ICE: `index out of bounds: the len is 0 but the index is 18446744073709551615`

[matthiaskrgr]

auto-reduced (treereduce-rust):

//@compile-flags: --edition=2024 -Wfuzzy-provenance-casts
#![feature(strict_provenance_lints)]
#![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]

pub(super) fn foo() -> *const Ts {
    unsafe {
        let p2 = 0x52 as *const u32;
    }
}

original:

#![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
#![feature(X211)]

pub(super) fn foo<F: Into<&'r#struct ()>>() -> *const Ts {
    extern "C" {
        fn deref(&self) -> &[T; N] {
        &self.0
    }
    }
    unsafe {
    let p1 = (0x42 as *const u32).wrapping_offset(4);
    let p2 = 0x52 as *const u32;
    p1.offset_from(p2) == 0
}
}

Version information

rustc 1.87.0-nightly (617aad8c2 2025-02-24)
binary: rustc
commit-hash: 617aad8c2e8783f6df8e5d1f8bb1e4bcdc70aa7b
commit-date: 2025-02-24
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

Possibly related line of code:

rust/compiler/rustc_errors/src/emitter.rs

Lines 2556 to 2568 in 617aad8

	// If the last line is exactly equal to the line we need to add, we can skip both of
	// them. This allows us to avoid output like the following:
	// 2 - &
	// 2 + if true { true } else { false }
	// 3 - if true { true } else { false }
	// If those lines aren't equal, we print their diff
	let last_line_index = file_lines.lines[file_lines.lines.len() - 1].line_index;
	let last_line = &file_lines.file.get_line(last_line_index).unwrap();
	if last_line != line_to_add {
	buffer.puts(
	*row_num - 1,
	0,
	&self.maybe_anonymized(line_num + file_lines.lines.len() - 1),

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2024 -Zcrate-attr=feature(strict_provenance_lints) -Wfuzzy-provenance-casts

Program output

error[E0658]: use of unstable library feature `contracts`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:4
  |
1 | #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
  |    ^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #128044 <https://github.com/rust-lang/rust/issues/128044> for more information
  = help: add `#![feature(contracts)]` to the crate attributes to enable
  = note: this compiler was built on 2025-02-24; consider upgrading it if it is out of date

error[E0658]: inner macro attributes are unstable
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:4
  |
1 | #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
  |    ^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #54726 <https://github.com/rust-lang/rust/issues/54726> for more information
  = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
  = note: this compiler was built on 2025-02-24; consider upgrading it if it is out of date

error[E0433]: failed to resolve: there are too many leading `super` keywords
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^ there are too many leading `super` keywords

error[E0412]: cannot find type `Ts` in this scope
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^ not found in this scope

error[E0658]: `#[prelude_import]` is for use by rustc only
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^
  |
  = help: add `#![feature(prelude_import)]` to the crate attributes to enable
  = note: this compiler was built on 2025-02-24; consider upgrading it if it is out of date

warning: unused import: `#![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
         
         pub(super) fn foo() -> *const Ts {
             unsafe {
                 let p2 = 0x52 as *const u32;
             }
         }`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused `#[macro_use]` import
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:7:2
  |
7 | }
  |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs`

error[E0282]: type annotations needed for `&_`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:30
  |
1 | #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
  |                              ^^^      ---------- type must be known at this point
  |
help: consider giving this closure parameter an explicit type, where the type for type parameter `Ret` is specified
  |
1 | #![core::contracts::ensures(|ret: &Ret| ret.is_none_or(Stars::is_valid))]
  |                                 ++++++

error[E0433]: failed to resolve: use of undeclared type `Stars`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:50
  |
1 | #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
  |                                                  ^^^^^ use of undeclared type `Stars`

warning: strict provenance disallows casting integer `usize` to pointer `*const u32`
 --> /tmp/icemaker_global_tempdir.k7JFg2tTZyVa/rustc_testrunner_tmpdir_reporting.GP1WXRQjER3Y/mvce.rs:1:1
  |
1 | / #![core::contracts::ensures(|ret| ret.is_none_or(Stars::is_valid))]
2 | |
3 | | pub(super) fn foo() -> *const Ts {
4 | |     unsafe {
... |
7 | | }
  | |_^
  |
  = help: if you can't comply with strict provenance and don't have a pointer with the correct provenance you can use `std::ptr::with_exposed_provenance()` instead
  = note: requested on the command line with `-W fuzzy-provenance-casts`

