Fix --sort-reexports crash with non-seekable streams (e.g. stdin)

isort/main.py

@@ -1059,6 +1059,8 @@ def main(argv: Sequence[str] | None = None, stdin: TextIOWrapper | None = None)
         file_path = Path(stream_filename) if stream_filename else None
         if show_files:
             sys.exit("Error: can't show files for streaming input.")
+        if config.sort_reexports:
+            sys.exit("Error: --sort-reexports is not supported with streaming input (stdin).")
 
         input_stream = sys.stdin if stdin is None else stdin
         if check:

tests/unit/test_regressions.py

@@ -1,10 +1,11 @@
 """A growing set of tests designed to ensure isort doesn't have regressions in new versions"""
 
-from io import StringIO
+from io import BytesIO, StringIO, TextIOWrapper
 
 import pytest
 
 import isort
+from isort.main import main
 
 
 def test_isort_duplicating_comments_issue_1264():
@@ -2012,3 +2013,11 @@ def test_comment_on_opening_line_of_aliased_import_does_not_move():
         isort.code(short_line, profile="black")
         == "from mod import attr as alias  # type: ignore[attr-defined]  # My comment\n"
     )
+
+
+def test_sort_reexports_with_stdin_raises_error_issue_2393():
+    """Ensure --sort-reexports raises a clear error when used with stdin."""
+    fake_stdin = TextIOWrapper(BytesIO(b"from test import B, A\n"))
+    with pytest.raises(SystemExit) as exc_info:
+        main(argv=["--sort-reexports", "-"], stdin=fake_stdin)
+    assert exc_info.value.code != 0