ICE: "assertion failed: !deep_decl.is_glob_import()" in chumsky

[graham-hardy]

Code

Contents of Cargo.toml:

[package]
name = "quack"
version = "0.1.0"
edition = "2024"

[profile.release]
lto = true
panic = "abort"
strip = true

[dependencies]
chumsky = { git = "http://github.com/zesterer/chumsky", features = ["nightly", "memoization", "extension", "pratt", "debug", "unstable", "lexical-numbers", "either", "regex", "serde", "bytes"] }

Contents of /src/main.rs:

use std::{borrow::Cow, io::stdin};

use chumsky::prelude::*;

fn string_parser<'src>()
-> impl Parser<'src, &'src str, Cow<'src, str>, extra::Err<Rich<'src, char>>> {
    let quote = just('"');
    let unescaped_character = none_of("\"\\");
    let basic = unescaped_character
        .repeated()
        .to_slice()
        .padded_by(quote)
        .map(Cow::Borrowed);
    let escaped = {
        let hex_digits = text::digits(16);
        let escape = just('\\');
        let byte = just('x')
            .ignore_then(hex_digits.exactly(2).to_slice())
            .try_map(|src, span| {
                u8::from_str_radix(src, 16)
                    .map(char::from)
                    .map_err(|parse_int_error| Rich::custom(span, parse_int_error))
            });
        let unicode = just('u')
            .ignore_then(
                hex_digits
                    .at_least(1)
                    .to_slice()
                    .delimited_by(just('{'), just('}')),
            )
            .try_map(|src, span| {
                let i = u32::from_str_radix(src, 16)
                    .map_err(|parse_int_error| Rich::custom(span, parse_int_error))?;
                char::from_u32(i).ok_or_else(|| {
                    Rich::custom(span, format!("`{src}` is not a valid Unicode character."))
                })
            });
        let escaped_character = escape.ignore_then(choice((
            one_of("\"\\"),
            just('n').to('\n'),
            just('r').to('\r'),
            unicode,
            byte,
        )));
        unescaped_character
            .or(escaped_character)
            .separated_by(escape.then(text::whitespace().at_least(1)).or_not())
            .allow_leading()
            .allow_trailing()
            .collect()
            .padded_by(quote)
            .map(Cow::Owned)
    };
    let delimited = {
        let delimiter = just('"').then(just("").configure(|cfg, ctx| cfg.seq(*ctx)));
        just('#')
            .repeated()
            .to_slice()
            .delimited_by(just('r'), just('"'))
            .ignore_with_ctx(
                any()
                    .and_is(delimiter.not())
                    .repeated()
                    .to_slice()
                    .then_ignore(delimiter),
            )
            .map(Cow::Borrowed)
    };
    choice((basic, escaped, delimited)).labelled("string")
}

fn main() {
    for input in stdin().lines().fuse().flatten() {
        let result = string_parser().parse(&input);
        for e in result.errors() {
            eprintln!("Error: {e}");
        }
        if let Some(output) = result.output() {
            match output {
                Cow::Borrowed(s) => println!("Zero-copy: {s}"),
                Cow::Owned(s) => println!("Owned: {s}"),
            }
        }
    }
}

Meta

rustc --version --verbose:

rustc 1.94.0-nightly (f57eac1bf 2026-01-10)
binary: rustc
commit-hash: f57eac1bf98cb5d578e3364b64365ec398c137df
commit-date: 2026-01-10
host: x86_64-pc-windows-msvc
release: 1.94.0-nightly
LLVM version: 21.1.8

Error output

thread 'rustc' (46792) panicked at /rustc-dev/f57eac1bf98cb5d578e3364b64365ec398c137df/compiler\rustc_resolve\src\imports.rs:378:13:
assertion failed: !deep_decl.is_glob_import()

