ICE "Cannot copy into already initialized unsized place"

[matthiaskrgr]

rustc ./src/test/ui/trivial-bounds/trivial-bounds-inconsistent-associated-functions.rs --emit mir
code:

// run-pass
// Inconsistent bounds with trait implementations

#![feature(trivial_bounds)]
#![allow(unused)]

trait A {
    fn foo(&self) -> Self where Self: Copy;
}

impl A for str {
    fn foo(&self) -> Self where Self: Copy { *"" }
}

impl A for i32 {
    fn foo(&self) -> Self { 3 }
}

backtrace:

thread 'rustc' panicked at 'Cannot copy into already initialized unsized place', src/librustc_mir/interpret/place.rs:891:13
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /home/matthias/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /home/matthias/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:77
   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:1057
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1426
   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:195
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:215
  10: <alloc::boxed::Box<F> as core::ops::function::Fn<A>>::call
             at /home/matthias/vcs/github/rust_debug_assertions/src/liballoc/boxed.rs:1029
  11: rustc_driver::report_ice
             at src/librustc_driver/lib.rs:1160
  12: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:476
  13: std::panicking::begin_panic
             at /home/matthias/vcs/github/rust_debug_assertions/src/libstd/panicking.rs:401
  14: rustc_mir::interpret::step::<impl rustc_mir::interpret::eval_context::InterpCx<M>>::eval_rvalue_into_place
             at /home/matthias/vcs/github/rust_debug_assertions/src/libcore/option.rs:0
  15: rustc_mir::transform::const_prop::ConstPropagator::const_prop::{{closure}}
             at src/librustc_mir/transform/const_prop.rs:561
  16: rustc_mir::transform::const_prop::ConstPropagator::use_ecx
             at src/librustc_mir/transform/const_prop.rs:367
  17: rustc_mir::transform::const_prop::ConstPropagator::const_prop
             at src/librustc_mir/transform/const_prop.rs:559
  18: <rustc_mir::transform::const_prop::ConstPropagator as rustc::mir::visit::MutVisitor>::visit_statement
             at src/librustc_mir/transform/const_prop.rs:762
  19: rustc::mir::visit::MutVisitor::super_basic_block_data
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/mir/visit.rs:322
  20: rustc::mir::visit::MutVisitor::visit_basic_block_data
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/mir/visit.rs:93
  21: rustc::mir::visit::MutVisitor::super_body
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/mir/visit.rs:275
  22: rustc::mir::visit::MutVisitor::visit_body
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/mir/visit.rs:87
  23: <rustc_mir::transform::const_prop::ConstProp as rustc_mir::transform::MirPass>::run_pass
             at src/librustc_mir/transform/const_prop.rs:97
  24: rustc_mir::transform::run_passes::{{closure}}
             at src/librustc_mir/transform/mod.rs:171
  25: rustc_mir::transform::run_passes
             at src/librustc_mir/transform/mod.rs:178
  26: rustc_mir::transform::run_optimization_passes
             at src/librustc_mir/transform/mod.rs:273
  27: rustc_mir::transform::optimized_mir
             at src/librustc_mir/transform/mod.rs:343
  28: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::optimized_mir>::compute::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:971
  29: rustc::ty::query::__query_compute::optimized_mir
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:922
  30: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::optimized_mir>::compute
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:963
  31: rustc::dep_graph::graph::DepGraph::with_task_impl
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/dep_graph/graph.rs:325
  32: rustc::dep_graph::graph::DepGraph::with_task
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/dep_graph/graph.rs:193
  33: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::force_query_with_job::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:543
  34: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::start_query::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:267
  35: rustc::ty::context::tls::enter_context::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1753
  36: rustc::ty::context::tls::set_tlv
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1686
  37: rustc::ty::context::tls::enter_context
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1753
  38: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::start_query::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:267
  39: rustc::ty::context::tls::with_related_context::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1841
  40: rustc::ty::context::tls::with_context::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1825
  41: rustc::ty::context::tls::with_context_opt
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1814
  42: rustc::ty::context::tls::with_context
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1825
  43: rustc::ty::context::tls::with_related_context
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1838
  44: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::start_query
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:256
  45: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::force_query_with_job::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:533
