[python-package] make scikit-learn estimator tags compatible with scikit-learn>=1.6.0dev

python-package/lightgbm/sklearn.py

@@ -662,6 +662,10 @@ def __init__(
         self._n_classes: int = -1
         self.set_params(**kwargs)
 
+    # scikit-learn 1.6 introduced an __sklearn__tags() method intended to replace _more_tags().
+    # _more_tags() can be removed whenever lightgbm's minimum supported scikit-learn version
+    # is >=1.6.
+    # ref: https://github.com/microsoft/LightGBM/pull/6651
     def _more_tags(self) -> Dict[str, Any]:
         return {
             "allow_nan": True,
@@ -673,6 +677,15 @@ def _more_tags(self) -> Dict[str, Any]:
             },
         }
 
+    def __sklearn_tags__(self):
+        tags = super().__sklearn_tags__()
+        more_tags = self._more_tags()
+        tags.input_tags.allow_nan = more_tags["allow_nan"]
+        tags.input_tags.sparse = "sparse" in more_tags["X_types"]
+        tags.target_tags.one_d_labels = "1dlabels" in more_tags["X_types"]
+        tags._xfail_checks = more_tags["_xfail_checks"]
+        return tags
+
     def __sklearn_is_fitted__(self) -> bool:
         return getattr(self, "fitted_", False)