Backtrace

   Compiling libm v0.2.15
   Compiling crc32fast v1.5.0
   Compiling simd-adler32 v0.3.8
   Compiling cfg-if v1.0.4
   Compiling log v0.4.29
   Compiling bytemuck v1.24.0
   Compiling shlex v1.3.0
   Compiling find-msvc-tools v0.1.7
   Compiling version_check v0.9.5
   Compiling adler2 v2.0.1
   Compiling static_assertions v1.1.0
   Compiling smallvec v1.15.1
   Compiling arrayvec v0.7.6
   Compiling memchr v2.7.6
   Compiling float-cmp v0.9.0
   Compiling proc-macro2 v1.0.105
   Compiling tinyvec_macros v0.1.1
   Compiling windows_x86_64_msvc v0.52.6
   Compiling unicode-ident v1.0.22
   Compiling quote v1.0.43
   Compiling arrayref v0.3.9
   Compiling lexical-util v0.8.5
   Compiling tinyvec v1.10.0
   Compiling miniz_oxide v0.8.9
   Compiling strict-num v0.1.1
   Compiling fdeflate v0.3.7
   Compiling unicode-bidi-mirroring v0.4.0
   Compiling unicode-script v0.5.8
   Compiling unicode-properties v0.1.4
   Compiling tiny-skia-path v0.11.4
   Compiling kurbo v0.11.3
   Compiling bitflags v2.10.0
   Compiling siphasher v1.0.1
   Compiling memmap2 v0.9.9
   Compiling bitflags v1.3.2
   Compiling slotmap v1.1.1
   Compiling unicode-ccc v0.4.0
   Compiling cc v1.2.52
   Compiling simplecss v0.2.2
   Compiling unicode-vo v0.1.0
   Compiling weezl v0.1.12
   Compiling object v0.32.2
   Compiling serde_core v1.0.228
   Compiling libc v0.2.180
   Compiling byteorder-lite v0.1.0
   Compiling imagesize v0.13.0
   Compiling color_quant v1.1.0
   Compiling unicode-bidi v0.3.18
   Compiling pico-args v0.5.0
   Compiling lexical-parse-integer v0.8.6
   Compiling flate2 v1.1.5
   Compiling lexical-write-integer v0.8.5
   Compiling data-url v0.3.2
   Compiling zune-core v0.4.12
   Compiling roxmltree v0.20.0
   Compiling quick-error v2.0.1
   Compiling base64 v0.22.1
   Compiling svgtypes v0.15.3
   Compiling xmlwriter v0.1.0
   Compiling lexical-write-float v0.8.5
   Compiling zune-jpeg v0.4.21
   Compiling image-webp v0.2.4
   Compiling lexical-parse-float v0.8.5
   Compiling png v0.17.16
   Compiling gif v0.13.3
   Compiling windows-targets v0.52.6
   Compiling rgb v0.8.52
   Compiling serde v1.0.228
   Compiling windows-sys v0.59.0
   Compiling syn v2.0.114
   Compiling regex-syntax v0.7.5
   Compiling allocator-api2 v0.2.21
   Compiling core_maths v0.1.1
   Compiling stacker v0.1.22
   Compiling unicode-width v0.2.2
   Compiling lexical-core v0.8.5
   Compiling foldhash v0.1.5
   Compiling ttf-parser v0.25.1
   Compiling equivalent v1.0.2
   Compiling aho-corasick v1.1.4
   Compiling lexical v6.1.1
   Compiling unicode-segmentation v1.12.0
   Compiling bytes v1.11.0
   Compiling either v1.15.0
   Compiling hashbrown v0.15.5
   Compiling tiny-skia v0.11.4
   Compiling serde_derive v1.0.228
   Compiling regex-automata v0.3.9
   Compiling ar_archive_writer v0.2.0
   Compiling fontdb v0.23.0
   Compiling rustybuzz v0.20.1
   Compiling psm v0.1.28
   Compiling usvg v0.45.1
   Compiling resvg v0.45.1
   Compiling railroad v0.3.3
   Compiling chumsky v0.13.0 (http://github.com/zesterer/chumsky#da922ff3)

