cargo +nightly fmt error

[supernovahs]

thread 'main' panicked at src/tools/rustfmt/src/parse/session.rs:42:9:
silent emitter attempted to translate a diagnostic
stack backtrace:
   0:        0x101c48144 - std::backtrace::Backtrace::create::h256217627b80cdbd
   1:        0x10b1c0a88 - std[35db171df217138c]::panicking::update_hook::<alloc[c6e243cbecd9122f]::boxed::Box<rustc_driver_impl[1bf557973cdc719f]::install_ice_hook::{closure#0}>>::{closure#0}
   2:        0x101c60ee4 - std::panicking::rust_panic_with_hook::hd3bc5c3697bff071
   3:        0x101c6087c - std::panicking::begin_panic_handler::{{closure}}::hbc804fa8fec1f081
   4:        0x101c5e1e0 - std::sys_common::backtrace::__rust_end_short_backtrace::h4ee9d5159f23371c
   5:        0x101c60620 - _rust_begin_unwind
   6:        0x101cbbadc - core::panicking::panic_fmt::h2ba3e5f79b77a45f
   7:        0x100e57904 - <rustfmt_nightly[8b3928c2bc97675d]::parse::session::SilentEmitter as rustc_errors[446ecdd8909798d]::translation::Translate>::fallback_fluent_bundle
   8:        0x100e55c04 - <rustfmt_nightly[8b3928c2bc97675d]::parse::session::SilentOnIgnoredFilesEmitter as rustc_errors[446ecdd8909798d]::translation::Translate>::translate_message
   9:        0x10c1819d0 - <rustc_errors[446ecdd8909798d]::DiagCtxt>::eagerly_translate::<indexmap[e73a5172dc32d604]::map::iter::Iter<alloc[c6e243cbecd9122f]::borrow::Cow<str>, rustc_errors[446ecdd8909798d]::diagnostic::DiagnosticArgValue>>
  10:        0x10c13b9dc - <rustc_parse[d404c25812033069]::errors::UnknownPrefix as rustc_errors[446ecdd8909798d]::diagnostic::IntoDiagnostic>::into_diagnostic
  11:        0x10c119890 - <rustc_parse[d404c25812033069]::lexer::StringReader>::report_unknown_prefix
  12:        0x10c116698 - <rustc_parse[d404c25812033069]::lexer::StringReader>::next_token
  13:        0x10c16fd60 - <rustc_parse[d404c25812033069]::lexer::tokentrees::TokenTreesReader>::bump
  14:        0x10c16ec24 - <rustc_parse[d404c25812033069]::lexer::tokentrees::TokenTreesReader>::parse_token_trees
  15:        0x10c16ecb0 - <rustc_parse[d404c25812033069]::lexer::tokentrees::TokenTreesReader>::parse_token_trees
  16:        0x10c16ea10 - <rustc_parse[d404c25812033069]::lexer::tokentrees::TokenTreesReader>::parse_all_token_trees
  17:        0x10c11c4e4 - rustc_parse[d404c25812033069]::maybe_file_to_stream
  18:        0x10c11c1a4 - rustc_parse[d404c25812033069]::maybe_source_file_to_parser
  19:        0x100e6dc04 - <rustfmt_nightly[8b3928c2bc97675d]::parse::parser::Parser>::parse_crate
  20:        0x100eb0480 - rustfmt_nightly[8b3928c2bc97675d]::formatting::format_project::<rustfmt_nightly[8b3928c2bc97675d]::Session<alloc[c6e243cbecd9122f]::vec::Vec<u8>>>
  21:        0x100edda8c - <scoped_tls[9ab5c67d09f21897]::ScopedKey<rustc_span[1bbdc5c46a383764]::SessionGlobals>>::with::<<rustfmt_nightly[8b3928c2bc97675d]::Session<alloc[c6e243cbecd9122f]::vec::Vec<u8>>>::format_input_inner::{closure#0}, core[86232531ee72a3db]::result::Result<rustfmt_nightly[8b3928c2bc97675d]::FormatReport, rustfmt_nightly[8b3928c2bc97675d]::ErrorKind>>
  22:        0x100e50b90 - rustc_span[1bbdc5c46a383764]::create_session_if_not_set_then::<core[86232531ee72a3db]::result::Result<rustfmt_nightly[8b3928c2bc97675d]::FormatReport, rustfmt_nightly[8b3928c2bc97675d]::ErrorKind>, <rustfmt_nightly[8b3928c2bc97675d]::Session<alloc[c6e243cbecd9122f]::vec::Vec<u8>>>::format_input_inner::{closure#0}>
  23:        0x100ea4f2c - std[35db171df217138c]::panicking::try::<core[86232531ee72a3db]::option::Option<rustfmt_nightly[8b3928c2bc97675d]::FormattedSnippet>, rustfmt_nightly[8b3928c2bc97675d]::format_snippet::{closure#0}>
