rustc panicked at 'assertion failed: !substs.has_erasable_regions()'

[darkwater]

thread 'rustc' panicked at 'assertion failed: !substs.has_erasable_regions()', librustc_trans_utils/symbol_names.rs:192:9

I tried this code:

#![feature(termination_trait)]

extern crate metaflac     as m_flac;
extern crate mp3_metadata as m_mp3;

use std::env;
use std::error::Error;

fn main() -> Result<(), Box<Error>> {
    let path = env::args().skip(1).next().unwrap();
    let meta = m_mp3::read_from_file(path)?;
    println!("{:?}", meta);

    Ok(())
}

Meta

rustc --version --verbose:

rustc 1.26.0-nightly (2789b067d 2018-03-06)
binary: rustc
commit-hash: 2789b067da2ac921b86199bde21dd231ace1da39
commit-date: 2018-03-06
host: x86_64-unknown-linux-gnu
release: 1.26.0-nightly
LLVM version: 6.0

Backtrace:

stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at libstd/sys_common/backtrace.rs:59
             at libstd/panicking.rs:207
   3: std::panicking::default_hook
             at libstd/panicking.rs:223
   4: core::ops::function::Fn::call
   5: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:403
   6: std::panicking::begin_panic
   7: rustc_trans_utils::symbol_names::symbol_name
   8: rustc::dep_graph::graph::DepGraph::with_task_impl
   9: rustc::ty::maps::<impl rustc::ty::maps::queries::symbol_name<'tcx>>::force
  10: rustc::ty::maps::<impl rustc::ty::maps::queries::symbol_name<'tcx>>::try_get
  11: rustc::ty::maps::TyCtxtAt::symbol_name
  12: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::symbol_name
  13: rustc_mir::monomorphize::item::MonoItemExt::symbol_name
  14: rustc_mir::monomorphize::assert_symbols_are_distinct
  15: rustc_trans::base::collect_and_partition_translation_items
  16: rustc::dep_graph::graph::DepGraph::with_task_impl
  17: rustc::ty::maps::<impl rustc::ty::maps::queries::collect_and_partition_translation_items<'
tcx>>::force
  18: rustc::ty::maps::<impl rustc::ty::maps::queries::collect_and_partition_translation_items<'
tcx>>::try_get
  19: rustc::ty::maps::TyCtxtAt::collect_and_partition_translation_items
  20: rustc::ty::maps::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::collect_and_partition_
translation_items
  21: rustc_trans::base::trans_crate
  22: <rustc_trans::LlvmTransCrate as rustc_trans_utils::trans_crate::TransCrate>::trans_crate
  23: rustc_driver::driver::phase_4_translate_to_llvm
  24: rustc_driver::driver::compile_input::{{closure}}
  25: rustc::ty::context::TyCtxt::create_and_enter
  26: rustc_driver::driver::compile_input
  27: rustc_driver::run_compiler

[KamilaBorowska]

This can be reproduced with simpler code, not involving external crates (or even std for that matter).

fn main() -> Result<(), &'static str> {
    Err("An error message for you")
}

[3442853561]

There is a similar issue
#49474

[frewsxcv]

Nominating because fn main() -> Result<(), Box<Error>> and fn main() -> Result<(), &str> seem like they'll be very common use cases and it's not great if we ICE for those, so we may want to look into destabilizing?

[shepmaster]

See also #48389