regression: could not fully normalize type

[Mark-Simulacrum]

dilbert-feed is ICEing on beta with error: internal compiler error: compiler/rustc_traits/src/normalize_erasing_regions.rs:37:32: could not fully normalize <tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>> as tokio::prelude::IntoFuture>::Future

https://crater-reports.s3.amazonaws.com/beta-1.48-1/beta-2020-10-09/gh/Soft.dilbert-feed/log.txt

[hameerabbasi]

Full error log:

[INFO] [stderr]    Compiling dilbert-feed v0.2.1 (/opt/rustwide/workdir)
[INFO] [stderr] thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
[INFO] [stdout] error: internal compiler error: compiler/rustc_traits/src/normalize_erasing_regions.rs:37:32: could not fully normalize `<tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>> as tokio::prelude::IntoFuture>::Future`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] stack backtrace:
[INFO] [stderr]    0:     0x7f495f236410 - std::backtrace_rs::backtrace::libunwind::trace::h7cf3ca97bd83fbab
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/../../backtrace/src/backtrace/libunwind.rs:96
[INFO] [stderr]    1:     0x7f495f236410 - std::backtrace_rs::backtrace::trace_unsynchronized::h5a69c674b2d9ea5c
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/../../backtrace/src/backtrace/mod.rs:66
[INFO] [stderr]    2:     0x7f495f236410 - std::sys_common::backtrace::_print_fmt::hdf72478dfcb50678
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/sys_common/backtrace.rs:79
[INFO] [stderr]    3:     0x7f495f236410 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e0bdbb35e83deca
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/sys_common/backtrace.rs:58
[INFO] [stderr]    4:     0x7f495f2a45cc - core::fmt::write::he67f9b17bcb7ee73
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/core/src/fmt/mod.rs:1080
[INFO] [stderr]    5:     0x7f495f228072 - std::io::Write::write_fmt::hac97d5cb5753e2ec
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/io/mod.rs:1516
[INFO] [stderr]    6:     0x7f495f23b18d - std::sys_common::backtrace::_print::haa20918e28a126c5
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/sys_common/backtrace.rs:61
[INFO] [stderr]    7:     0x7f495f23b18d - std::sys_common::backtrace::print::h49e772a4873d9076
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/sys_common/backtrace.rs:48
[INFO] [stderr]    8:     0x7f495f23b18d - std::panicking::default_hook::{{closure}}::hb218b305d15e3f11
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/panicking.rs:208
[INFO] [stderr]    9:     0x7f495f23ae38 - std::panicking::default_hook::h63997b7b949e1ce0
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/panicking.rs:227
[INFO] [stderr]   10:     0x7f495fac40b4 - rustc_driver::report_ice::h5b9fb8474972c25e
[INFO] [stderr]   11:     0x7f494ee38076 - <alloc::boxed::Box<F> as core::ops::function::Fn<A>>::call::h28cbcde4fa87c883
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/alloc/src/boxed.rs:1056
[INFO] [stderr]   12:     0x7f494ee1c0cb - proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter::{{closure}}::{{closure}}::h0b15805078ae0080
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/proc_macro/src/bridge/client.rs:320
[INFO] [stderr]   13:     0x7f495f23b9d6 - std::panicking::rust_panic_with_hook::hb54f09ccadf64bd3
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/panicking.rs:581
[INFO] [stderr]   14:     0x7f4962b4ab0d - std::panicking::begin_panic::{{closure}}::hf63b06b6f25b2bdf
[INFO] [stderr]   15:     0x7f4962b4aa66 - std::sys_common::backtrace::__rust_end_short_backtrace::h4a10ac286d57b878
[INFO] [stderr]   16:     0x7f4962b509df - std::panicking::begin_panic::hce65d2b360d5b6cd
[INFO] [stderr]   17:     0x7f4962b88a20 - rustc_errors::HandlerInner::bug::h6efa9d026e354399
[INFO] [stderr]   18:     0x7f4962b87500 - rustc_errors::Handler::bug::h65ab0cb6919f7f68
[INFO] [stderr]   19:     0x7f496249e4a4 - rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}::hece8a2fab170b9d8
