Also, this is actually fixed now, due to some  internal changes to `assert_eq` to fix exactly this problem: https://github.com/mozilla/rust/commit/d3c831ba4a4a2284f73e4f9147aa4900cab56815

(I think any macros which fail this should be regarded as being buggy, and need to be rewritten into using the `match` form as that commit does, so that they externally satisfy the same lifetime rules as other statements.)