Fix handling of typecasting in searchsorted (#13925)

Fixes: #13902 

This PR fixes a type-casting issue with `searchsorted` where typecast was done to the `values` dtype instead of inspecting both input and values columns and converting them to common dtypes.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Lawrence Mitchell (https://github.com/wence-)

URL: #13925

python/cudf/cudf/core/frame.py

@@ -1409,12 +1409,25 @@ def searchsorted(
         if len(values) != len(self._data):
             raise ValueError("Mismatch number of columns to search for.")
 
+        # TODO: Change behavior based on the decision in
+        # https://github.com/pandas-dev/pandas/issues/54668
+        common_dtype_list = [
+            find_common_type([col.dtype, val.dtype])
+            for col, val in zip(self._columns, values)
+        ]
         sources = [
             col
-            if is_dtype_equal(col.dtype, val.dtype)
-            else col.astype(val.dtype)
-            for col, val in zip(self._columns, values)
+            if is_dtype_equal(col.dtype, common_dtype)
+            else col.astype(common_dtype)
+            for col, common_dtype in zip(self._columns, common_dtype_list)
         ]
+        values = [
+            val
+            if is_dtype_equal(val.dtype, common_dtype)
+            else val.astype(common_dtype)
+            for val, common_dtype in zip(values, common_dtype_list)
+        ]
+
         outcol = libcudf.search.search_sorted(
             sources,
             values,

python/cudf/cudf/tests/test_indexing.py

@@ -2067,3 +2067,16 @@ def test_loc_index_notinindex_slice(
             expect = pdf.loc[lo:hi:take_order]
             actual = df.loc[lo:hi:take_order]
             assert_eq(expect, actual)
+
+
+@pytest.mark.parametrize(
+    "arg", [slice(2, 4), slice(2, 5), slice(2.3, 5), slice(4.6, 6)]
+)
+def test_series_iloc_float_int(arg):
+    gs = cudf.Series(range(4), index=[2.0, 3.0, 4.5, 5.5])
+    ps = gs.to_pandas()
+
+    actual = gs.loc[arg]
+    expected = ps.loc[arg]
+
+    assert_eq(actual, expected)

python/cudf/cudf/tests/test_search.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2018-2022, NVIDIA CORPORATION.
+# Copyright (c) 2018-2023, NVIDIA CORPORATION.
 import cupy
 import numpy as np
 import pandas as pd
@@ -156,3 +156,15 @@ def test_searchsorted_misc():
         psr.searchsorted([-100, 3.00001, 2.2, 2.0, 2.000000001]),
         sr.searchsorted([-100, 3.00001, 2.2, 2.0, 2.000000001]),
     )
+
+
+@pytest.mark.xfail(reason="https://github.com/pandas-dev/pandas/issues/54668")
+def test_searchsorted_mixed_str_int():
+    psr = pd.Series([1, 2, 3], dtype="int")
+    sr = cudf.from_pandas(psr)
+
+    with pytest.raises(ValueError):
+        actual = sr.searchsorted("a")
+    with pytest.raises(ValueError):
+        expect = psr.searchsorted("a")
+    assert_eq(expect, actual)