https://issues.dlang.org/show_bug.cgi?id=19114

          Issue ID: 19114
           Summary: cannot uniquely infer foreach argument types is not a
                    descriptive message
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: pro.mathias.lang@gmail.com

When `opApply` cannot infer the arguments, it gives this very obscure error message, leaving the developer with little to no idea as to what went wrong. It should be improved to show why the inference was not possible.

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