gh-98401: Invalid escape sequences emits SyntaxWarning (#99011)

A backslash-character pair that is not a valid escape sequence now
generates a SyntaxWarning, instead of DeprecationWarning.  For
example, re.compile("\d+\.\d+") now emits a SyntaxWarning ("\d" is an
invalid escape sequence), use raw strings for regular expression:
re.compile(r"\d+\.\d+"). In a future Python version, SyntaxError will
eventually be raised, instead of SyntaxWarning.

Octal escapes with value larger than 0o377 (ex: "\477"), deprecated
in Python 3.11, now produce a SyntaxWarning, instead of
DeprecationWarning. In a future Python version they will be
eventually a SyntaxError.

codecs.escape_decode() and codecs.unicode_escape_decode() are left
unchanged: they still emit DeprecationWarning.

* The parser only emits SyntaxWarning for Python 3.12 (feature
  version), and still emits DeprecationWarning on older Python
  versions.
* Fix SyntaxWarning by using raw strings in Tools/c-analyzer/ and
  wasm_build.py.

1 files changed, 9 insertions, 2 deletions

diff --git a/Parser/string_parser.c b/Parser/string_parser.c
index 9bc3b08..e13272c 100644
--- a/Parser/string_parser.c
+++ b/Parser/string_parser.c
@@ -21,9 +21,16 @@ warn_invalid_escape_sequence(Parser *p, const char *first_invalid_escape, Token
     if (msg == NULL) {
         return -1;
     }
-    if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg, p->tok->filename,
+    PyObject *category;
+    if (p->feature_version >= 12) {
+        category = PyExc_SyntaxWarning;
+    }
+    else {
+        category = PyExc_DeprecationWarning;
+    }
+    if (PyErr_WarnExplicitObject(category, msg, p->tok->filename,
                                  t->lineno, NULL, NULL) < 0) {
-        if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) {
+        if (PyErr_ExceptionMatches(category)) {
             /* Replace the DeprecationWarning exception with a SyntaxError
                to get a more accurate error report */
             PyErr_Clear();