Fix recursion in inline plugin when item_fields shadow DB fields (#6115)

beetsplug/inline.py

@@ -61,18 +61,18 @@ class InlinePlugin(BeetsPlugin):
             config["item_fields"].items(), config["pathfields"].items()
         ):
             self._log.debug("adding item field {}", key)
-            func = self.compile_inline(view.as_str(), False)
+            func = self.compile_inline(view.as_str(), False, key)
             if func is not None:
                 self.template_fields[key] = func
 
         # Album fields.
         for key, view in config["album_fields"].items():
             self._log.debug("adding album field {}", key)
-            func = self.compile_inline(view.as_str(), True)
+            func = self.compile_inline(view.as_str(), True, key)
             if func is not None:
                 self.album_template_fields[key] = func
 
-    def compile_inline(self, python_code, album):
+    def compile_inline(self, python_code, album, field_name):
         """Given a Python expression or function body, compile it as a path
         field function. The returned function takes a single argument, an
         Item, and returns a Unicode string. If the expression cannot be
@@ -97,7 +97,12 @@ class InlinePlugin(BeetsPlugin):
             is_expr = True
 
         def _dict_for(obj):
-            out = dict(obj)
+            out = {}
+            for key in obj.keys(computed=False):
+                if key == field_name:
+                    continue
+                out[key] = obj._get(key)
+
             if album:
                 out["items"] = list(obj.items())
             return out

test/plugins/test_plugins.py

@@ -0,0 +1,31 @@
+# test/plugins/test_plugins.py
+
+from beets import config, plugins
+from beets.test.helper import PluginTestCase
+
+class TestInlineRecursion(PluginTestCase):
+    def test_no_recursion_when_inline_shadows_fixed_field(self):
+        config['plugins'] = ['inline']
+
+        config['item_fields'] = {
+            'track_no': (
+                "f'{disc:02d}-{track:02d}' if disctotal > 1 "
+                "else f'{track:02d}'"
+            )
+        }
+
+        plugins._instances.clear()
+        plugins.load_plugins()
+
+        item = self.add_item_fixture(
+            artist='Artist',
+            album='Album',
+            title='Title',
+            track=1,
+            disc=1,
+            disctotal=1,
+        )
+
+        out = item.evaluate_template('$track_no')
+
+        assert out == '01'