Old type parameter syntax deprecation loses information

[ararslan]

The following message came from JSON.jl:

WARNING: deprecated syntax "parametric method syntax parse{T <: Associative}((parameters (kw (:: dicttype (curly Type T)) (curly Dict String Any))),io::IO) around /Users/alex/.julia/v0.7/JSON/src/Parser.jl:386".
Use "parse(#self#::Core.Typeof(parse),io::IO) where T" instead.

Note how the parsed representation leaks into the method signature, and how the initial use has the constraint T<:Associative, whereas the suggested replacement has no bound on T, nor does it list the keyword arguments present in the original signature.

This was introduced by #22834.