From b92666745e78bb252209af444761a586fe3a418b Mon Sep 17 00:00:00 2001
From: cooldome <ariabushenko@gmail.com>
Date: Mon, 16 Nov 2020 11:39:28 +0000
Subject: [PATCH] fix #15910 (#15984)

* fix #15910

* produce op of op is nil

* Trigger build

(cherry picked from commit a4d02f591c685b261a41a7b9b51aaba05c542499)
---
 compiler/liftdestructors.nim | 16 ++++++---
 tests/arc/t14383.nim         | 66 +++++++++++++++++++++++++++++++++++-
 2 files changed, 77 insertions(+), 5 deletions(-)

diff --git a/compiler/liftdestructors.nim b/compiler/liftdestructors.nim
index 1f9b031c03..0da4354dca 100644
--- a/compiler/liftdestructors.nim
+++ b/compiler/liftdestructors.nim
@@ -40,6 +40,9 @@ proc at(a, i: PNode, elemType: PType): PNode =
   result[1] = i
   result.typ = elemType
 
+proc destructorOverriden(t: PType): bool =
+  t.attachedOps[attachedDestructor] != nil and sfOverriden in t.attachedOps[attachedDestructor].flags
+
 proc fillBodyTup(c: var TLiftCtx; t: PType; body, x, y: PNode) =
   for i in 0..<t.len:
     let lit = lowerings.newIntLit(c.g, x.info, i)
@@ -290,8 +293,10 @@ proc instantiateGeneric(c: var TLiftCtx; op: PSym; t, typeInst: PType): PSym =
 proc considerAsgnOrSink(c: var TLiftCtx; t: PType; body, x, y: PNode;
                         field: var PSym): bool =
   if optSeqDestructors in c.g.config.globalOptions:
-    let op = field
-    if field != nil and sfOverriden in field.flags:
+    var op = field
+    let destructorOverriden = destructorOverriden(t)
+    if op != nil and op != c.fn and 
+        (sfOverriden in op.flags or destructorOverriden):
       if sfError in op.flags:
         incl c.fn.flags, sfError
       #else:
@@ -299,6 +304,10 @@ proc considerAsgnOrSink(c: var TLiftCtx; t: PType; body, x, y: PNode;
       onUse(c.info, op)
       body.add newHookCall(c, op, x, y)
       result = true
+    elif op == nil and destructorOverriden:
+      op = produceSym(c.g, c.c, t, c.kind, c.info, c.idgen)
+      body.add newHookCall(c, op, x, y)
+      result = true
   elif tfHasAsgn in t.flags:
     var op: PSym
     if sameType(t, c.asgnForType):
@@ -905,8 +914,7 @@ proc produceSym(g: ModuleGraph; c: PContext; typ: PType; kind: TTypeAttachedOp;
   # register this operation already:
   typ.attachedOps[kind] = result
 
-  if kind == attachedSink and typ.attachedOps[attachedDestructor] != nil and
-       sfOverriden in typ.attachedOps[attachedDestructor].flags:
+  if kind == attachedSink and destructorOverriden(typ):
     ## compiler can use a combination of `=destroy` and memCopy for sink op
     dest.flags.incl sfCursor
     result.ast[bodyPos].add newOpCall(a, typ.attachedOps[attachedDestructor], d[0])
diff --git a/tests/arc/t14383.nim b/tests/arc/t14383.nim
index 834c50def9..7c63f73335 100644
--- a/tests/arc/t14383.nim
+++ b/tests/arc/t14383.nim
@@ -4,6 +4,21 @@ discard """
 hello
 hello
 @["a", "b"]
+---------------------
+plain:
+destroying: ('first', 42)
+destroying: ('second', 20)
+destroying: ('third', 12)
+
+Option[T]:
+destroying: ('first', 42)
+destroying: ('second', 20)
+destroying: ('third', 12)
+
+seq[T]:
+destroying: ('first', 42)
+destroying: ('second', 20)
+destroying: ('third', 12)
 '''
 """
 
@@ -47,4 +62,53 @@ proc freeJVMObject(o: JVMObject) =
 proc fromJObject(T: typedesc[JVMObject]): T =
   result.new(cast[proc(r: T) {.nimcall.}](freeJVMObject))
 
-discard JVMObject.fromJObject()
\ No newline at end of file
+discard JVMObject.fromJObject()
+
+
+#------------------------------------------------------------------------------
+# Issue #15910
+#------------------------------------------------------------------------------
+
+import options
+
+type
+  Thing = object
+    name: string
+    age: int
+
+proc `=destroy`(thing: var Thing) =
+  if thing.name != "":
+    echo "destroying: ('", thing.name, "', ", thing.age, ")"
+  `=destroy`(thing.name)
+  `=destroy`(thing.age)
+
+proc plain() =
+  var t = Thing(name: "first", age: 42)
+  t = Thing(name: "second", age: 20)
+  t = Thing()
+  let u = Thing(name: "third", age: 12)
+
+proc optionT() =
+  var t = Thing(name: "first", age: 42).some
+  t = Thing(name: "second", age: 20).some
+  t = none(Thing)
+  let u = Thing(name: "third", age: 12).some
+
+proc seqT() =
+  var t = @[Thing(name: "first", age: 42)]
+  t = @[Thing(name: "second", age: 20)]
+  t = @[]
+  let u = @[Thing(name: "third", age: 12)]
+
+echo "---------------------"
+echo "plain:"
+plain()
+echo()
+
+echo "Option[T]:"
+optionT()
+echo()
+
+echo "seq[T]:"
+seqT()
+echo()
\ No newline at end of file