PyREPL: Send PS1 as string (#26197)

Improve the integration of prompt handling in the REPL, ensuring that
prompts are always passed as strings to
`_pyrepl.simple_interact.multiline_input`

* In `python_files/pythonrc.py`, patch
`_pyrepl.simple_interact.multiline_input` so that the `ps1` and `ps2`
prompt arguments are always converted to strings before being passed,
preventing issues with non-string prompt objects (see
python/cpython#158828)

### Testing

* Adds a new test
`test_pyrepl_multiline_input_converts_prompts_to_strings` in
`python_files/tests/test_shell_integration.py` to verify that the
patched `multiline_input` function correctly converts prompt arguments
to strings before calling the original function.

Author: edvilme

python_files/pythonrc.py

@@ -9,12 +9,23 @@ def _initialize():
     if sys.version_info >= (3, 13):
         import re
 
+        import _pyrepl.simple_interact
         import _pyrepl.utils
 
         _pyrepl.utils.ANSI_ESCAPE_SEQUENCE = re.compile(
             r"\x1b(?:\[[ -@]*[A-~]|\][^\x1b\x07]*(?:\x07|\x1b\\))"
         )
 
+        # Patch _pyrepl.simple_interact.multiline_input to ensure prompts are strings
+        _original_multiline_input = _pyrepl.simple_interact.multiline_input
+        if getattr(_original_multiline_input, "_vscode_prompts_as_strings", False) is not True:
+
+            def _multiline_input(more_lines, ps1, ps2):
+                return _original_multiline_input(more_lines, _str(ps1), _str(ps2))
+
+            _multiline_input.__dict__["_vscode_prompts_as_strings"] = True
+            _pyrepl.simple_interact.multiline_input = _multiline_input
+
     original_ps1 = ">>> "
     # PYTHONSTARTUP executes this file's code inside the user's __main__
     # namespace, so PS1.__str__'s globals are the user's globals. If the

python_files/tests/test_shell_integration.py

@@ -115,6 +115,29 @@ def test_replacement_regex_preserves_csi_handling():
     )
 
 
+def test_pyrepl_multiline_input_converts_prompts_to_strings(monkeypatch):
+    if sys.version_info < (3, 13):
+        return
+
+    pyrepl_simple_interact = importlib.import_module("_pyrepl.simple_interact")
+    original_multiline_input = Mock(return_value="statement")
+
+    with monkeypatch.context() as m:
+        m.setattr(pyrepl_simple_interact, "multiline_input", original_multiline_input)
+        importlib.reload(pythonrc)
+
+        more_lines = Mock()
+        ps1 = Mock()
+        ps1.__str__ = Mock(return_value="primary")
+        ps2 = Mock()
+        ps2.__str__ = Mock(return_value="secondary")
+
+        result = pyrepl_simple_interact.multiline_input(more_lines, ps1, ps2)
+
+    assert result == "statement"
+    original_multiline_input.assert_called_once_with(more_lines, "primary", "secondary")
+
+
 def test_prompt_survives_shadowed_builtins_under_pythonstartup():
     # PYTHONSTARTUP executes pythonrc's source directly inside the real
     # REPL's __main__ namespace, not as an imported module. The tests