segfault pp_token_begin_quote

auto-reduced (treereduce-rust):

//@compile-flags: -frust-incomplete-and-experimental-compiler-do-not-use -frust-crate-attr=no_core
/// 1

/// 6
#[print_attr(nodebug)]
macro_rules! ice {

    ( ice; ) => {

        ice!
    };
    ( { ice; } ) => {
        !;

        !
    };

}

ice! {
    ice;
}

original:

/// 1
#[rustfmt::attr2]
#[doc = "3"]
#[print_attr(nodebug)]
#[doc = "4"]
#[rustfmt::attr5]
/// 6
#[print_attr(nodebug)]
macro_rules! ice {
    // Entry point
    ( ice; ) => {
        // Just add braces
        ice! {{ ice; }}
    };
    ( { ice; } ) => {
        log_syntax!("Done");

        ice! { { } ice; }
    };
    ( { } ice; ) => {
        log_syntax!("Done");

        pub trait ThisWillIce {
            log_syntax!("Oh no!");
        }
    }
}

ice! {
    ice;
}

fn main() {
}

Version information:

cbf530387eaad3a200962a0937fea59fb0fca0a8

Command:
/home/matthias/vcs/github/gccrs/gccrs-build/gcc/crab1 -frust-incomplete-and-experimental-compiler-do-not-use -frust-crate-attr=no_core

/tmp/icemaker_global_tempdir.hvweQOVIBZSr/rustc_testrunner_tmpdir_reporting.dCzRs7wYWp4p/mvce.rs:4:3: error: macro not found
    4 | #[print_attr(nodebug)]
      |   ^~~~~~~~~~
crab1: internal compiler error: Segmentation fault
0x32cc087 internal_error(char const*, ...)
	../../gcc/diagnostic-global-context.cc:787
0x1a8a0ff crash_signal
	../../gcc/toplev.cc:325
0x0 pp_token_begin_quote::~pp_token_begin_quote()
	../../gcc/../libcpp/include/label-text.h:38
/home/matthias/vcs/github/gccrs/gccrs-build/gcc/crab1 /tmp/icemaker_global_tempdir.hvweQOVIBZSr/rustc_testrunner_tmpdir_reporting.dCzRs7wYWp4p/mvce.rs -o/tmp/icemaker_global_tempdir.hvweQOVIBZSr/rustc_testrunner_tmpdir_reporting.dCzRs7wYWp4p/binaryname -frust-incomplete-and-experimental-compiler-do-not-use -frust-crate-attr=no_core
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.

Reproduce the crash with the reduced Rust input and the provided crab1 command, then inspect the backtrace around pp_token_begin_quote in label-text.h. Done means the input reports the macro error without a segmentation fault or internal compiler crash.