WTF: dmd 2.066 vs. dmd 2.067 really dangerous code breakage

[John Colvin via Digitalmars-d]

On Wednesday, 22 April 2015 at 11:29:30 UTC, Daniel Kozak wrote:
> On Wednesday, 22 April 2015 at 11:28:44 UTC, Daniel Kozak wrote:
> static struct S
> {
>      immutable FLAG_ON = 1;
>      immutable FLAG_GPRS = 2;
>      immutable FLAG_HIDDEN = 4;
>      ubyte flags;
>      ubyte value;
>
>      bool isFlagSet(int flag)
>      {
>          return flags && flag == flag;
>      }
> }
>
> void main(string[ ] args)
> {
>      auto someData = [0x01, 0x10, 0x02, 0x16, 0x04, 0x08];
>      auto countS = someData.length / S.sizeof;
>
>      S[] sArray = (cast(S*)someData.ptr)[0 .. countS];
>      assert(sArray.length == 3);
> }

I agree that the change should be more prominent in the changelog.

Having said that, if your code makes an assumption about the 
layout (alignment and size) of a struct, it should `static 
assert` that assumption, or at least have a test case that relies 
it. You're just asking for trouble without that.