alias this and immutable shenanigans

[Yao G.]

Consider this code:

---
module test;

struct Foo
{
     this( int f ) {
         _foo = f;
     }

     @property int baz() {
         return _foo;
     }

     // alias _foo this;
     // alias baz this;	

     immutable int _foo;
}

struct Bar
{
     this( int f ) {
         _foo  = Foo(f);
     }

     private:
     immutable Foo _foo;
}
---

If I uncomment the alias _foo this line, I get the following error message:

% Test.d(22): Error: can only initialize const member _foo inside  
constructor

WTF! I'm initializing it in a constructor! Is this a bug? Or by design you  
cannot alias this to a immutable member of a struct. It seems that there's  
a hidden temp created that wants to initialize the field. Also, I wanted  
to alias the property Foo.baz, but it also caused the following errors:

% Test.d(22): Error: function test.Foo.baz () is not callable using  
argument types (Foo) immutable
% Test.d(22): Error: expected 0 arguments, not 1 for non-variadic function  
type @property int()

It seems that somehow the property is used as a "setter", not as a  
"getter".

So, my questions are:
1. Why is disallowed to alias this an immutable data inside a struct?
2. Why is disallowed to alias this a struct "getter" property?


-- 
Yao G.