[Issue 20868] DIP1000: scope delegate triggers error in unsafe code and it shouldn't

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20868

Bolpat <qs.il.paperinik at gmail.com> changed:

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                 CC|                            |qs.il.paperinik at gmail.com

--- Comment #7 from Bolpat <qs.il.paperinik at gmail.com> ---
(In reply to Walter Bright from comment #5)
> To be specific, when compiled with -dip1000:
> 
>   void scoped (scope void delegate() dg) {
>     static void delegate()[] dgs;
>     dgs ~= dg;  // Error: scope variable `dg` may not be copied into
> allocated memory
>   }

I only find the error message confusing. It should be an error: One cannot
assign a scope object to a global state. Local static variables are not at
global scope, but are a global state.

Allowing that would make `scope` absolutely useless as a guarantee and for
optimizations. When the function is called with a lambda, its can be allocated
on the stack, because the reference won't "survive" the call. With allowing
assignment to local static variables, this is no longer the case.

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