[ICE]: `symbol_names: unsupported constant of type`

[matthiaskrgr]

snippet:

//@compile-flags: -Clink-dead-code=true -Znext-solver=globally --crate-type=lib
#![feature(min_generic_const_args)]
#![feature(generic_const_args)]
#![feature(adt_const_params, lazy_type_alias)]
type Matrix = [usize; 1];
const EMPTY_MATRIX: Matrix = [1];
struct Walk<const REMAINING: Matrix>;
impl Walk<EMPTY_MATRIX> {
    fn new() {}
}

Version information

rustc 1.97.0-nightly (ffccab6ab 2026-05-07)
binary: rustc
commit-hash: ffccab6abef68b70c5e23cfbfb1ac7680104040d
commit-date: 2026-05-07
host: x86_64-unknown-linux-gnu
release: 1.97.0-nightly
LLVM version: 22.1.4

Possibly related line of code:

rust/compiler/rustc_symbol_mangling/src/v0.rs

Lines 832 to 844 in ffccab6

	}
	self.push("E");
	}
	}
	}
	_ => {
	bug!("symbol_names: unsupported constant of type `{}` ({:?})", ct_ty, ct);
	}
	}
	// Only cache consts that do not refer to an enclosing
	// binder (which would change depending on context).
	if !ct.has_escaping_bound_vars() {

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Clink-dead-code=true -Zcrate-attr=feature(min_generic_const_args) -Znext-solver=globally -Zcrate-attr=feature(generic_const_args) --crate-type=lib

Program output

warning: the feature `lazy_type_alias` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:1:30
  |
1 | #![feature(adt_const_params, lazy_type_alias)]
  |                              ^^^^^^^^^^^^^^^
  |
  = note: see issue #112792 <https://github.com/rust-lang/rust/issues/112792> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:12
  |
1 | #![feature(min_generic_const_args)]
  |            ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information

warning: the feature `generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:12
  |
1 | #![feature(generic_const_args)]
  |            ^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #151972 <https://github.com/rust-lang/rust/issues/151972> for more information

warning: type alias `Matrix` is never used
 --> /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:2:6
  |
2 | type Matrix = [usize; 1];
  |      ^^^^^^
  |
  = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default

warning: constant `EMPTY_MATRIX` is never used
 --> /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:3:7
  |
3 | const EMPTY_MATRIX: Matrix = [1];
  |       ^^^^^^^^^^^^

warning: struct `Walk` is never constructed
 --> /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:4:8
  |
4 | struct Walk<const REMAINING: Matrix>;
  |        ^^^^

warning: associated function `new` is never used
 --> /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:6:8
  |
5 | impl Walk<EMPTY_MATRIX> {
  | ----------------------- associated function in this implementation
6 |     fn new() {}
  |        ^^^

error: internal compiler error: /rustc-dev/ffccab6abef68b70c5e23cfbfb1ac7680104040d/compiler/rustc_symbol_mangling/src/v0.rs:838:17: symbol_names: unsupported constant of type `Matrix` (Branch([1_usize]): Matrix)


