$ echo -n 'fn f(){(print!(á' > bug.rs
$ rustc bug.rs
error: this file contains an unclosed delimiter
 --> bug.rs:1:17
  |
1 | fn f(){(print!(á
  |       --      - ^
  |       ||      |
  |       ||      unclosed delimiter
  |       |unclosed delimiter
  |       unclosed delimiter

error: format argument must be a string literal
 --> bug.rs:1:16
  |
1 | fn f(){(print!(á
  |                ^
  |
help: you might be missing a string literal to format with
  |
1 | fn f(){(print!("{}", á
  |                +++++

thread 'rustc' panicked at 'assertion failed: bpos.to_u32() >= mbc.pos.to_u32() + mbc.bytes as u32', compiler/rustc_span/src/lib.rs:1710:17
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 1.59.0-nightly (83b15bfe1 2021-12-28) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack
error: aborting due to 2 previous errors