thread 'rustc' (57940) panicked at /rustc-dev/f57eac1bf98cb5d578e3364b64365ec398c137df/compiler\rustc_resolve\src\imports.rs:378:13:
assertion failed: !deep_decl.is_glob_import()
stack backtrace:
   0: std::panicking::panic_handler
             at /rustc/f57eac1bf98cb5d578e3364b64365ec398c137df/library\std\src\panicking.rs:689
   1: core::panicking::panic_fmt
             at /rustc/f57eac1bf98cb5d578e3364b64365ec398c137df/library\core\src\panicking.rs:80
   2: core::panicking::panic
             at /rustc/f57eac1bf98cb5d578e3364b64365ec398c137df/library\core\src\panicking.rs:150
   3: core::slice::sort::stable::quicksort::quicksort::<(&str, &pulldown_cmark::parse::LinkDef), <[(&str, &pulldown_cmark::parse::LinkDef)]>::sort_by_key<&str, rustc_resolve::rustdoc::parse_links::{closure#1}>::{closure#0}>
   4: <hashbrown::raw::RawTable<(rustc_span::hygiene::LocalExpnId, ())>>::reserve_rehash::<hashbrown::map::make_hasher<rustc_span::hygiene::LocalExpnId, (), rustc_hash::FxBuildHasher>::{closure#0}>
   5: <hashbrown::raw::RawTable<(rustc_span::hygiene::LocalExpnId, ())>>::reserve_rehash::<hashbrown::map::make_hasher<rustc_span::hygiene::LocalExpnId, (), rustc_hash::FxBuildHasher>::{closure#0}>
   6: <hashbrown::raw::RawTable<(rustc_span::hygiene::LocalExpnId, ())>>::reserve_rehash::<hashbrown::map::make_hasher<rustc_span::hygiene::LocalExpnId, (), rustc_hash::FxBuildHasher>::{closure#0}>
   7: <hashbrown::raw::RawTable<(rustc_span::hygiene::LocalExpnId, ())>>::reserve_rehash::<hashbrown::map::make_hasher<rustc_span::hygiene::LocalExpnId, (), rustc_hash::FxBuildHasher>::{closure#0}>
   8: <hashbrown::raw::RawTable<(rustc_span::hygiene::LocalExpnId, ())>>::reserve_rehash::<hashbrown::map::make_hasher<rustc_span::hygiene::LocalExpnId, (), rustc_hash::FxBuildHasher>::{closure#0}>
   9: <rustc_resolve::Resolver as rustc_expand::base::ResolverExpand>::resolve_imports
  10: <rustc_expand::expand::MacroExpander>::fully_expand_fragment
  11: <rustc_expand::expand::MacroExpander>::expand_crate
  12: rustc_interface::proc_macro_decls::proc_macro_decls_static
  13: rustc_interface::passes::resolver_for_lowering_raw
  14: <rustc_lint::builtin::SpecialModuleName as rustc_lint::passes::EarlyLintPass>::check_crate
  15: rustc_query_impl::profiling_support::alloc_self_profile_query_strings
  16: RINvNtNtCs5P3H3drZr7k_18rustc_query_system5query8plumbing17try_execute_queryINtCsez81biN4khp_16rustc_query_impl13DynamicConfigINtNtB4_6caches11SingleCacheINtNtNtCs35hIyFdTHOr_12rustc_middle5query5erase6ErasedAhj10_EEKb0_KB3t_KB3t_ENtNtB1f_8plumbing9QueryCt
  17: rustc_query_impl::profiling_support::alloc_self_profile_query_strings
  18: <rustc_middle::ty::context::TyCtxt>::resolver_for_lowering
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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: please attach the file at `p:\.cargo\git\checkouts\chumsky-f75fa12f276e2bbf\da922ff\rustc-ice-2026-01-11T18_14_51-55972.txt` to your bug report

note: rustc 1.94.0-nightly (f57eac1bf 2026-01-10) running on x86_64-pc-windows-msvc

note: compiler flags: --crate-type lib -C opt-level=3 -C panic=abort -C linker-plugin-lto -C strip=symbols

