From 014c7aa5b5a1ab3aa8a294729a8d38595232aa81 Mon Sep 17 00:00:00 2001
From: Tian Gao <gaogaotiantian@hotmail.com>
Date: Tue, 15 Oct 2024 08:45:23 -0700
Subject: [PATCH] gh-100141: Allow pdb to deal with empty file (GH-125425)
 (cherry picked from commit bb9604b62ae7f043594ffea9287f9213067cc7fb)

Co-authored-by: Tian Gao <gaogaotiantian@hotmail.com>
---
 Lib/pdb.py                                             |  3 +--
 Lib/test/test_pdb.py                                   | 10 ++++++++++
 .../2024-10-14-02-27-03.gh-issue-100141.NuAcwa.rst     |  1 +
 3 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-10-14-02-27-03.gh-issue-100141.NuAcwa.rst

diff --git a/Lib/pdb.py b/Lib/pdb.py
index 89cf975164ac04..559517813cf600 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -321,8 +321,7 @@ def user_call(self, frame, argument_list):
     def user_line(self, frame):
         """This function is called when we stop or break at this line."""
         if self._wait_for_mainpyfile:
-            if (self.mainpyfile != self.canonic(frame.f_code.co_filename)
-                or frame.f_lineno <= 0):
+            if (self.mainpyfile != self.canonic(frame.f_code.co_filename)):
                 return
             self._wait_for_mainpyfile = False
         if self.bp_commands(frame):
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index 6da82fe04c0eaa..1542bb3bee1aea 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -2754,6 +2754,16 @@ def _create_fake_frozen_module():
         # verify that pdb found the source of the "frozen" function
         self.assertIn('x = "Sentinel string for gh-93696"', stdout, "Sentinel statement not found")
 
+    def test_empty_file(self):
+        script = ''
+        commands = 'q\n'
+        # We check that pdb stopped at line 0, but anything reasonable
+        # is acceptable here, as long as it does not halt
+        stdout, _ = self.run_pdb_script(script, commands)
+        self.assertIn('main.py(0)', stdout)
+        stdout, _ = self.run_pdb_module(script, commands)
+        self.assertIn('__main__.py(0)', stdout)
+
     def test_non_utf8_encoding(self):
         script_dir = os.path.join(os.path.dirname(__file__), 'encoded_modules')
         for filename in os.listdir(script_dir):
diff --git a/Misc/NEWS.d/next/Library/2024-10-14-02-27-03.gh-issue-100141.NuAcwa.rst b/Misc/NEWS.d/next/Library/2024-10-14-02-27-03.gh-issue-100141.NuAcwa.rst
new file mode 100644
index 00000000000000..c366b0ad4040d3
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-10-14-02-27-03.gh-issue-100141.NuAcwa.rst
@@ -0,0 +1 @@
+Fixed the bug where :mod:`pdb` will be stuck in an infinite loop when debugging an empty file.