BUG - imports.rs:901: inconsistent resolution for an import

[yatesco]

I get an error when cross building (using the cross crate, but I don't think the problem is there):

❯ cross build --target x86_64-pc-windows-gnu --release
   Compiling fstrings v0.2.2
thread 'rustc' panicked at 'src/librustc_resolve/imports.rs:901: inconsistent resolution for an import', <::std::macros::panic macros>:2:4
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/gitpro.ttaallkk.top-1ecc6299db9ec823/backtrace-0.3.40/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/gitpro.ttaallkk.top-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:1052
   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:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:476
  12: std::panicking::begin_panic
  13: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  14: rustc::ty::context::tls::with_opt::{{closure}}
  15: rustc::ty::context::tls::with_opt
  16: rustc::util::bug::opt_span_bug_fmt
  17: rustc::util::bug::span_bug_fmt
  18: rustc_resolve::imports::ImportResolver::finalize_import
  19: rustc_resolve::imports::ImportResolver::finalize_imports
  20: rustc_resolve::Resolver::resolve_crate
  21: rustc_interface::passes::configure_and_expand_inner
  22: rustc_interface::passes::configure_and_expand::{{closure}}
  23: rustc_data_structures::box_region::PinnedGenerator<I,A,R>::new
  24: rustc_interface::passes::configure_and_expand
  25: rustc_interface::queries::Queries::expansion
  26: rustc_interface::interface::run_compiler_in_existing_thread_pool
  27: scoped_tls::ScopedKey<T>::set
  28: syntax::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 1.42.0 (b8cedc004 2020-03-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -C opt-level=3 -C linker=x86_64-w64-mingw32-gcc --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 `fstrings`.

To reproduce this:

• cargo new --bin test-bin
• cargo install cross
• add fstrings = "0.2" to Cargo.toml
• add [build.env] passthrough = [ "RUST_BACKTRACE", ] to Cross.toml
• RUST_BACKTRACE=1 cross build --target x86_64-pc-windows-gnu --release

Hope this helps - let me know if I can debug further.

[jonas-schievink]

Duplicate of #56935

[yatesco]

(thanks @jonas-schievink - I couldn't find a duplicate)