https://issues.dlang.org/show_bug.cgi?id=16663

          Issue ID: 16663
           Summary: [REG 2.072] std.unit.toUpper rejects an alias this to
                    a string
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: regression
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: b2.temp@gmx.com

struct String
{
    string data;
    alias data this;
}

void main()
{
    import std.uni : toUpper;
    auto u = toUpper(String("a"));
}

works with DMD 2.071.2
with DMD 2.072 we get an error.

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