Compiler sometimes does not have generic_const_exprs and await play nice together

[gregoryquick]

Code

#![allow(incomplete_features,)]
#![feature(generic_const_exprs)]

use futures::executor::block_on;

fn main() {
    //Logging
    use std::env;
    env::set_var("RUST_BACKTRACE", "1");
    env::set_var("RUST_LOG", "info");

    block_on(test());
}

fn concat<const A: usize, const B: usize>(a: [f32; A], b: [f32; B]) -> [f32; A + B] {
    let mut array = [0f32; A + B];
    for (loc, value) in array.iter_mut().zip(a.iter().chain(b.iter())) {
        *loc = *value;
    }
    array
}

async fn reverse<const A: usize>(x: [f32; A]) -> [f32; A] {
    let mut array = [0f32; A];
    for (loc, value) in array.iter_mut().rev().zip(x.iter()) {
        *loc = *value;
    }
    array
}

async fn test() {
    let a = [0.0];
    println!("{:?}", a);
    let b = [1.0, 2.0];
    println!("{:?}", b);
    let ab = concat(a,b);
    println!("{:?}", ab);
    //You need to use await
    let ba = reverse(ab).await;
    println!("{:?}", ba);
}

Meta

Error is with generic_const_exprs

rustc --version --verbose:

rustc 1.56.0 (09c42c458 2021-10-18)
binary: rustc
commit-hash: 09c42c45858d5f3aedfa670698275303a3d19afa
commit-date: 2021-10-18
host: x86_64-apple-darwin
release: 1.56.0
LLVM version: 13.0.0

Error output

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/547a6ffee0cf4da9929a9e3d49546dc87d607735/compiler/rustc_errors/src/lib.rs:1093:9

note: the compiler unexpectedly panicked. this is a bug.

note: rustc 1.58.0-nightly (547a6ffee 2021-10-21) running on x86_64-apple-darwin

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

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

query stack during panic:
#0 [optimized_mir] optimizing MIR for `test::{closure#0}`
#1 [layout_of] computing layout of `[static generator@src/main.rs:31:17: 41:2]`
end of query stack

Backtrace

stack backtrace:
   0: std::panicking::begin_panic
   1: std::panic::panic_any
   2: rustc_errors::HandlerInner::span_bug
   3: rustc_errors::Handler::span_bug
   4: rustc_middle::ty::context::tls::with_opt
   5: rustc_middle::util::bug::opt_span_bug_fmt
   6: rustc_middle::util::bug::span_bug_fmt
   7: <rustc_mir_transform::generator::StateTransform as rustc_middle::mir::MirPass>::run_pass
   8: rustc_mir_transform::run_passes
   9: rustc_mir_transform::optimized_mir
  10: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  11: rustc_data_structures::stack::ensure_sufficient_stack
  12: rustc_query_system::query::plumbing::try_execute_query
  13: rustc_query_system::query::plumbing::get_query
  14: rustc_middle::ty::layout::LayoutCx<rustc_middle::ty::context::TyCtxt>::layout_of_uncached
  15: rustc_middle::ty::layout::layout_of
  16: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  17: rustc_data_structures::stack::ensure_sufficient_stack
  18: rustc_query_system::query::plumbing::try_execute_query
  19: rustc_query_system::query::plumbing::get_query
  20: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::layout_of
  21: rustc_middle::ty::layout::LayoutOf::layout_of
  22: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  23: <core::iter::adapters::ResultShunt<I,E> as core::iter::traits::iterator::Iterator>::next
  24: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
  25: rustc_middle::ty::layout::LayoutCx<rustc_middle::ty::context::TyCtxt>::layout_of_uncached
  26: rustc_middle::ty::layout::layout_of
  27: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  28: rustc_data_structures::stack::ensure_sufficient_stack
  29: rustc_query_system::query::plumbing::try_execute_query
  30: rustc_query_system::query::plumbing::get_query
  31: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::layout_of
  32: rustc_middle::ty::layout::layout_of
  33: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  34: rustc_data_structures::stack::ensure_sufficient_stack
  35: rustc_query_system::query::plumbing::try_execute_query
  36: rustc_query_system::query::plumbing::get_query
  37: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::layout_of
  38: <rustc_mir_transform::const_prop::ConstProp as rustc_middle::mir::MirPass>::run_pass
  39: rustc_mir_transform::run_passes
  40: rustc_mir_transform::optimized_mir
  41: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  42: rustc_data_structures::stack::ensure_sufficient_stack
  43: rustc_query_system::query::plumbing::try_execute_query
  44: rustc_query_system::query::plumbing::get_query
  45: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::instance_mir
  46: rustc_monomorphize::collector::collect_neighbours
  47: rustc_monomorphize::collector::collect_items_rec
  48: rustc_session::utils::<impl rustc_session::session::Session>::time
  49: rustc_monomorphize::collector::collect_crate_mono_items
  50: rustc_monomorphize::partitioning::collect_and_partition_mono_items
  51: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task
  52: rustc_data_structures::stack::ensure_sufficient_stack
  53: rustc_query_system::query::plumbing::try_execute_query
  54: rustc_query_system::query::plumbing::get_query
  55: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::collect_and_partition_mono_items
  56: rustc_codegen_ssa::base::codegen_crate
  57: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  58: rustc_session::utils::<impl rustc_session::session::Session>::time
  59: rustc_interface::queries::Queries::ongoing_codegen
  60: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  61: rustc_span::with_source_map
  62: scoped_tls::ScopedKey<T>::set

[compiler-errors]

I actually hit this same issue with capturing un-normalized types in generator interiors when playing around with #92449.

I think I know a fix.

@rustbot claim