false positives with Base.@kwdef

[dpinol]

Not sure if I should split into 2 issues:

1) plain Base.@kwdef

Create a package with

Base.@kwdef struct KWS
    myField::Int
end

report_package reports this error

═════ 2 possible errors found ═════
┌ @ util.jl:493 throw(UndefKeywordError(:myField))
│ UndefKeywordError: keyword argument myField not assigned: throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────
┌ @ util.jl:493  = throw(UndefKeywordError(:a))
│ UndefKeywordError: keyword argument myField not assigned:  = throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────

2) Base.@kwdef with non used parameter

Create a package with

Base.@kwdef struct KWS{T}
    myField::Int
end

report_package reports more errors

═════ 6 possible errors found ═════
┌ @ util.jl:504 SCEngine.KWS(myField)
│ no matching method found `SCEngine.KWS(::Any)`: SCEngine.KWS(myField::Any)
└───────────────
┌ @ util.jl:504 throw(UndefKeywordError(:myField))
│ UndefKeywordError: keyword argument myField not assigned: throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────
┌ @ util.jl:504  = throw(UndefKeywordError(:myField))
│ UndefKeywordError: keyword argument myField not assigned:  = throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────
┌ @ util.jl:504 Base.kwerr(_2, _3)
│┌ @ error.jl:163 Base.kwerr(::Any, ::Type{SCEngine.KWS})
││ may throw: Base.throw(Base.MethodError((((Base.typeof((args::Tuple{Type})[1]::Type{SCEngine.KWS})::DataType).name::Core.TypeName).mt::Core.MethodTable).kwsorter::Any, tuple(tuple(kw::Any)::Tuple{Any}, args::Tuple{Type}...)::Tuple{Any, Type})::MethodError)
│└────────────────
┌ @ util.jl:505 throw(UndefKeywordError(:myField))
│ UndefKeywordError: keyword argument myField not assigned: throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────
┌ @ util.jl:505  = throw(UndefKeywordError(:myField))
│ UndefKeywordError: keyword argument myField not assigned:  = throw(UndefKeywordError(:myField)::UndefKeywordError)
└───────────────

thanks!

[jakobnissen]

Reduced example:

struct Bar
    x
end
Bar(; x) = Bar(x)

It appears to be because the constructor Bar() contant-evaluates to throwing the error. It's a little tricky to debug because keyword arguments are "magic" and intentionally hide a bunch of their inner workings.

[dpinol]

Second issue reported at #615 (now it only generates 1 error)