[Issue 22298] New: [DIP1000] Nested function's scope parameters can be assigned to variables in enclosing function

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22298

          Issue ID: 22298
           Summary: [DIP1000] Nested function's scope parameters can be
                    assigned to variables in enclosing function
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: giacomo.ratto at protonmail.com

This makes possible to get a pointer to a local variable within an expired
stack frame:
---
void g(scope void delegate(scope int*) @safe cb) @safe {
        int x = 42;
        cb(&x);
}

void main() @safe {
        int* p;
        void f(scope int* i) @safe {
                p = i;
        }

        g(&f);
        // address of x has escaped g
        assert(*p == 42);
}
---

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