https://issues.dlang.org/show_bug.cgi?id=21362

          Issue ID: 21362
           Summary: Unclear specification of `in` parameter storage class
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dlang.org
          Assignee: nobody@puremagic.com
          Reporter: johanengelen@weka.io

At  https://dlang.org/spec/function.html#param-storage  it is unclear what the
meaning of `in` is, because of the last sentence "This requires the -preview=in
switch, available in v2.094.0 or higher." What does "This" refer to?
Please reformulate, for example by:

"The parameter is an input to the function. Input parameters behaves as if they
have the const scope storage classes....
When `-preview=in` switch is passed to compiler, the semantics become:
The parameter is an input to the function. Input parameters behaves as if they
have the const scope storage classes....
"

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