diff --git a/Lib/test/test_fstring.py b/Lib/test/test_fstring.py index 7ffe01d2d8c..0dc7dd8e254 100644 --- a/Lib/test/test_fstring.py +++ b/Lib/test/test_fstring.py @@ -524,7 +524,7 @@ non-important content # This looks like a nested format spec. ]) - self.assertAllRaise(SyntaxError, "invalid syntax", + self.assertAllRaise(SyntaxError, "f-string: invalid syntax", [# Invalid syntax inside a nested spec. "f'{4:{/5}}'", ]) @@ -598,7 +598,7 @@ non-important content # are added around it. But we shouldn't go from an invalid # expression to a valid one. The added parens are just # supposed to allow whitespace (including newlines). - self.assertAllRaise(SyntaxError, 'invalid syntax', + self.assertAllRaise(SyntaxError, 'f-string: invalid syntax', ["f'{,}'", "f'{,}'", # this is (,), which is an error ]) @@ -716,7 +716,7 @@ non-important content # lambda doesn't work without parens, because the colon # makes the parser think it's a format_spec - self.assertAllRaise(SyntaxError, 'invalid syntax', + self.assertAllRaise(SyntaxError, 'f-string: invalid syntax', ["f'{lambda x:x}'", ]) @@ -1194,6 +1194,10 @@ non-important content self.assertEqual(f'{(x:=10)}', '10') self.assertEqual(x, 10) + def test_invalid_syntax_error_message(self): + with self.assertRaisesRegex(SyntaxError, "f-string: invalid syntax"): + compile("f'{a $ b}'", "?", "exec") + if __name__ == '__main__': unittest.main() diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-23-15-10-19.bpo-41084.pt3y7F.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-23-15-10-19.bpo-41084.pt3y7F.rst new file mode 100644 index 00000000000..cd349af770b --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-23-15-10-19.bpo-41084.pt3y7F.rst @@ -0,0 +1 @@ +Prefix the error message with 'f-string: ', when parsing an f-string expression which throws a :exc:`SyntaxError`. diff --git a/Parser/pegen.c b/Parser/pegen.c index 594754cee5d..79fcd2f5999 100644 --- a/Parser/pegen.c +++ b/Parser/pegen.c @@ -391,6 +391,21 @@ _PyPegen_raise_error_known_location(Parser *p, PyObject *errtype, PyObject *tmp = NULL; p->error_indicator = 1; + if (p->start_rule == Py_fstring_input) { + const char *fstring_msg = "f-string: "; + Py_ssize_t len = strlen(fstring_msg) + strlen(errmsg); + + char *new_errmsg = PyMem_RawMalloc(len + 1); // Lengths of both strings plus NULL character + if (!new_errmsg) { + return (void *) PyErr_NoMemory(); + } + + // Copy both strings into new buffer + memcpy(new_errmsg, fstring_msg, strlen(fstring_msg)); + memcpy(new_errmsg + strlen(fstring_msg), errmsg, strlen(errmsg)); + new_errmsg[len] = 0; + errmsg = new_errmsg; + } errstr = PyUnicode_FromFormatV(errmsg, va); if (!errstr) { goto error; @@ -427,11 +442,17 @@ _PyPegen_raise_error_known_location(Parser *p, PyObject *errtype, Py_DECREF(errstr); Py_DECREF(value); + if (p->start_rule == Py_fstring_input) { + PyMem_RawFree((void *)errmsg); + } return NULL; error: Py_XDECREF(errstr); Py_XDECREF(error_line); + if (p->start_rule == Py_fstring_input) { + PyMem_RawFree((void *)errmsg); + } return NULL; }