`return const` parameters make `inout` obsolete

[Zach the Mystic via Digitalmars-d]

On Monday, 16 March 2015 at 14:23:42 UTC, ketmar wrote:
> On Mon, 16 Mar 2015 14:17:57 +0000, Zach the Mystic wrote:
>
>> char* fun(return const char* x);
>> 
>> Compiler has enough information to adjust the return type of 
>> `fun()` to
>> that of input `x`. This assumes return parameters have been 
>> generalized
>> to all reference types. Destroy.
>
> but why compiler has to rewrite return type? i never told it to 
> do that!

It has to if you pass an immutable to x, which you're allowed to 
do. It only gives an error if you assign the result to a mutable 
variable. The point is that the signature still contains all the 
information it needs without `inout`. What old errors will fail 
to be reported and what new errors would it cause? I haven't been 
able to think of any.