patterns: wrong tracking issue?

[matthiaskrgr]

While checkout out this ice (which does not require a feature gate btw, so potential beta-to-stable regression, which is inconvenient

snippet:

use std::pat::pattern_type;

type Always = pattern_type!(Option<u32> is Some(_));

Version information

rustc 1.79.0-nightly (537aab7a2 2024-04-08)
binary: rustc
commit-hash: 537aab7a2e7fe9cdf50b5ff18485e0793cd8db62
commit-date: 2024-04-08
host: x86_64-unknown-linux-gnu
release: 1.79.0-nightly
LLVM version: 18.1.3

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error[E0658]: use of unstable library feature 'core_pattern_type'
 --> /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:15
  |
3 | type Always = pattern_type!(Option<u32> is Some(_));
  |               ^^^^^^^^^^^^
  |
  = help: add `#![feature(core_pattern_type)]` to the crate attributes to enable
  = note: this compiler was built on 2024-04-08; consider upgrading it if it is out of date

error[E0658]: pattern types are unstable
 --> /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:15
  |
3 | type Always = pattern_type!(Option<u32> is Some(_));
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
  = help: add `#![feature(pattern_types)]` to the crate attributes to enable
  = note: this compiler was built on 2024-04-08; consider upgrading it if it is out of date

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:53
  |
3 | type Always = pattern_type!(Option<u32> is Some(_));
  |                                                     ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs`

error[E0658]: use of unstable library feature 'core_pattern_type'
 --> /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:1:5
  |
1 | use std::pat::pattern_type;
  |     ^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: add `#![feature(core_pattern_type)]` to the crate attributes to enable
  = note: this compiler was built on 2024-04-08; consider upgrading it if it is out of date

error: internal compiler error: compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs:2252:26: unsupported pattern for pattern type: Pat {
                                    hir_id: HirId(DefId(0:4 ~ mvce[b30d]::Always).7),
                                    kind: TupleStruct(
                                        Resolved(
                                            None,
                                            Path {
                                                span: /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:44: 3:48 (#0),
                                                res: Err,
                                                segments: [
                                                    PathSegment {
                                                        ident: Some#0,
                                                        hir_id: HirId(DefId(0:4 ~ mvce[b30d]::Always).5),
                                                        res: Err,
                                                        args: None,
                                                        infer_args: true,
                                                    },
                                                ],
                                            },
                                        ),
                                        [
                                            Pat {
                                                hir_id: HirId(DefId(0:4 ~ mvce[b30d]::Always).6),
                                                kind: Wild,
                                                span: /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:49: 3:50 (#0),
                                                default_binding_modes: true,
                                            },
                                        ],
                                        None,
                                    ),
                                    span: /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:44: 3:51 (#0),
                                    default_binding_modes: true,
                                }
 --> /tmp/icemaker_global_tempdir.ACwscHoXGDVj/rustc_testrunner_tmpdir_reporting.LrjHdxKAtSsK/mvce.rs:3:44
  |
3 | type Always = pattern_type!(Option<u32> is Some(_));
  |                                            ^^^^^^^

