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https://github.com/python/cpython
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bpo-43833: Emit warnings for numeric literals followed by keyword (GH-25466)
Emit a deprecation warning if the numeric literal is immediately followed by one of keywords: and, else, for, if, in, is, or. Raise a syntax error with more informative message if it is immediately followed by other keyword or identifier. Automerge-Triggered-By: GH:pablogsal
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2ea6d89028
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@ -1444,6 +1444,17 @@ Optimizations
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Deprecated
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==========
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* Currently Python accepts numeric literals immediately followed by keywords,
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for example ``0in x``, ``1or x``, ``0if 1else 2``. It allows confusing
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and ambigious expressions like ``[0x1for x in y]`` (which can be
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interpreted as ``[0x1 for x in y]`` or ``[0x1f or x in y]``). Starting in
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this release, a deprecation warning is raised if the numeric literal is
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immediately followed by one of keywords :keyword:`and`, :keyword:`else`,
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:keyword:`for`, :keyword:`if`, :keyword:`in`, :keyword:`is` and :keyword:`or`.
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If future releases it will be changed to syntax warning, and finally to
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syntax error.
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(Contributed by Serhiy Storchaka in :issue:`43833`).
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* Starting in this release, there will be a concerted effort to begin
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cleaning up old import semantics that were kept for Python 2.7
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compatibility. Specifically,
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@ -1670,6 +1681,18 @@ This section lists previously described changes and other bugfixes
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that may require changes to your code.
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Changes in the Python syntax
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----------------------------
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* Deprecation warning is now emitted when compiling previously valid syntax
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if the numeric literal is immediately followed by a keyword (like in ``0in x``).
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If future releases it will be changed to syntax warning, and finally to a
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syntax error. To get rid of the warning and make the code compatible with
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future releases just add a space between the numeric literal and the
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following keyword.
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(Contributed by Serhiy Storchaka in :issue:`43833`).
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Changes in the Python API
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-------------------------
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@ -162,7 +162,7 @@ def test_literals_with_leading_zeroes(self):
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for arg in ["077787", "0xj", "0x.", "0e", "090000000000000",
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"080000000000000", "000000000000009", "000000000000008",
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"0b42", "0BADCAFE", "0o123456789", "0b1.1", "0o4.2",
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"0b101j2", "0o153j2", "0b100e1", "0o777e1", "0777",
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"0b101j", "0o153j", "0b100e1", "0o777e1", "0777",
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"000777", "000000000000007"]:
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self.assertRaises(SyntaxError, eval, arg)
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@ -177,8 +177,10 @@ def test_floats(self):
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def test_float_exponent_tokenization(self):
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# See issue 21642.
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self.assertEqual(1 if 1else 0, 1)
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self.assertEqual(1 if 0else 0, 0)
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with warnings.catch_warnings():
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warnings.simplefilter('ignore', DeprecationWarning)
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self.assertEqual(eval("1 if 1else 0"), 1)
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self.assertEqual(eval("1 if 0else 0"), 0)
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self.assertRaises(SyntaxError, eval, "0 if 1Else 0")
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def test_underscore_literals(self):
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@ -211,6 +213,92 @@ def test_bad_numerical_literals(self):
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check("1e2_", "invalid decimal literal")
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check("1e+", "invalid decimal literal")
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def test_end_of_numerical_literals(self):
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def check(test):
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with self.assertWarns(DeprecationWarning):
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compile(test, "<testcase>", "eval")
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def check_error(test):
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with warnings.catch_warnings(record=True) as w:
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with self.assertRaises(SyntaxError):
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compile(test, "<testcase>", "eval")
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self.assertEqual(w, [])
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check_error("0xfand x")
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check("0o7and x")
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check("0b1and x")
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check("9and x")
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check("0and x")
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check("1.and x")
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check("1e3and x")
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check("1jand x")
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check("0xfor x")
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check("0o7or x")
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check("0b1or x")
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check("9or x")
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check_error("0or x")
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check("1.or x")
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check("1e3or x")
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check("1jor x")
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check("0xfin x")
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check("0o7in x")
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check("0b1in x")
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check("9in x")
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check("0in x")
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check("1.in x")
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check("1e3in x")
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check("1jin x")
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with warnings.catch_warnings():
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warnings.simplefilter('ignore', SyntaxWarning)
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check("0xfis x")
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check("0o7is x")
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check("0b1is x")
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check("9is x")
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check("0is x")
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check("1.is x")
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check("1e3is x")
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check("1jis x")
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check("0xfif x else y")
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check("0o7if x else y")
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check("0b1if x else y")
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check("9if x else y")
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check("0if x else y")
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check("1.if x else y")
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check("1e3if x else y")
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check("1jif x else y")
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check_error("x if 0xfelse y")
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check("x if 0o7else y")
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check("x if 0b1else y")
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check("x if 9else y")
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check("x if 0else y")
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check("x if 1.else y")
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check("x if 1e3else y")
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check("x if 1jelse y")
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check("[0x1ffor x in ()]")
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check("[0x1for x in ()]")
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check("[0xfor x in ()]")
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check("[0o7for x in ()]")
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check("[0b1for x in ()]")
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check("[9for x in ()]")
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check("[1.for x in ()]")
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check("[1e3for x in ()]")
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check("[1jfor x in ()]")
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check_error("0xfspam")
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check_error("0o7spam")
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check_error("0b1spam")
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check_error("9spam")
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check_error("0spam")
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check_error("1.spam")
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check_error("1e3spam")
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check_error("1jspam")
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def test_string_literals(self):
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x = ''; y = ""; self.assertTrue(len(x) == 0 and x == y)
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x = '\''; y = "'"; self.assertTrue(len(x) == 1 and x == y and ord(x) == 39)
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@ -0,0 +1,4 @@
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Emit a deprecation warning if the numeric literal is immediately followed by
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one of keywords: and, else, for, if, in, is, or. Raise a syntax error with
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more informative message if it is immediately followed by other keyword or
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identifier.
