crater failures due to unsupported features

[lcnr]

feature(specialization)

non rigid default associated types

• plonky2_field https://github.com/0xPolygonZero/plonky2/blob/6a2c1b47b7b00864c2b65a44c18099b0152f550e/field/src/batch_util.rs#L35

feature(generic_const_exprs)

• fast-0.1.1 https://crater-reports.s3.amazonaws.com/pr-133502-4/try%230c7fed2b7584d310ca8221267fa1b3bec4df427f/reg/span-0.1.0/log.txt