Internal error if license check fails #3679
Description
When the license header in rust code file doesn't match license template, cargo fmt would panic with internal error: entered unreachable code.
Backtrace is as follows:
$ RUST_BACKTRACE=1 cargo fmt
thread 'main' panicked at 'internal error: entered unreachable code', src/tools/rustfmt/src/formatting.rs:322:18
stack backtrace:
0: std::panicking::default_hook::{{closure}}
1: std::panicking::default_hook
2: std::panicking::rust_panic_with_hook
3: std::panicking::begin_panic
4: <rustfmt_nightly::format_report_formatter::FormatReportFormatter as core::fmt::Display>::fmt
5: core::fmt::write
6: <std::io::stdio::Stderr as std::io::Write>::write_fmt
7: std::io::stdio::_eprint
8: rustfmt::format_and_emit_report
9: rustfmt_nightly::Session<T>::override_config
10: rustfmt::execute
11: rustfmt::main
12: std::rt::lang_start::{{closure}}
13: std::panicking::try::do_call
14: __rust_maybe_catch_panic
15: std::rt::lang_start_internal
16: main
Meta
$ rustc --version --verbose
rustc 1.38.0-nightly (cd2cd4c96 2019-07-10)
binary: rustc
commit-hash: cd2cd4c9627e52c33e68e8c93a8916dc11094cbb
commit-date: 2019-07-10
host: x86_64-apple-darwin
release: 1.38.0-nightly
LLVM version: 8.0
$ cargo fmt --version
rustfmt 1.3.0-nightly (d3345024 2019-06-09)
Demo
I created a repo reproducing this issue at here.