_handler
  21: mingw_set_invalid_parameter_handler
  22: mingw_set_invalid_parameter_handler
  23: mingw_set_invalid_parameter_handler
  24: mingw_set_invalid_parameter_handler
  25: mingw_set_invalid_parameter_handler
  26: mingw_set_invalid_parameter_handler
  27: mingw_set_invalid_parameter_handler
  28: mingw_set_invalid_parameter_handler
  29: mingw_set_invalid_parameter_handler
  30: mingw_set_invalid_parameter_handler
  31: mingw_set_invalid_parameter_handler
  32: mingw_set_invalid_parameter_handler
  33: mingw_set_invalid_parameter_handler
  34: mingw_set_invalid_parameter_handler
  35: mingw_set_invalid_parameter_handler

Full version:
rustc 1.22.1 (05e2e1c 2017-11-22)
binary: rustc
commit-hash: 05e2e1c
commit-date: 2017-11-22
host: x86_64-pc-windows-gnu
release: 1.22.1
LLVM version: 4.0

rustc 1.24.0-nightly (0a2e9ad 2017-11-29)
binary: rustc
commit-hash: 0a2e9ad
commit-date: 2017-11-29
host: x86_64-pc-windows-gnu
release: 1.24.0-nightly
LLVM version: 4.0

[DemiMarie]

First, obviously the backtrace is borked.

[EPashkin]

Yes it broken, but I can't get better 😢

[Deewiant]

I tried to bisect this but turns out that it was introduced long enough ago that I had trouble getting those versions to build. (c033942 is the oldest commit I can build since the Cargo version specified in src/stage0.txt can no longer be downloaded, and I don't know an easy way of getting around this.)

So I turned to release binaries instead. After modifying the first line to explicitly specify the lifetime (static buf: &'static mut [u8] = &mut [1u8,2,3,4,5,7];) so that older Rust accepts the code, in the end I found that the ICE was introduced somewhere between 1.16.0 and 1.17.0.

Here's a proper backtrace from master (ba27415):

<snip>
error: internal compiler error: src/librustc_borrowck/borrowck/mod.rs:1091: aliasability violation for static `cannot assign to data`
<snip>
thread 'rustc' panicked at 'Box', src/librustc_errors/lib.rs:449:8
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:68
             at src/libstd/sys_common/backtrace.rs:57
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:391
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
             at ./src/libstd/panicking.rs:538
   6: rustc_errors::Handler::span_bug
             at ./:3
   7: >::with
             at ./src/librustc/session/mod.rs:1125
             at ./src/librustc/ty/context.rs:1587
             at ./src/librustc/ty/context.rs:1576
             at ./src/libstd/thread/local.rs:377
             at ./src/libstd/thread/local.rs:288
   8: rustc::ty::context::tls::with_opt
             at ./src/librustc/ty/context.rs:1572
             at ./src/librustc/ty/context.rs:1587
   9: rustc::session::span_bug_fmt
             at ./src/librustc/session/mod.rs:1122
             at ./src/librustc/session/mod.rs:1115
  10: rustc_borrowck::borrowck::BorrowckCtxt::report_aliasability_violation
             at src/librustc_borrowck/borrowck/mod.rs:1091
  11: rustc_borrowck::borrowck::gather_loans::check_aliasability
             at src/librustc_borrowck/borrowck/gather_loans/mod.rs:192
  12:  as rustc::middle::expr_use_visitor::Delegate<'tcx>>::mutate
             at src/librustc_borrowck/borrowck/gather_loans/mod.rs:268
             at src/librustc_borrowck/borrowck/gather_loans/mod.rs:150
  13: rustc::middle::expr_use_visitor::ExprUseVisitor::mutate_expr
             at src/librustc/middle/expr_use_visitor.rs:365
  14: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
             at src/librustc/middle/expr_use_visitor.rs:516
  15: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
             at src/librustc/middle/expr_use_visitor.rs:357
  16: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_block
             at src/librustc/middle/expr_use_visitor.rs:606
             at src/librustc/middle/expr_use_visitor.rs:638
  17: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
             at src/librustc/middle/expr_use_visitor.rs:0
  18: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
             at src/librustc/middle/expr_use_visitor.rs:357
  19: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_block
             at src/librustc/middle/expr_use_visitor.rs:642
  20: rustc::middle::expr_use_visitor::ExprUseVisitor::walk_expr
             at src/librustc/middle/expr_use_visitor.rs:0
  21: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_expr
             at src/librustc/middle/expr_use_visitor.rs:357
  22: rustc::middle::expr_use_visitor::ExprUseVisitor::consume_body
             at src/librustc/middle/expr_use_visitor.rs:328
  23: rustc_borrowck::borrowck::gather_loans::gather_loans_in_fn
             at src/librustc_borrowck/borrowck/gather_loans/mod.rs:52
  24: rustc_borrowck::borrowck::borrowck
             at src/librustc_borrowck/borrowck/mod.rs:168
             at src/librustc_borrowck/borrowck/mod.rs:138
  25: rustc::ty::maps::>::compute_result
             at src/librustc/ty/maps/plumbing.rs:383
  26: rustc::dep_graph::graph::DepGraph::with_task_impl
             at src/librustc/dep_graph/graph.rs:273
  27: rustc::dep_graph::graph::DepGraph::with_task
             at src/librustc/dep_graph/graph.rs:189
  28: rustc_errors::Handler::track_diagnostics
             at src/librustc/ty/maps/plumbing.rs:492
             at ./src/librustc_errors/lib.rs:565
  29: rustc::ty::maps::plumbing::>::cycle_check
             at src/librustc/ty/maps/plumbing.rs:485
             at src/librustc/ty/maps/plumbing.rs:121
  30: rustc::ty::maps::>::force
             at src/librustc/ty/maps/plumbing.rs:484
  31: rustc::ty::maps::>::try_get
             at src/librustc/ty/maps/plumbing.rs:301
             at src/librustc/ty/maps/plumbing.rs:526
  32: rustc::ty::maps::TyCtxtAt::borrowck
             at src/librustc/ty/maps/plumbing.rs:565
  33: rustc::ty::maps::>::borrowck
             at src/librustc/ty/maps/plumbing.rs:558
  34: rustc_borrowck::borrowck::check_crate
             at src/librustc_borrowck/borrowck/mod.rs:70
  35: >::with
             at src/librustc_driver/driver.rs:1080
             at ./src/librustc/ty/context.rs:1560
             at ./src/libstd/thread/local.rs:377
             at ./src/libstd/thread/local.rs:288
  36: rustc::ty::context::tls::enter
             at ./src/librustc/ty/context.rs:1557
  37: >::with
             at ./src/librustc/ty/context.rs:1544
             at ./src/libstd/thread/local.rs:377
             at ./src/libstd/thread/local.rs:288
  38: rustc::ty::context::TyCtxt::create_and_enter
             at ./src/librustc/ty/context.rs:1541
             at ./src/librustc/ty/context.rs:1184
  39: rustc_driver::driver::compile_input
             at src/librustc_driver/driver.rs:1033
             at src/librustc_driver/driver.rs:227
  40: rustc_driver::run_compiler
             at src/librustc_driver/lib.rs:253