[INFO] [stderr]   20:     0x7f4962497afb - rustc_middle::ty::context::tls::with_opt::{{closure}}::he2d94fe1646e47bf
[INFO] [stderr]   21:     0x7f4962497472 - rustc_middle::ty::context::tls::with_opt::h5babe8f0efdba1b5
[INFO] [stderr]   22:     0x7f496249e3c9 - rustc_middle::util::bug::opt_span_bug_fmt::heb60f98da3d119cb
[INFO] [stderr]   23:     0x7f496249e33e - rustc_middle::util::bug::bug_fmt::hc7a67a8c724be98c
[INFO] [stderr]   24:     0x7f49601ff06a - rustc_infer::infer::InferCtxtBuilder::enter::hdcfa59718b739dd1
[INFO] [stderr]   25:     0x7f496023e7d4 - rustc_traits::normalize_erasing_regions::normalize_generic_arg_after_erasing_regions::h4faa5ca4fd539b92
[INFO] [stderr]   26:     0x7f496239f7a2 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::hc9b7506c8b93697c
[INFO] [stderr]   27:     0x7f49624c93c8 - rustc_data_structures::stack::ensure_sufficient_stack::hd9ab99097ffe3d5e
[INFO] [stderr]   28:     0x7f496296b720 - rustc_query_system::query::plumbing::get_query_impl::hd34aababc4489571
[INFO] [stderr]   29:     0x7f496289058b - <rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::he529649e2980b5dd
[INFO] [stderr]   30:     0x7f4960167275 - rustc_ty::needs_drop::needs_drop_raw::hd417eb508c68d13b
[INFO] [stderr]   31:     0x7f49613b062a - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::needs_drop_raw>::compute::h0dbd8a48d8398db8
[INFO] [stderr]   32:     0x7f496118ae64 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h1251534d91b81268
[INFO] [stderr]   33:     0x7f49611aaeb4 - rustc_data_structures::stack::ensure_sufficient_stack::h5274271eaf9e5286
[INFO] [stderr]   34:     0x7f496107b8d0 - rustc_query_system::query::plumbing::get_query_impl::hf908e02f3102192c
[INFO] [stderr]   35:     0x7f49613ab037 - rustc_middle::ty::util::<impl rustc_middle::ty::TyS>::needs_drop::h656f3b489dc02bfb
[INFO] [stderr]   36:     0x7f49613d227a - rustc_mir::interpret::intrinsics::eval_nullary_intrinsic::hee586a8fdec5b2f1
[INFO] [stderr]   37:     0x7f49611d222c - rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider::h50fca309bc380e76
[INFO] [stderr]   38:     0x7f4961170f64 - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute::hdec9e8fd7d16a2a0
[INFO] [stderr]   39:     0x7f496119dd0a - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::he380ffdd791a99b1
[INFO] [stderr]   40:     0x7f49611af57d - rustc_data_structures::stack::ensure_sufficient_stack::h8a026875ee2a98c2
[INFO] [stderr]   41:     0x7f4961037167 - rustc_query_system::query::plumbing::get_query_impl::h827a4c4640c690f5
[INFO] [stderr]   42:     0x7f49611d21c9 - rustc_mir::const_eval::eval_queries::eval_to_const_value_raw_provider::h50fca309bc380e76
[INFO] [stderr]   43:     0x7f49625bf59a - rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::eval_to_const_value_raw>::compute::hdec9e8fd7d16a2a0
[INFO] [stderr]   44:     0x7f4962376232 - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl::h0da45621f956e501
[INFO] [stderr]   45:     0x7f49624c6fab - rustc_data_structures::stack::ensure_sufficient_stack::hc1b74219642dfd11
[INFO] [stderr]   46:     0x7f49628bdef4 - rustc_query_system::query::plumbing::get_query_impl::h05a7bc00404321f6
[INFO] [stderr]   47:     0x7f4962586282 - rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_global_id::he6317e65dda8742f
[INFO] [stderr]   48:     0x7f496258604e - rustc_middle::mir::interpret::queries::<impl rustc_middle::ty::context::TyCtxt>::const_eval_instance::h08ec2e26f3402a63
[INFO] [stderr]   49:     0x7f495fe9f6b7 - rustc_codegen_ssa::mir::intrinsic::<impl rustc_codegen_ssa::mir::FunctionCx<Bx>>::codegen_intrinsic_call::h28c5ed91586afe47
[INFO] [stderr]   50:     0x7f495fe9589d - rustc_codegen_ssa::mir::block::<impl rustc_codegen_ssa::mir::FunctionCx<Bx>>::codegen_call_terminator::hcab9d1205df20a31
[INFO] [stderr]   51:     0x7f495fe903a6 - rustc_codegen_ssa::mir::block::<impl rustc_codegen_ssa::mir::FunctionCx<Bx>>::codegen_block::h62948860027c86bc
