On Wednesday, 3 August 2016 at 17:16:10 UTC, Andre Pany wrote:
Hi,
I just stumbled over this behavior. I am not sure whether
the behavior is correct or not.
[...]
alias foo = () => new Object;
...is an alias for a delegate/function returning an Object. It is
analogous to
alias foo = () { return new Object; };
void bar(Object o){}
...is a function accepting an Object parameter. In main you are
trying to call this overload
void bar(Object function() o){}
...which is essentially
void bar(typeof(foo) o) {}
You can use pragma(msg, typeof(symbol).stringof) to inspect what
types are being thrown around.
void bar(T)(T t)
{
pragma(msg, T.stringof); // "Object function() pure nothrow
@safe"
}
void main()
{
auto n1 = foo;
pragma(msg, typeof(foo).stringof); // "Object function()
pure nothrow @safe"
bar(foo);
}
You could argue that parameterless function call rules should
apply here and have it implicitly converted to bar(foo()), but it
doesn't. I imagine the ambiguity (of delegate vs function return
value) would just cause more problems than it would solve.
