bpo-41058: Use source file encoding in pdb.find_function(). (GH-21010)

(cherry picked from commit 19fcffa) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Author: miss-islington

Lib/pdb.py

@@ -79,6 +79,7 @@
 import pprint
 import signal
 import inspect
+import tokenize
 import traceback
 import linecache
 
@@ -93,7 +94,7 @@ class Restart(Exception):
 def find_function(funcname, filename):
  cre = re.compile(r'def\s+%s\s*[(]' % re.escape(funcname))
  try:
- fp = open(filename)
+ fp = tokenize.open(filename)
  except OSError:
  return None
  # consumer of this info expects the first line to be 1

Lib/test/test_pdb.py

@@ -5,6 +5,7 @@
 import pdb
 import sys
 import types
+import codecs
 import unittest
 import subprocess
 import textwrap
@@ -1226,9 +1227,7 @@ def run_pdb_module(self, script, commands):
  return self._run_pdb(['-m', self.module_name], commands)
 
  def _assert_find_function(self, file_content, func_name, expected):
- file_content = textwrap.dedent(file_content)
-
- with open(support.TESTFN, 'w') as f:
+ with open(support.TESTFN, 'wb') as f:
  f.write(file_content)
 
  expected = None if not expected else (
@@ -1237,22 +1236,49 @@ def _assert_find_function(self, file_content, func_name, expected):
  expected, pdb.find_function(func_name, support.TESTFN))
 
  def test_find_function_empty_file(self):
- self._assert_find_function('', 'foo', None)
+ self._assert_find_function(b'', 'foo', None)
 
  def test_find_function_found(self):
  self._assert_find_function(
  """\
- def foo():
-  pass
+def foo():
+ pass
 
- def bar():
-  pass
+def bœr():
+ pass
 
- def quux():
- pass
- """,
- 'bar',
- ('bar', 4),
+def quux():
+ pass
+""".encode(),
+ 'bœr',
+ ('bœr', 4),
+ )
+
+ def test_find_function_found_with_encoding_cookie(self):
+ self._assert_find_function(
+ """\
+# coding: iso-8859-15
+def foo():
+ pass
+
+def bœr():
+ pass
+
+def quux():
+ pass
+""".encode('iso-8859-15'),
+ 'bœr',
+ ('bœr', 5),
+ )
+
+ def test_find_function_found_with_bom(self):
+ self._assert_find_function(
+ codecs.BOM_UTF8 + """\
+def bœr():
+ pass
+""".encode(),
+ 'bœr',
+ ('bœr', 1),
  )
 
  def test_issue7964(self):

Misc/NEWS.d/next/Library/2020-06-20-21-03-55.bpo-41058.gztdZy.rst

@@ -0,0 +1 @@
+:func:`pdb.find_function` now correctly determines the source file encoding.