test-suite/bugs/opened/1811.v


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Require Export Bool.

Lemma neg2xor : forall b, xorb true b = negb b.
Proof. auto. Qed.

Goal forall b1 b2, (negb b1 = b2)  ->  xorb true b1 = b2.
Proof.
  intros b1 b2.
  Fail rewrite neg2xor.
Abort.