update to rustc 656

[ctaggart]

I gets past the error in #4132 🎉

But compiling my app, I end up with this error:

   Compiling rustc-ap-rustc_data_structures v656.0.0
   Compiling rustc-ap-arena v656.0.0
   Compiling synstructure v0.12.3
   Compiling wasm-bindgen-backend v0.2.62
   Compiling wasm-bindgen-macro-support v0.2.62
   Compiling rustc-ap-rustc_macros v656.0.0
   Compiling serde_derive v1.0.106
   Compiling thiserror-impl v1.0.16
   Compiling rustfmt-config_proc_macro v0.5.0 (/Users/cameron/rs/rustfmt/rustfmt-core/rustfmt-lib/config_proc_macro)
   Compiling wasm-bindgen-macro v0.2.62
   Compiling thiserror v1.0.16
   Compiling rustc-ap-rustc_span v656.0.0
thread 'rustc' panicked at 'src/librustc_resolve/imports.rs:906: inconsistent resolution for an import', /rustc/2454a68cfbb63aa7b8e09fe05114d5f98b2f9740/src/libstd/macros.rs:13:23
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 (2454a68cf 2020-05-04) 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

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
Camerons-MacBook-Pro cameron$ rustc --version
rustc 1.45.0-nightly (2454a68cf 2020-05-04)

[calebcartwright]

Thanks! I know this doesn't fully solve your problem but good for us to bump the rustc versions anyways 😄

[karyon]

Backport not needed