[INFO] [stderr]   52:     0x7f495fe8ddbe - rustc_codegen_ssa::mir::codegen_mir::h28a81876122b9b75
[INFO] [stderr]   53:     0x7f495ff9f868 - rustc_codegen_ssa::base::codegen_instance::haac9416663ce073f
[INFO] [stderr]   54:     0x7f495fdf42a4 - <rustc_middle::mir::mono::MonoItem as rustc_codegen_ssa::mono_item::MonoItemExt>::define::h14112b0e0302d0b6
[INFO] [stderr]   55:     0x7f495fe33b1b - rustc_codegen_llvm::base::compile_codegen_unit::module_codegen::h392634f7370ae0df
[INFO] [stderr]   56:     0x7f495fef323a - rustc_query_system::dep_graph::graph::DepGraph<K>::with_task::hab6ab1281f48d446
[INFO] [stderr]   57:     0x7f495fe3363a - rustc_codegen_llvm::base::compile_codegen_unit::h66a62c9d61aa9cb1
[INFO] [stderr]   58:     0x7f495ff9d8c5 - rustc_codegen_ssa::base::codegen_crate::h0f310b8e6539577c
[INFO] [stderr]   59:     0x7f495ff937e5 - <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate::hf0175e4b8c8a4032
[INFO] [stderr]   60:     0x7f495fd08d10 - rustc_session::utils::<impl rustc_session::session::Session>::time::h2a17f1881818a252
[INFO] [stderr]   61:     0x7f495fd5083c - rustc_interface::passes::QueryContext::enter::h23a2ddc99d800d56
[INFO] [stderr]   62:     0x7f495fd7c253 - rustc_interface::queries::Queries::ongoing_codegen::h2c31f6799bcf60e3
[INFO] [stderr]   63:     0x7f495fb128e4 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::had791f63f727c367
[INFO] [stderr]   64:     0x7f495fae7a67 - rustc_span::with_source_map::h755817392b17a216
[INFO] [stderr]   65:     0x7f495fb0eac1 - scoped_tls::ScopedKey<T>::set::he59500e39ec4abad
[INFO] [stderr]   66:     0x7f495fb15e21 - std::sys_common::backtrace::__rust_begin_short_backtrace::hd47de080afaa24c1
[INFO] [stderr]   67:     0x7f495fa90f4e - core::ops::function::FnOnce::call_once{{vtable.shim}}::hd9b6798a9391b23c
[INFO] [stderr]   68:     0x7f495f24a70a - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::hd4d30e37db281e8f
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/alloc/src/boxed.rs:1042
[INFO] [stderr]   69:     0x7f495f24a70a - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h019185a215ba16e4
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/alloc/src/boxed.rs:1042
[INFO] [stderr]   70:     0x7f495f24a70a - std::sys::unix::thread::Thread::new::thread_start::h33c6d7cf25f9291f
[INFO] [stderr]                                at /rustc/212e76c31d461462544b5d516d3bdc99fc8f016e/library/std/src/sys/unix/thread.rs:87
[INFO] [stderr]   71:     0x7f495f166609 - start_thread
[INFO] [stderr]   72:     0x7f495f087103 - clone
[INFO] [stderr]   73:                0x0 - <unknown>
[INFO] [stderr] 
[INFO] [stderr] note: the compiler unexpectedly panicked. this is a bug.
[INFO] [stderr] 
[INFO] [stderr] 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
[INFO] [stderr] 
[INFO] [stderr] note: rustc 1.48.0-beta.2 (212e76c31 2020-10-08) running on x86_64-unknown-linux-gnu
[INFO] [stderr] 
[INFO] [stderr] note: compiler flags: -C embed-bitcode=no -C debuginfo=2 --crate-type bin
[INFO] [stderr] 
[INFO] [stderr] note: some of the compiler flags provided by cargo are hidden
[INFO] [stderr] 
[INFO] [stderr] query stack during panic:
[INFO] [stderr] #0 [normalize_generic_arg_after_erasing_regions] normalizing `<tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>> as tokio::prelude::IntoFuture>::Future`
[INFO] [stderr] #1 [needs_drop_raw] computing whether `tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, std::result::Result<ComicInfo, failure::Error>, [closure@src/main.rs:60:19: 80:10]>, tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>>, [closure@src/main.rs:154:35: 172:26]>, [closure@src/main.rs:172:32: 180:26]>` needs drop
[INFO] [stderr] #2 [eval_to_const_value_raw] simplifying constant for the type system `std::intrinsics::needs_drop`
[INFO] [stderr] #3 [eval_to_const_value_raw] simplifying constant for the type system `std::intrinsics::needs_drop`
[INFO] [stderr] end of query stack
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `dilbert-feed`

