From cf174280014dcfa3533e15b85a455bd2146e2951 Mon Sep 17 00:00:00 2001
From: Leni Aniva <v@leni.sh>
Date: Wed, 15 May 2024 21:34:15 -0700
Subject: [PATCH] fix: Panic in partial instantiation

---
 Pantograph/Expr.lean  | 10 ++++++++--
 Test/Integration.lean |  4 ++--
 Test/Proofs.lean      |  6 +++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/Pantograph/Expr.lean b/Pantograph/Expr.lean
index 7e691d5..85c7f35 100644
--- a/Pantograph/Expr.lean
+++ b/Pantograph/Expr.lean
@@ -14,18 +14,24 @@ def instantiatePartialDelayedMVars (e: Expr): MetaM Expr := do
   Meta.transform e
     (pre := fun e => e.withApp fun f args => do
       if let .mvar mvarId := f then
+        if ← mvarId.isAssigned then
+          return .visit <| (← instantiateMVars e)
         if let some decl ← getDelayedMVarAssignment? mvarId then
           if args.size ≥ decl.fvars.size then
+            -- Do not use instantiateMVars here. Only one step of instantiation should happen.
             let pending ← instantiateMVars (.mvar decl.mvarIdPending)
             if !pending.isMVar then
-              return .visit <| (← Meta.mkLambdaFVars decl.fvars pending).beta args
+              let pending := pending.abstract decl.fvars
+              let pending := pending.instantiateRevRange 0 decl.fvars.size args
+              let pending := mkAppRange pending decl.fvars.size args.size args
+              return .visit <| pending
       return .continue)
 
 @[export pantograph_instantiate_all_meta_m]
 def instantiateAll (e: Expr): MetaM Expr := do
   let e ← instantiateMVars e
+  let e ← instantiatePartialDelayedMVars e
   let e ← unfoldAuxLemmas e
-  --let e ← instantiatePartialDelayedMVars e
   return e
 
 structure DelayedMVarInvocation where
diff --git a/Test/Integration.lean b/Test/Integration.lean
index 9bd5db6..66b3637 100644
--- a/Test/Integration.lean
+++ b/Test/Integration.lean
@@ -88,11 +88,11 @@ def test_tactic : IO LSpec.TestSeq :=
     vars := #[{ name := "_uniq.10", userName := "x", isInaccessible? := .some false, type? := .some { pp? := .some "Prop" }}],
   }
   let goal2: Protocol.Goal := {
-    name := "_uniq.14",
+    name := "_uniq.17",
     target := { pp? := .some "x ∨ y → y ∨ x" },
     vars := #[
       { name := "_uniq.10", userName := "x", isInaccessible? := .some false, type? := .some { pp? := .some "Prop" }},
-      { name := "_uniq.13", userName := "y", isInaccessible? := .some false, type? := .some { pp? := .some "Prop" }}
+      { name := "_uniq.16", userName := "y", isInaccessible? := .some false, type? := .some { pp? := .some "Prop" }}
     ],
   }
   subroutine_runner [
diff --git a/Test/Proofs.lean b/Test/Proofs.lean
index b09e403..ea6ff11 100644
--- a/Test/Proofs.lean
+++ b/Test/Proofs.lean
@@ -771,7 +771,7 @@ def test_nat_zero_add_alt: TestM Unit := do
     | other => do
       addTest $ assertUnreachable $ other.toString
       return ()
-  let (eqL, eqR, eqT) := ("_uniq.85", "_uniq.86", "_uniq.84")
+  let (eqL, eqR, eqT) := ("_uniq.88", "_uniq.89", "_uniq.87")
   addTest $ LSpec.check tactic $ state3m2.goals.map (·.name.toString) = [eqL, eqR, eqT]
   let [_motive, _major, _step, conduit] := state2.goals | panic! "Goals conflict"
   let state2b ← match state3m2.resume [conduit] with
@@ -789,8 +789,8 @@ def test_nat_zero_add_alt: TestM Unit := do
         name := "_uniq.70",
         userName? := .some "conduit",
         target := {
-          pp? := .some "?m.79 ?m.68 = (n + 0 = n)",
-          sexp? := .some s!"((:c Eq) (:sort 0) (:subst ((:c Eq) (:mv {eqT}) (:mv {eqL}) (:mv {eqR})) (:fv {fvN}) (:mv {major})) ((:c Eq) (:c Nat) ({cNatAdd} (:fv {fvN}) {cNat0}) (:fv {fvN})))",
+          pp? := .some "(?motive.a = ?motive.a) = (n + 0 = n)",
+          sexp? := .some s!"((:c Eq) (:sort 0) ((:c Eq) (:mv {eqT}) (:mv {eqL}) (:mv {eqR})) ((:c Eq) (:c Nat) ({cNatAdd} (:fv {fvN}) {cNat0}) (:fv {fvN})))",
         },
         vars := #[{
           name := fvN,