Does the spec take priority over the compiler?

[Steven Schveighoffer]

On 12/16/18 2:42 PM, Neia Neutuladh wrote:
> On Sun, 16 Dec 2018 14:29:04 -0500, Steven Schveighoffer wrote:
>> I would expect the @nogc propagation would require a
>> language change.
> 
> A compiler change but not a spec change.

Right.

> 
>> Specifically, there's no good way to get the current
>> behavior if you implement the propagation.
> 
> Your options:
> 
> 1. Move your aggregates above the `@nogc nothrow pure:` line
> 2. Move your aggregates outside the `@nogc nothrow pure {}` block
> 3. Mark functions `@nogc nothrow pure` individually

None of those are good options.

> 
>> So you need some way to turn
>> off @nogc in order to make it more encompassing.
> 
> That would be quite useful.

Agreed.

> 
>> But the fact that the
>> spec says it should propagate probably increases the chances of a change
>> getting accepted.
> 
> I'm not terribly confident.
> 

Well, I don't know if such a change is possible without fore-mentioned 
features to turn off @nogc. So it's one of those things where really I 
think the compiler should implement what the spec says, but the reality 
is that it would break too much code in a horrible way to make it a reality.

But the spec saying it should be that way gives more weight to the 
argument that it should be that way, even if it's painful.

-Steve