Skip re pkg frames in warnings

This uses the warnings feature skip_file_prefixes added in 3.12
python#100840

Author: wimglenn

Lib/re/_parser.py

@@ -12,6 +12,7 @@
 
 # XXX: show string offset and offending character for all errors
 
+import os
 from ._constants import *
 
 SPECIAL_CHARS = ".\\[{()*+?^$|"
@@ -508,6 +509,8 @@ def _parse_sub(source, state, verbose, nested):
     subpattern.append((BRANCH, (None, items)))
     return subpattern
 
+_warn_skips = (os.path.dirname(__file__),)
+
 def _parse(source, state, verbose, nested, first=False):
     # parse a simple pattern
     subpattern = SubPattern(state)
@@ -557,7 +560,7 @@ def _parse(source, state, verbose, nested, first=False):
                 import warnings
                 warnings.warn(
                     'Possible nested set at position %d' % source.tell(),
-                    FutureWarning, stacklevel=nested + 5
+                    FutureWarning, skip_file_prefixes=_warn_skips
                 )
             negate = sourcematch("^")
             # check remaining characters
@@ -580,7 +583,7 @@ def _parse(source, state, verbose, nested, first=False):
                                 'symmetric difference' if this == '~' else
                                 'union',
                                 source.tell() - 1),
-                            FutureWarning, stacklevel=nested + 5
+                            FutureWarning, skip_file_prefixes=_warn_skips
                         )
                     code1 = LITERAL, _ord(this)
                 if sourcematch("-"):
@@ -603,7 +606,7 @@ def _parse(source, state, verbose, nested, first=False):
                             warnings.warn(
                                 'Possible set difference at position %d' % (
                                     source.tell() - 2),
-                                FutureWarning, stacklevel=nested + 5
+                                FutureWarning, skip_file_prefixes=_warn_skips
                             )
                         code2 = LITERAL, _ord(that)
                     if code1[0] != LITERAL or code2[0] != LITERAL: