Discussion Thread: DIP 1035-- at system Variables--Community Review Round 1

[Timon Gehr]

On 10.06.20 16:15, Stanislav Blinov wrote:
>  From the feedback thread:
> 
> On Wednesday, 10 June 2020 at 13:56:11 UTC, Timon Gehr wrote:
>> Memory safety cannot depend on the correctness of a `@safe` constructor.
> 
>> struct VmInstruction {
>>     @system Opcode opcode; // this need not be private, just a valid 
>> enum member
>>     this(Opcode opcode) @safe {
>>         this.opcode = opcode; // forgot to check
>>     }
>> }
>> ...
>> void main() @safe {
>>     auto code = [VmInstruction(cast(Opcode)20)];
>>     execute(code);
>> }
> 
> Good observation. It *almost* feels like there's a case lurking for 
> disallowing enum casts in @safe code.

enum Opcode{
     decrement, increment, print,
}
...
void main() @safe {
     auto code = [VmInstruction(Opcode.increment|Opcode.print)];
     execute(code);
}