January 14, 2019
https://issues.dlang.org/show_bug.cgi?id=19580

          Issue ID: 19580
           Summary: [non-DMD] std.random seed bootstrap: don't count on
                    reading an uninitialized variable being treated as an
                    ordinary read
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: n8sh.secondary@hotmail.com

Calculations that transform an uninitialized variable may be omitted by LDC when optimizations are enabled. This is allowed by the standard so even though this does not affect DMD it should be avoided.

See: https://github.com/ldc-developers/ldc/pull/2946#issuecomment-453828010

And:
https://dlang.org/spec/declaration.html#void_init
>If a void initialized variable's value is used before it is set, the behavior is undefined.

--