  24:        0x100e6e898 - rustfmt_nightly[8b3928c2bc97675d]::format_snippet
  25:        0x100e6ec90 - rustfmt_nightly[8b3928c2bc97675d]::format_code_block
  26:        0x100ee53c0 - rustfmt_nightly[8b3928c2bc97675d]::comment::rewrite_comment_inner
  27:        0x100ee24f8 - rustfmt_nightly[8b3928c2bc97675d]::comment::identify_comment
  28:        0x100e13e6c - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::process_comment
  29:        0x100e12f74 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::format_missing_indent
  30:        0x100e1d1cc - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::push_rewrite
  31:        0x100e1e680 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::walk_stmts
  32:        0x100e1eae8 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::walk_stmts
  33:        0x100e18620 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_block
  34:        0x100e1a8bc - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_fn
  35:        0x100e1c5e8 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_assoc_item
  36:        0x100e11240 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_impl_items
  37:        0x100f08a74 - rustfmt_nightly[8b3928c2bc97675d]::items::format_impl
  38:        0x100e1f028 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::with_context::<<rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_item::{closure#0}>
  39:        0x100e1b614 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_item
  40:        0x100e14c78 - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::visit_items_with_reordering
  41:        0x100e1ed5c - <rustfmt_nightly[8b3928c2bc97675d]::visitor::FmtVisitor>::format_separate_mod
  42:        0x100d6b30c - rustfmt_nightly[8b3928c2bc97675d]::formatting::format_project::<rustfmt_nightly[8b3928c2bc97675d]::Session<std[35db171df217138c]::io::stdio::Stdout>>
  43:        0x100d7b488 - <scoped_tls[9ab5c67d09f21897]::ScopedKey<rustc_span[1bbdc5c46a383764]::SessionGlobals>>::with::<<rustfmt_nightly[8b3928c2bc97675d]::Session<std[35db171df217138c]::io::stdio::Stdout>>::format_input_inner::{closure#0}, core[86232531ee72a3db]::result::Result<rustfmt_nightly[8b3928c2bc97675d]::FormatReport, rustfmt_nightly[8b3928c2bc97675d]::ErrorKind>>
  44:        0x100d7c350 - <rustfmt_nightly[8b3928c2bc97675d]::Session<std[35db171df217138c]::io::stdio::Stdout>>::format_input_inner
  45:        0x100d6a214 - rustfmt[e5e5934501096cb0]::format_and_emit_report::<std[35db171df217138c]::io::stdio::Stdout>
  46:        0x100d79520 - <rustfmt_nightly[8b3928c2bc97675d]::Session<std[35db171df217138c]::io::stdio::Stdout>>::override_config::<rustfmt[e5e5934501096cb0]::format::{closure#0}, ()>
  47:        0x100d69344 - rustfmt[e5e5934501096cb0]::execute
  48:        0x100d6784c - rustfmt[e5e5934501096cb0]::main
  49:        0x100d74070 - std[35db171df217138c]::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>
  50:        0x100d812d8 - std[35db171df217138c]::rt::lang_start::<()>::{closure#0}
  51:        0x101c46bf0 - std::rt::lang_start_internal::h1a04710e0720890c
  52:        0x100d6acb0 - _main


rustc version: 1.78.0-nightly (8f359beca 2024-02-23)
platform: aarch64-apple-darwin

[supernovahs]

Temporary workaround

rustup toolchain install nightly-2024-02-01
cargo +nightly-2024-02-01 fmt

thanks to @emhane

[ytmimi]

Thanks for the report! There were some changes made in the rust-lang/rust repo that are causing this issue in rustfmt. The panic message seems identical to #6082 so I'm going to close this one as a duplicate.