[Issue 21851] New: UTF8: Column numbers reported by -vcolumns don't respect multibyte characters

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21851

          Issue ID: 21851
           Summary: UTF8: Column numbers reported by -vcolumns don't
                    respect multibyte characters
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: ibuclaw at gdcproject.org

Same as issue 21849, except this is to do with the number reported by the
`-vcolumn' switch.

E.g:
---
void main()
{
    string straße = 42;
}
---

Will report the byte column number in the conversion error.
---
test.d(12,22): Error: cannot implicitly convert expression 42 of type int to
string
---

When the actual message it should generate is
---
test.d(12,21): Error: cannot implicitly convert expression 42 of type int to
string
---

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