Fix Python extractor treating subscript strings as messages

babel/messages/extract.py

@@ -567,6 +567,8 @@ def extract_python(
     """
     funcname = lineno = message_lineno = None
     call_stack = []  # line numbers of calls
+    # Strings inside subscripts, lists, dicts, and sets are not arguments.
+    bracket_depth = 0
     buf = []
     messages = []
     translator_comments = []
@@ -640,11 +642,22 @@ def extract_python(
 
                 funcname = lineno = message_lineno = None
                 call_stack.clear()
+                bracket_depth = 0
                 messages = []
                 translator_comments = []
                 in_translator_comments = False
                 if nested:
                     funcname = value
+            elif tok == OP and value in {'[', '{'}:
+                if not message_lineno:
+                    message_lineno = lineno
+                bracket_depth += 1
+            elif tok == OP and value in {']', '}'}:
+                if bracket_depth:
+                    bracket_depth -= 1
+            elif bracket_depth:
+                # The string belongs to the bracketed expression, not the call.
+                pass
             elif tok == STRING:
                 val = _parse_python_string(value, encoding, future_flags)
                 if val is not None:

tests/messages/test_extract_python.py

@@ -505,3 +505,26 @@ def test_nested_messages():
     assert messages[6][3] == []
     assert messages[7][2] == 'Armin'
     assert messages[7][3] == []
+
+
+def test_strings_inside_subscripts_and_literals_are_not_messages():
+    buf = BytesIO(b"""\
+pgettext(context, dictionary["key"])
+_(foo["a"], "b")
+_({"a": "b"})
+_(["a", "b"])
+_(dictionary[_("inner")])
+pgettext("navigation", "Guide")
+_("hello" "world")
+""")
+    messages = list(extract.extract_python(buf, extract.DEFAULT_KEYWORDS, [], {}))
+    assert messages == [
+        (1, 'pgettext', (None, None), []),
+        (2, '_', (None, 'b'), []),
+        (3, '_', None, []),
+        (4, '_', None, []),
+        (5, '_', None, []),
+        (5, '_', 'inner', []),
+        (6, 'pgettext', ('navigation', 'Guide'), []),
+        (7, '_', 'helloworld', []),
+    ]