thread 'rustc' panicked at compiler/rustc_errors/src/emitter.rs:2562:51:
index out of bounds: the len is 0 but the index is 18446744073709551615
stack backtrace:
   0:     0x7f0a4637bb74 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h596be22ec28e1f3c
   1:     0x7f0a46a1632c - core::fmt::write::h99935240e04ae94a
   2:     0x7f0a47a9b251 - std::io::Write::write_fmt::hd7d0e16eb6e5b705
   3:     0x7f0a4637b9d2 - std::sys::backtrace::BacktraceLock::print::h5fdaf52f50772596
   4:     0x7f0a4637e1de - std::panicking::default_hook::{{closure}}::hb7462bb0b1897901
   5:     0x7f0a4637ddb4 - std::panicking::default_hook::ha25e0f2ba325eca3
   6:     0x7f0a454dc257 - std[42cfc4424709a4ae]::panicking::update_hook::<alloc[8e0abe553a3b8888]::boxed::Box<rustc_driver_impl[cc1cc8592b4b3991]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7f0a4637ea53 - std::panicking::rust_panic_with_hook::h1d0593281290ed3a
   8:     0x7f0a4637e74a - std::panicking::begin_panic_handler::{{closure}}::hbe93a2fb1f3eac26
   9:     0x7f0a4637c049 - std::sys::backtrace::__rust_end_short_backtrace::h818502b20cb893f0
  10:     0x7f0a4637e40d - rust_begin_unwind
  11:     0x7f0a4303e460 - core::panicking::panic_fmt::h97fe394eab998410
  12:     0x7f0a4448f5dc - core::panicking::panic_bounds_check::he97cc1def0115c2e
  13:     0x7f0a476fdaac - <rustc_errors[980ccc5251f847a6]::emitter::HumanEmitter>::draw_code_line
  14:     0x7f0a476fec25 - <rustc_errors[980ccc5251f847a6]::emitter::HumanEmitter>::emit_suggestion_default
  15:     0x7f0a476e7876 - <rustc_errors[980ccc5251f847a6]::emitter::HumanEmitter as rustc_errors[980ccc5251f847a6]::emitter::Emitter>::emit_diagnostic
  16:     0x7f0a476fbff5 - <rustc_errors[980ccc5251f847a6]::DiagCtxtInner>::emit_diagnostic::{closure#3}
  17:     0x7f0a47adbfd8 - rustc_interface[d4bbb1348e70a3ea]::callbacks::track_diagnostic::<core[d63e11fd8aaf2e06]::option::Option<rustc_span[c1c2594b3cfeb2f9]::ErrorGuaranteed>>
  18:     0x7f0a47adaa22 - <rustc_errors[980ccc5251f847a6]::DiagCtxtInner>::emit_diagnostic
  19:     0x7f0a47ada8dd - <rustc_errors[980ccc5251f847a6]::DiagCtxtHandle>::emit_diagnostic
  20:     0x7f0a47ad9d9f - <() as rustc_errors[980ccc5251f847a6]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  21:     0x7f0a47011019 - rustc_middle[e8e577a537212ebe]::lint::lint_level::lint_level_impl
  22:     0x7f0a47088f05 - <rustc_hir_typeck[bb5bb3924d5fb64e]::cast::CastCheck>::do_check
  23:     0x7f0a4709d96f - rustc_hir_typeck[bb5bb3924d5fb64e]::typeck_with_inspect::{closure#0}
  24:     0x7f0a4709a2c8 - rustc_query_impl[fb7a0f64e8eaa069]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb7a0f64e8eaa069]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e8e577a537212ebe]::query::erase::Erased<[u8; 8usize]>>
  25:     0x7f0a46d2c1cc - rustc_query_system[3f74dc516bc5fce6]::query::plumbing::try_execute_query::<rustc_query_impl[fb7a0f64e8eaa069]::DynamicConfig<rustc_data_structures[72ae77860de7d9ec]::vec_cache::VecCache<rustc_span[c1c2594b3cfeb2f9]::def_id::LocalDefId, rustc_middle[e8e577a537212ebe]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[3f74dc516bc5fce6]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[fb7a0f64e8eaa069]::plumbing::QueryCtxt, false>
  26:     0x7f0a46d2acaa - rustc_query_impl[fb7a0f64e8eaa069]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  27:     0x7f0a46d2a94d - <rustc_middle[e8e577a537212ebe]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_hir_analysis[bcbc1ae2e7d0e58d]::check_crate::{closure#3}>::{closure#0}
  28:     0x7f0a46d29fd5 - rustc_hir_analysis[bcbc1ae2e7d0e58d]::check_crate
  29:     0x7f0a46daa4dc - rustc_interface[d4bbb1348e70a3ea]::passes::run_required_analyses
  30:     0x7f0a47a971fa - rustc_interface[d4bbb1348e70a3ea]::passes::analysis
  31:     0x7f0a47a971d9 - rustc_query_impl[fb7a0f64e8eaa069]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[fb7a0f64e8eaa069]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e8e577a537212ebe]::query::erase::Erased<[u8; 0usize]>>
  32:     0x7f0a47afe28b - rustc_query_system[3f74dc516bc5fce6]::query::plumbing::try_execute_query::<rustc_query_impl[fb7a0f64e8eaa069]::DynamicConfig<rustc_query_system[3f74dc516bc5fce6]::query::caches::SingleCache<rustc_middle[e8e577a537212ebe]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[fb7a0f64e8eaa069]::plumbing::QueryCtxt, false>
  33:     0x7f0a47afdf79 - rustc_query_impl[fb7a0f64e8eaa069]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  34:     0x7f0a47b3727c - rustc_interface[d4bbb1348e70a3ea]::passes::create_and_enter_global_ctxt::<core[d63e11fd8aaf2e06]::option::Option<rustc_interface[d4bbb1348e70a3ea]::queries::Linker>, rustc_driver_impl[cc1cc8592b4b3991]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  35:     0x7f0a47aec120 - rustc_interface[d4bbb1348e70a3ea]::interface::run_compiler::<(), rustc_driver_impl[cc1cc8592b4b3991]::run_compiler::{closure#0}>::{closure#1}
  36:     0x7f0a479ac51c - std[42cfc4424709a4ae]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[d4bbb1348e70a3ea]::util::run_in_thread_with_globals<rustc_interface[d4bbb1348e70a3ea]::util::run_in_thread_pool_with_globals<rustc_interface[d4bbb1348e70a3ea]::interface::run_compiler<(), rustc_driver_impl[cc1cc8592b4b3991]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  37:     0x7f0a479ac940 - <<std[42cfc4424709a4ae]::thread::Builder>::spawn_unchecked_<rustc_interface[d4bbb1348e70a3ea]::util::run_in_thread_with_globals<rustc_interface[d4bbb1348e70a3ea]::util::run_in_thread_pool_with_globals<rustc_interface[d4bbb1348e70a3ea]::interface::run_compiler<(), rustc_driver_impl[cc1cc8592b4b3991]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[d63e11fd8aaf2e06]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  38:     0x7f0a479ad2ab - std::sys::pal::unix::thread::Thread::new::thread_start::h70bf909eb5817fb7
  39:     0x7f0a41ca370a - <unknown>
  40:     0x7f0a41d27aac - <unknown>
  41:                0x0 - <unknown>