thread 'rustc' panicked at compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs:2252:26:
Box<dyn Any>
stack backtrace:
   0:     0x76636502a885 - std::backtrace_rs::backtrace::libunwind::trace::h3c5d6be2ca224618
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1:     0x76636502a885 - std::backtrace_rs::backtrace::trace_unsynchronized::h07f25bfbbc81f9b7
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x76636502a885 - std::sys_common::backtrace::_print_fmt::hf0313e0fd41b1242
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x76636502a885 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::ha80bcf755077e3a1
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x766365079b4b - core::fmt::rt::Argument::fmt::hea7d7a647aef4433
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/core/src/fmt/rt.rs:142:9
   5:     0x766365079b4b - core::fmt::write::h0eafe6836efd2236
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/core/src/fmt/mod.rs:1153:17
   6:     0x76636501f47f - std::io::Write::write_fmt::hee25aa3e7912fe48
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/io/mod.rs:1843:15
   7:     0x76636502a65e - std::sys_common::backtrace::_print::h0c8b5670573775f7
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x76636502a65e - std::sys_common::backtrace::print::hb0c84899d27bc992
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x76636502d159 - std::panicking::default_hook::{{closure}}::hdd10a62b37f83705
  10:     0x76636502ce75 - std::panicking::default_hook::h491d7bd053f3c065
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/panicking.rs:291:9
  11:     0x76636185be5f - std[8cce646dcc9f51a2]::panicking::update_hook::<alloc[7e5e1bdade7884f3]::boxed::Box<rustc_driver_impl[b1693766bfe96bed]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x76636502d85c - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h673a5ec9e27814ea
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/alloc/src/boxed.rs:2032:9
  13:     0x76636502d85c - std::panicking::rust_panic_with_hook::h2f18055510e9d6ac
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/panicking.rs:792:13
  14:     0x76636188bed4 - std[8cce646dcc9f51a2]::panicking::begin_panic::<rustc_errors[6ec141f8b50a2d31]::ExplicitBug>::{closure#0}
  15:     0x766361888c46 - std[8cce646dcc9f51a2]::sys_common::backtrace::__rust_end_short_backtrace::<std[8cce646dcc9f51a2]::panicking::begin_panic<rustc_errors[6ec141f8b50a2d31]::ExplicitBug>::{closure#0}, !>
  16:     0x766361888926 - std[8cce646dcc9f51a2]::panicking::begin_panic::<rustc_errors[6ec141f8b50a2d31]::ExplicitBug>
  17:     0x7663618952d1 - <rustc_errors[6ec141f8b50a2d31]::diagnostic::BugAbort as rustc_errors[6ec141f8b50a2d31]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  18:     0x76636190ab28 - <rustc_errors[6ec141f8b50a2d31]::DiagCtxt>::span_bug::<rustc_span[c8203a7ebedcd79e]::span_encoding::Span, alloc[7e5e1bdade7884f3]::string::String>
  19:     0x76636194573d - rustc_middle[29872c107b60a246]::util::bug::opt_span_bug_fmt::<rustc_span[c8203a7ebedcd79e]::span_encoding::Span>::{closure#0}
  20:     0x7663619461aa - rustc_middle[29872c107b60a246]::ty::context::tls::with_opt::<rustc_middle[29872c107b60a246]::util::bug::opt_span_bug_fmt<rustc_span[c8203a7ebedcd79e]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  21:     0x76636192abfb - rustc_middle[29872c107b60a246]::ty::context::tls::with_context_opt::<rustc_middle[29872c107b60a246]::ty::context::tls::with_opt<rustc_middle[29872c107b60a246]::util::bug::opt_span_bug_fmt<rustc_span[c8203a7ebedcd79e]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  22:     0x766361927107 - rustc_middle[29872c107b60a246]::util::bug::span_bug_fmt::<rustc_span[c8203a7ebedcd79e]::span_encoding::Span>
  23:     0x766362e71d12 - <dyn rustc_hir_analysis[79635f1fa32cabba]::hir_ty_lowering::HirTyLowerer>::lower_ty_common
  24:     0x766360971cf3 - rustc_hir_analysis[79635f1fa32cabba]::collect::type_of::type_of
  25:     0x766362cc64a2 - rustc_query_impl[51661ff1e116d73e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[51661ff1e116d73e]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 8usize]>>
  26:     0x766362cc50e1 - rustc_query_system[2cf76174bd7e0814]::query::plumbing::try_execute_query::<rustc_query_impl[51661ff1e116d73e]::DynamicConfig<rustc_query_system[2cf76174bd7e0814]::query::caches::DefIdCache<rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[51661ff1e116d73e]::plumbing::QueryCtxt, false>
  27:     0x766362cc4bdb - rustc_query_impl[51661ff1e116d73e]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  28:     0x76636321343a - <rustc_hir_analysis[79635f1fa32cabba]::collect::CollectItemTypesVisitor as rustc_hir[7361c4e2026484da]::intravisit::Visitor>::visit_item
  29:     0x76636320987f - rustc_hir_analysis[79635f1fa32cabba]::check::wfcheck::check_well_formed
  30:     0x766363209773 - rustc_query_impl[51661ff1e116d73e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[51661ff1e116d73e]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>
  31:     0x766363208f00 - rustc_query_system[2cf76174bd7e0814]::query::plumbing::try_execute_query::<rustc_query_impl[51661ff1e116d73e]::DynamicConfig<rustc_query_system[2cf76174bd7e0814]::query::caches::VecCache<rustc_hir[7361c4e2026484da]::hir_id::OwnerId, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[51661ff1e116d73e]::plumbing::QueryCtxt, false>
  32:     0x766363208c7f - rustc_query_impl[51661ff1e116d73e]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  33:     0x766363206bd3 - rustc_hir_analysis[79635f1fa32cabba]::check::wfcheck::check_mod_type_wf
  34:     0x766363206a1b - rustc_query_impl[51661ff1e116d73e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[51661ff1e116d73e]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>
  35:     0x7663636a3870 - rustc_query_system[2cf76174bd7e0814]::query::plumbing::try_execute_query::<rustc_query_impl[51661ff1e116d73e]::DynamicConfig<rustc_query_system[2cf76174bd7e0814]::query::caches::DefaultCache<rustc_span[c8203a7ebedcd79e]::def_id::LocalModDefId, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[51661ff1e116d73e]::plumbing::QueryCtxt, false>
  36:     0x7663636a361b - rustc_query_impl[51661ff1e116d73e]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  37:     0x766362ec418f - rustc_hir_analysis[79635f1fa32cabba]::check_crate
  38:     0x766362ed816a - rustc_interface[e7aac3eeb74c4c0c]::passes::analysis
  39:     0x766362ed7cc7 - rustc_query_impl[51661ff1e116d73e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[51661ff1e116d73e]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>
  40:     0x766363a54ce5 - rustc_query_system[2cf76174bd7e0814]::query::plumbing::try_execute_query::<rustc_query_impl[51661ff1e116d73e]::DynamicConfig<rustc_query_system[2cf76174bd7e0814]::query::caches::SingleCache<rustc_middle[29872c107b60a246]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[51661ff1e116d73e]::plumbing::QueryCtxt, false>
  41:     0x766363a54a49 - rustc_query_impl[51661ff1e116d73e]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  42:     0x7663638eec22 - rustc_interface[e7aac3eeb74c4c0c]::interface::run_compiler::<core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>, rustc_driver_impl[b1693766bfe96bed]::run_compiler::{closure#0}>::{closure#0}
  43:     0x7663639cc01d - std[8cce646dcc9f51a2]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[e7aac3eeb74c4c0c]::util::run_in_thread_with_globals<rustc_interface[e7aac3eeb74c4c0c]::util::run_in_thread_pool_with_globals<rustc_interface[e7aac3eeb74c4c0c]::interface::run_compiler<core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>, rustc_driver_impl[b1693766bfe96bed]::run_compiler::{closure#0}>::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>
  44:     0x7663639cbe2a - <<std[8cce646dcc9f51a2]::thread::Builder>::spawn_unchecked_<rustc_interface[e7aac3eeb74c4c0c]::util::run_in_thread_with_globals<rustc_interface[e7aac3eeb74c4c0c]::util::run_in_thread_pool_with_globals<rustc_interface[e7aac3eeb74c4c0c]::interface::run_compiler<core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>, rustc_driver_impl[b1693766bfe96bed]::run_compiler::{closure#0}>::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7ebb3dbf9c5383ca]::result::Result<(), rustc_span[c8203a7ebedcd79e]::ErrorGuaranteed>>::{closure#1} as core[7ebb3dbf9c5383ca]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  45:     0x76636503728b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hea2f762c1fe3db14
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/alloc/src/boxed.rs:2018:9
  46:     0x76636503728b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h79ea2eedb7e4df53
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/alloc/src/boxed.rs:2018:9
  47:     0x76636503728b - std::sys::pal::unix::thread::Thread::new::thread_start::h83279d19c2446390
                               at /rustc/537aab7a2e7fe9cdf50b5ff18485e0793cd8db62/library/std/src/sys/pal/unix/thread.rs:108:17
  48:     0x766364dd555a - <unknown>
  49:     0x766364e52a3c - <unknown>
  50:                0x0 - <unknown>

