add context for warnings emitted from configure_mappers(), autoflush()

Improved the notification of warnings that are emitted within the configure
mappers or flush process, which are often invoked as part of a different
operation, to add additional context to the message that indicates one of
these operations as the source of the warning within operations that may
not be obviously related.

Fixes: #7305
Change-Id: I79da7a6a5d4cf67d57615d0ffc2b8d8454011c84

1 files changed, 40 insertions, 7 deletions

diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index 767148045..01f083bec 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -24,6 +24,7 @@ import sys
 import textwrap
 import threading
 import types
+from types import CodeType
 from typing import Any
 from typing import Callable
 from typing import cast
@@ -1825,6 +1826,19 @@ def warn_limited(msg: str, args: Sequence[Any]) -> None:
     _warnings_warn(msg, exc.SAWarning)
 
 
+_warning_tags: Dict[CodeType, Tuple[str, Type[Warning]]] = {}
+
+
+def tag_method_for_warnings(
+    message: str, category: Type[Warning]
+) -> Callable[[_F], _F]:
+    def go(fn):
+        _warning_tags[fn.__code__] = (message, category)
+        return fn
+
+    return go
+
+
 _not_sa_pattern = re.compile(r"^(?:sqlalchemy\.(?!testing)|alembic\.)")
 
 
@@ -1846,14 +1860,33 @@ def _warnings_warn(
         # ok, but don't crash
         stacklevel = 0
     else:
-        # using __name__ here requires that we have __name__ in the
-        # __globals__ of the decorated string functions we make also.
-        # we generate this using {"__name__": fn.__module__}
-        while frame is not None and re.match(
-            _not_sa_pattern, frame.f_globals.get("__name__", "")
-        ):
+        stacklevel_found = warning_tag_found = False
+        while frame is not None:
+            # using __name__ here requires that we have __name__ in the
+            # __globals__ of the decorated string functions we make also.
+            # we generate this using {"__name__": fn.__module__}
+            if not stacklevel_found and not re.match(
+                _not_sa_pattern, frame.f_globals.get("__name__", "")
+            ):
+                # stop incrementing stack level if an out-of-SQLA line
+                # were found.
+                stacklevel_found = True
+
+                # however, for the warning tag thing, we have to keep
+                # scanning up the whole traceback
+
+            if frame.f_code in _warning_tags:
+                warning_tag_found = True
+                (_prefix, _category) = _warning_tags[frame.f_code]
+                category = category or _category
+                message = f"{message} ({_prefix})"
+
             frame = frame.f_back  # type: ignore[assignment]
-            stacklevel += 1
+
+            if not stacklevel_found:
+                stacklevel += 1
+            elif stacklevel_found and warning_tag_found:
+                break
 
     if category is not None:
         warnings.warn(message, category, stacklevel=stacklevel + 1)