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack
error: could not compile `chumsky` (lib)

Caused by:
  process didn't exit successfully: `C:\Users\Graham\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\bin\rustc.exe --crate-name chumsky --edition=2021 p:\.cargo\git\checkouts\chumsky-f75fa12f276e2bbf\da922ff\src\lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=119 --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C panic=abort -C linker-plugin-lto --cfg "feature=\"bytes\"" --cfg "feature=\"debug\"" --cfg "feature=\"default\"" --cfg "feature=\"either\"" --cfg "feature=\"extension\"" --cfg "feature=\"lexical\"" --cfg "feature=\"lexical-numbers\"" --cfg "feature=\"memoization\"" --cfg "feature=\"nightly\"" --cfg "feature=\"pratt\"" --cfg "feature=\"regex\"" --cfg "feature=\"serde\"" --cfg "feature=\"stacker\"" --cfg "feature=\"std\"" --cfg "feature=\"unstable\"" --check-cfg cfg(docsrs,test) --check-cfg "cfg(feature, values(\"_test_stable\", \"bytes\", \"debug\", \"default\", \"docsrs\", \"either\", \"extension\", \"lexical\", \"lexical-numbers\", \"memoization\", \"nightly\", \"pratt\", \"regex\", \"serde\", \"stacker\", \"std\", \"unstable\"))" -C metadata=e650041a508fe409 -C extra-filename=-11d91bbee8ee7a3d --out-dir p:\quack\target\release\deps -C strip=symbols -L dependency=p:\quack\target\release\deps --extern bytes=p:\quack\target\release\deps\libbytes-f528da0b3b2470a6.rmeta --extern either=p:\quack\target\release\deps\libeither-f3fc8e52b0dcbc5b.rmeta --extern hashbrown=p:\quack\target\release\deps\libhashbrown-8cd128a582f15986.rmeta --extern lexical=p:\quack\target\release\deps\liblexical-a308c2f3e59e0200.rmeta --extern railroad=p:\quack\target\release\deps\librailroad-d55278a241b4ee3e.rmeta --extern regex_automata=p:\quack\target\release\deps\libregex_automata-074cc1e86c70c31b.rmeta --extern serde=p:\quack\target\release\deps\libserde-e3bda5b9c7c80662.rmeta --extern stacker=p:\quack\target\release\deps\libstacker-f9bfda846abe18a0.rmeta --extern unicode_ident=p:\quack\target\release\deps\libunicode_ident-064c5846efa15a98.rmeta --extern unicode_segmentation=p:\quack\target\release\deps\libunicode_segmentation-e03e86d295490978.rmeta --cap-lints allow -L native=p:\quack\target\release\build\stacker-e6601898b7e8410b\out -L native=p:\quack\target\release\build\psm-387ed9509956ee0e\out -L "native=C:\Program Files\Microsoft Visual Studio\18\Community\VC\Tools\MSVC\14.50.35717\atlmfc\lib\x64" -L "native=C:\Program Files\Microsoft Visual Studio\18\Community\VC\Tools\MSVC\14.50.35717\atlmfc\lib\x64" -L native=p:\.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\windows_x86_64_msvc-0.52.6\lib` (exit code: 101)

[petrochenkov]

Oh, interesting, this is not currently fixed by #150939 (although the ICE is different), I'll look.

New ICE:

