gh-126019 Fix inspect.getsource for classes created in PyREPL

Lib/_pyrepl/main.py

@@ -35,6 +35,7 @@ def interactive_console(mainmodule=None, quiet=False, pythonstartup=False):
         import __main__
         namespace = __main__.__dict__
         namespace.pop("__pyrepl_interactive_console", None)
+        namespace.pop("__file__", None)
 
     # sys._baserepl() above does this internally, we do it here
     startup_path = os.getenv("PYTHONSTARTUP")

Lib/test/support/__init__.py

@@ -62,6 +62,7 @@
     "force_not_colorized",
     "BrokenIter",
     "in_systemd_nspawn_sync_suppressed",
+    "initialized_with_pyrepl",
     ]
 
 
@@ -2849,8 +2850,8 @@ def wrapper(*args, **kwargs):
 
 def initialized_with_pyrepl():
     """Detect whether PyREPL was used during Python initialization."""
-    # If the main module has a __file__ attribute it's a Python module, which means PyREPL.
-    return hasattr(sys.modules["__main__"], "__file__")
+    spec = getattr(sys.modules.get("__main__", None), "__spec__", None)
+    return getattr(spec, "name", None) == "_pyrepl.__main__"
 
 
 WINDOWS_STATUS = {

Lib/test/test_pyrepl/test_pyrepl.py

@@ -1087,19 +1087,13 @@ def test_exposed_globals_in_repl(self):
             self.skipTest("pyrepl not available")
         self.assertEqual(exit_code, 0)
 
-        # if `__main__` is not a file (impossible with pyrepl)
+        # if `__main__` is an uncached .py file (no .pyc), `__file__` was removed
         case1 = f"{pre}, '__doc__', {post}" in output
 
-        # if `__main__` is an uncached .py file (no .pyc)
-        case2 = f"{pre}, '__doc__', '__file__', {post}" in output
+        # if `__main__` is a cached .pyc, `__file__` was removed
+        case2 = f"{pre}, '__cached__', '__doc__', {post}" in output
 
-        # if `__main__` is a cached .pyc file and the .py source exists
-        case3 = f"{pre}, '__cached__', '__doc__', '__file__', {post}" in output
-
-        # if `__main__` is a cached .pyc file but there's no .py source file
-        case4 = f"{pre}, '__cached__', '__doc__', {post}" in output
-
-        self.assertTrue(case1 or case2 or case3 or case4, output)
+        self.assertTrue(case1 or case2, output)
 
     def _assertMatchOK(
             self, var: str, expected: str | re.Pattern, actual: str
@@ -1175,7 +1169,6 @@ def test_inspect_keeps_globals_from_inspected_module(self):
             "FOO": "42",
             "__name__": "'__main__'",
             "__package__": "'blue'",
-            "__file__": re.compile(r"^'.*calx.py'$"),
         }
         self._run_repl_globals_test(expectations, as_module=True)
 
@@ -1318,6 +1311,12 @@ def test_null_byte(self):
         self.assertEqual(exit_code, 0)
         self.assertNotIn("TypeError", output)
 
+    def test_inspect_getsource(self):
+        code = "import inspect\nclass A: pass\n\nprint(inspect.getsource(A))\nexit()\n"
+        output, exit_code = self.run_repl(code)
+        self.assertEqual(exit_code, 0)
+        self.assertIn("OSError('source code not available')", output)
+
     def test_readline_history_file(self):
         # skip, if readline module is not available
         readline = import_module('readline')

Misc/NEWS.d/next/Library/2024-10-27-11-46-13.gh-issue-126019.I_GHhZ.rst

@@ -0,0 +1,3 @@
+Remove the ``__file__`` attribute from the ``__main__`` namespace created by
+PyREPL, to avoid :func:`inspect.getsource` from fetching unrelated source
+code for classes defined in the REPL.