Flush local filter and test cache when processing parent_instructions

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to MiniJinja are documented here.
 
+## 2.1.2
+
+- Flush filter and test cache when processing extended template.
+  This fixes a bug that caused the wrong filters to be used in some
+  cases. #551
+
 ## 2.1.1
 
 - Added `indent` parameter to `tojson` filter.  #546

minijinja/src/vm/mod.rs

@@ -211,7 +211,7 @@ impl<'env> Vm<'env> {
             }};
         }
 
-        // looks nicer nice way
+        // looks nicer this way
         #[allow(clippy::while_let_loop)]
         loop {
             let instr = match state.instructions.get(pc) {
@@ -231,6 +231,11 @@ impl<'env> Vm<'env> {
                     };
                     out.end_capture(AutoEscape::None);
                     pc = 0;
+                    // because we swap out the instructions we also need to unload all
+                    // the filters and tests to ensure that we are not accidentally
+                    // reusing the local_ids for completely different filters.
+                    loaded_filters = [None; MAX_LOCALS];
+                    loaded_tests = [None; MAX_LOCALS];
                     continue;
                 }
             };

minijinja/tests/test_templates.rs

@@ -629,3 +629,32 @@ fn test_multiple_extended_includes_in_loop() {
     let rv = env.get_template("main.txt").unwrap().render(()).unwrap();
     assert_eq!(rv, "012");
 }
+
+/// See https://github.com/mitsuhiko/minijinja/issues/551
+#[test]
+fn test_filter_caching() {
+    let mut env = Environment::new();
+    env.add_template("parent.txt", "{{ 'Hello Foo' | lower }}")
+        .unwrap();
+    env.add_template(
+        "child.txt",
+        "{% extends 'parent.txt' %}{% set dummy = 'a' | upper %}",
+    )
+    .unwrap();
+    let rv = env.get_template("child.txt").unwrap().render(()).unwrap();
+    assert_eq!(rv, "hello foo");
+}
+
+/// See https://github.com/mitsuhiko/minijinja/issues/551
+#[test]
+fn test_test_caching() {
+    let mut env = Environment::new();
+    env.add_template("parent.txt", "{{ 42 is odd }}").unwrap();
+    env.add_template(
+        "child.txt",
+        "{% extends 'parent.txt' %}{% set dummy = 23 is even %}",
+    )
+    .unwrap();
+    let rv = env.get_template("child.txt").unwrap().render(()).unwrap();
+    assert_eq!(rv, "false");
+}