Internal compiler error on malformed match arm pattern #54379
Description
The compiler panics when trying to compile the following code:
pub struct MyStruct { pub value: u64, pub s1: Option<String>, } fn main() { let v = vec![]; for thing in v.iter() { match thing { MyStruct { .., Some(_) } => {} _ => {} } } }Expectation: A compiler error complaining about the malformed match guard pattern.
Actual result: A compiler panic
error: internal compiler error: Error constructed but not emitted thread 'main' panicked at 'explicit panic', librustc_errors\diagnostic_builder.rs:308:13 Meta
This happens with both the lastest stable and nightly versions:
$ rustc +nightly --version --verbose rustc 1.30.0-nightly (20dc0c507 2018-09-19) binary: rustc commit-hash: 20dc0c50704ba1fc8c56a88ae2bf05ddb3e419bc commit-date: 2018-09-19 host: x86_64-pc-windows-msvc release: 1.30.0-nightly LLVM version: 8.0 $ rustc +stable --version --verbose rustc 1.29.0 (aa3ca1994 2018-09-11) binary: rustc commit-hash: aa3ca1994904f2e056679fce1f185db8c7ed2703 commit-date: 2018-09-11 host: x86_64-pc-windows-msvc release: 1.29.0 LLVM version: 7.0 Backtrace (nightly):
$ rustc +nightly src\main.rs error: internal compiler error: Error constructed but not emitted thread 'main' panicked at 'explicit panic', librustc_errors\diagnostic_builder.rs:308:13 stack backtrace: 0: <std::sync::barrier::BarrierWaitResult as core::fmt::Debug>::fmt 1: std::io::error::Error::get_ref 2: std::panicking::take_hook 3: std::panicking::take_hook 4: std::panicking::rust_panic_with_hook 5: <rustc_errors::diagnostic::SubDiagnostic as core::fmt::Debug>::fmt 6: <rustc_errors::diagnostic_builder::DiagnosticBuilder<'a> as core::ops::drop::Drop>::drop 7: syntax::parse::parser::Parser::parse_expr 8: syntax::parse::parser::Parser::parse_pat 9: syntax::parse::parser::Parser::parse_expr 10: syntax::parse::parser::Parser::parse_expr 11: syntax::parse::parser::Parser::parse_async_block 12: syntax::parse::parser::Parser::mk_mac_expr 13: syntax::parse::parser::Parser::mk_mac_expr 14: syntax::parse::parser::Parser::parse_tokens 15: syntax::parse::parser::Parser::parse_tokens 16: syntax::parse::parser::Parser::parse_stmt 17: syntax::parse::parser::Parser::parse_block 18: syntax::parse::parser::Parser::parse_block 19: syntax::parse::parser::Parser::parse_block 20: syntax::parse::parser::Parser::parse_tokens 21: syntax::parse::parser::Parser::mk_mac_expr 22: syntax::parse::parser::Parser::mk_mac_expr 23: syntax::parse::parser::Parser::parse_tokens 24: syntax::parse::parser::Parser::parse_tokens 25: syntax::parse::parser::Parser::parse_stmt 26: syntax::parse::parser::Parser::parse_block 27: syntax::parse::parser::Parser::parse_block 28: syntax::parse::parser::Parser::parse_block 29: syntax::parse::parser::Parser::parse_block 30: syntax::parse::parser::Parser::default_submod_path 31: syntax::parse::parser::Parser::default_submod_path 32: syntax::parse::parser::Parser::parse_item 33: syntax::parse::parser::Parser::parse_visibility 34: syntax::parse::parser::Parser::parse_crate_mod 35: syntax::parse::parse_crate_from_file 36: rustc_driver::target_features::add_configuration 37: rustc_driver::target_features::add_configuration 38: rustc_driver::driver::phase_1_parse_input 39: rustc_driver::driver::compile_input 40: rustc_driver::run_compiler 41: rustc_driver::target_features::add_configuration 42: rustc_driver::run_compiler 43: rustc_driver::target_features::add_configuration 44: _rust_maybe_catch_panic 45: rustc_driver::profile::dump 46: rustc_driver::main 47: <unknown> 48: std::panicking::update_panic_count 49: _rust_maybe_catch_panic 50: std::rt::lang_start_internal 51: <unknown> 52: <unknown> 53: BaseThreadInitThunk 54: RtlUserThreadStart error: aborting due to previous error Backtrace (stable):
