C++ pattern matching is coming

[Steven Schveighoffer]

On 10/23/22 8:29 PM, Walter Bright wrote:
>> DIP1000 is very keen to conflate different lifetimes and to cut the 
>> longer one off based on the shorter one.
> 
> Yup.
> 
> DIP1000 does not handle what you describe, and isn't designed to. 
> However, it is still very useful for the vast bulk of cases. It's also 
> carefully set up to be conservative, i.e. it will always err on the side 
> of safety.
> 
> To loosen up the safety is the job of @trusted containers, similar to 
> Rust's unsafe code blocks, because Rust's expressiveness is limited, too.

Is this a bug? Because I can't do this from @trusted code:

```d
void foo() @trusted
{
     static struct T
     {
         Exception ex;
         ubyte[] buf;
     }

     scope buffer = new ubyte[100];
     T t;

     t.ex = new Exception("hello");
     t.buf = buffer;
     throw t.ex;
}

void main() @safe
{
     foo();
}
```

Fails with:
```
onlineapp.d(14): Error: scope variable `t` may not be thrown
```

when compiled with -dip1000. Note that the exception is not intended to 
be scope.

(this is a reduction of the aforementioned discord case, and it's from 
vibe-core originally)

-Steve