Const generics ICE: no type-dependent def for method

[DutchGhost]

Code

#![feature(const_generics)]

use core::marker::PhantomData;

// this namespace is necessary for the ICE to trigger
struct namespace;

impl namespace {
    pub fn const_chunks_exact<T, const N: usize>() -> ConstChunksExact<'static, T, { N }> {
        ConstChunksExact { inner: PhantomData }
    }
}


#[derive(Debug)]
pub struct ConstChunksExact<'a, T, const N: usize> {
    inner:  PhantomData<&'a T>
}

impl <'a, T, const N: usize> Iterator for ConstChunksExact<'a, T, { N }> {
    type Item = &'a [T; N];

    fn next(&mut self) -> Option<Self::Item> {
        unreachable!()
    }
}

fn main() {
    let mut chunks = namespace::const_chunks_exact::<i32, {3usize}>();
    let next: &[i32; 3] = chunks.next().unwrap();
}

Meta

rustc --version --verbose:

rustc 1.44.0-nightly (699f83f52 2020-03-29) running on x86_64-unknown-linux-gnu

Error output

error: internal compiler error: src/librustc_passes/dead.rs:111: no type-dependent def for method

Backtrace

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:880:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.colasdn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.colasdn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1439
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
  12: std::panicking::begin_panic
  13: rustc_errors::HandlerInner::bug
  14: rustc_errors::Handler::bug
  15: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc::ty::context::tls::with_opt::{{closure}}
  17: rustc::ty::context::tls::with_opt
  18: rustc::util::bug::opt_span_bug_fmt
  19: rustc::util::bug::bug_fmt
  20: <rustc_passes::dead::MarkSymbolVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  21: rustc_hir::intravisit::walk_stmt
  22: rustc_hir::intravisit::walk_expr
  23: rustc_hir::intravisit::walk_fn
  24: rustc_hir::intravisit::Visitor::visit_fn
  25: rustc_hir::intravisit::walk_item
  26: rustc_passes::dead::check_crate
  27: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  28: rustc_session::utils::<impl rustc_session::session::Session>::time
  29: rustc_interface::passes::analysis
  30: rustc::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc::ty::context::TyCtxt> for rustc::ty::query::queries::analysis>::compute
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_query_system::query::plumbing::get_query
  33: rustc::ty::context::tls::enter_global
  34: rustc_interface::interface::run_compiler_in_existing_thread_pool
  35: scoped_tls::ScopedKey<T>::set
  36: rustc_ast::attr::with_globals
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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (699f83f52 2020-03-29) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

error: could not compile `playground`.

[steffahn]

Example made smaller

#![feature(const_generics)]

struct T;
impl T {
    fn new_s<const N: u8>() -> S<N> { S }
}

struct S<const N: u8>;
impl<const N: u8> S<N> {
    fn method(&self) {}
}

fn main() {
    T::new_s::<1u8>().method();
}

(Playground)

Errors:

   Compiling playground v0.0.1 (/playground)
warning: the feature `const_generics` is incomplete and may cause the compiler to crash
 --> src/main.rs:1:12
  |
1 | #![feature(const_generics)]
  |            ^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default

error: internal compiler error: src/librustc_passes/dead.rs:111: no type-dependent def for method

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:880:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.colasdn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.colasdn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1439
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
  12: std::panicking::begin_panic
  13: rustc_errors::HandlerInner::bug
  14: rustc_errors::Handler::bug
  15: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc_middle::ty::context::tls::with_opt::{{closure}}
  17: rustc_middle::ty::context::tls::with_opt
  18: rustc_middle::util::bug::opt_span_bug_fmt
  19: rustc_middle::util::bug::bug_fmt
  20: <rustc_passes::dead::MarkSymbolVisitor as rustc_hir::intravisit::Visitor>::visit_expr
  21: rustc_hir::intravisit::walk_expr
  22: rustc_hir::intravisit::walk_fn
  23: rustc_hir::intravisit::Visitor::visit_fn
  24: rustc_hir::intravisit::walk_item
  25: rustc_passes::dead::check_crate
  26: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  27: rustc_session::utils::<impl rustc_session::session::Session>::time
  28: rustc_interface::passes::analysis
  29: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  30: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  31: rustc_query_system::query::plumbing::get_query
  32: rustc_middle::ty::context::tls::enter_global
  33: rustc_interface::interface::run_compiler_in_existing_thread_pool
  34: scoped_tls::ScopedKey<T>::set
  35: rustc_ast::attr::with_globals
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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (211365947 2020-03-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

error: could not compile `playground`.

To learn more, run the command again with --verbose.

Edit: The current error message “no type-dependent def for method” happens (on the smaller example) since nightly-2020-03-25. This is the same nightly as in #70507. Downloading the relevant CI builds in bisect-rustc is impossibly slow (i.e. not working) for me at the moment, but I’d be surprised if it isn’t 342c5f3 for this one as well.