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 1.79.0-nightly (537aab7a2 2024-04-08) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [type_of] expanding type alias `Always`
#1 [check_well_formed] checking that `Always` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 5 previous errors

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

I clicked the tracking issue from

= note: see issue #54882 #54882 for more information
= help: add #![feature(pattern_types)] to the crate attributes to enable
= note: this compiler was built on 2024-04-08; consider upgrading it if it is out of date

which is about an optimize attribute and does not mention patterns or links to a related PR at all? 🤔

[compiler-errors]

While checkout out this ice (which does not require a feature gate btw, so potential beta-to-stable regression, which is inconvenient

What do you mean? Why would this beta a beta-to-stable regression? It regressed with #107606.

[compiler-errors]

cc @oli-obk pattern types need a real tracking issue, and you need to delay a span bug here rather than ICE

[matthiaskrgr]

right now: beta -> nightly regression
once nightly gets promoted to beta: stable -> beta regression
once beta gets promoted to stable: stable -> stable regression?

[compiler-errors]

yes? but you can say that about every single regression that ever gets filed lol

[matthiaskrgr]

exactly, unless it gets fixed in time :)

[compiler-errors]

I don't see the purpose of pointing out that this is a potential beta regression before it has even landed on nightly, unless there's some reason that this is particularly difficult to fix, particularly affects user-facing code, or we expect it to slip the beta promotion for some reason.

[matthiaskrgr]

Well, there are a few cases where feature gates actually do work and prevent crashes on stable 🙃

[oli-obk]

maybe internal features should just hard abort compilation if they aren't set

[matthiaskrgr]

might also solve some of the internal-feature ices we are getting from time to time

[workingjubilee]

...I do not see how it would be a regression, because we can safely bet on no one requiring the pattern_type! macro before the feature's library API landed.

The code did not travel back in time to 1.77 compilers and suddenly become usable stable API.