thread 'rustc' (3925605) panicked at /rustc-dev/ffccab6abef68b70c5e23cfbfb1ac7680104040d/compiler/rustc_symbol_mangling/src/v0.rs:838:17:
Box<dyn Any>
stack backtrace:
   0:     0x7f370c065859 - <<std[b44b2a9af91b8814]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[5fd9be8f539cadc0]::fmt::Display>::fmt
   1:     0x7f370c61b748 - core[5fd9be8f539cadc0]::fmt::write
   2:     0x7f370c07c286 - <std[b44b2a9af91b8814]::sys::stdio::unix::Stderr as std[b44b2a9af91b8814]::io::Write>::write_fmt
   3:     0x7f370c03b8fe - std[b44b2a9af91b8814]::panicking::default_hook::{closure#0}
   4:     0x7f370c058f13 - std[b44b2a9af91b8814]::panicking::default_hook
   5:     0x7f370af4a431 - std[b44b2a9af91b8814]::panicking::update_hook::<alloc[52580bf504f902c0]::boxed::Box<rustc_driver_impl[b097e61246baddd0]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7f370c0591f2 - std[b44b2a9af91b8814]::panicking::panic_with_hook
   7:     0x7f370af77e91 - std[b44b2a9af91b8814]::panicking::begin_panic::<rustc_errors[7dc0ae575d2f60e7]::ExplicitBug>::{closure#0}
   8:     0x7f370af70e86 - std[b44b2a9af91b8814]::sys::backtrace::__rust_end_short_backtrace::<std[b44b2a9af91b8814]::panicking::begin_panic<rustc_errors[7dc0ae575d2f60e7]::ExplicitBug>::{closure#0}, !>
   9:     0x7f370af70beb - std[b44b2a9af91b8814]::panicking::begin_panic::<rustc_errors[7dc0ae575d2f60e7]::ExplicitBug>
  10:     0x7f370af83371 - <rustc_errors[7dc0ae575d2f60e7]::diagnostic::BugAbort as rustc_errors[7dc0ae575d2f60e7]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7f370b5908f9 - rustc_middle[a2cb8ab9f4e9488e]::util::bug::opt_span_bug_fmt::<rustc_span[d4e956e734626f0]::span_encoding::Span>::{closure#0}
  12:     0x7f370b590a62 - rustc_middle[a2cb8ab9f4e9488e]::ty::context::tls::with_opt::<rustc_middle[a2cb8ab9f4e9488e]::util::bug::opt_span_bug_fmt<rustc_span[d4e956e734626f0]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  13:     0x7f370b57f6cb - rustc_middle[a2cb8ab9f4e9488e]::ty::context::tls::with_context_opt::<rustc_middle[a2cb8ab9f4e9488e]::ty::context::tls::with_opt<rustc_middle[a2cb8ab9f4e9488e]::util::bug::opt_span_bug_fmt<rustc_span[d4e956e734626f0]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  14:     0x7f3708f61b24 - rustc_middle[a2cb8ab9f4e9488e]::util::bug::bug_fmt
  15:     0x7f370e213afd - <rustc_symbol_mangling[9c5633ec7d669aa9]::v0::V0SymbolMangler as rustc_middle[a2cb8ab9f4e9488e]::ty::print::Printer>::print_const.cold
  16:     0x7f370cfa0c9f - <rustc_symbol_mangling[9c5633ec7d669aa9]::v0::V0SymbolMangler as rustc_middle[a2cb8ab9f4e9488e]::ty::print::Printer>::print_def_path
  17:     0x7f370cf9c561 - <rustc_symbol_mangling[9c5633ec7d669aa9]::v0::V0SymbolMangler as rustc_middle[a2cb8ab9f4e9488e]::ty::print::Printer>::print_type
  18:     0x7f370cf9efeb - <rustc_symbol_mangling[9c5633ec7d669aa9]::v0::V0SymbolMangler as rustc_middle[a2cb8ab9f4e9488e]::ty::print::Printer>::print_def_path
  19:     0x7f370cf9d564 - <rustc_symbol_mangling[9c5633ec7d669aa9]::v0::V0SymbolMangler as rustc_middle[a2cb8ab9f4e9488e]::ty::print::Printer>::print_def_path
  20:     0x7f370cf99401 - rustc_symbol_mangling[9c5633ec7d669aa9]::symbol_name_provider
  21:     0x7f370cf987d5 - rustc_query_impl[469555595b0d02a6]::query_impl::symbol_name::invoke_provider_fn::__rust_begin_short_backtrace
  22:     0x7f370cf977b0 - rustc_query_impl[469555595b0d02a6]::execution::try_execute_query::<rustc_middle[a2cb8ab9f4e9488e]::query::caches::DefaultCache<rustc_middle[a2cb8ab9f4e9488e]::ty::instance::Instance, rustc_middle[a2cb8ab9f4e9488e]::query::erase::ErasedData<[u8; 16usize]>>, false>
  23:     0x7f370cf97442 - rustc_query_impl[469555595b0d02a6]::query_impl::symbol_name::execute_query_non_incr::__rust_end_short_backtrace
  24:     0x7f370cf96f43 - rustc_monomorphize[5ab1e60d2de18f3f]::partitioning::assert_symbols_are_distinct::<core[5fd9be8f539cadc0]::slice::iter::Iter<rustc_middle[a2cb8ab9f4e9488e]::mono::MonoItem>>
  25:     0x7f370d10f1a1 - rustc_monomorphize[5ab1e60d2de18f3f]::partitioning::collect_and_partition_mono_items
