ICE: prefix is unknown

[matthiaskrgr]

snippet:

macro_rules! TrivialTypeTraversalImpls {
    ( ) => {
        $(
            impl<'tcx> $crate::ty::fold::<$crate::ty::TyCtxt<'tcx>> for $ty {
                fn <F: $crate::ty::fold::<$crate::ty::TyCtxtty'format_args>>> -> ::std::result::Result<Self, F::Error>

                #[inline]
                fn fold_with<F: $crate::ty::fold::TypeFolder<$crate::ty::TyCtxt<'tcx>>> -> Self
            }

            impl<'tcx> $crate::ty::visit::<$crate::ty::TyCtxt<'tcx>> for $fmt
        )+
    };
}

Version information

rustc 1.79.0-nightly (35936c483 2024-03-25)
binary: rustc
commit-hash: 35936c4839dd272646394779d151e060d0f6b3ac
commit-date: 2024-03-25
host: x86_64-unknown-linux-gnu
release: 1.79.0-nightly
LLVM version: 18.1.2

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2021 --crate-type=lib

Program output

warning: unused macro definition: `TrivialTypeTraversalImpls`
 --> /tmp/icemaker_global_tempdir.FffekGIQB7Un/rustc_testrunner_tmpdir_reporting.U2wAqBOnvaRS/mvce.rs:1:14
  |
1 | macro_rules! TrivialTypeTraversalImpls {
  |              ^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_macros)]` on by default

warning: 1 warning emitted

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: prefix `TyCtxtty` is unknown
 --> /tmp/icemaker_global_tempdir.FffekGIQB7Un/rustc_testrunner_tmpdir_reporting.U2wAqBOnvaRS/mvce.rs:5:55
  |
5 |                 fn <F: $crate::ty::fold::<$crate::ty::TyCtxtty'format_args>>> -> ::std::result::Result<Self, F::Error>
  |                                                       ^^^^^^^^ unknown prefix
  |
  = note: prefixed identifiers and literals are reserved since Rust 2021
note: delayed at compiler/rustc_parse/src/lexer/mod.rs:724:28
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxt>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_parse::lexer::StringReader>::report_unknown_prefix
         4: <rustc_parse::lexer::tokentrees::TokenTreesReader>::bump
         5: <rustc_parse::lexer::tokentrees::TokenTreesReader>::parse_token_trees
         6: <rustc_parse::lexer::tokentrees::TokenTreesReader>::parse_token_trees
         7: <rustc_parse::lexer::tokentrees::TokenTreesReader>::parse_token_trees
         8: <rustc_parse::lexer::tokentrees::TokenTreesReader>::parse_token_trees
         9: <rustc_parse::lexer::tokentrees::TokenTreesReader>::parse_token_trees
        10: rustc_parse::maybe_file_to_stream
        11: rustc_parse::maybe_source_file_to_parser
        12: rustc_parse::new_parser_from_file
        13: rustc_interface::passes::parse
        14: <rustc_interface::queries::Queries>::parse
        15: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}
        16: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        17: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        18: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/35936c4839dd272646394779d151e060d0f6b3ac/library/alloc/src/boxed.rs:2015:9
        19: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/35936c4839dd272646394779d151e060d0f6b3ac/library/alloc/src/boxed.rs:2015:9
        20: std::sys::pal::unix::thread::Thread::new::thread_start
                   at /rustc/35936c4839dd272646394779d151e060d0f6b3ac/library/std/src/sys/pal/unix/thread.rs:108:17
        21: <unknown>
        22: <unknown>
 --> /tmp/icemaker_global_tempdir.FffekGIQB7Un/rustc_testrunner_tmpdir_reporting.U2wAqBOnvaRS/mvce.rs:5:55
  |
5 |                 fn <F: $crate::ty::fold::<$crate::ty::TyCtxtty'format_args>>> -> ::std::result::Result<Self, F::Error>
  |                                                       ^^^^^^^^
help: if you meant to write a string literal, use double quotes
  |
4 ~             impl<'tcx> $crate::ty::fold::<$crate::ty::TyCtxt<"tcx>> for $ty {
5 ~                 fn <F: $crate::ty::fold::<$crate::ty::TyCtxtty"format_args>>> -> ::std::result::Result<Self, F::Error>
  |

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 (35936c483 2024-03-25) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -Z dump-mir-dir=dir

query stack during panic:
end of query stack

[matthiaskrgr]

🤔 this bisects to #122217 cc @estebank

[fmease]

🤔 this bisects to #122217

very plausible 👍

[GrigorenkoPV]

Reduced

macro_rules! a {
    ( ) => {
        impl<'b> c for d {
            e::<f'g>
        }
    };
}