Issue #22493: Inline flags now should be used only at the start of the

regular expression.  Deprecation warning is emitted if uses them in the
middle of the regular expression.

filelist.py

@@ -302,21 +302,26 @@ def translate_pattern(pattern, anchor=1, prefix=None, is_regex=0):
         else:
             return pattern
 
+    # ditch start and end characters
+    start, _, end = glob_to_re('_').partition('_')
+
     if pattern:
         pattern_re = glob_to_re(pattern)
+        assert pattern_re.startswith(start) and pattern_re.endswith(end)
     else:
         pattern_re = ''
 
     if prefix is not None:
-        # ditch end of pattern character
-        empty_pattern = glob_to_re('')
-        prefix_re = glob_to_re(prefix)[:-len(empty_pattern)]
+        prefix_re = glob_to_re(prefix)
+        assert prefix_re.startswith(start) and prefix_re.endswith(end)
+        prefix_re = prefix_re[len(start): len(prefix_re) - len(end)]
         sep = os.sep
         if os.sep == '\\':
             sep = r'\\'
-        pattern_re = "^" + sep.join((prefix_re, ".*" + pattern_re))
+        pattern_re = pattern_re[len(start): len(pattern_re) - len(end)]
+        pattern_re = r'%s\A%s%s.*%s%s' % (start, prefix_re, sep, pattern_re, end)
     else:                               # no prefix -- respect anchor flag
         if anchor:
-            pattern_re = "^" + pattern_re
+            pattern_re = r'%s\A%s' % (start, pattern_re[len(start):])
 
     return re.compile(pattern_re)

tests/test_filelist.py

@@ -51,14 +51,14 @@ class FileListTestCase(support.LoggingSilencer,
 
         for glob, regex in (
             # simple cases
-            ('foo*', r'foo[^%(sep)s]*\Z(?ms)'),
-            ('foo?', r'foo[^%(sep)s]\Z(?ms)'),
-            ('foo??', r'foo[^%(sep)s][^%(sep)s]\Z(?ms)'),
+            ('foo*', r'(?s:foo[^%(sep)s]*)\Z'),
+            ('foo?', r'(?s:foo[^%(sep)s])\Z'),
+            ('foo??', r'(?s:foo[^%(sep)s][^%(sep)s])\Z'),
             # special cases
-            (r'foo\\*', r'foo\\\\[^%(sep)s]*\Z(?ms)'),
-            (r'foo\\\*', r'foo\\\\\\[^%(sep)s]*\Z(?ms)'),
-            ('foo????', r'foo[^%(sep)s][^%(sep)s][^%(sep)s][^%(sep)s]\Z(?ms)'),
-            (r'foo\\??', r'foo\\\\[^%(sep)s][^%(sep)s]\Z(?ms)')):
+            (r'foo\\*', r'(?s:foo\\\\[^%(sep)s]*)\Z'),
+            (r'foo\\\*', r'(?s:foo\\\\\\[^%(sep)s]*)\Z'),
+            ('foo????', r'(?s:foo[^%(sep)s][^%(sep)s][^%(sep)s][^%(sep)s])\Z'),
+            (r'foo\\??', r'(?s:foo\\\\[^%(sep)s][^%(sep)s])\Z')):
             regex = regex % {'sep': sep}
             self.assertEqual(glob_to_re(glob), regex)