Inference substitutes Any for MethodError

[timholy]

As reported in #14335:

julia> function foo(A::VecOrMat)
           if size(A,1) == 2 && size(A,2) == 2
               return bar(A)
           end
           sum(A)
       end
foo (generic function with 1 method)

julia> bar(A::Matrix) = sum(A)
bar (generic function with 1 method)

julia> using Base.Test

julia> @inferred(foo([1,2]))
ERROR: return type Int64 does not match inferred return type Any
 in error at ./error.jl:21

It seems that it could be Union{}, as with other errors, and not destroy inference for the rest of the function.

[andreasnoack]

I think I was wondering about the exact same issue here https://groups.google.com/forum/#!topic/julia-dev/OWImSfq-cuM

[JeffBezanson]

Yes, Union{} is more precise but we've found returning this to be unsafe, probably because of #265. Returning Any avoids problems when the needed methods are added later.

[timholy]

OK, so should I close this and/(EDIT: add "or") merge #14335? I think it's best to leave open as a reminder for when we fix #265.

[kshyatt]

This is still happening on master.

[vtjnash]

fixed by #21892