For the ui/borrowck/borrowck-union-borrow.ast.nll.stderr test, the AST borrow checker indicates that the borrow of u.b is causing the borrow of the union u itself, thus justifying the complaint about the borrow of u.a.
However, the NLL borrow checker just says that u.b is already borrowed, which is less clear when its pointing at a borrow of u.a.
For the
ui/borrowck/borrowck-union-borrow.ast.nll.stderrtest, the AST borrow checker indicates that the borrow ofu.bis causing the borrow of the unionuitself, thus justifying the complaint about the borrow ofu.a.However, the NLL borrow checker just says that
u.bis already borrowed, which is less clear when its pointing at a borrow ofu.a.