  26:     0x7f370d78a7e0 - rustc_query_impl[469555595b0d02a6]::query_impl::collect_and_partition_mono_items::invoke_provider_fn::__rust_begin_short_backtrace
  27:     0x7f370d78a136 - rustc_query_impl[469555595b0d02a6]::execution::try_execute_query::<rustc_middle[a2cb8ab9f4e9488e]::query::caches::SingleCache<rustc_middle[a2cb8ab9f4e9488e]::query::erase::ErasedData<[u8; 24usize]>>, false>
  28:     0x7f370d789ecc - rustc_query_impl[469555595b0d02a6]::query_impl::collect_and_partition_mono_items::execute_query_non_incr::__rust_end_short_backtrace
  29:     0x7f370cfe4e9f - rustc_codegen_ssa[a1f415a7bf6a480b]::back::symbol_export::exported_generic_symbols_provider_local
  30:     0x7f370d5d3e68 - rustc_query_impl[469555595b0d02a6]::query_impl::exported_generic_symbols::invoke_provider_fn::__rust_begin_short_backtrace
  31:     0x7f370d5d20f1 - rustc_query_impl[469555595b0d02a6]::execution::try_execute_query::<rustc_data_structures[fddbf0b6d549df5f]::vec_cache::VecCache<rustc_span[d4e956e734626f0]::def_id::CrateNum, rustc_middle[a2cb8ab9f4e9488e]::query::erase::ErasedData<[u8; 16usize]>, rustc_middle[a2cb8ab9f4e9488e]::dep_graph::graph::DepNodeIndex>, false>
  32:     0x7f370d5d1c03 - rustc_query_impl[469555595b0d02a6]::query_impl::exported_generic_symbols::execute_query_non_incr::__rust_end_short_backtrace
  33:     0x7f370d5eb9d4 - <rustc_metadata[bac4f2ae346852a7]::rmeta::encoder::EncodeContext>::encode_crate_root
  34:     0x7f370d95e5a3 - rustc_metadata[bac4f2ae346852a7]::rmeta::encoder::encode_metadata::{closure#3}
  35:     0x7f370d95b8e7 - rustc_metadata[bac4f2ae346852a7]::rmeta::encoder::encode_metadata
  36:     0x7f370d29bfcb - rustc_metadata[bac4f2ae346852a7]::fs::encode_and_write_metadata
  37:     0x7f370d7d70fb - <rustc_interface[4f993990338980d2]::queries::Linker>::codegen_and_build_linker
  38:     0x7f370d7d18cb - rustc_interface[4f993990338980d2]::interface::run_compiler::<(), rustc_driver_impl[b097e61246baddd0]::run_compiler::{closure#0}>::{closure#1}
  39:     0x7f370d78187e - std[b44b2a9af91b8814]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[4f993990338980d2]::util::run_in_thread_with_globals<rustc_interface[4f993990338980d2]::util::run_in_thread_pool_with_globals<rustc_interface[4f993990338980d2]::interface::run_compiler<(), rustc_driver_impl[b097e61246baddd0]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  40:     0x7f370d781f6d - <std[b44b2a9af91b8814]::thread::lifecycle::spawn_unchecked<rustc_interface[4f993990338980d2]::util::run_in_thread_with_globals<rustc_interface[4f993990338980d2]::util::run_in_thread_pool_with_globals<rustc_interface[4f993990338980d2]::interface::run_compiler<(), rustc_driver_impl[b097e61246baddd0]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[5fd9be8f539cadc0]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  41:     0x7f370d782d6c - <std[b44b2a9af91b8814]::sys::thread::unix::Thread>::new::thread_start
  42:     0x7f37072a597a - <unknown>
  43:     0x7f37073292bc - <unknown>
  44:                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: please make sure that you have updated to the latest nightly

note: rustc 1.97.0-nightly (ffccab6ab 2026-05-07) running on x86_64-unknown-linux-gnu

note: compiler flags: -C link-dead-code=true -Z crate-attr=feature(min_generic_const_args) -Z next-solver=globally -Z crate-attr=feature(generic_const_args) --crate-type lib -Z dump-mir-dir=dir

query stack during panic:
#0 [symbol_name] computing the symbol for `<impl at /tmp/icemaker_global_tempdir.WwBfTMxQwjZ9/rustc_testrunner_tmpdir_reporting.JLhyj1UfHy23/mvce.rs:5:1: 5:24>::new`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
#2 [exported_generic_symbols] collecting exported generic symbols for crate `0`
end of query stack
error: aborting due to 1 previous error; 7 warnings emitted

@rustbot label +F-adt_const_params +F-lazy_type_alias +F-min_generic_const_args +F-generic_const_args +WG-trait-system-refactor

[matthiaskrgr]

since #155341