thread 'rustc' (12508) panicked at compiler\rustc_resolve\src\imports.rs:304:9:
assertion `left == right` failed
  left: Some(DeclData { kind: Import { source_decl: DeclData { kind: Import { source_decl: DeclData { kind: Def(Def(Struct, DefId(0:8091 ~ chumsky[f238]::span::Spanned))), ambiguity: CmCell(None), warn_ambiguity: CmCell(false), expansion: expn145, span: src\span.rs:256:1
: 261:2 (#0), vis: CmCell(Public) }, import: ImportData { kind: Single { source: Spanned#0, target: Spanned#0, decls: PerNS { value_ns: None, type_ns: None, macro_ns: None }, type_ns_only: false, nested: true, id: NodeId(44970) }, root_id: NodeId(44899), use_span: src\li
b.rs:79:5: 91:7 (#0), use_span_with_attributes: src\lib.rs:79:5: 91:7 (#0), has_attributes: false, span: src\lib.rs:89:54: 89:61 (#0), root_span: src\lib.rs:79:13: 91:6 (#0), parent_scope: ParentScope { module: Some(Def(Mod, DefId(0:3975 ~ chumsky[f238]::prelude))), expa
nsion: expn0, macro_rules: Cell { value: Def(MacroRulesDecl { decl: DeclData { kind: Def(Def(Macro(MacroKinds(1)), DefId(0:5 ~ chumsky[f238]::go_extra))), ambiguity: CmCell(None), warn_ambiguity: CmCell(false), expansion: expn0, span: src\lib.rs:22:1: 33:2 (#0), vis: CmC
ell(Restricted(DefId(0:0 ~ chumsky[f238]))) }, parent_macro_rules_scope: Cell { value: Empty }, ident: go_extra#0 }) }, derives: [] }, module_path: [Segment { ident: super#0, id: Some(NodeId(44900)), has_generic_args: false, has_lifetime_args: false, args_span: no-locati
on (#0) }, Segment { ident: span#0, id: Some(NodeId(44962)), has_generic_args: false, has_lifetime_args: false, args_span: no-location (#0) }], imported_module: CmCell(Some(Module(Some(Def(Mod, DefId(0:3464 ~ chumsky[f238]::span)))))), vis: Public, vis_span: src\lib.rs:7
9:5: 79:8 (#0) } }, ambiguity: CmCell(None), warn_ambiguity: CmCell(false), expansion: expn0, span: src\lib.rs:89:54: 89:61 (#0), vis: CmCell(Public) }, import: ImportData { kind: Glob { max_vis: CmCell(Some(Restricted(DefId(0:3632 ~ chumsky[f238]::text)))), id: NodeId(4
0549) }, root_id: NodeId(40549), use_span: src\text.rs:9:1: 9:23 (#0), use_span_with_attributes: src\text.rs:9:1: 9:23 (#0), has_attributes: false, span: src\text.rs:9:5: 9:22 (#0), root_span: src\text.rs:9:5: 9:22 (#0), parent_scope: ParentScope { module: Some(Def(Mod,
DefId(0:3632 ~ chumsky[f238]::text))), expansion: expn0, macro_rules: Cell { value: Def(MacroRulesDecl { decl: DeclData { kind: Def(Def(Macro(MacroKinds(1)), DefId(0:5 ~ chumsky[f238]::go_extra))), ambiguity: CmCell(None), warn_ambiguity: CmCell(false), expansion: expn0,
 span: src\lib.rs:22:1: 33:2 (#0), vis: CmCell(Restricted(DefId(0:0 ~ chumsky[f238]))) }, parent_macro_rules_scope: Cell { value: Empty }, ident: go_extra#0 }) }, derives: [] }, module_path: [Segment { ident: crate#0, id: Some(NodeId(40550)), has_generic_args: false, has
_lifetime_args: false, args_span: no-location (#0) }, Segment { ident: prelude#0, id: Some(NodeId(40551)), has_generic_args: false, has_lifetime_args: false, args_span: no-location (#0) }], imported_module: CmCell(Some(Module(Some(Def(Mod, DefId(0:3975 ~ chumsky[f238]::p
relude)))))), vis: Restricted(DefId(0:3632 ~ chumsky[f238]::text)), vis_span: src\text.rs:9:1: 9:1 (#0) } }, ambiguity: CmCell(None), warn_ambiguity: CmCell(false), expansion: expn0, span: src\text.rs:9:5: 9:22 (#0), vis: CmCell(Restricted(DefId(0:3632 ~ chumsky[f238]::t
ext))) })
 right: None

[petrochenkov]

This is now also fixed in #150939.

[apiraino]

Assigning priority (discussion on Zulip).

@rustbot label -I-prioritize +P-high