Why do "const inout" and "const inout shared" exist?

[ag0aep6g via Digitalmars-d]

On 07/02/2017 10:55 AM, Walter Bright wrote:
> If it is declared as:
> 
>      inout(char)[] foo(bool condition, inout(char)[] chars);
> 
> your specific case will work as expected. Perhaps you meant:

No, it doesn't. The function doesn't compile with that signature.

----
inout(char)[] foo(bool condition, inout(char)[] chars)
{
     if (!condition)
         return "condition failed!"; /* Error: cannot implicitly convert 
expression "condition failed!" of type string to inout(char)[] */
     return chars;
}
----