gh-89774: Fix pprint ignoring the depth limit at small width

Skip the per-type re-dispatch in _format once the depth limit is reached, so depth truncation no longer depends on width.

Author: tonghuaroot

Lib/pprint.py

@@ -195,7 +195,10 @@ def _format(self, object, stream, indent, allowance, context, level):
             return
         rep = self._repr(object, context, level)
         max_width = self._width - indent - allowance
-        if len(rep) > max_width:
+        # Past the depth limit _safe_repr already folded this to '...'; do not
+        # re-expand it just because it does not fit the width.
+        if len(rep) > max_width and not (
+                self._depth is not None and level >= self._depth):
             p = self._dispatch.get(type(object).__repr__, None)
             # Lazy import to improve module import time
             from dataclasses import is_dataclass

Lib/test/test_pprint.py

@@ -1039,6 +1039,24 @@ def test_depth(self):
         self.assertEqual(pprint.pformat(nested_dict, depth=1), lv1_dict)
         self.assertEqual(pprint.pformat(nested_list, depth=1), lv1_list)
 
+    def test_depth_with_narrow_width(self):
+        # gh-89774: a narrow width must not override the depth limit.
+        nested_dict = {1: {2: {3: 3}}}
+        nested_list = [1, [2, [3, [4]]]]
+        nested_tuple = (1, (2, (3,)))
+        self.assertEqual(pprint.pformat(nested_dict, depth=1, width=5),
+                         '{1: {...}}')
+        self.assertEqual(pprint.pformat(nested_dict, depth=2, width=5),
+                         '{1: {2: {...}}}')
+        self.assertEqual(pprint.pformat(nested_list, depth=1, width=6),
+                         '[1,\n [...]]')
+        self.assertEqual(pprint.pformat(nested_tuple, depth=1, width=6),
+                         '(1,\n (...))')
+        # Depth folding is independent of width: a narrow width folds at the
+        # same level as the default wide width.
+        self.assertEqual(pprint.pformat(nested_dict, depth=1, width=5),
+                         pprint.pformat(nested_dict, depth=1))
+
     def test_sort_unorderable_values(self):
         # Issue 3976:  sorted pprints fail for unorderable values.
         n = 20

Misc/NEWS.d/next/Library/2026-07-06-10-00-00.gh-issue-89774.d3Pth1.rst

@@ -0,0 +1,2 @@
+Fix :mod:`pprint` ignoring the *depth* limit when a small *width* forces
+nested structures onto multiple lines.