Relaxed the constraint introduced in r14190 that froze the existing

evars when rewriting. Use it for autorewrite and subst. Accept evars
instantiation in multi_rewrite so that rewrite alone remains
compatible (it is used in contribs, e.g. Godel, in places where it
does not seem absurd to allow it), but there are no good reason for
it. Comments welcome.
+ addition of some tests for rewriting (one being related to commit 14217)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@14222 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 29 insertions, 0 deletions

diff --git a/test-suite/success/autorewrite.v b/test-suite/success/autorewrite.v
new file mode 100644
index 000000000..5e9064f8a
--- /dev/null
+++ b/test-suite/success/autorewrite.v
@@ -0,0 +1,29 @@
+Variable Ack : nat -> nat -> nat.
+
+Axiom Ack0 : forall m : nat, Ack 0 m = S m.
+Axiom Ack1 : forall n : nat, Ack (S n) 0 = Ack n 1.
+Axiom Ack2 : forall n m : nat, Ack (S n) (S m) = Ack n (Ack (S n) m).
+
+Hint Rewrite Ack0 Ack1 Ack2 : base0.
+
+Lemma ResAck0 : (Ack 2 2 = 7 -> False) -> False.
+Proof.
+  intros.
+  autorewrite with base0 in H using try (apply H; reflexivity).
+Qed.
+
+Lemma ResAck1 : forall H:(Ack 2 2 = 7 -> False), True -> False.
+Proof.
+  intros.
+  autorewrite with base0 in *.
+    apply H;reflexivity.
+Qed.
+
+(* Check autorewrite does not solve existing evars *)
+(* See discussion started by A. Chargueraud in Oct 2010 on coqdev *)
+
+Hint Rewrite <- plus_n_O : base1.
+Goal forall y, exists x, y+x = y.
+eexists. autorewrite with base1.
+Fail reflexivity.
+