don't export 3-arg Task constructor

Author: JeffBezanson

base/boot.jl

@@ -380,7 +380,7 @@ eval(Core, :(LineInfoNode(mod::Module, method::Symbol, file::Symbol, line::Int,
 
 Module(name::Symbol=:anonymous, std_imports::Bool=true) = ccall(:jl_f_new_module, Ref{Module}, (Any, Bool), name, std_imports)
 
-function Task(@nospecialize(f), reserved_stack::Int, completion_future)
+function _Task(@nospecialize(f), reserved_stack::Int, completion_future)
     return ccall(:jl_new_task, Ref{Task}, (Any, Any, Int), f, completion_future, reserved_stack)
 end
 

base/task.jl

@@ -3,7 +3,7 @@
 ## basic task functions and TLS
 
 const ThreadSynchronizer = GenericCondition{Threads.SpinLock}
-Core.Task(@nospecialize(f), reserved_stack::Int=0) = Task(f, reserved_stack, ThreadSynchronizer())
+Core.Task(@nospecialize(f), reserved_stack::Int=0) = Core._Task(f, reserved_stack, ThreadSynchronizer())
 
 # Container for a captured exception and its backtrace. Can be serialized.
 struct CapturedException <: Exception