ICE when match arms have incompatible types

JuanSamuelVB commented 4 years ago

Code:

struct A { }

impl A {
    fn f(self) {
        let mut i: i64 = 0;

        match i {
            1 => true,
            2 => true,
            3 => i = 1,
            _ => (),
        }

        println!("{}", i);
    }
}

fn main() { }

Playground

Backtrace

hellow554 commented 4 years ago

@rustbot modify labels: I-ICE C-Bug T-compiler A-mir

Regression from 1.34 to 1.35

Patryk27 commented 4 years ago

Additionally, this one ICEs with different error message:

fn main() {
    let mut i: i64;

    match i {
        1 => true,
        2 => true,
        3 => i = 1,
        _ => (),
    }
}

(playground)

Backtrace

``` warning: value assigned to `i` is never read --> src/main.rs:7:14 | 7 | 3 => i = 1, | ^ | = note: `#[warn(unused_assignments)]` on by default = help: maybe it is overwritten before being read? error: internal compiler error: src/librustc_codegen_llvm/context.rs:872: failed to get layout for `[type error]`: the type `[type error]` has an unknown layout thread 'rustc' panicked at 'Box', src/librustc_errors/lib.rs:812:9 stack backtrace: 0: backtrace::backtrace::libunwind::trace at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/libunwind.rs:88 1: backtrace::backtrace::trace_unsynchronized at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/mod.rs:66 2: std::sys_common::backtrace::_print_fmt at src/libstd/sys_common/backtrace.rs:76 3: ::fmt at src/libstd/sys_common/backtrace.rs:60 4: core::fmt::write at src/libcore/fmt/mod.rs:1030 5: std::io::Write::write_fmt at src/libstd/io/mod.rs:1412 6: std::sys_common::backtrace::_print at src/libstd/sys_common/backtrace.rs:64 7: std::sys_common::backtrace::print at src/libstd/sys_common/backtrace.rs:49 8: std::panicking::default_hook::{{closure}} at src/libstd/panicking.rs:196 9: std::panicking::default_hook at src/libstd/panicking.rs:210 10: rustc_driver::report_ice 11: std::panicking::rust_panic_with_hook at src/libstd/panicking.rs:477 12: std::panicking::begin_panic 13: rustc_errors::HandlerInner::bug 14: rustc_errors::Handler::bug 15: rustc::util::bug::opt_span_bug_fmt::{{closure}} 16: rustc::ty::context::tls::with_opt::{{closure}} 17: rustc::ty::context::tls::with_context_opt 18: rustc::ty::context::tls::with_opt 19: rustc::util::bug::opt_span_bug_fmt 20: rustc::util::bug::bug_fmt 21: ::spanned_layout_of::{{closure}} 22: ::spanned_layout_of 23: rustc_codegen_ssa::mir::analyze::non_ssa_locals 24: rustc_codegen_ssa::mir::codegen_mir 25: rustc_codegen_ssa::base::codegen_instance 26: ::define 27: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen 28: rustc::dep_graph::graph::DepGraph::with_task 29: rustc_codegen_llvm::base::compile_codegen_unit 30: rustc_codegen_ssa::base::codegen_crate 31: ::codegen_crate 32: rustc::util::common::time 33: rustc_interface::passes::start_codegen 34: rustc::ty::context::tls::enter_global 35: rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}} 36: rustc_interface::passes::create_global_ctxt::{{closure}} 37: rustc_interface::passes::BoxedGlobalCtxt::enter 38: rustc_interface::queries::Query::compute 39: rustc_interface::queries::::ongoing_codegen 40: rustc_interface::interface::run_compiler_in_existing_thread_pool 41: std::thread::local::LocalKey::with 42: scoped_tls::ScopedKey::set 43: syntax::with_globals note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.39.0 (4560ea788 2019-11-04) running on x86_64-unknown-linux-gnu note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin note: some of the compiler flags provided by cargo are hidden query stack during panic: end of query stack error: aborting due to previous error error: could not compile `playground`. To learn more, run the command again with --verbose.. ```

jonas-schievink commented 4 years ago

This code should not get all the way to codegen without an error

hellow554 commented 4 years ago

Another, different ICE?

Backtrace

