opApply @safety

[Chris Wright via Digitalmars-d-learn]

On Fri, 29 Jan 2016 14:00:08 -0500, Steven Schveighoffer wrote:

> On 1/29/16 12:44 PM, Chris Wright wrote:
>> I want to create an opApply for a type.
>>
>> I've marked my code @safe, because everything I wrote was @safe. The
>> body of opApply is @safe, but it calls a delegate that may or may not
>> be @safe.
>>
>> How do I make it so I can iterate through this type safely and
>> systemly?
> 
> Likely an overload. Tag the delegate as being @safe or not.
> 
> -Steve

That's handy. It works. I can make it so someone can call:
foo.opApply((i, k, v) @safe => 0);
foo.opApply((i, k, v) @system => 0);

And that works.

However, if you have:
@safe void bar() {
  foreach(i, k, v; foo) {
  }
}

the compiler complains:

opapplysafe.d(12): Error: foo.opApply matches more than one declaration:
opapplysafe.d(2):     @safe int(int delegate(int, string, string) @safe 
dg)
and:
opapplysafe.d(5):     @system int(int delegate(int, string, string) 
@system dg)

Guess I'll file a bug.