thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0' #89868
Description
rustc crashes on the following input, found by fuzz_rustc:
struct A<B>(B);
impl<B>A<B>{fn d(){fn d(){Self(1)}}}$ rustc main.rs
error[E0601]: `main` function not found in crate `main`
--> main.rs:1:1
|
1 | / struct A<B>(B);
2 | | impl<B>A<B>{fn d(){fn d(){Self(1)}}}
| |____________________________________^ consider adding a `main` function to `main.rs`
error[E0277]: the size for values of type `B` cannot be known at compilation time
--> main.rs:2:27
|
2 | impl<B>A<B>{fn d(){fn d(){Self(1)}}}
| - ^^^^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
|
note: required by `A`
--> main.rs:1:1
|
1 | struct A<B>(B);
| ^^^^^^^^^^^^^^^
thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', compiler/rustc_middle/src/ty/generics.rs:164:14
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: internal compiler error: unexpected panic
note: 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: rustc 1.57.0-nightly (d7c97a02d 2021-10-12) running on x86_64-unknown-linux-gnu
query stack during panic:
#0 [typeck] type-checking `<impl at main.rs:2:1: 2:37>::d::d`
#1 [typeck_item_bodies] type-checking all item bodies
end of query stack
error: aborting due to 2 previous errors