9217ef2018
Clean up type alias impl trait implementation - Removes special case for top-level impl trait - Removes associated opaque types - Forbid lifetime elision in let position impl trait. This is consistent with the behavior for inferred types. - Handle lifetimes in type alias impl trait more uniformly with other parameters cc #69323 cc #63063 Closes #57188 Closes #62988 Closes #69136 Closes #73061