ICE with `use_self` on trait implementation in seperate file

[daxpedda]

Most minimal case I could figure out:
lib.rs:

#![warn(clippy::use_self)]

mod module;

module.rs:

pub trait Trait {
	fn fun(par: &str) -> &str;
}

impl Trait for str {
	fn fun(par: &str) -> &str {
		&par[0..1]
	}
}

I played around a bit with this, following cases stop the ICE from triggering:

• Implementing Trait for &str instead for str
• Removing module.rs and having it defined in lib.rs
• Doing something else in fun than indexing a str

The output:

cargo :     Checking ice-test v0.1.0 (C:\ice-test)
At line:1 char:1
+ cargo +nightly-2019-10-24 clippy *> output.txt
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (    Checking ic...0 (C:\ice-test):String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError
 
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: DistinctSources(DistinctSources { begin: (Real("src\\lib.rs"), BytePos(0)), end: (Real("src\\module.rs"), BytePos(41)) })', 
src\libcore\result.rs:1165:5

stack backtrace:
   0:     0x7ff9ca3a5629 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h99905b9bdd869405
   1:     0x7ff9ca3d35db - core::fmt::write::he42993c0fbc52473
   2:     0x7ff9ca3989f4 - <std::io::IoSlice as core::fmt::Debug>::fmt::h8559b5cde0785a61
   3:     0x7ff9ca3a9be9 - std::panicking::take_hook::hca300b53cb6483e1
   4:     0x7ff9ca3a983c - std::panicking::take_hook::hca300b53cb6483e1
   5:     0x7ff9b8233814 - rustc_driver::report_ice::h791a73b4b7354036
   6:     0x7ff9ca3aa46d - std::panicking::rust_panic_with_hook::ha7cfc6ccf6fcfc70
   7:     0x7ff9ca3a9fb4 - std::panicking::begin_panic_fmt::h31c79faaf0225e97
   8:     0x7ff9ca3a9e99 - rust_begin_unwind
   9:     0x7ff9ca3ccb59 - core::panicking::panic_fmt::h43ebb6ee7ce29706
  10:     0x7ff9ca3ccdaf - core::result::unwrap_failed::hd6c18a9f4959217d
  11:     0x7ff9b9fc056e - rustc_errors::emitter::is_case_difference::hd98bb8609477d08e
  12:     0x7ff9b9fb2e40 - rustc_errors::emitter::HumanReadableErrorType::new_emitter::hd82744bbf07a3d0a
  13:     0x7ff9b9fb4565 - <rustc_errors::emitter::EmitterWriter as rustc_errors::emitter::Emitter>::emit_diagnostic::hf74c6c73af652035
  14:     0x7ff9b9d7f273 - <syntax::json::JsonEmitter as rustc_errors::emitter::Emitter>::emit_diagnostic::hcb1ee7b5d79d44ff
  15:     0x7ff9b9fad0f8 - rustc_errors::HandlerInner::emit_diagnostic::hec6a375b5a042de5
  16:     0x7ff9b9faf965 - rustc_errors::diagnostic_builder::DiagnosticBuilder::emit::h3ae8207a6b755a5e
  17:     0x7ff70778e05a - <unknown>
  18:     0x7ff7078ef5f0 - <unknown>
  19:     0x7ff7078efe16 - <unknown>
  20:     0x7ff70799583b - <unknown>
  21:     0x7ff7078efc75 - <unknown>
  22:     0x7ff9b952f2f0 - <rustc::lint::context::LateLintPassObjects as rustc::lint::LateLintPass>::check_item::hf428803c833320e1
  23:     0x7ff9b83a786c - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  24:     0x7ff9b83bd71e - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  25:     0x7ff9b83a7877 - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  26:     0x7ff9b83b84ee - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  27:     0x7ff9b83ac9f5 - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  28:     0x7ff9b83abaaf - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  29:     0x7ff9b82ade39 - <env_logger::filter::inner::Filter as core::fmt::Debug>::fmt::had697e9fb70f5628
  30:     0x7ff9b82afcf2 - <env_logger::filter::inner::Filter as core::fmt::Debug>::fmt::had697e9fb70f5628
  31:     0x7ff9ca3bbfc2 - _rust_maybe_catch_panic
  32:     0x7ff9b8386a45 - rustc_interface::passes::BoxedGlobalCtxt::complete::h755aa5aedb4a18ce
  33:     0x7ff9ca3bbfc2 - _rust_maybe_catch_panic
  34:     0x7ff9b82b43cb - rustc_interface::interface::parse_cfgspecs::h0a7c2c65a19710c1
  35:     0x7ff9b8358590 - rustc_interface::passes::BoxedResolver::to_expansion_result::h3512962e7f620bd7
  36:     0x7ff9b8279373 - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  37:     0x7ff9b827feed - <rustc::mir::Body as rustc_data_structures::graph::WithStartNode>::start_node::h0474409d4fc48e16
  38:     0x7ff9b820e749 - <syntax::ast::Attribute as core::ops::deref::Deref>::deref::h1ba0932f4b888baa
  39:     0x7ff9b8240f4d - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  40:     0x7ff9b8204eeb - <syntax::ast::Attribute as core::ops::deref::Deref>::deref::h1ba0932f4b888baa
  41:     0x7ff9b82e7f1b - <rustc_interface::util::ReplaceBodyWithLoop as syntax::mut_visit::MutVisitor>::visit_mac::h97efee51203582a1
  42:     0x7ff9b8204d8e - <syntax::ast::Attribute as core::ops::deref::Deref>::deref::h1ba0932f4b888baa
  43:     0x7ff9b824ea3c - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  44:     0x7ff9b8235921 - <rustc_driver::Compilation as core::fmt::Debug>::fmt::h32a65f08e8a1242f
  45:     0x7ff9b8254949 - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  46:     0x7ff9b826fd24 - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  47:     0x7ff9ca3bbfc2 - _rust_maybe_catch_panic
  48:     0x7ff9b827c012 - <syntax_pos::symbol::LocalInternedString as core::fmt::Display>::fmt::h4ee18b40c3ec54a6
  49:     0x7ff9ca387af7 - ZN244_$LT$std..error..$LT$impl$u20$core..convert..From$LT$alloc..string..String$GT$$u20$for$u20$alloc..boxed..Box$LT$dyn$u20$std..error..Error$u2b$core..marker..Sync$u2b$core..mar
ker..Send$GT$$GT$..from..StringError$u20$as$u20$core..fmt..Display$GT$3fmt17
  50:     0x7ff9ca3b9897 - std::sys::windows::thread::Thread::new::ha8c1c5acff515210
  51:     0x7ffa18e57974 - BaseThreadInitThunk
  52:     0x7ffa1a34a271 - RtlUserThreadStart

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 1.40.0-nightly (4a8c5b20c 2019-10-23) running on x86_64-pc-windows-msvc

note: compiler flags: -C debuginfo=2 -C incremental --crate-type lib

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
: could not compile `ice-test`.

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