Type Mismatch and ICE on Slice Constant Pattern Matching in gccrs

Reproduce the failure with the Rust snippet or the linked Godbolt example, then inspect the pattern type-checking path named in the backtrace, especially TypeCheckPattern::visit in rust/typecheck/rust-tyty-util.cc. Trace both the slice-constant coercion and the match-pattern handling; done means the example compiles without the type mismatch or ICE and preserves the expected slice-content match behavior.

Summary

The provided Rust code compiles successfully with rustc but fails with gccrs due to a type mismatch and an internal compiler error (ICE). The issues occur when initializing a slice constant and using it in a pattern match.

Reproducer

I tried this code:

#![allow(dead_code)]

const PATH_DOT: &[u8] = &[b'.'];// Type mismatch error here

fn match_slice(element: &[u8]) {
    match element {
        &[] => {}
        PATH_DOT => {}// ICE occurs during type checking
        _ => {}
    }
}

fn main() {}

Does the code make use of any (1.49) nightly feature ?

• Nightly

Godbolt link

https://godbolt.org/z/8PETWKfK5

Actual behavior

:4:1: error: mismatched types, expected '& [u8]' but got '& [u8:CAPACITY]' [E0308]
4 | const PATH_DOT: &[u8] = &[b'.'];
| ^~~~~ ~ ~
:8:10: sorry, unimplemented: type checking qualified path patterns not supported
8 | &[] => {}
| ^
crab1: internal compiler error: in TyVar, at rust/typecheck/rust-tyty-util.cc:31
0x2e9eb6c internal_error(char const*, ...)
???:0
0xf5e963 fancy_abort(char const*, int, char const*)
???:0
0x12795a2 Rust::Resolver::TypeCheckPattern::visit(Rust::HIR::ReferencePattern&)
???:0
0x12793d8 Rust::Resolver::TypeCheckPattern::Resolve(Rust::HIR::Pattern*, Rust::TyTy::BaseType*)
???:0
0x127eaef Rust::Resolver::TypeCheckExpr::visit(Rust::HIR::MatchExpr&)
???:0
0x127bd13 Rust::Resolver::TypeCheckExpr::Resolve(Rust::HIR::Expr*)
???:0
0x127d11d Rust::Resolver::TypeCheckExpr::visit(Rust::HIR::BlockExpr&)
???:0
0x127bd13 Rust::Resolver::TypeCheckExpr::Resolve(Rust::HIR::Expr*)
???:0
0x126a82b Rust::Resolver::TypeCheckItem::visit(Rust::HIR::Function&)
???:0
0x1263750 Rust::Resolver::TypeCheckItem::Resolve(Rust::HIR::Item&)
???:0
0x122427b Rust::Resolver::TypeResolution::Resolve(Rust::HIR::Crate&)
???:0
0x109a454 Rust::Session::compile_crate(char const*)
???:0
Please submit a full bug report, with preprocessed source (by using -freport-bug).
Please include the complete backtrace with any bug report.
See https://gcc.gnu.org/bugs/ for instructions.
Compiler returned: 1

Expected behavior

The code should compile successfully. The constant PATH_DOT (type &[u8]) should be initialized from &[u8; 1] via implicit array-to-slice coercion. The match arm PATH_DOT should compare slice contents structurally.

GCC Version

14.0.1