"cargo fix --edition" claims no failure, but crate can not be built with edition = "2018"

[strake]

Problem
I want to migrate the containers crate to the 2018 edition. I do "cargo fix --edition" in the crate root, which emits no error message, then write 'edition = "2018"' in Cargo.toml, but building the crate so fails.

Wanted outcome: Crate can be built with edition = "2018".
Actual outcome: "cargo build" fails.

Steps

1. git clone https://github.com/strake/containers.rs
2. git checkout a0a3e5df95057a015e6935a13f3a4b893329f39e
3. cargo fix --edition
4. <write 'edition = "2018"' in Cargo.toml>
5. cargo build

Possible Solution(s)

Notes

Seems to be due to name conflicts between the ptr crate and core::ptr. I am not sure how to bestly disambiguate, but "cargo fix" should at least emit an error message and fail.

Output of cargo version:
cargo 1.45.0 (744bd1f 2020-06-15)

[ehuss]

Thanks for the report! This is a known issue, tracked in rust-lang/rust#53797. For now you'll need to manually fix any remaining errors.