Has someone encountered similar issues with -cov?

[Andrei Alexandrescu via Digitalmars-d]

On 07/02/2016 09:23 AM, Johan Engelen wrote:
> On Saturday, 2 July 2016 at 12:26:34 UTC, Andrei Alexandrescu wrote:
>>
>> How would you reshape this?
>
> Maybe:
>
> U opCast(U, T)(T payload)
> {
>      import std.traits;
>
>      enum descriptiveName = !isUnsigned!T && isUnsigned!U && T.sizeof <=
> U.sizeof;
>      enum unsT_sigU = isUnsigned!T && !isUnsigned!U;
>      static if (unsT_sigU)
>      {
>          static assert(U.sizeof <= T.sizeof);
>      }
>
>      if (!descriptiveName || payload >= 0)
>      {
>          auto result = cast(U) payload;
>          if (result == payload)
>          {
>              if (!unsT_sigU || result >= 0)
>              {
>                  return result;
>              }
>          }
>      }
>
>      return hook!U(payload);
> }

Nice, thanks. I've tried to not rely too much on mixing statically-known 
and dynamically-known Boolean expressions. Can I safely assume that all 
compilers will generate good code for such? According to asm.dlang.org, 
dmd generates identical code at least for the two functions above. -- Andrei