[LeSeulArtichaut]

I'll bisect this one

[hameerabbasi]

Doesn't happen on the latest commit by bors on master.

ERROR: the commit at the end of the range (9832374f6e378971e1a933362cf9781b121bb845) does not reproduce the regression

[LeSeulArtichaut]

I can still reproduce with 9832374:

rustc 1.49.0-nightly (9832374f6 2020-10-20)
binary: rustc
commit-hash: 9832374f6e378971e1a933362cf9781b121bb845
commit-date: 2020-10-20
host: x86_64-apple-darwin
release: 1.49.0-nightly
LLVM version: 11.0

[hameerabbasi]

It may just be an instance of me not doing something right, I used:

cargo bisect-rustc --start=eeaf497b2a6bc065874e3d3367b1f3023c5bb3d3 --regress=ice

[LeSeulArtichaut]

cargo-bisect-rustc gives me

searched toolchains 8ba2250 through 6ebad43
regression in 0d0f6b1

So this would have regressed in #70793, cc @the8472 @Amanieu

[the8472]

[INFO] [stderr] query stack during panic:
[INFO] [stderr] #0 [normalize_generic_arg_after_erasing_regions] normalizing `<tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>> as tokio::prelude::IntoFuture>::Future`
[INFO] [stderr] #1 [needs_drop_raw] computing whether `tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, std::result::Result<ComicInfo, failure::Error>, [closure@src/main.rs:60:19: 80:10]>, tokio::prelude::future::Either<tokio::prelude::future::Map<tokio::prelude::future::AndThen<tokio::prelude::future::AndThen<tokio::prelude::future::FutureResult<std::string::String, failure::Error>, std::result::Result<hyper::Uri, failure::Error>, [closure@src/main.rs:162:51: 162:96]>, tokio::prelude::future::Map<tokio::prelude::future::FromErr<tokio::prelude::future::AndThen<hyper::client::ResponseFuture, tokio::prelude::future::Map<tokio::prelude::stream::Concat2<hyper::Body>, [closure@src/main.rs:46:40: 46:62]>, fn(hyper::Response<hyper::Body>) -> impl hyper::rt::Future {concat_body}>, failure::Error>, [closure@src/main.rs:91:14: 95:10]>, [closure@src/main.rs:163:51: 163:92]>, [closure@src/main.rs:164:46: 167:42]>, tokio::prelude::future::FutureResult<ComicInfo, failure::Error>>, [closure@src/main.rs:154:35: 172:26]>, [closure@src/main.rs:172:32: 180:26]>` needs drop
[INFO] [stderr] #2 [eval_to_const_value_raw] simplifying constant for the type system `std::intrinsics::needs_drop`
[INFO] [stderr] #3 [eval_to_const_value_raw] simplifying constant for the type system `std::intrinsics::needs_drop`
[INFO] [stderr] end of query stack

The PR did introduce some additional uses of std::mem::needs_drop inside specialized implementations. needs_drop itself it is a stable function so I am not aware of any restrictions on its use. Perhaps this is some interaction with specialization?

[the8472]

Both sites where it is used are of this pattern:

        if mem::needs_drop::<T>() {
            unsafe {
                ptr::drop_in_place(...);
            }
        }

They're just there as hints to to let llvm DCE the drop_in_place earlier. So if needed removing them should be safe.

[spastorino]

Assigning P-critical as discussed as part of the Prioritization Working Group procedure and removing I-prioritize.

[Mark-Simulacrum]

Assigning myself to revert #70793 on beta (and potentially nightly, depending on if we can get a fix soon).

[nikomatsakis]

Do we know if removing needs_drop fixes the problem? We also could use an MVCE, right?

[Mark-Simulacrum]

MCVE would be good, yes.

[jplatte]

I hit (what seems like) this ICE with feature(const_evaluatable_checked) in a pretty small experiment, would it be useful to try reducing that?

[Mark-Simulacrum]

Yes, it would be -- even if it's a separate issue we can just open that :) MCVE is always useful.

