Truly algebraic Variant and Nullable

[ag0aep6g]

On Tuesday, 22 December 2020 at 16:54:56 UTC, 9il wrote:
> On Tuesday, 22 December 2020 at 16:43:30 UTC, ag0aep6g wrote:
[...]
>> The issue isn't that the reference outlives the struct. It's 
>> that the reference outlives a tag change of the tagged union.
>
> If I am correct Dlang doesn't provide an instrument to validate 
> it, isn't it?
>
> What alternative is possible?
>
> Returning it by value isn't acceptable at least because of 
> performance reasons: the first target of the library is struts 
> with a lot of Mir ref-counted fields.

Mark it @system then.

>>> The docs maybe not clear enough. `trustedGet` asserts type is 
>>> matched, while `get` throws an exception if the type doesn't 
>>> match.
>>
>> You can't rely on an assert for @safe (unless it's 
>> `assert(false);`).
>
> This is why it is the market as `trusted`. It is much more 
> convenient than forcing users to wrap each access with @trusted 
> lambda, which feels like masochism.

@trusted makes the exact same promise to the user as @safe.

If your method doesn't have a safe interface, don't mark it @safe 
or @trusted. Mark it @system.