Merge pull request rails#53959 from byroot/template-tracker-recursion

Handle cyclic template dependencies

Author: byroot

actionview/lib/action_view/digestor.rb

@@ -107,8 +107,12 @@ def dependency_digest(finder, stack)
         end.join("-")
       end
 
-      def to_dep_map
-        children.any? ? { name => children.map(&:to_dep_map) } : name
+      def to_dep_map(seen = Set.new.compare_by_identity)
+        if seen.add?(self)
+          children.any? ? { name => children.map { |c| c.to_dep_map(seen) } } : name
+        else # the tree has a cycle
+          name
+        end
       end
     end
 

actionview/test/fixtures/digestor/comments/_cycle_a.html.erb

@@ -0,0 +1,3 @@
+<% if some_condition %>
+  <%= render partial: "cycle_b" %>
+<% end %>

actionview/test/fixtures/digestor/comments/_cycle_b.html.erb

@@ -0,0 +1,3 @@
+<% if some_other_condition %>
+  <%= render partial: "cycle_a" %>
+<% end %>

actionview/test/fixtures/digestor/comments/cycle.html.erb

@@ -0,0 +1 @@
+<%= render partial: "cycle_a" %>

actionview/test/template/digestor_test.rb

@@ -296,6 +296,21 @@ def test_digest_cache_cleanup_with_recursion
     assert_equal first_digest, second_digest
   end
 
+  def test_digest_cache_with_cycle
+    expected_deps = [
+      {
+        "comments/cycle_a" => [
+          {
+            "comments/cycle_b" => [
+              "comments/cycle_a",
+            ],
+          },
+        ],
+      },
+    ]
+    assert_equal expected_deps, nested_dependencies("comments/cycle")
+  end
+
   def test_digest_cache_cleanup_with_recursion_and_template_caching_off
     disable_resolver_caching do
       first_digest = digest("level/_recursion")