Test unbound arguments false positive in presence of vararg and typeassert

[Krastanov]

module MMM
f(xs::Vector{T}...) where {T<:Integer} = [one(T)*x for x in xs] # raises an error
g(x::Vector{T}) where {T<:Integer} = one(T)*x
h(xs...)= [one(eltype(x))*x for x in xs]
i(x) = one(eltype(x))*x
end

using Aqua

Aqua.test_unbound_args(MMM)

raises an error:

Test Failed at /home/stefan/.julia/packages/Aqua/HWLbM/src/unbound_args.jl:10
  Expression: detect_unbound_args_recursively(m) == []
   Evaluated: Any[f(xs::Vector{T}...) where T<:Integer @ Main.MMM scratch.jl:4] == Any[]
ERROR: There was an error during testing

julia> versioninfo()
Julia Version 1.9.0-DEV.1566
Commit ea991745a99 (2022-10-10 13:10 UTC)
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 16 × AMD Ryzen 7 1700 Eight-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, znver1)
  Threads: 1 on 16 virtual cores
Environment:
  JULIA_EDITOR = code
  JULIA_NUM_THREADS = 1

pkg> st Aqua
Status `Project.toml`
  [4c88cf16] Aqua v0.5.5

[jakobnissen]

This is not a false positive:

julia> f(xs::Vector{T}...) where {T<:Integer} = [one(T)*x for x in xs]
f (generic function with 1 method)

julia> f()
ERROR: UndefVarError: T not defined

When xs is Vararg, this includes zero args. With zero args, T is unbound

[Krastanov]

Oh... thank you!

I will not close this issue myself in case the maintainers deem a special error message explaining this is warranted. Of course, it is perfectly reasonable for the maintainers to simply close the issue too.

[lbenet]

Is there a way to solve unbound cases which involve N unspecified as in Array{T<:Real, N}?

[jlapeyre]

This kind of changes the subject since this is not a false positive. But it would be nice to have a more informative error message. Or better and easier perhaps a link to a page explaining typical causes of the error

It might take a while to understand that instead of this

struct MyStruct{IntT<:Integer}
    v::Tuple{Vararg{IntT}}
end

you really wanted this

struct MyStruct{IntT<:Integer}
    v::Tuple{IntT, Vararg{IntT}}
end

I was using this in conjunction with a macro in Parameters.jl, so the line identifying the error was in Parameters.jl. I assumed it had something to do with the macro rewriting my struct. Of course this was not the case.