Assert type instability

General Usage Performance
,
5

Technically it already figured out that your function will return something of type Nothing. I’m not quite sure why there is an Any there, but perhaps it has been judged that it is not worth inferring the type of the exception? Anyways, if it is a problem, it’s not really your problem.

The explicit return nothing helps for clarity, but I’m not sure if it actually changes the behavior of anything.

If you really wanted to resolve the type warning, you could try writing it explicitly as follows.

julia> function bogus(n::Int)
           if n > 1
               nothing
           else
               Base.throw(Base.AssertionError("n > 1"))
           end
       end
bogus (generic function with 1 method)

julia> @code_warntype bogus(5)
MethodInstance for bogus(::Int64)
  from bogus(n::Int64) in Main at REPL[15]:1
Arguments
  #self#::Core.Const(bogus)
  n::Int64
Body::Nothing
1 ─ %1 = (n > 1)::Bool
└──      goto #3 if not %1
2 ─      return Main.nothing
3 ─ %4 = Base.throw::Core.Const(throw)
│   %5 = Base.AssertionError::Core.Const(AssertionError)
│   %6 = (%5)("n > 1")::AssertionError
│        (%4)(%6)
└──      Core.Const(:(return %7))

Perhaps this is a macro issue or bug?

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