Merge pull request #1449 from amy-lei/loop-scoping

fix loop scoping bug

3 files changed, 15 insertions, 0 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index fc540af..7bfebff 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -5,6 +5,9 @@ Version 3.0.2
 
 Unreleased
 
+-   Fix a loop scoping bug that caused assignments in nested loops
+    to still be referenced outside of it. :issue:`1427`
+
 
 Version 3.0.1
 -------------
diff --git a/src/jinja2/compiler.py b/src/jinja2/compiler.py
index ef4c0a1..5fe9349 100644
--- a/src/jinja2/compiler.py
+++ b/src/jinja2/compiler.py
@@ -1290,6 +1290,11 @@ class CodeGenerator(NodeVisitor):
             self.write(", loop)")
             self.end_write(frame)
 
+        # at the end of the iteration, clear any assignments made in the
+        # loop from the top level
+        if self._assign_stack:
+            self._assign_stack[-1].difference_update(loop_frame.symbols.stores)
+
     def visit_If(self, node: nodes.If, frame: Frame) -> None:
         if_frame = frame.soft()
         self.writeline("if ", node)
diff --git a/tests/test_regression.py b/tests/test_regression.py
index 4491dab..7e23369 100644
--- a/tests/test_regression.py
+++ b/tests/test_regression.py
@@ -746,6 +746,13 @@ End"""
         tmpl = env.get_template("base")
         assert tmpl.render() == "42 y"
 
+    def test_nested_loop_scoping(self, env):
+        tmpl = env.from_string(
+            "{% set output %}{% for x in [1,2,3] %}hello{% endfor %}"
+            "{% endset %}{{ output }}"
+        )
+        assert tmpl.render() == "hellohellohello"
+
 
 @pytest.mark.parametrize("unicode_char", ["\N{FORM FEED}", "\x85"])
 def test_unicode_whitespace(env, unicode_char):