ICE: downgrade_to_delayed_bug: cannot downgrade Warning(None) to DelayedBug: not an error

[matthiaskrgr]

auto-reduced (treereduce-rust):

fn call_this<F>(f: F) : Fn(&str) + call_that {}

original:

// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

// pp-exact

fn call_it(f: Box<FnMut(f: Box<FnMut(String) -> String>) -> String>) {}

fn call_this<F>(f: F) : Fn(&str) + call_that {}

fn call_that<F>(f: F) where F: for<'a> Fn(&'a isize, &'a isize) -> isize {}

fn call_extern(f: fn() -> isize) {}

fn call_abid_extern(call_it: extern "C" fn() -> isize) {}

pub fn main(&str) {}

Version information

rustc 1.77.0-nightly (11035f9f5 2024-01-05)
binary: rustc
commit-hash: 11035f9f52c65739d9613f5b9ecd332e9e640e71
commit-date: 2024-01-05
host: x86_64-unknown-linux-gnu
release: 1.77.0-nightly
LLVM version: 17.0.6

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

Program output

error: return types are denoted using `->`
 --> /tmp/icemaker_global_tempdir.ZcuHjInOmhfr/rustc_testrunner_tmpdir_reporting.BaGXrEBoFcyz/mvce.rs:8:23
  |
8 | fn call_this<F>(f: F) : Fn(&str) + call_that {}
  |                       ^ help: use `->` instead

error[E0405]: cannot find trait `call_that` in this scope
 --> /tmp/icemaker_global_tempdir.ZcuHjInOmhfr/rustc_testrunner_tmpdir_reporting.BaGXrEBoFcyz/mvce.rs:8:36
  |
8 | fn call_this<F>(f: F) : Fn(&str) + call_that {}
  |                                    ^^^^^^^^^ not found in this scope

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.ZcuHjInOmhfr/rustc_testrunner_tmpdir_reporting.BaGXrEBoFcyz/mvce.rs:8:48
  |
8 | fn call_this<F>(f: F) : Fn(&str) + call_that {}
  |                                                ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.ZcuHjInOmhfr/rustc_testrunner_tmpdir_reporting.BaGXrEBoFcyz/mvce.rs`

