Internal Compiler Error when writing to an immutable reference

[zommiommy]

I tried to minimize the code as much as possible. Basically in this code, we are trying to write using an immutable reference.
For some reason, it panics instead of pointing out the problem.

I created a repository with a proof of concept. If you need more info I'm happy to help.

Code

struct Field (usize);

struct Crasherini {
    field: Field,
}

impl Crasherini {
    pub fn write_to_immut_ref(&mut self){
        for value in vec![&self.field] {
            value.0 = 10;
        } 
    }
}

Meta

rustc --version --verbose:

rustc 1.52.0-nightly (5fa22fe6f 2021-02-14)
binary: rustc
commit-hash: 5fa22fe6f821ac3801d05f624b123dda25fde32c
commit-date: 2021-02-14
host: x86_64-unknown-linux-gnu
release: 1.52.0-nightly
LLVM version: 11.0.1

Error output

   Compiling rustc_crash v0.1.0 (/Workspace/Github/rustc_crash)
     Running `rustc --crate-name rustc_crash --edition=2018 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=3d2379ed6d914a3d -C extra-filename=-3d2379ed6d914a3d --out-dir /Workspace/Github/rustc_crash/target/debug/deps -C incremental=/Workspace/Github/rustc_crash/target/debug/incremental -L dependency=/Workspace/Github/rustc_crash/target/debug/deps`
error: internal compiler error: compiler/rustc_middle/src/hir/map/mod.rs:306:18: impossible case reached

thread 'rustc' panicked at 'Box<Any>', /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/panic.rs:59:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.52.0-nightly (5fa22fe6f 2021-02-14) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [mir_borrowck] borrow-checking `Crasherini::write_to_immut_ref`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

error: could not compile `rustc_crash`

Caused by:
  process didn't exit successfully: `rustc --crate-name rustc_crash --edition=2018 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=3d2379ed6d914a3d -C extra-filename=-3d2379ed6d914a3d --out-dir /Workspace/Github/rustc_crash/target/debug/deps -C incremental=/Workspace/Github/rustc_crash/target/debug/incremental -L dependency=/Workspace/Github/rustc_crash/target/debug/deps` (exit code: 101)

Backtrace

error: internal compiler error: compiler/rustc_middle/src/hir/map/mod.rs:306:18: impossible case reached

