Internal Compiler Error while compiling diesel

[weiznich]

Code

Diesel master

Meta

rustc --version --verbose:

rustc 1.50.0-nightly (349b3b324 2020-11-29)
binary: rustc
commit-hash: 349b3b324dade7ca638091db93ba08bbc443c63d
commit-date: 2020-11-29
host: x86_64-unknown-linux-gnu
release: 1.50.0-nightly

Last known working version: rust 1.50.0-nightly (b48cafd9e 2020-11-25) (Haven't tried the nightlies in between yet)

Error output

thread 'rustc' panicked at 'forcing query with already existing `DepNode`
- query-key: (DefId(0:1086 ~ diesel[f0f0]::expression::ValidGrouping), Some(IsAggregate#1483))
- dep-node: super_predicates_that_define_assoc_type(67abfa33ab7d90da-56b8cbe8d1ca79a9)', /rustc/349b3b324dade7ca638091db93ba08bbc443c63d\compiler\rustc_query_system\src\query\plumbing.rs:586:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic
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 1.50.0-nightly (349b3b324 2020-11-29) running on x86_64-pc-windows-msvc

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:
#0 [explicit_predicates_of] computing explicit predicates of `type_impls::tuples::_::_::<impl expression::ValidGrouping<__GroupByClause> for (A, B, C)>`
#1 [predicates_defined_on] computing predicates of `type_impls::tuples::_::_::<impl expression::ValidGrouping<__GroupByClause> for (A, B, C)>`
end of query stack
error: could not compile `diesel`
Error: could not compile `diesel`
To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
Warning: thread 'rustc' panicked at 'forcing query with already existing `DepNode`
- query-key: (DefId(0:1098 ~ diesel[8909]::expression::ValidGrouping), Some(IsAggregate#3574))
- dep-node: super_predicates_that_define_assoc_type(10b7a81c445a7cf0-f4bea10f7f9b919e)', /rustc/349b3b324dade7ca638091db93ba08bbc443c63d\compiler\rustc_query_system\src\query\plumbing.rs:586:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

As this is the second regression for diesel in less then a week: Would it possible to add diesel to the compiler test suite to prevent breaking diesel again and again. I would like to use my free time for something else than reporting regression bugs every day 😉

@rustbot modify labels: +regression-from-beta-to-nightly

[matthiaskrgr]

I would like to use my free time for something else than reporting regression bugs every day

Have you considered switching to the beta toolchain?

[weiznich]

@matthiaskrgr As I'm the maintainer of diesel that's not an option for me. I think it's obvious that our users expect that diesel will work on any version of rustc + issues occurring on nightly will be in beta in max. 6 weeks + in stable in max. 12 weeks, therefore that wouldn't help in any way.

[matthiaskrgr]

According to my bisection, 349b3b3 is the cause. cc @spastorino

searched toolchains 1c389ffeff814726dec325f0f2b0c99107df2673 through 28b86e0860f0593b85cda6c2c7b03ae8a582962f

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Regression in 349b3b324dade7ca638091db93ba08bbc443c63d
********************************************************************************

[matthiaskrgr]

@rustbot prioritize

[hameerabbasi]

Introduced in PR #79209.

[hameerabbasi]

Labelling P-critical according to the Zulip discussion. Many of the reasons were already outlined above.