  46: rustc::ty::query::plumbing::with_diagnostics
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:201
  47: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::force_query_with_job
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:532
  48: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:369
  49: rustc::ty::query::TyCtxtAt::optimized_mir
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:1048
  50: rustc::ty::query::<impl rustc::ty::context::TyCtxt>::optimized_mir
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/query/plumbing.rs:1040
  51: rustc_mir::util::pretty::write_mir_pretty
             at src/librustc_mir/util/pretty.rs:239
  52: rustc_mir::transform::dump_mir::emit_mir
             at src/librustc_mir/transform/dump_mir.rs:65
  53: rustc_interface::passes::start_codegen
             at src/librustc_interface/passes.rs:994
  54: rustc_interface::queries::Queries::ongoing_codegen::{{closure}}::{{closure}}
             at src/librustc_interface/queries.rs:282
  55: rustc_interface::passes::QueryContext::enter::{{closure}}
             at src/librustc_interface/passes.rs:711
  56: rustc::ty::context::tls::enter_global::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1776
  57: rustc::ty::context::tls::enter_context::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1753
  58: rustc::ty::context::tls::set_tlv
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1686
  59: rustc::ty::context::tls::enter_context
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1753
  60: rustc::ty::context::tls::enter_global
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1776
  61: rustc_interface::passes::QueryContext::enter
             at src/librustc_interface/passes.rs:711
  62: rustc_interface::queries::Queries::ongoing_codegen::{{closure}}
             at src/librustc_interface/queries.rs:276
  63: rustc_interface::queries::Query<T>::compute
             at src/librustc_interface/queries.rs:34
  64: rustc_interface::queries::Queries::ongoing_codegen
             at src/librustc_interface/queries.rs:274
  65: rustc_driver::run_compiler::{{closure}}::{{closure}}
             at src/librustc_driver/lib.rs:404
  66: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/queries.rs:332
  67: rustc_driver::run_compiler::{{closure}}
             at src/librustc_driver/lib.rs:295
  68: rustc_interface::interface::run_compiler_in_existing_thread_pool
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/interface.rs:184
  69: rustc_interface::interface::run_compiler::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/interface.rs:193
  70: rustc_interface::util::spawn_thread_pool::{{closure}}::{{closure}}::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/util.rs:154
  71: rustc::ty::context::tls::with_thread_locals::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1742
  72: std::thread::local::LocalKey<T>::try_with
             at /home/matthias/vcs/github/rust_debug_assertions/src/libstd/thread/local.rs:262
  73: std::thread::local::LocalKey<T>::with
             at /home/matthias/vcs/github/rust_debug_assertions/src/libstd/thread/local.rs:239
  74: rustc::ty::context::tls::with_thread_locals::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1734
  75: std::thread::local::LocalKey<T>::try_with
             at /home/matthias/vcs/github/rust_debug_assertions/src/libstd/thread/local.rs:262
  76: std::thread::local::LocalKey<T>::with
             at /home/matthias/vcs/github/rust_debug_assertions/src/libstd/thread/local.rs:239
  77: rustc::ty::context::tls::with_thread_locals
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc/ty/context.rs:1726
  78: rustc_interface::util::spawn_thread_pool::{{closure}}::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/util.rs:154
  79: scoped_tls::ScopedKey<T>::set
             at /home/matthias/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-1.0.0/src/lib.rs:137
  80: rustc_interface::util::spawn_thread_pool::{{closure}}::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/util.rs:150
  81: scoped_tls::ScopedKey<T>::set
             at /home/matthias/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-1.0.0/src/lib.rs:137
  82: syntax::with_globals::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/libsyntax/lib.rs:60
  83: scoped_tls::ScopedKey<T>::set
             at /home/matthias/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-1.0.0/src/lib.rs:137
  84: syntax::with_globals
             at /home/matthias/vcs/github/rust_debug_assertions/src/libsyntax/lib.rs:60
  85: rustc_interface::util::spawn_thread_pool::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/util.rs:149
  86: rustc_interface::util::scoped_thread::{{closure}}
             at /home/matthias/vcs/github/rust_debug_assertions/src/librustc_interface/util.rs:126
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.42.0-dev running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [optimized_mir] processing `<str as A>::foo`
end of query stack

[matthewjasper]

This doesn't require nightly:

#![allow(unused)]

trait A {
    fn foo(&self) -> Self where Self: Copy;
}

impl A for [fn(&())] {
    fn foo(&self) -> Self where Self: Copy { *(&[] as &[_]) }
}

impl A for i32 {
    fn foo(&self) -> Self { 3 }
}

[pnkfelix]

triage: has PR. P-high, removing I-nominated label.