error: internal compiler error: librustc\traits\specialize\mod.rs:104: When translating substitutions for specialization, the expected specialization failed to hold

[EyeOfPython]

When trying to follow the PyO3 tutorial, I receive the following error message:

Command: cargo +nightly build

   Compiling version_check v0.1.5
   Compiling proc-macro2 v0.4.20
   Compiling cfg-if v0.1.6
   Compiling unicode-xid v0.1.0
   Compiling libc v0.2.43
   Compiling ucd-util v0.1.1
   Compiling regex v1.0.5
   Compiling utf8-ranges v1.0.1
   Compiling proc-macro-hack-impl v0.4.1
   Compiling num-traits v0.2.6
   Compiling spin v0.4.9
   Compiling log v0.4.6
   Compiling lazy_static v1.1.0
   Compiling memchr v2.1.0
   Compiling regex-syntax v0.6.2
   Compiling proc-macro-hack v0.4.1
   Compiling thread_local v0.3.6
   Compiling aho-corasick v0.6.8
   Compiling quote v0.6.8
   Compiling mashup-impl v0.1.9
   Compiling syn v0.14.9
   Compiling mashup v0.1.9
   Compiling pyo3 v0.4.1
   Compiling pyo3-derive-backend v0.4.1
   Compiling pyo3cls v0.4.1
error: internal compiler error: librustc\traits\specialize\mod.rs:104: When tran
slating substitutions for specialization, the expected specialization failed to
hold

thread 'main' panicked at 'Box<Any>', librustc_errors\lib.rs:600:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: aborting due to previous error


note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/m
aster/CONTRIBUTING.md#bug-reports

note: rustc 1.31.0-nightly (cae6efc37 2018-10-27) running on x86_64-pc-windows-m
svc

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

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

error: Could not compile `pyo3`.

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

My Cargo.toml looks like this:

[package]
name = "pyext"
version = "0.1.0"
authors = ["me"]

[lib]
name = "pyext"
crate-type = ["dylib"]

[dependencies.pyo3]
version = "0.4.1"
features = ["extension-module"]

My lib.rs looks like this:

#[macro_use]
extern crate pyo3;

use pyo3::prelude::*;

#[pyfunction]
/// Formats the sum of two numbers as string
fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
    Ok((a + b).to_string())
}

/// This module is a python module implemented in Rust.
#[pymodinit]
fn string_sum(py: Python, m: &PyModule) -> PyResult<()> {
    m.add_function(wrap_function!(sum_as_string))?;

    Ok(())
}

I opened this issue as I was asked to do so. Please close it immediately if this has been reported already.

[EyeOfPython]

Duplicate of #55380