typeof function literals which define the types of its parameters but do not give their parameters names

[Johannes Loher]

Hey all,

I am a bit confused about the inferred types of function literals 
which do not name their parameters (something like `(int) {}`). 
The confusion arises from the fact that the inferred type 
sometimes is `void` (might be the case, because the function 
literal is inferred to be a template) and sometimes it is 
something like `void function(bool _param_0) pure nothrow @nogc 
@safe`. What is really weir is that seems to depend on the type 
of the parameter. Here is small example showing what happens for 
different parameter types: https://run.dlang.io/is/xSMZZu

Also note that this only happens for function literals. For 
regular functions and member functions, `void` is never inferred, 
but only types like `pure nothrow @nogc @safe void(MyClass 
_param_0)`.

Has anybody any idea what is going on here? Is this a bug?