Signs by which to recognize D1

[rumbu via Digitalmars-d-learn]

On Wednesday, 6 May 2015 at 07:56:53 UTC, Daren Scot Wilson wrote:
> Someone looks at a chunk of D code of murky origin.  Possibly, 
> it is old, maybe D1 not D2.  Inadequately commented, believe it 
> or not, and not other information.
>
> What are some easy to spot details in the syntax by which the 
> onlooker can know it's D1 not D2?

keywords - lack of pure @safe nothrow @nogc immutable __gshared
strings - use of d|w|char[] instead of d|w|string
operators - use of old operator overloads: opCom, opAdd, opSub ...