$ rustc +stable src\main.rs error: internal compiler error: Error constructed but not emitted thread 'main' panicked at 'explicit panic', librustc_errors\diagnostic_builder.rs:250:13 stack backtrace: 0: <std::sync::mpsc::RecvTimeoutError as core::fmt::Debug>::fmt 1: <std::sys::windows::dynamic_lib::DynamicLibrary as core::ops::drop::Drop>::drop 2: std::panicking::take_hook 3: std::panicking::take_hook 4: std::panicking::rust_panic_with_hook 5: <rustc_errors::emitter::ColorConfig as core::fmt::Debug>::fmt 6: <rustc_errors::diagnostic_builder::DiagnosticBuilder<'a> as core::ops::drop::Drop>::drop 7: syntax::parse::parser::Parser::parse_expr 8: syntax::parse::parser::Parser::parse_pat 9: syntax::parse::parser::Parser::parse_expr 10: syntax::parse::parser::Parser::parse_expr 11: syntax::parse::parser::Parser::parse_async_block 12: syntax::parse::parser::Parser::mk_mac_expr 13: syntax::parse::parser::Parser::mk_mac_expr 14: syntax::parse::parser::Parser::parse_tokens 15: syntax::parse::parser::Parser::parse_tokens 16: syntax::parse::parser::Parser::parse_stmt 17: syntax::parse::parser::Parser::parse_block 18: syntax::parse::parser::Parser::parse_block 19: syntax::parse::parser::Parser::parse_block 20: syntax::parse::parser::Parser::parse_tokens 21: syntax::parse::parser::Parser::mk_mac_expr 22: syntax::parse::parser::Parser::mk_mac_expr 23: syntax::parse::parser::Parser::parse_tokens 24: syntax::parse::parser::Parser::parse_tokens 25: syntax::parse::parser::Parser::parse_stmt 26: syntax::parse::parser::Parser::parse_block 27: syntax::parse::parser::Parser::parse_block 28: syntax::parse::parser::Parser::parse_block 29: syntax::parse::parser::Parser::parse_block 30: syntax::parse::parser::Parser::default_submod_path 31: syntax::parse::parser::Parser::default_submod_path 32: syntax::parse::parser::Parser::parse_item 33: syntax::parse::parser::Parser::parse_visibility 34: syntax::parse::parser::Parser::parse_crate_mod 35: syntax::parse::parse_crate_from_file 36: <rustc_driver::derive_registrar::Finder as rustc::hir::itemlikevisit::ItemLikeVisitor<'v>>::visit_item 37: <rustc_driver::derive_registrar::Finder as rustc::hir::itemlikevisit::ItemLikeVisitor<'v>>::visit_item 38: rustc_driver::driver::phase_1_parse_input 39: rustc_driver::driver::compile_input 40: rustc_driver::run_compiler 41: <rustc_driver::profile::trace::Query as core::fmt::Debug>::fmt 42: <rustc_driver::derive_registrar::Finder as rustc::hir::itemlikevisit::ItemLikeVisitor<'v>>::visit_item 43: _rust_maybe_catch_panic 44: rustc_driver::profile::dump 45: rustc_driver::main 46: <unknown> 47: std::panicking::update_panic_count 48: _rust_maybe_catch_panic 49: std::rt::lang_start_internal 50: <unknown> 51: <unknown> 52: BaseThreadInitThunk 53: RtlUserThreadStart error: aborting due to previous error