thread 'rustc' panicked at 'Box<Any>', /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/panic.rs:59:5
stack backtrace:
   0:     0x7fe5a101da90 - std::backtrace_rs::backtrace::libunwind::trace::hb4de9797f80b7b8c
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x7fe5a101da90 - std::backtrace_rs::backtrace::trace_unsynchronized::h59566d0bd20efff7
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fe5a101da90 - std::sys_common::backtrace::_print_fmt::hcfa5ce6be50275d4
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7fe5a101da90 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd8c307a38b9bab04
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7fe5a108ef5c - core::fmt::write::h3868db8542c90941
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/core/src/fmt/mod.rs:1096:17
   5:     0x7fe5a10109c2 - std::io::Write::write_fmt::hab90295d5a0f197d
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/io/mod.rs:1568:15
   6:     0x7fe5a1021985 - std::sys_common::backtrace::_print::h19224910b8700cf1
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7fe5a1021985 - std::sys_common::backtrace::print::h25dedfa68c5fb84a
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7fe5a1021985 - std::panicking::default_hook::{{closure}}::h12c5765653a72a42
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/panicking.rs:208:50
   9:     0x7fe5a1021433 - std::panicking::default_hook::he65cee71c4209f0c
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/panicking.rs:225:9
  10:     0x7fe5a187d14b - rustc_driver::report_ice::h9bfcf5769c15fbf2
  11:     0x7fe5a1022286 - std::panicking::rust_panic_with_hook::h01a674d863fe0d8a
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/panicking.rs:595:17
  12:     0x7fe5a3050fde - std::panicking::begin_panic::{{closure}}::h04d9d59beaf7438f
  13:     0x7fe5a3050d19 - std::sys_common::backtrace::__rust_end_short_backtrace::h91912ecacddbde4e
  14:     0x7fe5a3050f82 - std::panicking::begin_panic::h3001af3848957078
  15:     0x7fe5a3043730 - std::panic::panic_any::h4f4426de976e6adf
  16:     0x7fe5a3046b3a - rustc_errors::HandlerInner::bug::hdf11185f92e2a22a
  17:     0x7fe5a3046613 - rustc_errors::Handler::bug::h2dfda4f443e5c9b7
  18:     0x7fe5a2d464ca - rustc_middle::ty::context::tls::with_opt::h931a04da690f236d
  19:     0x7fe5a4666430 - rustc_middle::util::bug::opt_span_bug_fmt::h550b33bd70d0f311
  20:     0x7fe5a2d48946 - rustc_middle::util::bug::bug_fmt::h36f36510cd9d6fb0
  21:     0x7fe5a3ac4e53 - rustc_middle::hir::map::Map::item::h38779ea831b29407
  22:     0x7fe5a23c4fc5 - rustc_mir::borrow_check::diagnostics::mutability_errors::<impl rustc_mir::borrow_check::MirBorrowckCtxt>::report_mutability_error::h9f31953fdeab2a41
  23:     0x7fe5a371e777 - rustc_mir::borrow_check::MirBorrowckCtxt::access_place::h7d6f5b9d65ba8ac9
  24:     0x7fe5a371ecc9 - rustc_mir::borrow_check::MirBorrowckCtxt::mutate_place::hea6a7404e13ec6bc
  25:     0x7fe5a371c03e - <rustc_mir::borrow_check::MirBorrowckCtxt as rustc_mir::dataflow::framework::visitor::ResultsVisitor>::visit_statement_before_primary_effect::hfed3a82644adb2d8
  26:     0x7fe5a36386ea - <rustc_mir::dataflow::framework::direction::Forward as rustc_mir::dataflow::framework::direction::Direction>::visit_results_in_block::hadc8c1a5509312c0
  27:     0x7fe5a35c28e7 - rustc_mir::dataflow::framework::visitor::visit_results::hc22c9f4ceef08c61
  28:     0x7fe5a3717aca - rustc_mir::borrow_check::do_mir_borrowck::h3413661263ce29f4
  29:     0x7fe5a3610053 - rustc_infer::infer::InferCtxtBuilder::enter::hb74fd86320ea36f1
  30:     0x7fe5a37168a7 - rustc_mir::borrow_check::mir_borrowck::h57947c7876ea879f
  31:     0x7fe5a31ae87c - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::mir_borrowck>::compute::h626f7b9e9b78ef2d
  32:     0x7fe5a3c007c7 - rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps::h2b9a3e2453557291
  33:     0x7fe5a31a3d99 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h90db12b228ddedb6
  34:     0x7fe5a31c2f95 - rustc_data_structures::stack::ensure_sufficient_stack::h22af48d26d15ef1a
  35:     0x7fe5a31b3851 - rustc_query_system::query::plumbing::force_query_with_job::h5fa612051f70510d
  36:     0x7fe5a31b0fc8 - rustc_query_system::query::plumbing::get_query_impl::h6055f87cc26b791b
  37:     0x7fe5a31b3667 - rustc_query_system::query::plumbing::ensure_query_impl::he177fc338b1f472c
  38:     0x7fe5a31b52b9 - rustc_session::utils::<impl rustc_session::session::Session>::time::h6c2f1e639f350429
  39:     0x7fe5a3c134dd - rustc_interface::passes::analysis::heddb9cef62da4ab1
  40:     0x7fe5a3b90a49 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute::hc584fab50c0e9742
  41:     0x7fe5a183971a - rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps::he189719f47fb03a4
  42:     0x7fe5a3ba2ee4 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h90cdb9d4b5390542
  43:     0x7fe5a3bb1d85 - rustc_data_structures::stack::ensure_sufficient_stack::hc03964f1cadb8cd3
  44:     0x7fe5a3b91771 - rustc_query_system::query::plumbing::force_query_with_job::h085fb2f93a800461
  45:     0x7fe5a3b90d81 - rustc_query_system::query::plumbing::get_query_impl::hc18a830d288c39e4
  46:     0x7fe5a3baa02a - rustc_interface::passes::QueryContext::enter::hf896adfd99e9040f
  47:     0x7fe5a3bb0e14 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::h2ac7000621882a7f
  48:     0x7fe5a3ba9911 - rustc_span::with_source_map::h9c33ff8439fe9783
  49:     0x7fe5a3bb05e3 - scoped_tls::ScopedKey<T>::set::h0eb8893a0191dbc1
  50:     0x7fe5a3bb1ff8 - std::sys_common::backtrace::__rust_begin_short_backtrace::hccc56e59b0e3233c
  51:     0x7fe5a3b9071a - core::ops::function::FnOnce::call_once{{vtable.shim}}::h09f6484b7e2514ef
  52:     0x7fe5a1032fda - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h321523073ee11258
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/alloc/src/boxed.rs:1546:9
  53:     0x7fe5a1032fda - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hf0e85e12c83b99b3
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/alloc/src/boxed.rs:1546:9
  54:     0x7fe5a1032fda - std::sys::unix::thread::Thread::new::thread_start::hba22c7961aa0e2f8
                               at /rustc/5fa22fe6f821ac3801d05f624b123dda25fde32c/library/std/src/sys/unix/thread.rs:71:17
  55:     0x7fe5a0f3b3e9 - start_thread
  56:     0x7fe5a0e58293 - __GI___clone
  57:                0x0 - <unknown>

[jyn514]

Duplicate of #82032, fixed in #82056.