syn 0.15.22 breaks diesel_derives

[trha]

Setup

Versions

• Rust: 1.30.1
• Diesel: 1.33
• Database: PostgreSQL
• Operating System macOS 10.14.1

Feature Flags

• diesel: default

Problem Description

The latest version of the syn crate exports a new Result type alias, which collides with std::result::Result and makes diesel_derives fail to compile.

What are you trying to accomplish?

Use diesel_derives.

What is the expected output?

diesel_derives compiles successfully.

What is the actual output?

error[E0107]: wrong number of type arguments: expected 1, found 2
  --> diesel_derives/src/util.rs:48:84
   |
48 | pub fn ty_for_foreign_derive(item: &DeriveInput, flags: &MetaItem) -> Result<Type, Diagnostic> {

Are you seeing any additional errors?

No

Steps to reproduce

Compile diesel_derives from master.

Checklist

• I have already looked over the issue tracker for similar issues.
• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)

[weiznich]

cc @dtolnay because potential breaking change in syn.

[dtolnay]

Thanks for the ping. This is why you should only glob import from modules that are documented for glob importing, like preludes. Neither the standard library nor I am going to consider something like this a breaking change for affecting glob imports.

[weiznich]

@dtolnay See this comment on the corresponding PR. I do not consider that as major breaking change that requires some action from your side. The ping was to just let you know that this issue exists 😉

[weiznich]

Fixed on master