Why does this not compile?

[Shachar Shemesh]

On 06/03/18 16:06, Steven Schveighoffer wrote:
> On 3/6/18 8:56 AM, Steven Schveighoffer wrote:
>> So a bug report is in order. It should be decided one way or another 
>> -- either the context pointer is part of the struct type or it isn't.
> 
> There is a third possibility:
> 
> It's part of the type AND it's typed as const if it can be (i.e. none of 
> the methods in the struct modify the context data, and any use of the 
> context data implicitly casts from const).
> 
> -Steve

For what it's worth, I vote for option #2 (it isn't const even if the 
struct is), for the same reason that const structs can modify static 
variables - it's not part of the struct.

I'll phrase is another way, if this shouldn't compile:

unittest {
   int i;

   struct S {
     int a;

     void func() const {
       ++i;
     }
   }
}

Then neither should this:
struct S {
   static int i;
   int a;

   void func() const {
     ++i;
   }
}

I fail to see any reasoning[1] that disallows the former but allows the 
later.

Shachar

1 - That is obviously not true. I see the reasoning all too well. Static 
vars are like globals, and you're not getting to them via the struct's 
instance. I would argue that, as far as the programmer, however, there 
is no difference. There is no semantic difference between allowing the 
first and not the second.