Dicebot on leaving D: It is anarchy driven development in all its glory.

[David Nadlinger]

On Saturday, 25 August 2018 at 22:53:44 UTC, Walter Bright wrote:
> On 8/25/2018 2:46 PM, David Nadlinger wrote:
>> At least for the transition period, I'd have attributes only 
>> apply to the user-specified code and infer them for the actual 
>> full constructor. (We can still print a deprecation warning if 
>> they don't match.) —David
>
> Inferring is not good enough, for example:
>
> https://github.com/dlang/dmd/pull/6816#issuecomment-307972790
>
> There the @safe constructor is calling a destructor that calls 
> free(). It can't be inferred as @safe.

How did you interpret "only apply to the user-specified code"? In 
this example, the `@safe` in `this() @safe {}` would only apply 
to `{}`.

This necessitates being careful with the error message in a case 
like this

   struct UnsafeDtor { @system ~this() {} }

   struct Foo {
     UnsafeDtor ud;
     this(int a) @safe {
       if (!a) throw Exception("boo");
     }
   }

   void bar() @safe {
     auto f = Foo(1);
   }

as just printing "cannot call @system constructor" would be a bit 
misleading. It should work without surprises otherwise, though, 
and can be supplemented with deprecation warnings if the 
specified "inner" and inferred "outer" attributes don't match.

   —David