thread 'rustc' panicked at compiler/rustc_hir_analysis/src/astconv/lint.rs:127:22:
downgrade_to_delayed_bug: cannot downgrade Warning(None) to DelayedBug: not an error
stack backtrace:
   0:     0x7f302d38b806 - std::backtrace_rs::backtrace::libunwind::trace::h72ed163bf54ed335
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f302d38b806 - std::backtrace_rs::backtrace::trace_unsynchronized::ha9eeffcac0159741
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f302d38b806 - std::sys_common::backtrace::_print_fmt::hd878d288400665ec
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f302d38b806 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hee1d8c1810fab8e4
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f302d3ddf00 - core::fmt::rt::Argument::fmt::he899d11a584078ee
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/core/src/fmt/rt.rs:142:9
   5:     0x7f302d3ddf00 - core::fmt::write::h9fb58a907feb62f5
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/core/src/fmt/mod.rs:1120:17
   6:     0x7f302d37f15f - std::io::Write::write_fmt::h7e0c3492389aed93
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/io/mod.rs:1810:15
   7:     0x7f302d38b5e4 - std::sys_common::backtrace::_print::hb4e839736d952adb
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f302d38b5e4 - std::sys_common::backtrace::print::ha846f6638d2e1501
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f302d38e377 - std::panicking::default_hook::{{closure}}::hcd8a486cb84a6ace
  10:     0x7f302d38e0d9 - std::panicking::default_hook::hfa2ffdc3f2a8ce4a
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/panicking.rs:292:9
  11:     0x7f3030160cac - std[735fb5c0265dddc8]::panicking::update_hook::<alloc[2bd63a676ca9eb5]::boxed::Box<rustc_driver_impl[d85864648598caad]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f302d38eac6 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hc9ef68fbc75324a4
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/alloc/src/boxed.rs:2030:9
  13:     0x7f302d38eac6 - std::panicking::rust_panic_with_hook::h869d110b23694b5d
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/panicking.rs:783:13
  14:     0x7f302d38e812 - std::panicking::begin_panic_handler::{{closure}}::hd3a60d30fcbcee10
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/panicking.rs:657:13
  15:     0x7f302d38bd06 - std::sys_common::backtrace::__rust_end_short_backtrace::hcea5d524563d6535
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f302d38e570 - rust_begin_unwind
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/panicking.rs:645:5
  17:     0x7f302d3da605 - core::panicking::panic_fmt::hc641175b49629a2b
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/core/src/panicking.rs:72:14
  18:     0x7f302f7c4858 - <rustc_errors[5a03629f0326f870]::diagnostic::Diagnostic>::downgrade_to_delayed_bug
  19:     0x7f303028382f - <dyn rustc_hir_analysis[4501648514be1474]::astconv::AstConv>::maybe_lint_impl_trait
  20:     0x7f303023d6ec - <<dyn rustc_hir_analysis[4501648514be1474]::astconv::AstConv>::maybe_lint_bare_trait::{closure#1} as core[d0d16022f048c5c1]::ops::function::FnOnce<(&mut rustc_errors[5a03629f0326f870]::diagnostic_builder::DiagnosticBuilder<()>,)>>::call_once::{shim:vtable#0}
  21:     0x7f3030258722 - <alloc[2bd63a676ca9eb5]::boxed::Box<dyn for<'a, 'b> core[d0d16022f048c5c1]::ops::function::FnOnce<(&'a mut rustc_errors[5a03629f0326f870]::diagnostic_builder::DiagnosticBuilder<'b, ()>,), Output = ()>> as core[d0d16022f048c5c1]::ops::function::FnOnce<(&mut rustc_errors[5a03629f0326f870]::diagnostic_builder::DiagnosticBuilder<()>,)>>::call_once
  22:     0x7f303221a7e4 - rustc_middle[8ef003f1e476f553]::lint::struct_lint_level::struct_lint_level_impl::<&str>
  23:     0x7f3031601b8c - <dyn rustc_hir_analysis[4501648514be1474]::astconv::AstConv>::ast_ty_to_ty_inner
  24:     0x7f30315fed76 - <dyn rustc_hir_analysis[4501648514be1474]::astconv::AstConv>::ty_of_fn
  25:     0x7f30315fde2e - rustc_hir_analysis[4501648514be1474]::collect::infer_return_ty_for_fn_sig
  26:     0x7f30315fd0bc - rustc_hir_analysis[4501648514be1474]::collect::fn_sig
  27:     0x7f30315f6585 - rustc_query_impl[c94a6fda47c12dc7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c94a6fda47c12dc7]::query_impl::fn_sig::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 24usize]>>
  28:     0x7f30315f6555 - <rustc_query_impl[c94a6fda47c12dc7]::query_impl::fn_sig::dynamic_query::{closure#2} as core[d0d16022f048c5c1]::ops::function::FnOnce<(rustc_middle[8ef003f1e476f553]::ty::context::TyCtxt, rustc_span[fb1dd2d991832768]::def_id::DefId)>>::call_once
  29:     0x7f30315f5b93 - rustc_query_system[aa09d2e731c481a9]::query::plumbing::try_execute_query::<rustc_query_impl[c94a6fda47c12dc7]::DynamicConfig<rustc_query_system[aa09d2e731c481a9]::query::caches::DefaultCache<rustc_span[fb1dd2d991832768]::def_id::DefId, rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[c94a6fda47c12dc7]::plumbing::QueryCtxt, false>
