Add an `iSimpl in "%"` test.

tests/proofmode.ref

@@ -122,6 +122,13 @@ Tactic failure: iSpecialize: cannot instantiate (⌜φ⌝ → P -∗ False)%I wi
   --------------------------------------∗
   ⌜S (S (S x)) = y⌝
   
+"test_iSimpl_in4"
+     : string
+The command has indeed failed with message:
+In nested Ltac calls to "iSimpl in (constr)",
+"iEval (tactic) in (constr)" and "<iris.proofmode.ltac_tactics.iEval_go>",
+last call failed.
+Tactic failure: iEval: %: unsupported selection pattern.
 "test_iFrame_later_1"
      : string
 1 subgoal

tests/proofmode.v

@@ -483,6 +483,10 @@ Lemma test_iSimpl_in3 x y z :
   ⌜ S (S (S x)) = y ⌝ : PROP.
 Proof. iIntros "#H1 H2". iSimpl in "#". Show. done. Qed.
 
+Check "test_iSimpl_in4".
+Lemma test_iSimpl_in4 x y : ⌜ (3 + x)%nat = y ⌝ -∗ ⌜ S (S (S x)) = y ⌝ : PROP.
+Proof. iIntros "H". Fail iSimpl in "%". by iSimpl in "H". Qed.
+
 Lemma test_iIntros_pure_neg : (⌜ ¬False ⌝ : PROP)%I.
 Proof. by iIntros (?). Qed.