From 8b780b6ea3257dc51097f12920be018a36a9f78d Mon Sep 17 00:00:00 2001 From: "Gregory P. Smith [Google LLC]" Date: Fri, 9 Aug 2019 15:47:57 -0700 Subject: [PATCH] bpo-32912: Revert SyntaxWarning on invalid escape sequences. DeprecationWarning will continue to be emitted for invalid escape sequences in string and bytes literals in 3.8 just as it did in 3.7. SyntaxWarning may be emitted in the future. But per mailing list discussion, we don't yet know when because we haven't settled on how to do so in a non-disruptive manner. (Applies 4c5b6bac2408f879231c7cd38d67657dd4804e7c to the master branch). --- Doc/reference/lexical_analysis.rst | 8 ++-- Doc/whatsnew/3.8.rst | 5 --- Lib/test/test_fstring.py | 2 +- Lib/test/test_string_literals.py | 37 +++++++++++++++++-- .../2019-08-06-14-03-59.bpo-32912.UDwSMJ.rst | 3 ++ Python/ast.c | 6 +-- 6 files changed, 43 insertions(+), 18 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-08-06-14-03-59.bpo-32912.UDwSMJ.rst diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst index cc1b2f57a70e3b..7e1e17edb2d8da 100644 --- a/Doc/reference/lexical_analysis.rst +++ b/Doc/reference/lexical_analysis.rst @@ -594,11 +594,9 @@ escape sequences only recognized in string literals fall into the category of unrecognized escapes for bytes literals. .. versionchanged:: 3.6 - Unrecognized escape sequences produce a :exc:`DeprecationWarning`. - - .. versionchanged:: 3.8 - Unrecognized escape sequences produce a :exc:`SyntaxWarning`. In - some future version of Python they will be a :exc:`SyntaxError`. + Unrecognized escape sequences produce a :exc:`DeprecationWarning`. In + a future Python version they will be a :exc:`SyntaxWarning` and + eventually a :exc:`SyntaxError`. Even in a raw literal, quotes can be escaped with a backslash, but the backslash remains in the result; for example, ``r"\""`` is a valid string diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst index d8062e772f6e0c..82da10cc3be86e 100644 --- a/Doc/whatsnew/3.8.rst +++ b/Doc/whatsnew/3.8.rst @@ -414,11 +414,6 @@ Other Language Changes and :keyword:`return` statements. (Contributed by David Cuthbert and Jordan Chapman in :issue:`32117`.) -* A backslash-character pair that is not a valid escape sequence generates - a :exc:`DeprecationWarning` since Python 3.6. In Python 3.8 it generates - a :exc:`SyntaxWarning` instead. - (Contributed by Serhiy Storchaka in :issue:`32912`.) - * The compiler now produces a :exc:`SyntaxWarning` in some cases when a comma is missed before tuple or list. For example:: diff --git a/Lib/test/test_fstring.py b/Lib/test/test_fstring.py index fb761441fcee5c..49663923e7f5aa 100644 --- a/Lib/test/test_fstring.py +++ b/Lib/test/test_fstring.py @@ -649,7 +649,7 @@ def test_backslashes_in_string_part(self): self.assertEqual(f'2\x203', '2 3') self.assertEqual(f'\x203', ' 3') - with self.assertWarns(SyntaxWarning): # invalid escape sequence + with self.assertWarns(DeprecationWarning): # invalid escape sequence value = eval(r"f'\{6*7}'") self.assertEqual(value, '\\42') self.assertEqual(f'\\{6*7}', '\\42') diff --git a/Lib/test/test_string_literals.py b/Lib/test/test_string_literals.py index 5961d591c44803..0cea2edc32afa2 100644 --- a/Lib/test/test_string_literals.py +++ b/Lib/test/test_string_literals.py @@ -32,6 +32,7 @@ import shutil import tempfile import unittest +import warnings TEMPLATE = r"""# coding: %s @@ -110,10 +111,24 @@ def test_eval_str_invalid_escape(self): for b in range(1, 128): if b in b"""\n\r"'01234567NU\\abfnrtuvx""": continue - with self.assertWarns(SyntaxWarning): + with self.assertWarns(DeprecationWarning): self.assertEqual(eval(r"'\%c'" % b), '\\' + chr(b)) - self.check_syntax_warning("'''\n\\z'''") + with warnings.catch_warnings(record=True) as w: + warnings.simplefilter('always', category=DeprecationWarning) + eval("'''\n\\z'''") + self.assertEqual(len(w), 1) + self.assertEqual(w[0].filename, '') + self.assertEqual(w[0].lineno, 1) + + with warnings.catch_warnings(record=True) as w: + warnings.simplefilter('error', category=DeprecationWarning) + with self.assertRaises(SyntaxError) as cm: + eval("'''\n\\z'''") + exc = cm.exception + self.assertEqual(w, []) + self.assertEqual(exc.filename, '') + self.assertEqual(exc.lineno, 1) def test_eval_str_raw(self): self.assertEqual(eval(""" r'x' """), 'x') @@ -145,10 +160,24 @@ def test_eval_bytes_invalid_escape(self): for b in range(1, 128): if b in b"""\n\r"'01234567\\abfnrtvx""": continue - with self.assertWarns(SyntaxWarning): + with self.assertWarns(DeprecationWarning): self.assertEqual(eval(r"b'\%c'" % b), b'\\' + bytes([b])) - self.check_syntax_warning("b'''\n\\z'''") + with warnings.catch_warnings(record=True) as w: + warnings.simplefilter('always', category=DeprecationWarning) + eval("b'''\n\\z'''") + self.assertEqual(len(w), 1) + self.assertEqual(w[0].filename, '') + self.assertEqual(w[0].lineno, 1) + + with warnings.catch_warnings(record=True) as w: + warnings.simplefilter('error', category=DeprecationWarning) + with self.assertRaises(SyntaxError) as cm: + eval("b'''\n\\z'''") + exc = cm.exception + self.assertEqual(w, []) + self.assertEqual(exc.filename, '') + self.assertEqual(exc.lineno, 1) def test_eval_bytes_raw(self): self.assertEqual(eval(""" br'x' """), b'x') diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-08-06-14-03-59.bpo-32912.UDwSMJ.rst b/Misc/NEWS.d/next/Core and Builtins/2019-08-06-14-03-59.bpo-32912.UDwSMJ.rst new file mode 100644 index 00000000000000..e18d8adfbee9e6 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2019-08-06-14-03-59.bpo-32912.UDwSMJ.rst @@ -0,0 +1,3 @@ +Reverted :issue:`32912`: emitting :exc:`SyntaxWarning` instead of +:exc:`DeprecationWarning` for invalid escape sequences in string and bytes +literals. diff --git a/Python/ast.c b/Python/ast.c index 976be70d4d7010..8b3dbead2fdc26 100644 --- a/Python/ast.c +++ b/Python/ast.c @@ -4671,12 +4671,12 @@ warn_invalid_escape_sequence(struct compiling *c, const node *n, if (msg == NULL) { return -1; } - if (PyErr_WarnExplicitObject(PyExc_SyntaxWarning, msg, + if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg, c->c_filename, LINENO(n), NULL, NULL) < 0) { - if (PyErr_ExceptionMatches(PyExc_SyntaxWarning)) { - /* Replace the SyntaxWarning exception with a SyntaxError + if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) { + /* Replace the DeprecationWarning exception with a SyntaxError to get a more accurate error report */ PyErr_Clear(); ast_error(c, n, "%U", msg);