gh-134097: Print number of refs & blocks after each statement in new REPL (gh-134136)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>

Lib/_pyrepl/simple_interact.py

@@ -110,6 +110,10 @@ def run_multiline_interactive_console(
     more_lines = functools.partial(_more_lines, console)
     input_n = 0
 
+    _is_x_showrefcount_set = sys._xoptions.get("showrefcount")
+    _is_pydebug_build = hasattr(sys, "gettotalrefcount")
+    show_ref_count = _is_x_showrefcount_set and _is_pydebug_build
+
     def maybe_run_command(statement: str) -> bool:
         statement = statement.strip()
         if statement in console.locals or statement not in REPL_COMMANDS:
@@ -167,3 +171,8 @@ def run_multiline_interactive_console(
         except:
             console.showtraceback()
             console.resetbuffer()
+        if show_ref_count:
+            console.write(
+                f"[{sys.gettotalrefcount()} refs,"
+                f" {sys.getallocatedblocks()} blocks]\n"
+            )

Lib/test/test_pyrepl/test_pyrepl.py

@@ -10,7 +10,7 @@ import sys
 import tempfile
 from unittest import TestCase, skipUnless, skipIf
 from unittest.mock import patch
-from test.support import force_not_colorized, make_clean_env
+from test.support import force_not_colorized, make_clean_env, Py_DEBUG
 from test.support import SHORT_TIMEOUT, STDLIB_DIR
 from test.support.import_helper import import_module
 from test.support.os_helper import EnvironmentVarGuard, unlink
@@ -1610,3 +1610,16 @@ class TestMain(ReplTestCase):
         # Extra stuff (newline and `exit` rewrites) are necessary
         # because of how run_repl works.
         self.assertNotIn(">>> \n>>> >>>", cleaned_output)
+
+    @skipUnless(Py_DEBUG, '-X showrefcount requires a Python debug build')
+    def test_showrefcount(self):
+        env = os.environ.copy()
+        env.pop("PYTHON_BASIC_REPL", "")
+        output, _ = self.run_repl("1\n1+2\nexit()\n", cmdline_args=['-Xshowrefcount'], env=env)
+        matches = re.findall(r'\[-?\d+ refs, \d+ blocks\]', output)
+        self.assertEqual(len(matches), 3)
+
+        env["PYTHON_BASIC_REPL"] = "1"
+        output, _ = self.run_repl("1\n1+2\nexit()\n", cmdline_args=['-Xshowrefcount'], env=env)
+        matches = re.findall(r'\[-?\d+ refs, \d+ blocks\]', output)
+        self.assertEqual(len(matches), 3)

Misc/NEWS.d/next/Library/2025-05-17-13-46-20.gh-issue-134097.fgkjE1.rst

@@ -0,0 +1 @@
+Fix interaction of the new :term:`REPL` and :option:`-X showrefcount <-X>` command line option.