fixes #24879; Data getting wiped on copy with iterators and =copy on refc (#24880)

fixes #24879

Author: ringabout

compiler/liftdestructors.nim

@@ -1003,9 +1003,13 @@ proc fillBody(c: var TLiftCtx; t: PType; body, x, y: PNode) =
       # 'selectedGC' here to determine if we have the new runtime.
       discard considerUserDefinedOp(c, t, body, x, y)
     elif tfHasAsgn in t.flags:
+      # seqs with elements using custom hooks in refc
       if c.kind in {attachedAsgn, attachedSink, attachedDeepCopy}:
         body.add newSeqCall(c, x, y)
-      forallElements(c, t, body, x, y)
+      if c.kind == attachedWasMoved:
+        body.add genBuiltin(c, mWasMoved, "wasMoved", x)
+      else:
+        forallElements(c, t, body, x, y)
     else:
       defaultOp(c, t, body, x, y)
   of tyString:

tests/arc/t19457.nim

@@ -1,5 +1,5 @@
 discard """
-  matrix: "--gc:refc; --gc:arc"
+  matrix: "--mm:refc; --mm:arc"
 """
 
 # bug #19457
@@ -13,4 +13,36 @@ proc gcd(x, y: seq[int]): seq[int] =
       b = c
     return a
 
-doAssert gcd(@[1], @[2]) == @[1]
+doAssert gcd(@[1], @[2]) == @[1]
+
+
+
+import std/sequtils
+
+type IrrelevantType* = object
+
+proc `=copy`*(dest: var IrrelevantType, src: IrrelevantType) =
+  discard
+
+type
+  Inner* = object
+    value*: string
+    someField*: IrrelevantType
+  
+  Outer* = object
+    inner*: Inner
+
+iterator valueIt(self: Outer): Inner =
+  yield self.inner
+
+proc getValues*(self: var Outer): seq[Inner] =
+  var peers = self.valueIt().toSeq
+  return peers
+
+var outer = Outer()
+
+outer.inner = Inner(value: "hello, world")
+
+doAssert (outer.valueIt().toSeq)[0].value == "hello, world" # Passes
+doAssert outer.inner.value == "hello, world" # Passes too, original value is doing fine
+doAssert outer.getValues()[0].value == "hello, world" # Fails, value is empty