ICE: unable to turn pointer into raw bytes

[DutchGhost]

Code

#![feature(const_raw_ptr_deref)]

mod internal {
    static UNIT: &'static () = &();

    static OTHER_UNIT: &'static u8 = unsafe { &*(&self::UNIT as *const _ as *const u8) };
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.45.0-nightly (9912925c2 2020-05-10)

Error output

error: internal compiler error: src/librustc_mir/interpret/validity.rs:867: Unexpected error during validation: unable to turn pointer into raw bytes

Backtrace

   Compiling playground v0.0.1 (/playground)
warning: static is never used: `UNIT`
 --> src/main.rs:4:5
  |
4 |     static UNIT: &'static () = &();
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: static is never used: `OTHER_UNIT`
 --> src/main.rs:6:5
  |
6 |     static OTHER_UNIT: &'static u8 = unsafe { &*(&self::UNIT as *const _ as *const u8) };
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: src/librustc_mir/interpret/validity.rs:867: Unexpected error during validation: unable to turn pointer into raw bytes

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:907:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1537
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:481
  12: std::panicking::begin_panic
  13: rustc_errors::HandlerInner::bug
  14: rustc_errors::Handler::bug
  15: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc_middle::ty::context::tls::with_opt::{{closure}}
  17: rustc_middle::ty::context::tls::with_opt
  18: rustc_middle::util::bug::opt_span_bug_fmt
  19: rustc_middle::util::bug::bug_fmt
  20: rustc_mir::interpret::validity::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::validate_operand_internal
  21: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  22: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_validated>::compute
  23: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  24: rustc_data_structures::stack::ensure_sufficient_stack
  25: rustc_query_system::query::plumbing::get_query_impl
  26: rustc_mir::const_eval::eval_queries::const_eval_validated_provider
  27: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::const_eval_validated>::compute
  28: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  29: rustc_data_structures::stack::ensure_sufficient_stack
  30: rustc_query_system::query::plumbing::get_query_impl
  31: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  32: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_poly
  33: <rustc_lint::BuiltinCombinedLateLintPass as rustc_lint::passes::LateLintPass>::check_item
  34: rustc_hir::intravisit::Visitor::visit_nested_item
  35: rustc_hir::intravisit::walk_item
  36: rustc_hir::intravisit::Visitor::visit_nested_item
  37: rustc_hir::intravisit::walk_crate
  38: rustc_session::utils::<impl rustc_session::session::Session>::time
  39: rustc_session::utils::<impl rustc_session::session::Session>::time
  40: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  41: rustc_session::utils::<impl rustc_session::session::Session>::time
  42: rustc_interface::passes::analysis
  43: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  44: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  45: rustc_data_structures::stack::ensure_sufficient_stack
  46: rustc_query_system::query::plumbing::get_query_impl
  47: rustc_middle::ty::context::tls::enter_global
  48: rustc_interface::interface::run_compiler_in_existing_thread_pool
  49: scoped_tls::ScopedKey<T>::set
  50: rustc_ast::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 1.45.0-nightly (9912925c2 2020-05-10) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [const_eval_validated] const-evaluating + checking `internal::OTHER_UNIT`
#1 [const_eval_validated] const-evaluating + checking `internal::OTHER_UNIT`
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error; 2 warnings emitted

error: could not compile `playground`.

[hellow554]

Little bit shorter:

#![feature(const_raw_ptr_deref)]

const OTHER_UNIT: &'static u8 = unsafe { &*(&&() as *const _ as *const u8) };

fn main() {}

const or static doesn't matter, if inside main or outside, doesn't matter. Just writing &() doesn't ICE:

error: any use of this value will cause an error
 --> src/main.rs:3:42
  |
3 | const OTHER_UNIT: &'static u8 = unsafe { &*(&() as *const _ as *const u8) };
  | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
  |                                          |
  |                                          memory access failed: pointer must be in-bounds at offset 1, but is outside bounds of alloc2 which has size 0
  |
  = note: `#[deny(const_err)]` on by default

[oli-obk]

This has been fixed and either works (in case of the original example, the error is delayed until an actual use happens), or it errors (in case constants are involved)