beta-regression: type_level_examples "the name _ is defined multiple times"

[alexcrichton]

Discovered by crater:

$ git clone https://github.com/rodrimati1992/type_level
$ cd type_level/type_level_examples
$ git reset --hard fc536e556daba9d818767f4df1ba323abb0948ad
$ cargo +beta test

cc @rust-lang/compiler

Note that this regression doesn't affect the master branch, so not cc'ing the author yet

[Mark-Simulacrum]

I believe this is a duplicate but IIRC the previous one was closed so perhaps it re-regressed.

[alexcrichton]

Ah yes indeed, duplicate of #55811