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bpo-41084: Adjust message when an f-string expression causes a SyntaxError (GH-21084) 

Prefix the error message with `fstring: `, when parsing an f-string expression throws a `SyntaxError`.
This commit is contained in:
Lysandros Nikolaou 2020-06-26 14:24:05 +03:00 committed by GitHub
parent ef19bad7d6
commit 2e0a920e9e
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3 changed files with 29 additions and 3 deletions
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10
Lib/test/test_fstring.py
View File

@ -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()

1
Misc/NEWS.d/next/Core and Builtins/2020-06-23-15-10-19.bpo-41084.pt3y7F.rst Normal file
View File

@ -0,0 +1 @@
Prefix the error message with 'f-string: ', when parsing an f-string expression which throws a :exc:`SyntaxError`.

21
Parser/pegen.c
View File

@ -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;
}