Fails to build with minimal versions

[konstin]

In pubgrub, we're using ron = "=0.9.0-alpha.0". I can't build pubgrub with

cargo +nightly check -Zminimal-versions

due to ron not being compatible with the lowest versions it declares:

error[E0277]: the trait bound `usize: Bits` is not satisfied
 --> /home/konsti/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ron-0.9.0-alpha.0/src/extensions.rs:6:28
  |
6 |     pub struct Extensions: usize {
  |                            ^^^^^ the trait `Bits` is not implemented for `usize`
  |
  = help: the following other types implement trait `Bits`:
            i128
            i16
            i32
            i64
            i8
            u128
            u16
            u32
          and 2 others
note: required by a bound in `bitflags::BitFlags::Bits`
 --> /home/konsti/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/bitflags-2.0.0/src/traits.rs:8:16
  |
8 |     type Bits: Bits;
  |                ^^^^ required by this bound in `BitFlags::Bits`

error[E0277]: the trait bound `usize: Bits` is not satisfied
 --> /home/konsti/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ron-0.9.0-alpha.0/src/extensions.rs:6:28
  |
6 |     pub struct Extensions: usize {
  |                            ^^^^^ the trait `Bits` is not implemented for `usize`
  |
  = help: the following other types implement trait `Bits`:
            i128
            i16
            i32
            i64
            i8
            u128
            u16
            u32
          and 2 others

Building ron itself with -Zminimal-versions, there a bigger number of build errors:

rm Cargo.lock && cargo +nightly check -Zminimal-versions

Output: https://gist.github.com/konstin/c4a9cd2ad9170e1ae3e476f5946db5ee

Would it be possible to tighten the lower bounds so that downstream crates can test with minimal versions?

[juntyr]

Thanks for the report @konstin! I've opened #557 - could you check if that would fix your issue, if so I'll merge it and publish a new pre-release.

[konstin]

Thanks, this fixes it!

[juntyr]

https://crates.io/crates/ron/0.9.0-alpha.1 has now been released