BUG: Concatenation warning still appears with sort=False

pandas/core/frame.py

@@ -7217,10 +7217,14 @@ def _join_compat(
             # join indexes only using concat
             if can_concat:
                 if how == "left":
-                    res = concat(frames, axis=1, join="outer", verify_integrity=True)
+                    res = concat(
+                        frames, axis=1, join="outer", verify_integrity=True, sort=sort
+                    )
                     return res.reindex(self.index, copy=False)
                 else:
-                    return concat(frames, axis=1, join=how, verify_integrity=True)
+                    return concat(
+                        frames, axis=1, join=how, verify_integrity=True, sort=sort
+                    )
 
             joined = frames[0]
 

pandas/tests/frame/test_join.py

@@ -24,6 +24,14 @@ def right():
     return DataFrame({"b": [300, 100, 200]}, index=[3, 1, 2])
 
 
+@pytest.fixture(params=[True, False, None])
+def sort_kw(request):
+    """Boolean sort keyword for join.
+    Includes the default of None.
+    """
+    return request.param
+
+
 @pytest.mark.parametrize(
     "how, sort, expected",
     [
@@ -193,3 +201,26 @@ def test_join_left_sequence_non_unique_index():
     )
 
     tm.assert_frame_equal(joined, expected)
+
+
+def test_suppress_future_warning_with_sort_kw(sort_kw):
+    a = DataFrame(
+        {"col1": [1, 2, 3, 4, 5], "col2": [6, 7, 8, 9, 10]},
+        index=["a", "c", "e", "f", "i"],
+    )
+
+    b = DataFrame(
+        {"col4": [1, 2, 3, 4, 5], "col3": [1, 2, 3, 4, 5]},
+        index=["a", "b", "c", "d", "e"],
+    )
+
+    c = DataFrame({"col5": [1, 2, 3, 4, 5]}, index=["f", "g", "h", "i", "j"])
+
+    if sort_kw is None:
+        # only warn if not explicitly specified
+        ctx = tm.assert_produces_warning(FutureWarning, check_stacklevel=False)
+    else:
+        ctx = tm.assert_produces_warning(None, check_stacklevel=False)
+
+    with ctx:
+        a.join([b, c], sort=sort_kw)