Fix splitarg to correctly handle ::Int

Author: cstjean

src/utils.jl

@@ -225,7 +225,12 @@ call) such as `x::Int=2` and returns `(arg_name, arg_type, default)`. `default`
 ```
 """
 function splitarg(arg_expr)
-    split_var(arg) = (@capture(arg, name_::T_)) ? (name, T) : (arg, :Any)
+    split_var(arg) =
+        @match arg begin
+            ::T_ => (nothing, T)
+            name_::T_ => (name, T)
+            x_ => (arg, :Any)
+        end
     if @capture(arg_expr, arg_ = default_)
         @assert default !== nothing "splitarg cannot handle `nothing` as a default. Use a quoted `nothing` if possible. (MacroTools#35)"
         return (split_var(arg)..., default)

test/runtests.jl

@@ -100,6 +100,7 @@ let
     @test splitarg(def_elts[:args][1])[3] === nothing
     @test map(splitarg, (:(f(a=2, x::Int=nothing, y))).args[2:end]) ==
         [(:a, :Any, 2), (:x, :Int, :nothing), (:y, :Any, nothing)]
+    @test splitarg(:(::Int)) == (nothing, :Int, nothing)
 end
 
 include("destruct.jl")