https://issues.dlang.org/show_bug.cgi?id=21767

          Issue ID: 21767
           Summary: Underflow reported as overflow
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: trivial
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: Ajieskola@gmail.com

auto x = -1234890712367412347124895720349587;

Output:
app.d(1): Error: integer overflow

That is an underflow, not an overflow.

--