Compilation fail with serde v1.0.122

[tesuji]

How to reproduce ?

• Check out this repo with latest commit: b52fc0a
• Run: cargo update -p serde:1.0.122
• Run cargo check in this repo

Error message:

error[E0283]: type annotations needed
   --> src/cargo/util/config/de.rs:530:63
    |
530 |                 seed.deserialize(Tuple2Deserializer(1i32, env.as_ref()))
    |                                                           ----^^^^^^--
    |                                                           |   |
    |                                                           |   cannot infer type for type parameter `T` declared on the trait `AsRef`
    |                                                           this method call resolves to `&T`
    |
    = note: cannot satisfy `std::string::String: AsRef<_>`
help: use the fully qualified path for the potential candidates
    |
530 |                 seed.deserialize(Tuple2Deserializer(1i32, <std::string::String as AsRef<OsStr>>::as_ref(env)))
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
530 |                 seed.deserialize(Tuple2Deserializer(1i32, <std::string::String as AsRef<std::path::Path>>::as_ref(env)))
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
530 |                 seed.deserialize(Tuple2Deserializer(1i32, <std::string::String as AsRef<str>>::as_ref(env)))
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
530 |                 seed.deserialize(Tuple2Deserializer(1i32, <std::string::String as AsRef<[u8]>>::as_ref(env)))
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

cc rust-lang/rust#81327 (comment)

[RalfJung]

Cc rust-lang/rust#81378

[RalfJung]

Cc @dtolnay

[macalimlim]

I also got same error on a fresh installation of macos catalina...

Steps to reproduce

1. Usual Rust environment setup thru rustup
2. Run cargo install cargo-generate

[tesuji]

@macalimlim try cargo install --locked <package> instead.

[macalimlim]

@lzutao thanks that worked! 👍

[miketimofeev]

Same here, cargo-outdated installation fails on any OS — ubuntu, macOS, windows

2021-01-25T12:29:09.3660856Z error[E0283]: type annotations needed
2021-01-25T12:29:09.3662485Z    --> /home/vsts/.cargo/registry/src/github.com-1ecc6299db9ec823/cargo-0.50.0/src/cargo/util/config/de.rs:530:63
2021-01-25T12:29:09.3663348Z     |
2021-01-25T12:29:09.3663785Z 530 |                 seed.deserialize(Tuple2Deserializer(1i32, env.as_ref()))
2021-01-25T12:29:09.3664576Z     |                                                           ----^^^^^^--
2021-01-25T12:29:09.3665129Z     |                                                           |   |
2021-01-25T12:29:09.3665719Z     |                                                           |   cannot infer type for type parameter `T` declared on the trait `AsRef`
2021-01-25T12:29:09.3666558Z     |                                                           this method call resolves to `&T`
2021-01-25T12:29:09.3667021Z     |
2021-01-25T12:29:09.3667552Z     = note: cannot satisfy `std::string::String: AsRef<_>`

upd: Thanks @lzutao for the workaround!

[ehuss]

Thanks for the report, I filed an issue with serde at serde-rs/serde#1967, but it looks like Alex already has a fix (so fast! 😄).

[lu-zero]

Can we have a point release with the fix?