API: ensure IntervalIndex.left/right are 64bit if numeric (#50130)

Author: topper-123

pandas/core/indexes/interval.py

@@ -59,6 +59,8 @@
     is_number,
     is_object_dtype,
     is_scalar,
+    is_signed_integer_dtype,
+    is_unsigned_integer_dtype,
 )
 from pandas.core.dtypes.dtypes import IntervalDtype
 from pandas.core.dtypes.missing import is_valid_na_for_dtype
@@ -521,6 +523,7 @@ def _maybe_convert_i8(self, key):
         original = key
         if is_list_like(key):
             key = ensure_index(key)
+            key = self._maybe_convert_numeric_to_64bit(key)
 
         if not self._needs_i8_conversion(key):
             return original
@@ -566,6 +569,20 @@ def _maybe_convert_i8(self, key):
 
         return key_i8
 
+    def _maybe_convert_numeric_to_64bit(self, idx: Index) -> Index:
+        # IntervalTree only supports 64 bit numpy array
+        dtype = idx.dtype
+        if np.issubclass_(dtype.type, np.number):
+            return idx
+        elif is_signed_integer_dtype(dtype) and dtype != np.int64:
+            return idx.astype(np.int64)
+        elif is_unsigned_integer_dtype(dtype) and dtype != np.uint64:
+            return idx.astype(np.uint64)
+        elif is_float_dtype(dtype) and dtype != np.float64:
+            return idx.astype(np.float64)
+        else:
+            return idx
+
     def _searchsorted_monotonic(self, label, side: Literal["left", "right"] = "left"):
         if not self.is_non_overlapping_monotonic:
             raise KeyError(