Use the inference cache when no context is provided (#2257)

ChangeLog

@@ -51,6 +51,14 @@ Release date: TBA
  Closes pylint-dev/pylint#7464
  Closes pylint-dev/pylint#8074
 
+* Use the global inference cache when inferring, even without an explicit
+ ``InferenceContext``. This is a significant performance improvement given how
+ often methods default to ``None`` for the context argument. (Linting ``astroid``
+ itself now takes ~5% less time on Python 3.12; other projects requiring more
+ complex inference calculations will see greater speedups.)
+
+ Refs #529
+
 * Fix interrupted ``InferenceContext`` call chains, thereby addressing performance
  problems when linting ``sqlalchemy``.
 

astroid/nodes/node_ng.py

@@ -138,18 +138,13 @@ def infer(
  :returns: The inferred values.
  :rtype: iterable
  """
- if context is not None:
+ if context is None:
+ context = InferenceContext()
+ else:
  context = context.extra_context.get(self, context)
  if self._explicit_inference is not None:
  # explicit_inference is not bound, give it self explicitly
  try:
- if context is None:
- yield from self._explicit_inference(
- self, # type: ignore[arg-type]
- context,
- **kwargs,
- )
- return
  for result in self._explicit_inference(
  self, # type: ignore[arg-type]
  context,
@@ -161,11 +156,6 @@ def infer(
  except UseInferenceDefault:
  pass
 
- if not context:
- # nodes_inferred?
- yield from self._infer(context=context, **kwargs)
- return
-
  key = (self, context.lookupname, context.callcontext, context.boundnode)
  if key in context.inferred:
  yield from context.inferred[key]

tests/test_inference.py

@@ -6157,6 +6157,24 @@ class InferMeTwice:
  assert util.Uninferable not in instance.igetattr("item", context_to_be_used_twice)
 
 
+@patch("astroid.nodes.Call._infer")
+def test_cache_usage_without_explicit_context(mock) -> None:
+ code = """
+ class InferMeTwice:
+ item = 10
+
+ InferMeTwice()
+ """
+ call = extract_node(code)
+ mock.return_value = [Uninferable]
+
+ # no explicit InferenceContext
+ call.inferred()
+ call.inferred()
+
+ mock.assert_called_once()
+
+
 def test_infer_context_manager_with_unknown_args() -> None:
  code = """
  class client_log(object):