[Issue 23530] New: casting immutable away allowed in safe

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23530

          Issue ID: 23530
           Summary: casting immutable away allowed in safe
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: Ajieskola at gmail.com

The following code compiles and runs without crash with DMD 2.100.2, flags
-preview=dip1000: 

------
@safe void main()
{   immutable int x = 5; //alternatively const
    auto a = &x;
    auto b = &cast() x;
    assert(a == b); //passes
    *b = 3; //undefined behaviour
}
------

This is a major hole in memory safety, so I'm assigning severity to critical.

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