ICE in use_self lints

[tesuji]

ICE in https://travis-ci.com/rust-lang/rust-clippy/jobs/249905118#L3505

thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: DistinctSources(DistinctSources { begin: (Real("src/lib.rs") BytePos(0)), end: (Real("src/comment.rs"), BytePos(107716)) })', src/libcore/result.rs:1165:5

stack backtrace:

   0:     0x7f0646116054 - backtrace::backtrace::libunwind::trace::h6ab2c103cc6fc063
                               at /cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/lbunwind.rs:88
   1:     0x7f0646116054 - backtrace::backtrace::trace_unsynchronized::h95032b5e76a90e2c
                               at /cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/md.rs:66
   2:     0x7f0646116054 - std::sys_common::backtrace::_print_fmt::ha3b1ff83ecbcdb5f
                               at src/libstd/sys_common/backtrace.rs:77
   3:     0x7f0646116054 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h2733e51e8a6d9b9d
                               at src/libstd/sys_common/backtrace.rs:61
   4:     0x7f064614e5cc - core::fmt::write::hc6f7822f638db26f
                               at src/libcore/fmt/mod.rs:1028
   5:     0x7f064610a437 - std::io::Write::write_fmt::ha156ae6cd02f2c84
                               at src/libstd/io/mod.rs:1412
   6:     0x7f064611a87e - std::sys_common::backtrace::_print::h20221e5a6edf398a
                               at src/libstd/sys_common/backtrace.rs:65
   7:     0x7f064611a87e - std::sys_common::backtrace::print::h982ab87d128d0fd1
                               at src/libstd/sys_common/backtrace.rs:50
   8:     0x7f064611a87e - std::panicking::default_hook::{{closure}}::h61cbb21beda1eee3
                               at src/libstd/panicking.rs:188
   9:     0x7f064611a581 - std::panicking::default_hook::hef981bb6b2fb7e35
                               at src/libstd/panicking.rs:205
  10:     0x7f06465fc133 - rustc_driver::report_ice::h3989a038ce29854d

  11:     0x7f064611b05c - std::panicking::rust_panic_with_hook::hc0f75c1814688ac8
                               at src/libstd/panicking.rs:472
  12:     0x7f064611ab12 - std::panicking::continue_panic_fmt::h4c19cc8a9675594c
                               at src/libstd/panicking.rs:375
  13:     0x7f064611aa06 - rust_begin_unwind
                               at src/libstd/panicking.rs:302
  14:     0x7f064614813a - core::panicking::panic_fmt::h88248d86527ee347
                               at src/libcore/panicking.rs:84
  15:     0x7f0646148377 - core::result::unwrap_failed::h239fa4b3235cb4bf
                               at src/libcore/result.rs:1165
  16:     0x7f06484b7a14 - rustc_errors::emitter::is_case_difference::hc0c96e664bd96574
  17:     0x7f06484ac603 - rustc_errors::emitter::Emitter::primary_span_formatted::h713cfeb3d89d48f0
  18:     0x7f06484ad95b - <rustc_errors::emitter::EmitterWriter as rustc_errors::emitter::Emitter>::emit_diagnostic::h2923ecfd46d99bd9
  19:     0x7f0648330067 - <syntax::json::JsonEmitter as rustc_errors::emitter::Emitter>::emit_diagnostic::h66a9a356fa8770ec
  20:     0x7f06484c41f9 - rustc_errors::HandlerInner::emit_diagnostic::h1eb07d02315b40bd
  21:     0x7f06484922bb - rustc_errors::diagnostic_builder::DiagnosticBuilder::emit::h3792b30815230d9f
  22:     0x5644c01296ff - <clippy_lints::utils::diagnostics::DiagnosticWrapper as core::ops::drop::Drop>::drop::h60e1e4be5ea8cce3
                               at clippy_lints/src/utils/diagnostics.rs:15
  23:     0x5644c00b2a25 - core::ptr::real_drop_in_place::h54a1e5334ec52196
                               at /rustc/cf148a717a275741a35b5f51eab182aa42bd06a6/src/libcore/ptr/mod.rs:175
  24:     0x5644c01509ed - clippy_lints::utils::diagnostics::span_lint_and_then::haf05a40b33ba445d
                               at clippy_lints/src/utils/diagnostics.rs:124
  25:     0x5644c0153ada - clippy_lints::utils::diagnostics::span_lint_and_sugg::haec60d20d3ec9f97
                               at clippy_lints/src/utils/diagnostics.rs:167
  26:     0x5644bfd58f07 - clippy_lints::use_self::span_use_self_lint::he169aa60b50121cf
                               at clippy_lints/src/use_self.rs:67
  27:     0x5644bfd5a472 - <clippy_lints::use_self::UseSelfVisitor as rustc::hir::intravisit::Visitor>::visit_path::hdb008b09016b012f
                               at clippy_lints/src/use_self.rs:239

Originally posted by @lzutao in #4720 (comment)

[tesuji]

cc @llogiq

[flip1995]

#4671 should have fixed that. this is probably the same error, but doesn't get catched by checking differing_macro_contexts check

[tesuji]

Duplicate of #4727. Closing this issue.