https://issues.dlang.org/show_bug.cgi?id=24575

          Issue ID: 24575
           Summary: sumtype fails to match lambdas with anonymous
                    arguments
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: crazymonkyyy@gmail.com

```d
import std;
struct tree(T){
        alias node=typeof(this)[2]*;
        SumType!(T,node) data;
        bool isleaf()=>
                data.match!(
                        (T)=>true,
                        (node)=>false);
}
unittest{
        tree!int foo;
}
```

adding names to the lamdas arguments cause it to compile

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