'rustc' panicked at 'called Option::unwrap() on a None value'

[dwrensha]

rustc crashes on the following input, found by fuzz_rustc:

fn`2222222222222222222222222222222222222222

error: unknown start of token: `
 --> bug2.rs:1:3
  |
1 | fn`2222222222222222222222222222222222222222
  |   ^
  |
help: Unicode character '`' (Grave Accent) looks like ''' (Single Quote), but it is not
  |
1 | fn'2222222222222222222222222222222222222222
  |   ~

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', compiler/rustc_parse/src/parser/diagnostics.rs:430:49
stack backtrace:
   0:     0x7f65a4b65f8a - std::backtrace_rs::backtrace::libunwind::trace::h543e5a71eb1b5eeb
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f65a4b65f8a - std::backtrace_rs::backtrace::trace_unsynchronized::h8798c87c5fd54c42
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f65a4b65f8a - std::sys_common::backtrace::_print_fmt::h982e629a02833f3b
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f65a4b65f8a - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd16097abfc45a49a
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f65a4bca04f - core::fmt::write::haccd80b41eab472e
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/core/src/fmt/mod.rs:1254:17
   5:     0x7f65a4b58bc5 - std::io::Write::write_fmt::h578b3def4330fd2b
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/io/mod.rs:1698:15
   6:     0x7f65a4b65d55 - std::sys_common::backtrace::_print::he237786f41276d1a
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f65a4b65d55 - std::sys_common::backtrace::print::h504fa2bef175cc1e
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f65a4b689fe - std::panicking::default_hook::{{closure}}::hac9a65d5f66db25e
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:269:22
   9:     0x7f65a4b687a5 - std::panicking::default_hook::h4e334937c58bdca9
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:288:9
  10:     0x7f65a7e73635 - rustc_driver_impl[bd452c501c51eef0]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f65a4b691f4 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h2c058cd2c0afd653
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/alloc/src/boxed.rs:1990:9
  12:     0x7f65a4b691f4 - std::panicking::rust_panic_with_hook::h1fcbef96fdc6ec0c
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:694:13
  13:     0x7f65a4b68f22 - std::panicking::begin_panic_handler::{{closure}}::h246d986a28aa7c83
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:579:13
  14:     0x7f65a4b663f6 - std::sys_common::backtrace::__rust_end_short_backtrace::h99f10a55eb368f21
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys_common/backtrace.rs:150:18
  15:     0x7f65a4b68cc2 - rust_begin_unwind
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:577:5
  16:     0x7f65a4bc6363 - core::panicking::panic_fmt::h493527ddc74034ba
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/core/src/panicking.rs:67:14
  17:     0x7f65a4bc63fd - core::panicking::panic::hb2955f7731e01f3f
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/core/src/panicking.rs:117:5
  18:     0x7f65a6e53556 - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::expected_ident_found
  19:     0x7f65a6e14a3e - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::parse_ident_common
  20:     0x7f65a6e06245 - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::parse_fn
  21:     0x7f65a6df3df8 - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::parse_item_kind
  22:     0x7f65a6df0449 - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::parse_item_common
  23:     0x7f65a6b71b18 - <rustc_parse[77f428f3632bd5e8]::parser::Parser>::parse_mod
  24:     0x7f65a70c66d8 - rustc_parse[77f428f3632bd5e8]::parse_crate_from_file
  25:     0x7f65a70c62bf - <rustc_session[8a142d07c6ec552f]::session::Session>::time::<core[d2a11d220902df1]::result::Result<rustc_ast[ce4ca91d19d8f3b]::ast::Crate, rustc_errors[b273ccddd230f82e]::diagnostic_builder::DiagnosticBuilder<rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>, rustc_interface[c7956fe9641ea70c]::passes::parse::{closure#0}>
  26:     0x7f65a70c09ff - rustc_interface[c7956fe9641ea70c]::passes::parse
  27:     0x7f65a70c0134 - <rustc_interface[c7956fe9641ea70c]::queries::Queries>::parse
  28:     0x7f65a70bf650 - <rustc_interface[c7956fe9641ea70c]::interface::Compiler>::enter::<rustc_driver_impl[bd452c501c51eef0]::run_compiler::{closure#1}::{closure#2}, core[d2a11d220902df1]::result::Result<core[d2a11d220902df1]::option::Option<rustc_interface[c7956fe9641ea70c]::queries::Linker>, rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>
  29:     0x7f65a70baae1 - rustc_span[b847b06bcddf9aef]::set_source_map::<core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>, rustc_interface[c7956fe9641ea70c]::interface::run_compiler<core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>, rustc_driver_impl[bd452c501c51eef0]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  30:     0x7f65a70ba08f - std[1137eeb067dcff5d]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[c7956fe9641ea70c]::util::run_in_thread_pool_with_globals<rustc_interface[c7956fe9641ea70c]::interface::run_compiler<core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>, rustc_driver_impl[bd452c501c51eef0]::run_compiler::{closure#1}>::{closure#0}, core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>
  31:     0x7f65a77278b1 - <<std[1137eeb067dcff5d]::thread::Builder>::spawn_unchecked_<rustc_interface[c7956fe9641ea70c]::util::run_in_thread_pool_with_globals<rustc_interface[c7956fe9641ea70c]::interface::run_compiler<core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>, rustc_driver_impl[bd452c501c51eef0]::run_compiler::{closure#1}>::{closure#0}, core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d2a11d220902df1]::result::Result<(), rustc_span[b847b06bcddf9aef]::ErrorGuaranteed>>::{closure#1} as core[d2a11d220902df1]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  32:     0x7f65a4b732d5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hcb3c543eabd3883a
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/alloc/src/boxed.rs:1976:9
  33:     0x7f65a4b732d5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h4c6155c5f5f14f7d
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/alloc/src/boxed.rs:1976:9
  34:     0x7f65a4b732d5 - std::sys::unix::thread::Thread::new::thread_start::he5347f8288d9936e
                               at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/sys/unix/thread.rs:108:17
  35:     0x7f65a4894b43 - start_thread
                               at ./nptl/./nptl/pthread_create.c:442:8
  36:     0x7f65a4926a00 - clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
  37:                0x0 - <unknown>

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: rustc 1.70.0-nightly (2eaeb1eee 2023-04-05) running on x86_64-unknown-linux-gnu

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

[dwrensha]

searched nightlies: from nightly-2022-03-27 to nightly-2023-04-05
regressed nightly: nightly-2023-03-24
searched commit range: a266f11...1459b31
regressed commit: 84dd6df

bisected with cargo-bisect-rustc v0.6.6

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --end=2023-04-05 --regress ice 

[dwrensha]

Attempting to search unrolled perf builds
Found commits ["fe8da10f", "1fa4eb1d", "879a5ec7", "ca7d1e93", "23779c7b", "ebeccc8e", "82edea25", "bfaae772", "6331a0c6"]
...
installing bfaae77226bf50fc37da98b8cf5781dcc97ad3a0
rust-std-nightly-x86_64-unknown-linux-gnu: 28.88 MB / 28.88 MB [=========================================================] 100.00 % 8.90 MB/s testing...
RESULT: bfaae77226bf50fc37da98b8cf5781dcc97ad3a0, ===> Yes
uninstalling bfaae77226bf50fc37da98b8cf5781dcc97ad3a0

Regression in https://github.com/rust-lang-ci/rust/commit/bfaae77226bf50fc37da98b8cf5781dcc97ad3a0

[dwrensha]

Looks like this regressed in #109203. cc @Ezrashaw