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panic: Option::unwrap() on a None value #5738

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langston-barrett opened this issue Apr 6, 2023 · 6 comments · May be fixed by #6396
Open

panic: Option::unwrap() on a None value #5738

langston-barrett opened this issue Apr 6, 2023 · 6 comments · May be fixed by #6396
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@ding-young
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bug Panic, non-idempotency, invalid code, etc. p-low

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@langston-barrett
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langston-barrett commented Apr 6, 2023 •
edited by rustbot
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This is a fuzzer-generated bug, please feel free to close and/or let me know if it's not helpful!

rustfmt 1.5.2-nightly (2eaeb1e 2023-04-05)

enum En4<'x1, 'x2, T: Tr1<As1:  >> {
    V0,
    V1,
}

enum _En5<'x1, 'x2, T: Tr1<As1:  >> {
    _V0,
    _V1,
}

enum En6
where
    T: Tr1<En2<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S>>>>>>>>>>>>>>>>>>>>>>>>,
{
    V0,
    V1,
    V2,
    V3,
}

enum _En7 
where
    T: ,
{
    V0,
    V1,
}

fn _make_en7()
where
    T: ,
{
    
}

enum EnSelf<T> where Self: Tr1<As1: > {
    V0(T),
    V1,
    V2,
}

impl  EnSelf {  }

fn main() {
    if  ::Outest("") = wrap_en1_1::<_> {  };
    ;
    ;
}
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/tools/rustfmt/src/items.rs:439:10
stack backtrace:
   0: rust_begin_unwind
             at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/std/src/panicking.rs:577:5
   1: core::panicking::panic_fmt
             at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/core/src/panicking.rs:67:14
   2: core::panicking::panic
             at /rustc/2eaeb1eee1b21772de8b935236d16ff8e03fdcf5/library/core/src/panicking.rs:117:5
   3: <rustfmt_nightly::visitor::FmtVisitor>::visit_item
   4: <rustfmt_nightly::visitor::FmtVisitor>::visit_items_with_reordering
   5: <rustfmt_nightly::visitor::FmtVisitor>::walk_mod_items
   6: <rustfmt_nightly::visitor::FmtVisitor>::format_separate_mod
   7: rustfmt_nightly::formatting::format_project::<rustfmt_nightly::Session<std::io::stdio::Stdout>>
   8: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::with::<<rustfmt_nightly::Session<std::io::stdio::Stdout>>::format_input_inner::{closure#0}, core::result::Result<rustfmt_nightly::FormatReport, rustfmt_nightly::ErrorKind>>
   9: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_span::create_session_if_not_set_then<core::result::Result<rustfmt_nightly::FormatReport, rustfmt_nightly::ErrorKind>, <rustfmt_nightly::Session<std::io::stdio::Stdout>>::format_input_inner::{closure#0}>::{closure#0}, core::result::Result<rustfmt_nightly::FormatReport, rustfmt_nightly::ErrorKind>>
  10: <rustfmt_nightly::Session<std::io::stdio::Stdout>>::format
  11: rustfmt::format_and_emit_report::<std::io::stdio::Stdout>
  12: <rustfmt_nightly::Session<std::io::stdio::Stdout>>::override_config::<rustfmt::format::{closure#0}, ()>
  13: rustfmt::execute
  14: rustfmt::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
@langston-barrett
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Smaller:

enum Node where P::<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S<S>>>>>>>>>>>>>>>>>>>>>>>>:  {
    Cons,
}

@ytmimi
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ytmimi commented Apr 9, 2023

@langston-barrett thanks for the report and for condensing the reproducible example. Confirming I can reproduce the panic with rustfmt 1.5.2-nightly (a3b2bfc2 2023-04-01)

@ytmimi ytmimi added bug Panic, non-idempotency, invalid code, etc. p-low labels Apr 9, 2023
@calebcartwright
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@HarrisonHemstreet - this is another one that could be interesting for you to look at. At the end of the day, we've got a bad invariant where we've got an assumption that we can safely unwrap() because the option will always be a Some variant (which clearly isn't always the case).

As such there's two aspects to this panic-triggering bug, (1) get rid of the panic by addressing that invariant (note that this could involve having to update various function signatures and respective call sites, and (2) whatever is producing the None in the first place, I'd guess probably some generic-formatting related failure based on the contents in the minimal snippet in #5738 (comment)

@HarrisonHemstreet
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@Tanjaint21
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@rustbot claim

@ytmimi ytmimi mentioned this issue Apr 3, 2024
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@ytmimi ytmimi mentioned this issue Sep 9, 2024
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@ytmimi ytmimi mentioned this issue Oct 29, 2024
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@ding-young
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@rustbot rustbot assigned ding-young and unassigned Tanjaint21 Nov 17, 2024
@ding-young ding-young linked a pull request Nov 17, 2024 that will close this issue
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ding-young added a commit to ding-young/rustfmt that referenced this issue Nov 29, 2024
@ding-young
fix panic on failure to format generics in enum
ff6ebd3 
- related issues: rust-lang#5738, rust-lang#6137, rust-lang#6318, rust-lang#6378
- instead of calling unwrap(), restore original snippet when we fail to format generics in enum
- we need to propagate this rewrite failure later
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fix panic on failure to format generics in enum ding-young/rustfmt
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@langston-barrett @calebcartwright @ytmimi @HarrisonHemstreet @ding-young @Tanjaint21