  30:     0x7f30315f55af - rustc_query_impl[c94a6fda47c12dc7]::query_impl::fn_sig::get_query_non_incr::__rust_end_short_backtrace
  31:     0x7f30318cca04 - <rustc_hir_analysis[4501648514be1474]::collect::CollectItemTypesVisitor as rustc_hir[200e79af71247e2]::intravisit::Visitor>::visit_item
  32:     0x7f30318caa3d - rustc_hir_analysis[4501648514be1474]::collect::collect_mod_item_types
  33:     0x7f30318ca9d1 - rustc_query_impl[c94a6fda47c12dc7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c94a6fda47c12dc7]::query_impl::collect_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 0usize]>>
  34:     0x7f3031db3b0f - rustc_query_system[aa09d2e731c481a9]::query::plumbing::try_execute_query::<rustc_query_impl[c94a6fda47c12dc7]::DynamicConfig<rustc_query_system[aa09d2e731c481a9]::query::caches::DefaultCache<rustc_span[fb1dd2d991832768]::def_id::LocalModDefId, rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[c94a6fda47c12dc7]::plumbing::QueryCtxt, false>
  35:     0x7f3031db3643 - rustc_query_impl[c94a6fda47c12dc7]::query_impl::collect_mod_item_types::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7f303160359f - rustc_hir_analysis[4501648514be1474]::check_crate
  37:     0x7f3032035ed9 - rustc_interface[82ea3601d258e7e1]::passes::analysis
  38:     0x7f3032035b1f - rustc_query_impl[c94a6fda47c12dc7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[c94a6fda47c12dc7]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 1usize]>>
  39:     0x7f30323a55a4 - rustc_query_system[aa09d2e731c481a9]::query::plumbing::try_execute_query::<rustc_query_impl[c94a6fda47c12dc7]::DynamicConfig<rustc_query_system[aa09d2e731c481a9]::query::caches::SingleCache<rustc_middle[8ef003f1e476f553]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[c94a6fda47c12dc7]::plumbing::QueryCtxt, false>
  40:     0x7f30323a5395 - rustc_query_impl[c94a6fda47c12dc7]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  41:     0x7f3032066f35 - rustc_interface[82ea3601d258e7e1]::interface::run_compiler::<core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>, rustc_driver_impl[d85864648598caad]::run_compiler::{closure#0}>::{closure#0}
  42:     0x7f30323db78a - std[735fb5c0265dddc8]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[82ea3601d258e7e1]::util::run_in_thread_with_globals<rustc_interface[82ea3601d258e7e1]::util::run_in_thread_pool_with_globals<rustc_interface[82ea3601d258e7e1]::interface::run_compiler<core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>, rustc_driver_impl[d85864648598caad]::run_compiler::{closure#0}>::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>
  43:     0x7f30323db5b9 - <<std[735fb5c0265dddc8]::thread::Builder>::spawn_unchecked_<rustc_interface[82ea3601d258e7e1]::util::run_in_thread_with_globals<rustc_interface[82ea3601d258e7e1]::util::run_in_thread_pool_with_globals<rustc_interface[82ea3601d258e7e1]::interface::run_compiler<core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>, rustc_driver_impl[d85864648598caad]::run_compiler::{closure#0}>::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d0d16022f048c5c1]::result::Result<(), rustc_span[fb1dd2d991832768]::ErrorGuaranteed>>::{closure#1} as core[d0d16022f048c5c1]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  44:     0x7f302d3989f5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h29d894b5e99070ca
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/alloc/src/boxed.rs:2016:9
  45:     0x7f302d3989f5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hee2cef6a97c8434b
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/alloc/src/boxed.rs:2016:9
  46:     0x7f302d3989f5 - std::sys::unix::thread::Thread::new::thread_start::h2bd633f8986b3333
                               at /rustc/11035f9f52c65739d9613f5b9ecd332e9e640e71/library/std/src/sys/unix/thread.rs:108:17
  47:     0x7f302d1849eb - <unknown>
  48:     0x7f302d2087cc - <unknown>
  49:                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: rustc 1.77.0-nightly (11035f9f5 2024-01-05) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [fn_sig] computing function signature of `call_this`
#1 [collect_mod_item_types] collecting item types in top-level module
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 3 previous errors

Some errors have detailed explanations: E0405, E0601.
For more information about an error, try `rustc --explain E0405`.

[matthiaskrgr]

@nnethercote I suspect this is caused by one of your prs that were merged in #119621

[matthiaskrgr]

Oh nevermind, sorry, the was line added by #119148 cc @estebank :D
I couldn't bisect yet because we didn't have the per-pr artifacts available yet.

[matthiaskrgr]

code snippet that triggers the other downgarde_to_delayed_bug that was added:

fn id<F>(f: Copy) -> usize {
    f()
}