TypeError in getproperty on container types

[akirakyle]

I think I may have stumbled upon a bug with getproperty on accessing container types, although I suspect it's actually a missing convert in the constructor's definition. For example

using Moshi.Data: @data

@data OptionVec{T} begin
    None
    struct Some
        n::T
        xs::Vector{Any}
    end
end

A = OptionVec.Some{String}("hi", [1, 2])
A.xs

gives the error

ERROR: TypeError: in typeassert, expected Vector{Any}, got a value of type Vector{Int64}
Stacktrace:
 [1] getproperty(value::Main.OptionVec.var"typeof(OptionVec)"{String}, name::Symbol)
   @ Main.OptionVec ~/.julia/packages/Moshi/SEGHC/src/data/emit/getproperty.jl:21
 [2] top-level scope
   @ REPL[5]:1

This can obviously be fixed by just converting before the constructor OptionVec.Some{String}("hi", Any[1, 2]) but I would expect the constructor to automatically handle the conversion to the specified variant's type?

[visr]

After doing a macroexpand on a simple data type with Vector{Any}, I saw that the variant storage struct had an Any field instead of Vector{Any}, hence there was no automatic conversion from Vector{Int} to Vector{Any} on construction. The variant_fieldtypes however correctly shows Vector{Any}. This results is a mismatch in the typeassert in getproperty.

using Moshi.Data.Prelude

@data M begin
    V(Vector{Any})
end

v = M.V([5])

variant_fieldtypes(v)  # => (Vector{Any},)

dump(variant_storage(v))
Main.M.var"##Storage#V"
  ##field#230: Array{Int64}((1,)) [5]

getproperty(v, 1)  # => TypeError in typeassert

The reason for this any is that it gives up when encountering an Any type parameter like in Vector{Any}. Removing this line gets the desired behavior for this example:

Moshi.jl/src/data/scan.jl

Line 50 in 0667fc8

Any in typevars && return Any # no need to specialize further

I don't quite understand what goes wrong though, the typeassert now is sometimes wrong in a different way, causing tests to fail. Probably related to self referencing data types?

julia> using Moshi

julia> r = Moshi.Match.Pattern.Row([]);

julia> r.xs
ERROR: TypeError: in typeassert, expected Vector{Moshi.Match.Pattern.var"typeof(Pattern)"}, got a value of type Vector{Any}
Stacktrace:
 [1] getproperty(value::Moshi.Match.Pattern.var"typeof(Pattern)", name::Symbol)
   @ Moshi.Match.Pattern a:\.julia\dev\Moshi\src\data\emit\getproperty.jl:21

julia> variant_fieldtypes(r)
(Vector{Moshi.Match.Pattern.var"typeof(Pattern)"},)

julia> dump(variant_storage(r))
Moshi.Match.Pattern.var"##Storage#Row"
  xs: Array{Any}((0,))