error: 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: please make sure that you have updated to the latest nightly

note: rustc 1.87.0-nightly (617aad8c2 2025-02-24) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=feature(strict_provenance_lints) -Z dump-mir-dir=dir

query stack during panic:
#0 [typeck] type-checking `foo`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 8 previous errors; 3 warnings emitted

Some errors have detailed explanations: E0282, E0412, E0433, E0601, E0658.
For more information about an error, try `rustc --explain E0282`.

@rustbot label +F-X211 +F-strict_provenance_lints

[xizheyin]

@rustbot claim

[xizheyin]

The problem is a bit tricky, the span of this suggestion message goes from the beginning to the end of the program(maybe because attribute), however the beginning of the program is a dummy_span. resulting in empty file_lines (which should have been line 0 of the program). Is it possible for Span structures to span from 0:0 to 0:0 but not dummy?

rust/compiler/rustc_errors/src/emitter.rs

Lines 2098 to 2100 in ed897d5

	let file_lines = sm
	.span_to_lines(parts[0].span)
	.expect("span_to_lines failed when emitting suggestion");

[workingjubilee]

The problem is a bit tricky, the span of this suggestion message goes from the beginning to the end of the program(maybe because attribute), however the beginning of the program is a dummy_span. resulting in empty file_lines (which should have been line 0 of the program). Is it possible for Span structures to span from 0:0 to 0:0 but not dummy?

Hm. What do you mean? The dummy span is indeed the span from 0:0 to 0:0. Are you asking if anything important ever has the dummy span, or if there are other cases where we construct the 0:0 span that are not the dummy span?

[xizheyin]

The dummy line is where the diag suggestion starts. When a dummy span is passed, the span_to_lines method will return a empty lines.

rust/compiler/rustc_span/src/source_map.rs

Line 514 in c3dd4ee

return Ok(FileLines { file: lo.file, lines: Vec::new() });

The draw_code_line will panic here, because file_lines.len() is 0.

rust/compiler/rustc_errors/src/emitter.rs

Line 2612 in ed897d5

let last_line_index = file_lines.lines[file_lines.lines.len() - 1].line_index;

I don't tend to modify span_to_lines because it's relied on by many other components of rustc. But span_to_lines should indeed return a line that is not empty, i.e. line 0 of the file. @workingjubilee