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@ -1121,6 +1121,113 @@ indenterror(struct tok_state *tok)
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return ERRORTOKEN;
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}
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static int
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parser_warn(struct tok_state *tok, const char *format, ...)
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{
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PyObject *errmsg;
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va_list vargs;
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#ifdef HAVE_STDARG_PROTOTYPES
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va_start(vargs, format);
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#else
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va_start(vargs);
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#endif
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errmsg = PyUnicode_FromFormatV(format, vargs);
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va_end(vargs);
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if (!errmsg) {
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goto error;
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}
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if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, errmsg, tok->filename,
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tok->lineno, NULL, NULL) < 0) {
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if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) {
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/* Replace the DeprecationWarning exception with a SyntaxError
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to get a more accurate error report */
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PyErr_Clear();
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syntaxerror(tok, "%U", errmsg);
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}
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goto error;
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}
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Py_DECREF(errmsg);
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return 0;
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error:
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Py_XDECREF(errmsg);
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tok->done = E_ERROR;
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return -1;
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}
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static int
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lookahead(struct tok_state *tok, const char *test)
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{
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const char *s = test;
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int res = 0;
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while (1) {
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int c = tok_nextc(tok);
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if (*s == 0) {
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res = !is_potential_identifier_char(c);
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}
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else if (c == *s) {
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s++;
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continue;
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}
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tok_backup(tok, c);
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while (s != test) {
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tok_backup(tok, *--s);
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}
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return res;
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}
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}
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static int
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verify_end_of_number(struct tok_state *tok, int c, const char *kind)
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{
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/* Emit a deprecation warning only if the numeric literal is immediately
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* followed by one of keywords which can occurr after a numeric literal
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* in valid code: "and", "else", "for", "if", "in", "is" and "or".
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* It allows to gradually deprecate existing valid code without adding
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* warning before error in most cases of invalid numeric literal (which
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* would be confusiong and break existing tests).
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* Raise a syntax error with slighly better message than plain
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* "invalid syntax" if the numeric literal is immediately followed by
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* other keyword or identifier.
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*/
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int r = 0;
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if (c == 'a') {
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r = lookahead(tok, "nd");
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}
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else if (c == 'e') {
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r = lookahead(tok, "lse");
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}
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else if (c == 'f') {
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r = lookahead(tok, "or");
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}
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else if (c == 'i') {
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int c2 = tok_nextc(tok);
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if (c2 == 'f' || c2 == 'n' || c2 == 's') {
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r = 1;
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}
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tok_backup(tok, c2);
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}
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else if (c == 'o') {
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r = lookahead(tok, "r");
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}
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if (r) {
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tok_backup(tok, c);
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if (parser_warn(tok, "invalid %s literal", kind)) {
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return 0;
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}
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tok_nextc(tok);
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}
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else /* In future releases, only error will remain. */
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if (is_potential_identifier_char(c)) {
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tok_backup(tok, c);
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syntaxerror(tok, "invalid %s literal", kind);
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return 0;
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}
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return 1;
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}
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/* Verify that the identifier follows PEP 3131.
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All identifier strings are guaranteed to be "ready" unicode objects.
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*/
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@ -1569,6 +1676,9 @@ tok_get(struct tok_state *tok, const char **p_start, const char **p_end)
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c = tok_nextc(tok);
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} while (isxdigit(c));
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} while (c == '_');
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if (!verify_end_of_number(tok, c, "hexadecimal")) {
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return ERRORTOKEN;
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}
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}
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else if (c == 'o' || c == 'O') {
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/* Octal */
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@ -1595,6 +1705,9 @@ tok_get(struct tok_state *tok, const char **p_start, const char **p_end)
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return syntaxerror(tok,
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"invalid digit '%c' in octal literal", c);
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}
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if (!verify_end_of_number(tok, c, "octal")) {
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return ERRORTOKEN;
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}
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}
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else if (c == 'b' || c == 'B') {
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/* Binary */
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return syntaxerror(tok,
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"invalid digit '%c' in binary literal", c);
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}
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if (!verify_end_of_number(tok, c, "binary")) {
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return ERRORTOKEN;
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}
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}
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else {
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int nonzero = 0;
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"literals are not permitted; "
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"use an 0o prefix for octal integers");
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}
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if (!verify_end_of_number(tok, c, "decimal")) {
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return ERRORTOKEN;
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}
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}
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}
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else {
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@ -1699,6 +1818,9 @@ tok_get(struct tok_state *tok, const char **p_start, const char **p_end)
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}
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} else if (!isdigit(c)) {
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tok_backup(tok, c);
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if (!verify_end_of_number(tok, e, "decimal")) {
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return ERRORTOKEN;
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}
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tok_backup(tok, e);
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*p_start = tok->start;
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*p_end = tok->cur;
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/* Imaginary part */
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imaginary:
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c = tok_nextc(tok);
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if (!verify_end_of_number(tok, c, "imaginary")) {
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return ERRORTOKEN;
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}
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}
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else if (!verify_end_of_number(tok, c, "decimal")) {
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return ERRORTOKEN;
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}
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}
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}
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