Associate union notes with their parent error

mypy/checkexpr.py

@@ -4423,12 +4423,14 @@ def check_op(
                 recent_context.line = err.line
                 recent_context.column = err.column
                 if len(left_variants) >= 2 and len(right_variants) >= 2:
-                    self.msg.warn_both_operands_are_from_unions(recent_context)
+                    self.msg.warn_both_operands_are_from_unions(recent_context, parent_error=err)
                 elif len(left_variants) >= 2:
-                    self.msg.warn_operand_was_from_union("Left", base_type, context=recent_context)
+                    self.msg.warn_operand_was_from_union(
+                        "Left", base_type, context=recent_context, parent_error=err
+                    )
                 elif len(right_variants) >= 2:
                     self.msg.warn_operand_was_from_union(
-                        "Right", right_type, context=recent_context
+                        "Right", right_type, context=recent_context, parent_error=err
                     )
 
             # See the comment in 'check_overload_call' for more details on why

mypy/messages.py

@@ -1775,14 +1775,18 @@ def overloaded_signatures_ret_specific(self, index: int, context: Context) -> No
             context,
         )
 
-    def warn_both_operands_are_from_unions(self, context: Context) -> None:
-        self.note("Both left and right operands are unions", context, code=codes.OPERATOR)
+    def warn_both_operands_are_from_unions(
+        self, context: Context, *, parent_error: ErrorInfo
+    ) -> None:
+        self.note("Both left and right operands are unions", context, parent_error=parent_error)
 
-    def warn_operand_was_from_union(self, side: str, original: Type, context: Context) -> None:
+    def warn_operand_was_from_union(
+        self, side: str, original: Type, context: Context, *, parent_error: ErrorInfo
+    ) -> None:
         self.note(
             f"{side} operand is of type {format_type(original, self.options)}",
             context,
-            code=codes.OPERATOR,
+            parent_error=parent_error,
         )
 
     def operator_method_signatures_overlap(

test-data/unit/check-errorcodes.test

@@ -136,6 +136,18 @@ y = 1  # type: int, int  # type: ignore[syntax]
                                  # N: Error code "attr-defined" not covered by "type: ignore[xyz]" comment
 'x'.foobar  # type: ignore
 
+[case testOperatorUnionNoteWithIgnoredArgType]
+class OnlyA:
+    def __call__(self, other: "A") -> bool:
+        return True
+
+class A:
+    __le__ = OnlyA()
+
+def f(x: A, y: A | int) -> None:
+    x <= y  # type: ignore[arg-type]
+[out]
+
 [case testErrorCodeIgnore2]
 a = 'x'.foobar  # type: int  # type: ignore[attr-defined]
 b = 'x'.foobar  # type: int  # type: ignore[xyz]  # E: "str" has no attribute "foobar"  [attr-defined] \