From: Tan Long <tanloong@foxmail.com>
Date: Fri, 1 May 2026 05:32:57 +0000 (+0800)
Subject: gh-149173: Fix inverted PYTHON_BASIC_REPL environment check in _pyrepl_available... 
X-Git-Tag: v3.15.0b1~146
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8066db57535161dda316a70c1b00a89581bf3399;p=thirdparty%2FPython%2Fcpython.git

gh-149173: Fix inverted PYTHON_BASIC_REPL environment check in _pyrepl_available() (#149174)
---

diff --git a/Lib/pdb.py b/Lib/pdb.py
index c4bc0020646b..4dd974b375c2 100644
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -376,7 +376,7 @@ def get_default_backend():
 
 def _pyrepl_available():
     """return whether pdb should use _pyrepl for input"""
-    if not os.getenv("PYTHON_BASIC_REPL"):
+    if os.getenv("PYTHON_BASIC_REPL"):
         CAN_USE_PYREPL = False
     else:
         try:
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index c5171f3388c9..db9001997552 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -4753,6 +4753,16 @@ def bœr():
         stdout, stderr = self.run_pdb_script(script, commands)
         self.assertIn("The specified object 'C.foo' is not a function", stdout)
 
+    def test_pyrepl_available(self):
+        with patch.dict(os.environ, {"PYTHON_BASIC_REPL": "1"}):
+            self.assertFalse(pdb._pyrepl_available())
+
+        with patch.dict(os.environ, {}, clear=True):
+            mod = types.ModuleType("_pyrepl.main")
+            mod.CAN_USE_PYREPL = True
+            with patch.dict("sys.modules", {"_pyrepl.main": mod}):
+                self.assertTrue(pdb._pyrepl_available())
+
 
 class ChecklineTests(unittest.TestCase):
     def setUp(self):
diff --git a/Misc/NEWS.d/next/Library/2026-04-30-14-21-26.gh-issue-149173.KJqZm0.rst b/Misc/NEWS.d/next/Library/2026-04-30-14-21-26.gh-issue-149173.KJqZm0.rst
new file mode 100644
index 000000000000..019ab76b8635
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-04-30-14-21-26.gh-issue-149173.KJqZm0.rst
@@ -0,0 +1,2 @@
+Fix inverted :envvar:`PYTHON_BASIC_REPL` environment check in
+``pdb._pyrepl_available``.