[ICE] Encountered errors resolving bounds after type-checking

[tesuji]

The below content was posted by @bkchr, I moved it into a separated issue to keep track of the ICE.

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Hey, so I tried porting our code to compile with latest nightly and I almost got it working but ultimately it ended with an internal compiler error:

error: internal compiler error: compiler/rustc_trait_selection/src/traits/codegen/mod.rs:121:9: Encountered errors `[FulfillmentError(Obligation(predicate=TraitPredicate(<dyn sc_client_api::PrunableStateChangesTrieStorage<sp_runtime::generic::Block<sp_runtime::generic::Header<u32, sp_runtime::traits::BlakeTwo256>, sp_runtime::OpaqueExtrinsic>> as sp_state_machine::changes_trie::Storage<sp_runtime::traits::BlakeTwo256, u32>>), depth=0),Unimplemented)]` resolving bounds after type-checking

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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 1.49.0-nightly (98edd1fbf 2020-10-06) 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

error: aborting due to previous error

error: could not compile `node-testing`

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed

I created a branch that fails with this or a similar ICE when you run cargo test --all. You can find it here: https://github.com/paritytech/substrate/tree/bkchr-fix-for-latest-nightly

Originally posted by @bkchr in #77638 (comment)

@rustbot modify labels: regression-from-stable-to-nightly E-needs-mcve A-associated-items

[spastorino]

@rustbot ping cleanup

Would be nice to find the regression and an MCVE.

[rustbot]

Hey Cleanup Crew ICE-breakers! This bug has been identified as a good
"Cleanup ICE-breaking candidate". In case it's useful, here are some
instructions for tackling these sorts of bugs. Maybe take a look?
Thanks! <3

cc @AminArria @camelid @chrissimpkins @contrun @DutchGhost @elshize @ethanboxx @h-michael @HallerPatrick @hdhoang @hellow554 @imtsuki @JamesPatrickGill @kanru @KarlK90 @LeSeulArtichaut @MAdrianMattocks @matheus-consoli @mental32 @nmccarty @Noah-Kennedy @pard68 @PeytonT @pierreN @Redblueflame @RobbieClarken @RobertoSnap @robjtede @SarthakSingh31 @shekohex @sinato @smmalis37 @spastorino @Stupremee @tamuhey @turboladen @woshilapin @yerke

[apiraino]

Assigning P-critical as per linked issue, Prioritization Working Group discussion, removing I-prioritize.