Add [] spec patterns for missing premises of iApply.

This fixes issue #51.

theories/proofmode/tactics.v

@@ -426,13 +426,14 @@ Tactic Notation "iApply" open_constr(lem) :=
     | ITrm ?t ?xs ?pat => constr:(ITrm t xs ("*" +:+ pat))
     | _ => constr:(ITrm lem hnil "*")
     end in
-  iPoseProofCore lem as false true (fun H => first
-    [iExact H
-    |eapply tac_apply with _ H _ _ _;
+  let rec go H := first
+    [eapply tac_apply with _ H _ _ _;
       [env_cbv; reflexivity
-      |let P := match goal with |- IntoWand ?P _ _ => P end in
-       apply _ || fail 1 "iApply: cannot apply" P
-      |lazy beta (* reduce betas created by instantiation *)]]).
+      |apply _
+      |lazy beta (* reduce betas created by instantiation *)]
+    |iSpecializePat H "[-]"; last go H] in
+  iPoseProofCore lem as false true (fun H =>
+    first [iExact H|go H|iTypeOf H (fun Q => fail 1 "iApply: cannot apply" Q)]).
 
 (** * Revert *)
 Local Tactic Notation "iForallRevert" ident(x) :=

theories/tests/proofmode.v

@@ -116,3 +116,7 @@ Proof.
   iAssert True%I with "[HP]" as %_. { Fail iClear "HQ". by iClear "HP". }
   done.
 Qed.
+
+Lemma demo_11 (M : ucmraT) (P Q R : uPred M) :
+  (P -∗ Q -∗ True -∗ True -∗ R) -∗ P -∗ Q -∗ R.
+Proof. iIntros "H HP HQ". by iApply ("H" with "[HP]"). Qed.