panicked in libstd/macros.rs: inconsistent resolution for an import

[ctaggart]

I tried this code:
I'll try to create a minimal test repository. I get this after adding rustfmt from master with the code similar to rust-lang/rustfmt#4132 (comment) .

I expected to see this happen: the code to build without panic.

Instead, this happened:

   Compiling rustc-ap-rustc_span v656.0.0
thread 'rustc' panicked at 'src/librustc_resolve/imports.rs:906: inconsistent resolution for an import', /rustc/1836e3b42a5b2f37fd79104eedbe8f48a5afdee6/src/libstd/macros.rs:13:23

Meta

rustc --version --verbose:

rustc 1.45.0-nightly (1836e3b42 2020-05-06)
binary: rustc
commit-hash: 1836e3b42a5b2f37fd79104eedbe8f48a5afdee6
commit-date: 2020-05-06
host: x86_64-apple-darwin
release: 1.45.0-nightly
LLVM version: 9.0

Backtrace

$ RUST_BACKTRACE=1 cargo build
   Compiling toml v0.5.6
   Compiling serde_json v1.0.52
   Compiling web-sys v0.3.39
   Compiling rustc-ap-rustc_span v656.0.0
thread 'rustc' panicked at 'src/librustc_resolve/imports.rs:906: inconsistent resolution for an import', /rustc/1836e3b42a5b2f37fd79104eedbe8f48a5afdee6/src/libstd/macros.rs:13:23
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: std::io::Write::write_fmt
   3: std::panicking::default_hook::{{closure}}
   4: std::panicking::default_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: std::panicking::begin_panic
   8: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   9: rustc_middle::ty::context::tls::with_opt::{{closure}}
  10: rustc_middle::ty::context::tls::with_opt
  11: rustc_middle::util::bug::opt_span_bug_fmt
  12: rustc_middle::util::bug::span_bug_fmt
  13: rustc_resolve::imports::ImportResolver::finalize_import
  14: rustc_resolve::imports::ImportResolver::finalize_imports
  15: rustc_resolve::Resolver::resolve_crate
  16: rustc_interface::passes::configure_and_expand_inner
  17: rustc_interface::passes::configure_and_expand::{{closure}}
  18: rustc_data_structures::box_region::PinnedGenerator<I,A,R>::new
  19: rustc_interface::passes::configure_and_expand
  20: rustc_interface::queries::Queries::expansion
  21: rustc_interface::interface::run_compiler_in_existing_thread_pool
  22: scoped_tls::ScopedKey<T>::set
  23: rustc_ast::attr::with_globals
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 1.45.0-nightly (1836e3b42 2020-05-06) running on x86_64-apple-darwin

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

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

query stack during panic:
end of query stack
error: could not compile `rustc-ap-rustc_span`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed

[petrochenkov]

Interesting.
A self-contained reproduction would be appreciated.

[ctaggart]

Here is a minimal reproduction:
https://github.com/ctaggart/rust-lang_71998

It is a combination of target = "wasm32-unknown-unknown" and rustc-ap-rustc_span = "656.0.0".

[petrochenkov]

The issue happens only during cross-compilation, so it's likely a duplicate of #56935 #64450.

[ctaggart]

I thought I might be able to reproduce it by compiling librustc_span with wasm32, but I was wrong. It worked fine:

Camerons-MacBook-Pro:librustc_span cameron$ pwd
/Users/cameron/rs/rust/src/librustc_span
Camerons-MacBook-Pro:librustc_span cameron$ cargo build --target wasm32-unknown-unknown
    Finished dev [unoptimized] target(s) in 0.75s