error: left recursive rules create an infinite loop: rec -> rec
 --> $DIR/left_recursion.rs:4:18
  |
4 |     rule rec() = rec() //~ ERROR left recursive rules create an infinite loop: rec -> rec
  |                  ^^^

error: left recursive rules create an infinite loop: foo -> bar -> foo
  --> $DIR/left_recursion.rs:12:11
   |
12 |         / foo() //~ ERROR left recursive rules create an infinite loop: foo -> bar -> foo
   |           ^^^

error: left recursive rules create an infinite loop: bar -> foo -> bar
 --> $DIR/left_recursion.rs:8:11
  |
8 |         / bar() //~ ERROR left recursive rules create an infinite loop: bar -> foo -> bar
  |           ^^^