Shouldn't invalid references like this fail at compile time?

[ag0aep6g]

On 01/23/2018 03:38 AM, Mike Franklin wrote:
> import std.stdio;
> 
> void main() @safe
> {
>      string foo = "foo";
>      string* ls0;
>      string* p1, p2;
> 
>      ls0 = &foo;
>      p1 = ls0;
>      ls0.destroy();
>      p2 = ls0;
>      writeln(p2.length);
> }
> 
> Compile with `-dip1000`
> 
> Error: program killed by signal 11
> 
> https://run.dlang.io/is/6L6zcH
> 
> So that's bad.  But it looks like a bug in `-dip1000`, because if I 
> compile without `-dip1000`, I get:
> 
> onlineapp.d(9): Error: cannot take address of local foo in @safe 
> function main
> 
> https://run.dlang.io/is/rHpuf1

No bug.

`&foo` never leaves the scope, so `-dip1000` correctly allows it. If you 
try to `return p1;` or `return p2;`, you get errors from `-dip1000`.

Other than that, `ls0.destroy();` just does `ls0 = null;` and then the 
`writeln` does a null dereference which is considered to be a guaranteed 
segfault. Segfaults are considered safe and `@safe` is not supposed to 
prevent them.