ICE: compiler/rustc_mir/src/interpret/validity.rs:918:17: Unexpected error during validation: unable to turn pointer into raw bytes

[chengniansun]

Code

union Transmute<T: Copy, U: Copy> {
    t: T,
    u: U,
}
trait Bar {
    fn bar(&self) -> u32;
}
struct Foo {
    foo: u32,
    bar: bool,
}
impl Bar for Foo {
    fn bar(&self) -> u32 {
        self.foo
    }
}
#[derive(Copy, Clone)]
struct Fat<'a>(&'a Foo, &'static VTable);
struct VTable {
    size: Foo,
}
const FOO: &Bar = &Foo {
    foo: 128,
    bar: false,
};
const G: Fat = unsafe { Transmute { t: FOO }.u };

Meta

rustc --version --verbose:

rustc 1.50.0-nightly (5be3f9f10 2020-12-03)
binary: rustc
commit-hash: 5be3f9f10e9fd59ea03816840a6051413fbdefae
commit-date: 2020-12-03
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly

Error output

warning: trait objects without an explicit `dyn` are deprecated
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:22:13
   |
22 | const FOO: &Bar = &Foo {
   |             ^^^ help: use `dyn`: `dyn Bar`
   |
   = note: `#[warn(bare_trait_objects)]` on by default

warning: union is never used: `Transmute`
 --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:1:7
  |
1 | union Transmute<T: Copy, U: Copy> {
  |       ^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: field is never read: `bar`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:10:5
   |
10 |     bar: bool,
   |     ^^^^^^^^^

warning: field is never read: `size`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:20:5
   |
20 |     size: Foo,
   |     ^^^^^^^^^

warning: constant is never used: `FOO`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:22:1
   |
22 | / const FOO: &Bar = &Foo {
23 | |     foo: 128,
24 | |     bar: false,
25 | | };
   | |__^

warning: constant is never used: `G`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:26:1
   |
26 | const G: Fat = unsafe { Transmute { t: FOO }.u };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: compiler/rustc_mir/src/interpret/validity.rs:918:17: Unexpected error during validation: unable to turn pointer into raw bytes

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:958:9
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 1.50.0-nightly (5be3f9f10 2020-12-03) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type staticlib

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `G`
#1 [eval_to_const_value_raw] simplifying constant for the type system `G`
end of query stack
error: aborting due to previous error; 6 warnings emitted

Backtrace

warning: trait objects without an explicit `dyn` are deprecated
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:22:13
   |
22 | const FOO: &Bar = &Foo {
   |             ^^^ help: use `dyn`: `dyn Bar`
   |
   = note: `#[warn(bare_trait_objects)]` on by default

warning: union is never used: `Transmute`
 --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:1:7
  |
1 | union Transmute<T: Copy, U: Copy> {
  |       ^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: field is never read: `bar`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:10:5
   |
10 |     bar: bool,
   |     ^^^^^^^^^

warning: field is never read: `size`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:20:5
   |
20 |     size: Foo,
   |     ^^^^^^^^^

warning: constant is never used: `FOO`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:22:1
   |
22 | / const FOO: &Bar = &Foo {
23 | |     foo: 128,
24 | |     bar: false,
25 | | };
   | |__^

warning: constant is never used: `G`
  --> perses_node_priority_with_dfs_delta_reduced_mutant.rs:26:1
   |
26 | const G: Fat = unsafe { Transmute { t: FOO }.u };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: internal compiler error: compiler/rustc_mir/src/interpret/validity.rs:918:17: Unexpected error during validation: unable to turn pointer into raw bytes

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:958:9
stack backtrace:
   0: std::panicking::begin_panic
   1: rustc_errors::HandlerInner::bug
   2: rustc_errors::Handler::bug
   3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   4: rustc_middle::ty::context::tls::with_opt::{{closure}}
   5: rustc_middle::ty::context::tls::with_opt
   6: rustc_middle::util::bug::opt_span_bug_fmt
   7: rustc_middle::util::bug::bug_fmt
   8: rustc_mir::interpret::validity::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::validate_operand_internal
   9: rustc_mir::const_eval::eval_queries::eval_to_allocation_raw_provider
  10: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_allocation_raw>::compute
  11: rustc_middle::ty::query::plumbing::<impl rustc_query_system::query::QueryContext for rustc_middle::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}::{{closure}}
  12: rustc_query_system::query::plumbing::get_query_impl
  13: rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider
  14: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute
  15: rustc_middle::ty::query::plumbing::<impl rustc_query_system::query::QueryContext for rustc_middle::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}::{{closure}}
  16: rustc_query_system::query::plumbing::get_query_impl
  17: rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider
  18: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute
  19: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  20: rustc_data_structures::stack::ensure_sufficient_stack
  21: rustc_query_system::query::plumbing::get_query_impl
  22: rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_poly
  23: <rustc_lint::BuiltinCombinedLateLintPass as rustc_lint::passes::LateLintPass>::check_item
  24: rustc_hir::intravisit::Visitor::visit_nested_item
  25: rustc_hir::intravisit::walk_crate
  26: rustc_session::utils::<impl rustc_session::session::Session>::time
  27: rustc_interface::passes::analysis::{{closure}}::{{closure}}
  28: rustc_session::utils::<impl rustc_session::session::Session>::time
  29: rustc_interface::passes::analysis
  30: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_eval_always_task
  32: rustc_data_structures::stack::ensure_sufficient_stack
  33: rustc_query_system::query::plumbing::get_query_impl
  34: rustc_interface::passes::QueryContext::enter
  35: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  36: rustc_span::with_source_map
  37: scoped_tls::ScopedKey<T>::set
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.50.0-nightly (3ff10e74a 2020-12-04) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type staticlib

query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `G`
#1 [eval_to_const_value_raw] simplifying constant for the type system `G`
#2 [eval_to_const_value_raw] simplifying constant for the type system `G`
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error; 6 warnings emitted

[camelid]

@rustbot glacier "https://gist.github.com/rust-play/1d2b9d36a074c3f6a88d817266516fd2"

[rustbot]

Error: Parsing glacier command in comment failed: ...'cier https' | error: invalid link - must be from a playground gist at >| '://gist.gi'...

Please let @rust-lang/release know if you're having trouble with this bot.

[matthiaskrgr]

Compiler error on 1.45 but ICE on 1.46
@rustbot label +regression-from-stable-to-stable

[oli-obk]

cc @rust-lang/wg-const-eval

[DutchGhost]

A previous (now-fixed) ICE with the same error message is #72113

[RalfJung]

Thanks for the report!

Would be good to get a better backtrace; this one seems to be missing many frames and there are no line numbers.