Allocations in powers with literal exponents

[rdeits]

It looks like we're not quite handling literal_pow correctly:

julia> using SimpleQP

julia> model = SimpleQP.MockModel()
SimpleQP.MockModel(SimpleQP.Parameter[], Base.RefValue{Int64}(1))

julia> p = Parameter(() -> 1.0, model)
Parameter{Float64, …}(…)

julia> e = @expression(p^2)
LazyExpression{FunctionWrapper{…}(LazyExpression{Base.#literal_pow, …}(…))}(…)

julia> e()
1.0

julia> SimpleQP.findallocs(e)
LazyExpression{FunctionWrapper{…}(LazyExpression{Base.#literal_pow, …}(…))}(…): 48 bytes
  [1]: Base.#^
  [2]: Parameter{Float64, …}(…): 0 bytes
  [3]: DataType

[tkoolen]

This is because 1.0^2 becomes Base.literal_pow(^, 1.0, Val{2}), and Val{2} is a DataType (as opposed to Val{2}()), so dynamic dispatch happens. The issue is fixed on Julia master, so I'm inclined to just wait for 0.7.

[rdeits]

No problem. It's easy to replace with x * x until then