https://issues.dlang.org/show_bug.cgi?id=19582

          Issue ID: 19582
           Summary: Make core.internal.convert.toUbyte in CTFE for arrays
                    work with reference type elements and not call
                    postblits/dtors
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody@puremagic.com
          Reporter: n8sh.secondary@hotmail.com

Make `core.internal.convert.toUbyte` in CTFE for arrays work with reference type elements and not call postblits/dtors. This is necessary for the CTFE path of `hashOf` in some circumstances.

Example currently non-compiling code:
---
import core.internal.convert : toUbyte;
final static class C : Object {}
enum b1 = (() @nogc nothrow pure @safe { C[10] o; return toUbyte(o[])[0]; })();
static struct S
{
    int x;
    @disable this(this);
    ~this() @nogc nothrow
    {
        import core.stdc.stdio : puts;
        if (x) puts("impure");
    }
}
enum b2 = () {
        S[10] a;
        return ((const S[] a) @nogc nothrow pure @safe => toUbyte(a))(a);
    }();
---

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