https://issues.dlang.org/show_bug.cgi?id=14627

          Issue ID: 14627
           Summary: Implicit conversion from uint to dchar allows dchar >
                    dhcar.max
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: DMD
          Assignee: nobody@puremagic.com
          Reporter: lio+bugzilla@lunesu.com

This code compiles & runs:

void main()
{
  uint u = ~0;
  dchar d = u;//implicit conversion
  assert(d > d.max);
}

It should use VRP to determine whether the range fits dchar range.
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