``` error: internal compiler error[E0308]: match arms have incompatible types --> src/main.rs:6:14 | 3 | / match 0_i32 { 4 | | 0 => true, | | ---- this is found to be of type `bool` 5 | | 1 => true, | | ---- this is found to be of type `bool` 6 | | _ => i = (), | | ^^^^^^ expected `bool`, found `()` 7 | | }; | |_____- `match` arms have incompatible types error: internal compiler error: cat_expr Errd --> src/main.rs:1:11 | 1 | fn main() { | ___________^ 2 | | let i; 3 | | match 0_i32 { 4 | | 0 => true, ... | 7 | | }; 8 | | } | |_^ error: internal compiler error: cat_expr Errd --> src/main.rs:3:5 | 3 | / match 0_i32 { 4 | | 0 => true, 5 | | 1 => true, 6 | | _ => i = (), 7 | | }; | |_____^ error: internal compiler error: PromoteTemps: MIR had errors --> src/main.rs:1:1 | 1 | / fn main() { 2 | | let i; 3 | | match 0_i32 { 4 | | 0 => true, ... | 7 | | }; 8 | | } | |_^ error: internal compiler error: broken MIR in DefId(0:3 ~ foo[a7ed]::main[0]) ("return type"): bad type [type error] --> src/main.rs:1:1 | 1 | / fn main() { 2 | | let i; 3 | | match 0_i32 { 4 | | 0 => true, ... | 7 | | }; 8 | | } | |_^ error: internal compiler error: broken MIR in DefId(0:3 ~ foo[a7ed]::main[0]) (LocalDecl { mutability: Mut, local_info: Other, internal: false, is_block_tail: None, ty: [type error], user_ty: UserTypeProjections { contents: [] }, source_info: SourceInfo { span: src/main.rs:1:1: 8:2, scope: scope[0] } }): bad type [type error] --> src/main.rs:1:1 | 1 | / fn main() { 2 | | let i; 3 | | match 0_i32 { 4 | | 0 => true, ... | 7 | | }; 8 | | } | |_^ thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:347:17 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/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.41.0-nightly (27d6f55f4 2019-12-11) running on x86_64-unknown-linux-gnu note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin note: some of the compiler flags provided by cargo are hidden ```

hellow554 commented 4 years ago

Regression somewhere between 33ef0bad2...237bf3244

jonas-schievink commented 4 years ago

https://github.com/rust-lang/rust/pull/59439 looks suspicious, cc @Centril

In particular, maybe is_assign_to_bool is falsly returning true here since the expected type is bool due to the other match arms?

    pub fn is_assign_to_bool(&self, expr: &hir::Expr, expected: Ty<'tcx>) -> bool {
        if let hir::ExprKind::Assign(..) = expr.node {
            return expected == self.tcx.types.bool;
        }
        false
    }

Centril commented 4 years ago

$ RUST_BACKTRACE=1 rustc +gamma-stage1 foo.rs -Z no-codegen -Z report-delayed-bugs -Z treat-err-as-bug=1
error: internal compiler error[E0308]: match arms have incompatible types
 --> foo.rs:7:14
  |
4 | /     match i {
5 | |         1 => true,
  | |              ---- this is found to be of type `bool`
6 | |         2 => true,
  | |              ---- this is found to be of type `bool`
7 | |         3 => i = 1,
  | |              ^^^^^ expected `bool`, found `()`
8 | |         _ => (),
9 | |     }
  | |_____- `match` arms have incompatible types

thread 'rustc' panicked at 'aborting due to `-Z treat-err-as-bug=1`', src/librustc_errors/lib.rs:921:13stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: std::io::Write::write_fmt
   3: std::panicking::default_hook::{{closure}}
   4: std::panicking::default_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: std::panicking::begin_panic
   8: rustc_errors::HandlerInner::emit_diagnostic
   9: rustc_errors::HandlerInner::delay_as_bug
  10: rustc_errors::Handler::delay_as_bug
  11: rustc_errors::diagnostic_builder::DiagnosticBuilder::delay_as_bug
  12: rustc_typeck::check::coercion::CoerceMany<E>::coerce_inner
  13: rustc_typeck::check::_match::<impl rustc_typeck::check::FnCtxt>::check_match
  14: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  15: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  16: rustc_typeck::check::FnCtxt::with_breakable_ctxt
  17: rustc_typeck::check::FnCtxt::check_block_with_expected
  18: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_kind
  19: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation_and_needs
  20: rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_return_expr
  21: rustc_typeck::check::check_fn
  22: rustc::ty::context::tls::with_context::{{closure}}
  23: rustc::ty::context::GlobalCtxt::enter_local
  24: rustc_typeck::check::typeck_tables_of
  25: rustc::ty::query::__query_compute::typeck_tables_of
  26: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::typeck_tables_of>::compute
  27: rustc::dep_graph::graph::DepGraph::with_task_impl
  28: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  29: rustc::ty::<impl rustc::ty::context::TyCtxt>::par_body_owners
  30: rustc_typeck::check::typeck_item_bodies
  31: rustc::ty::query::__query_compute::typeck_item_bodies
  32: rustc::dep_graph::graph::DepGraph::with_task_impl
  33: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  34: rustc::util::common::time
  35: rustc_typeck::check_crate
  36: rustc_interface::passes::analysis
  37: rustc::ty::query::__query_compute::analysis
  38: rustc::dep_graph::graph::DepGraph::with_task_impl
  39: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  40: rustc::ty::context::tls::enter_global
  41: rustc_interface::interface::run_compiler_in_existing_thread_pool
  42: std::thread::local::LocalKey<T>::with
  43: scoped_tls::ScopedKey<T>::set
  44: syntax::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose 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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.41.0-dev running on x86_64-unknown-linux-gnu

note: compiler flags: -Z no-codegen -Z report-delayed-bugs -Z treat-err-as-bug=1

query stack during panic:
#0 [typeck_tables_of] processing `main`
#1 [typeck_item_bodies] type-checking all item bodies
#2 [analysis] running analysis passes on this crate
end of query stack

rust-lang / rust

ICE when match arms have incompatible types #67273