Add `FromForall` instance for `not`. This fixes issue #108.

theories/proofmode/class_instances.v

@@ -772,6 +772,9 @@ Proof. done. Qed.
 Global Instance from_forall_pure {A} (φ : A → Prop) :
   @FromForall M A (⌜∀ a : A, φ a⌝) (λ a, ⌜ φ a ⌝)%I.
 Proof. by rewrite /FromForall pure_forall. Qed.
+Global Instance from_forall_pure_not (φ : Prop) :
+  @FromForall M φ (⌜¬ φ⌝) (λ a : φ, False)%I.
+Proof. by rewrite /FromForall pure_forall. Qed.
 Global Instance from_forall_impl_pure P Q φ :
   IntoPureT P φ → FromForall (P → Q) (λ _ : φ, Q)%I.
 Proof.

theories/tests/proofmode.v

@@ -233,6 +233,9 @@ Qed.
 Lemma test_iIntros_rewrite P (x1 x2 x3 x4 : nat) :
   x1 = x2 → (⌜ x2 = x3 ⌝ ∗ ⌜ x3 ≡ x4 ⌝ ∗ P) -∗ ⌜ x1 = x4 ⌝ ∗ P.
 Proof. iIntros (?) "(-> & -> & $)"; auto. Qed.
+
+Lemma test_iItros_pure : (⌜ ¬False ⌝ : uPred M)%I.
+Proof. by iIntros (?). Qed.
 End tests.
 
 Section more_tests.