From 39839dbc39a683f094996a4078815c2249abc38d Mon Sep 17 00:00:00 2001
From: Guilherme Leobas <gleobas@quansight.com>
Date: Tue, 30 Dec 2025 02:37:32 +0000
Subject: [PATCH] Include one level of stack trace in the `lru_cache` warning
 msg (#171496)

Fixes #167991

Example of the new warning message:

```python
/home/guilhermel/git/pytorch313/torch/_dynamo/variables/functions.py:2159: UserWarning: Dynamo detected a call to a `functools.lru_cache`-wrapped function at 'script.py:12'. Dynamo ignores the cache wrapper and directly traces the wrapped function. Silent incorrectness is only a *potential* risk, not something we have observed. Enable TORCH_LOGS=+dynamo for a DEBUG stack trace.

This call originates from:
  File "/path/to/script.py", line 12, in bar
    return baz(x)

  torch._dynamo.utils.warn_once(msg)
```

Pull Request resolved: https://github.com/pytorch/pytorch/pull/171496
Approved by: https://github.com/Lucaskabela
---
 test/dynamo/test_error_messages.py   | 20 ++++++++++++++++++++
 torch/_dynamo/variables/functions.py | 15 +++++++++++----
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/test/dynamo/test_error_messages.py b/test/dynamo/test_error_messages.py
index a125bb53a27..8d660d7a7b5 100644
--- a/test/dynamo/test_error_messages.py
+++ b/test/dynamo/test_error_messages.py
@@ -1588,6 +1588,26 @@ call to a lru_cache wrapped function at: test_error_messages.py:N
 """,
         )
 
+    def test_lru_cache_warning(self):
+        # test only the warning message itself
+        @lru_cache
+        def bax(x):
+            return x + 1
+
+        def bar(x):
+            return bax(x)
+
+        @torch.compile(backend="eager", fullgraph=True)
+        def foo(x):
+            return bar(x)
+
+        x = torch.randn(2)
+        with self.assertWarnsOnceRegex(
+            UserWarning,
+            r"(?s).*This call originates from:\n.*File .*, line (\d+), in bar",
+        ):
+            foo(x)
+
     def test_disable_message(self):
         @torch.compile(backend="eager", fullgraph=True)
         def outer(fn, x):
diff --git a/torch/_dynamo/variables/functions.py b/torch/_dynamo/variables/functions.py
index f7703f406ba..47a7edc1901 100644
--- a/torch/_dynamo/variables/functions.py
+++ b/torch/_dynamo/variables/functions.py
@@ -26,6 +26,7 @@ import functools
 import inspect
 import itertools
 import logging
+import os
 import sys
 import traceback
 import types
@@ -2131,12 +2132,18 @@ class WrapperUserFunctionVariable(VariableTracker):
             module_name = getattr(target_fn, "__module__", "") or ""
 
             if module_name.split(".", maxsplit=1)[0] != "torch":
+                frame_summary = tx.frame_summary()
+                filename = os.path.basename(frame_summary.filename)
+                lineno = frame_summary.lineno
                 msg = (
                     "Dynamo detected a call to a `functools.lru_cache`-wrapped "
-                    "function. Dynamo ignores the cache wrapper and directly "
-                    "traces the wrapped function. Silent incorrectness is only "
-                    "a *potential* risk, not something we have observed. "
-                    'Enable TORCH_LOGS="+dynamo" for a DEBUG stack trace.'
+                    f"function at '{filename}:{lineno}'. Dynamo ignores the "
+                    "cache wrapper and directly traces the wrapped function. "
+                    "Silent incorrectness is only a *potential* risk, not "
+                    "something we have observed. "
+                    "Enable TORCH_LOGS=+dynamo for a DEBUG stack trace.\n\n"
+                    "This call originates from:\n"
+                    f"{''.join(traceback.format_list([frame_summary]))}"
                 )
 
                 torch._dynamo.utils.warn_once(msg)