[Issue 21801] New: std.typecons.ReplaceType does not work for `in` parameters

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21801

          Issue ID: 21801
           Summary: std.typecons.ReplaceType does not work for `in`
                    parameters
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: johanengelen at weka.io

Failing testcase:
```
import std.typecons;

void foo() {
    static assert(is(ReplaceType!(int, float, int function(in long, ref const
int)) ==
            float function(in long, ref const float)));
    static assert(is(ReplaceType!(int, float, int function(long, in int*)) ==
            float function(long, in float*)));
}
```

Problem related to https://github.com/dlang/phobos/pull/7570

--