Merge c3c09de1ba into a4151bd41e

src/implicit_effect.luau

@@ -62,7 +62,7 @@ local function update_children_effect(p: {
 
             push_cleanup(assert(get_scope()), function()
                 for child in node.cache.cur_children_set do
-                    child.Parent = nil
+                    if child.Parent == p.instance then child.Parent = nil end
                 end
             end)
         end
@@ -71,7 +71,7 @@ local function update_children_effect(p: {
     process_child(new_children)
 
     for child in cur_children_set do
-        child.Parent = nil -- unparent all children that weren't in the new children set
+        if child.Parent == p.instance then child.Parent = nil end -- unparent all children that weren't in the new children set
     end
 
     table.clear(cur_children_set) -- clear cache, preserve capacity
@@ -116,7 +116,7 @@ return {
 
         push_cleanup(assert_stable_scope(), function()
             for child in node.cache.cur_children_set do
-                child.Parent = nil
+                if child.Parent == instance then child.Parent = nil end
             end
         end)
 

test/tests.luau

@@ -1050,6 +1050,33 @@ TEST("create()", wrap_root(function()
         CHECK(parent:FindFirstChild "c")
     end
 
+    do CASE "children moved to another parent"
+        local other = create "Frame" {}
+
+        local child = create "Frame" {}
+        local children_a = source { child }
+        local children_b = source {}
+        create "Frame" { children_a }
+        local parent_b = create "Frame" { children_b }
+
+        children_b { child }
+        children_a {}
+        CHECK(child.Parent == parent_b)
+
+        local a = create "Frame" {}
+        local b = create "Frame" {}
+        local destroy = root(function()
+            create "Frame" { function() return a end }
+            create "Frame" { function() return { function() return b end } end }
+        end)
+
+        a.Parent = other
+        b.Parent = other
+        destroy()
+        CHECK(a.Parent == other)
+        CHECK(b.Parent == other)
+    end
+
     do CASE "garbage collection test"
         local wref