[Issue 24242] New: forward inside templates with -dip1000 causes memory corruption

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24242

          Issue ID: 24242
           Summary: forward inside templates with -dip1000 causes memory
                    corruption
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: d.bugs at webfreak.org

minimal reproduction code:

```d
// bug.d
struct S()
{
        ulong[] payload;

        this(ulong[] value)
        {
                import core.lifetime;

                payload = forward!value;
        }
}

S!() test()
{
        return S!()([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
}

void main()
{
        import std.stdio;

        auto val = test().payload;
        writeln("[0]=", val[0], " (should be 0)");
        writeln("[1]=", val[1], " (should be 1)");
        writeln("[2]=", val[2], " (should be 2)");
        writeln("[3]=", val[3], " (should be 3)");
        writeln("[4]=", val[4], " (should be 4)");
        writeln("[5]=", val[5], " (should be 5)");
        writeln("[6]=", val[6], " (should be 6)");
        writeln("[7]=", val[7], " (should be 7)");
        writeln("[8]=", val[8], " (should be 8)");
        writeln("[9]=", val[9], " (should be 9)");
}
```

`dmd -dip1000 -run source/app.d` (also happening with LDC)

causes:

```
[0]=0 (should be 0)
[1]=1 (should be 1)
[2]=140720508484016 (should be 2)
[3]=140720508484400 (should be 3)
[4]=14 (should be 4)
[5]=94655388051378 (should be 5)
[6]=94655388051378 (should be 6)
[7]=7 (should be 7)
[8]=4 (should be 8)
[9]=94655388051453 (should be 9)
```

real-world code: assign a `string[]` to mir-core's `Algebraic!(string[])`, the
strings will be messed up

note that everything works as expected without -dip1000

--