gh-118908: Use __main__ for the default PyREPL namespace (#121054)

Lib/_pyrepl/main.py

@@ -0,0 +1,55 @@
+import os
+import sys
+
+CAN_USE_PYREPL: bool
+if sys.platform != "win32":
+    CAN_USE_PYREPL = True
+else:
+    CAN_USE_PYREPL = sys.getwindowsversion().build >= 10586  # Windows 10 TH2
+
+
+def interactive_console(mainmodule=None, quiet=False, pythonstartup=False):
+    global CAN_USE_PYREPL
+    if not CAN_USE_PYREPL:
+        return sys._baserepl()
+
+    if mainmodule:
+        namespace = mainmodule.__dict__
+    else:
+        import __main__
+        namespace = __main__.__dict__
+        namespace.pop("__pyrepl_interactive_console", None)
+
+    startup_path = os.getenv("PYTHONSTARTUP")
+    if pythonstartup and startup_path:
+        import tokenize
+        with tokenize.open(startup_path) as f:
+            startup_code = compile(f.read(), startup_path, "exec")
+            exec(startup_code, namespace)
+
+    # set sys.{ps1,ps2} just before invoking the interactive interpreter. This
+    # mimics what CPython does in pythonrun.c
+    if not hasattr(sys, "ps1"):
+        sys.ps1 = ">>> "
+    if not hasattr(sys, "ps2"):
+        sys.ps2 = "... "
+
+    run_interactive = None
+    try:
+        import errno
+        if not os.isatty(sys.stdin.fileno()):
+            raise OSError(errno.ENOTTY, "tty required", "stdin")
+        from .simple_interact import check
+        if err := check():
+            raise RuntimeError(err)
+        from .simple_interact import run_multiline_interactive_console
+        run_interactive = run_multiline_interactive_console
+    except Exception as e:
+        from .trace import trace
+        msg = f"warning: can't use pyrepl: {e}"
+        trace(msg)
+        print(msg, file=sys.stderr)
+        CAN_USE_PYREPL = False
+    if run_interactive is None:
+        return sys._baserepl()
+    run_interactive(namespace)