Build failure related to AsJson/JsonFrom

[clehner]

When building/testing v0.6.0 (7df142c), I get errors like this:

error[E0311]: the associated type `<K as generic_json::Json>::Array` may not live long enough
   --> src/util/json/build.rs:118:53
    |
118 | impl<J: JsonClone, K: JsonFrom<J>, T: AsJson<J, K>> AsJson<J, K> for [T] {
    |                                                     ^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `<K as generic_json::Json>::Array: 'a`...
    = note: ...so that the type `<K as generic_json::Json>::Array` will meet its required lifetime bounds...
note: ...that is required by this bound
   --> src/util/json/build.rs:13:35
    |
13  | pub trait AsJson<J: JsonClone, K: JsonFrom<J>> {
    |                                   ^^^^^^^^^^^

cargo 1.60.0-nightly (95bb3c92b 2022-01-18)

[timothee-haudebourg]

That's new... At first glance I would say it is related to rust-lang/rust#87479. I'll investigate.

[timothee-haudebourg]

This looks like a compiler bug to me. The lifetime is inconsistently required depending on where the HRTB (comming from the JsonMut trait alias used in JsonFrom) is placed. I've opened an issue.

In the meantime, I think I can get around the issue just by removing the JsonFrom bound from the AsJson trait definition. I hope.