Non-inferrability in broadcasting

[timholy]

Noticed in JuliaMath/Interpolations.jl#269:

using StaticArrays, Test
h = SMatrix{1,1}([1.0])
steps = SVector(1.0)
testinf(h, steps) = h ./ (steps .* steps')

julia> testinf(h, steps)
1×1 SArray{Tuple{1,1},Float64,2,1}:
 1.0

julia> @inferred testinf(h, steps)
ERROR: return type SArray{Tuple{1,1},Float64,2,1} does not match inferred return type Any
Stacktrace:
 [1] error(::String) at ./error.jl:33
 [2] top-level scope at none:0

[timholy]

Reduced to:

julia> a = axes(v)
(SOneTo(2),)

julia> b = axes(v')
(Base.OneTo(1), SOneTo(2))

julia> @inferred Broadcast.broadcast_shape(a, b)
ERROR: return type Tuple{SOneTo{2},SOneTo{2}} does not match inferred return type Tuple{Union{SOneTo{2}, OneTo{Int64}},SOneTo{2}}
Stacktrace:
 [1] error(::String) at ./error.jl:33
 [2] top-level scope at none:0

Fix coming.