[spastorino]

@rustbot ping cleanup

This issue needs an MVCE

[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 @steffahn @Stupremee @tamuhey @turboladen @woshilapin @yerke

[jplatte]

Here's my nightly feature(const_evaluatable_checked) MCVE: https://gist.github.com/jplatte/12981cbdedf6cc824685aace41b8af42

Interestingly, it goes away when putting all of the code into one crate.

Full error message (with RUST_BACKTRACE=1):

error: constant expression depends on a generic parameter
  |
  = note: this may fail depending on what value the parameter takes

error: internal compiler error: compiler/rustc_traits/src/normalize_erasing_regions.rs:37:32: could not fully normalize `<my_crate::Const<U> as my_crate::Trait>::AssocTy`

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:945:9
stack backtrace:
   0: std::panicking::begin_panic
   1: rustc_errors::HandlerInner::bug
   2: rustc_errors::Handler::bug
   3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   4: rustc_middle::ty::context::tls::with_opt::{{closure}}
   5: rustc_middle::ty::context::tls::with_opt
   6: rustc_middle::util::bug::opt_span_bug_fmt
   7: rustc_middle::util::bug::bug_fmt
   8: rustc_infer::infer::InferCtxtBuilder::enter
   9: rustc_traits::normalize_erasing_regions::normalize_generic_arg_after_erasing_regions
  10: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  11: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  12: rustc_data_structures::stack::ensure_sufficient_stack
  13: rustc_query_system::query::plumbing::get_query_impl
  14: rustc_middle::ty::structural_impls::fold_list
  15: rustc_middle::ty::normalize_erasing_regions::<impl rustc_middle::ty::context::TyCtxt>::normalize_erasing_regions
  16: rustc_middle::ty::layout::<impl rustc_middle::ty::instance::Instance>::fn_sig_for_fn_abi
  17: <rustc_target::abi::call::FnAbi<&rustc_middle::ty::TyS> as rustc_middle::ty::layout::FnAbiExt<C>>::of_instance
  18: rustc_codegen_ssa::mir::block::<impl rustc_codegen_ssa::mir::FunctionCx<Bx>>::codegen_call_terminator
  19: rustc_codegen_ssa::mir::block::<impl rustc_codegen_ssa::mir::FunctionCx<Bx>>::codegen_block
  20: rustc_codegen_ssa::mir::codegen_mir
  21: rustc_codegen_ssa::base::codegen_instance
  22: <rustc_middle::mir::mono::MonoItem as rustc_codegen_ssa::mono_item::MonoItemExt>::define
  23: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
  24: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  25: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  26: rustc_codegen_llvm::base::compile_codegen_unit
  27: rustc_codegen_ssa::base::codegen_crate
  28: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  29: rustc_session::utils::<impl rustc_session::session::Session>::time
  30: rustc_interface::queries::Queries::ongoing_codegen
  31: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  32: rustc_span::with_source_map
  33: scoped_tls::ScopedKey<T>::set
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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.49.0-nightly (e3051d8c2 2020-10-16) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `<my_crate::Const<U> as my_crate::Trait>::AssocTy`
end of query stack
error: aborting due to 2 previous errors

error: could not compile `my_crate`

[nikomatsakis]

Hmm, this may be a distinct problem, but maybe not. Hard to tell.

[Mark-Simulacrum]

I'm re-adding the MCVE label because the crate on beta does not require features, so we should be able to come up with a non-nightly MCVE.

(Also, it would be good to have a single-crate MCVE, but perhaps the multicrate nature is critical here?)

[Mark-Simulacrum]

cc #54114, which may be the same underlying bug (but pre-existing?)

[pnkfelix]

hey @Mark-Simulacrum , did you manage to land a revert of #70793 on beta (and nightly?)?

[the8472]

If reverting the PR proves difficult more targeted options would be either removing the use of needs_drop or only removing / stubbing the specialization that makes use of it while leaving the rest of the machinery unchanged. But the former may be insufficient since it also uses similar methods such as size_of and align_of.

[Mark-Simulacrum]

@nikomatsakis @pnkfelix Do we think given that we're likely to fix the regression here at least in #78845 and #78854 we should close this bug? Neither of those PRs fixes the underlying issue (whatever it is) since the lack of normalization is almost certainly still present, but we also don't have (AFAIK) a good test case here for the bug.

[nikomatsakis]

@Mark-Simulacrum I expect so.