ICE failed to process buffered lint here (dummy = false) introduced by #87146

[rylev]

Code

It seems that #87146 introduced an ICE which happens when building the piston_image benchmark for rustc-perf.

The ICE seems to be caused by delay_span_bug being issues but no errors being encountered.

Panic message: "no errors encountered even though delay_span_bug issued"

Unfortunately, I've not been able to reproduce this with something smaller and more manageable yet.

cc @Aaron1011 @petrochenkov

Meta

Built using:

cargo +0ecff8c623fa29cccad6f946c657e81dacd85847 rustc -- -A warnings

Error output

error: internal compiler error: failed to process buffered lint here (dummy = false)
   --> src/tiff/decoder/mod.rs:383:10
    |
383 |         (try!(self.get_tag(tag))).as_u32_vec()
    |          ^^^
    |
    = note: delayed at /rustc/0ecff8c623fa29cccad6f946c657e81dacd85847/compiler/rustc_lint/src/early.rs:402:18

error: internal compiler error: failed to process buffered lint here (dummy = false)
   --> src/tiff/decoder/mod.rs:378:10
    |
378 |         (try!(self.get_tag(tag))).as_u32()
    |          ^^^
    |
    = note: delayed at /rustc/0ecff8c623fa29cccad6f946c657e81dacd85847/compiler/rustc_lint/src/early.rs:402:18

thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', compiler/rustc_errors/src/lib.rs:1050:13
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (0ecff8c62 2021-07-19) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
error: could not compile `image`

Backtrace

stack backtrace:
   0: rust_begin_unwind
             at /rustc/0ecff8c623fa29cccad6f946c657e81dacd85847/library/std/src/panicking.rs:515:5
   1: std::panicking::begin_panic_fmt
             at /rustc/0ecff8c623fa29cccad6f946c657e81dacd85847/library/std/src/panicking.rs:457:5
   2: rustc_errors::HandlerInner::flush_delayed
   3: <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop
   4: core::ptr::drop_in_place<rustc_session::parse::ParseSess>
   5: <alloc::rc::Rc<T> as core::ops::drop::Drop>::drop
   6: core::ptr::drop_in_place<rustc_interface::interface::Compiler>
   7: rustc_span::with_source_map
   8: rustc_interface::interface::create_compiler_and_run
   9: scoped_tls::ScopedKey<T>::set

[lqd]

pub struct Value {}
impl Value {
    pub fn as_u32_vec(self) -> Result<Vec<u32>, Box<dyn std::error::Error>> {
        unimplemented!()
    }
}
pub struct TIFFDecoder {}
impl TIFFDecoder {
    fn get_tag(&mut self) -> Result<Value, Box<dyn std::error::Error>> {
        unimplemented!()
    }
    pub fn get_tag_u32_vec(&mut self) -> Result<Vec<u32>, Box<dyn std::error::Error>> {
        (try!(self.get_tag())).as_u32_vec()
    }
}

rustc +0ecff8c623fa29cccad6f946c657e81dacd85847 --crate-name image src/lib.rs --crate-type lib

[Aaron1011]

Minimized:

fn foo() -> Result<(), String>  {
    (try!(Ok::<u8, String>(1)));
    Ok(())
}

fn main() {}

This is caused by a weird special-case for ExprKind::Paren that was added back in 2016: #34355. I'm working on a fix.

[hellow554]

#87284 is merged, this can be closed. :)