Detect the bug in the following code

[ixid via Digitalmars-d]

On Wednesday, 15 April 2015 at 15:17:32 UTC, Steven Schveighoffer 
wrote:
> On 4/15/15 10:44 AM, Idan Arye wrote:
>> import std.stdio;
>>
>> struct Foo {
>>     bool registered = false;
>>
>>     void register(int x) {
>>         writeln("Registering ", x);
>>         register = true;
>>     }
>> }
>>
>> void main() {
>>     Foo foo;
>>     foo.register(10);
>> }
>
> Easy, the bug is in DMD improperly accepting property 
> assignment without @property annotation :P
>
> -Steve

writeln = "Now this is abused of the syntax."