[3.13] gh-121790: Fix interactive console initialization (GH-121793) (GH-121822)

(cherry picked from commit e5c7216f376a06d2c931daf999e2980e494e747e)

Co-authored-by: Milan Oberkirch <milan.oberkirch@geops.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

1 files changed, 5 insertions, 3 deletions

diff --git a/Lib/_pyrepl/readline.py b/Lib/_pyrepl/readline.py
index 28f592d..3d94f91 100644
--- a/Lib/_pyrepl/readline.py
+++ b/Lib/_pyrepl/readline.py
@@ -58,7 +58,7 @@ from .types import Callback, Completer, KeySpec, CommandName
 TYPE_CHECKING = False
 
 if TYPE_CHECKING:
-    from typing import Any
+    from typing import Any, Mapping
 
 
 MoreLinesCallable = Callable[[str], bool]
@@ -559,7 +559,7 @@ for _name, _ret in [
 # ____________________________________________________________
 
 
-def _setup(namespace: dict[str, Any]) -> None:
+def _setup(namespace: Mapping[str, Any]) -> None:
     global raw_input
     if raw_input is not None:
         return  # don't run _setup twice
@@ -575,7 +575,9 @@ def _setup(namespace: dict[str, Any]) -> None:
     _wrapper.f_in = f_in
     _wrapper.f_out = f_out
 
-    # set up namespace in rlcompleter
+    # set up namespace in rlcompleter, which requires it to be a bona fide dict
+    if not isinstance(namespace, dict):
+        namespace = dict(namespace)
     _wrapper.config.readline_completer = RLCompleter(namespace).complete
 
     # this is not really what readline.c does.  Better than nothing I guess