1 error: expected one of `>`, identifier, or lifetime, found `,`
2 --> $DIR/issue-20616-9.rs:46:15
4 LL | type Type_9<T,,> = Box<T>; //~ error: expected one of `>`, identifier, or lifetime, found `,`
5 | ^ expected one of `>`, identifier, or lifetime here
7 error: aborting due to previous error