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gh-123562: Improve SyntaxError message for case ... as a.b (#123563)

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sobolevn 2024-09-02 14:11:44 +03:00 committed by GitHub
parent c3ed775899
commit 23f159ae71
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5 changed files with 59 additions and 10 deletions
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4
Grammar/python.gram
View File

@ -1375,7 +1375,9 @@ invalid_case_block:
RAISE_INDENTATION_ERROR("expected an indented block after 'case' statement on line %d", a->lineno) }
invalid_as_pattern:
| or_pattern 'as' a="_" { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot use '_' as a target") }
| or_pattern 'as' !NAME a=expression { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "invalid pattern target") }
| or_pattern 'as' a=expression {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
a, "cannot use %s as pattern target", _PyPegen_get_expr_name(a)) }
invalid_class_pattern:
| name_or_attr '(' a=invalid_class_argument_pattern { RAISE_SYNTAX_ERROR_KNOWN_RANGE(
PyPegen_first_item(a, pattern_ty),

7
Lib/test/test_patma.py
View File

@ -3015,6 +3015,13 @@ class TestSyntaxErrors(unittest.TestCase):
pass
""")
def test_multiple_assignments_to_name_in_pattern_6(self):
self.assert_syntax_error("""
match ...:
case a as a + 1: # NAME and expression with no ()
pass
""")
def test_multiple_starred_names_in_sequence_pattern_0(self):
self.assert_syntax_error("""
match ...:

42
Lib/test/test_syntax.py
View File

@ -1932,7 +1932,31 @@ Corner-cases that used to crash:
... case 42 as 1+2+4:
... ...
Traceback (most recent call last):
SyntaxError: invalid pattern target
SyntaxError: cannot use expression as pattern target
>>> match ...:
... case 42 as a.b:
... ...
Traceback (most recent call last):
SyntaxError: cannot use attribute as pattern target
>>> match ...:
... case 42 as (a, b):
... ...
Traceback (most recent call last):
SyntaxError: cannot use tuple as pattern target
>>> match ...:
... case 42 as (a + 1):
... ...
Traceback (most recent call last):
SyntaxError: cannot use expression as pattern target
>>> match ...:
... case (32 as x) | (42 as a()):
... ...
Traceback (most recent call last):
SyntaxError: cannot use function call as pattern target
>>> match ...:
... case Foo(z=1, y=2, x):
@ -2817,6 +2841,22 @@ while 1:
end_offset=22 + len("obj.attr"),
)
def test_match_stmt_invalid_as_expr(self):
self._check_error(
textwrap.dedent(
"""
match 1:
case x as obj.attr:
...
"""
),
errtext="cannot use attribute as pattern target",
lineno=3,
end_lineno=3,
offset=15,
end_offset=15 + len("obj.attr"),
)
def load_tests(loader, tests, pattern):
tests.addTest(doctest.DocTestSuite())

2
Misc/NEWS.d/next/Core_and_Builtins/2024-09-01-12-08-39.gh-issue-123562.aJPKVu.rst Normal file
View File

@ -0,0 +1,2 @@
Improve :exc:`SyntaxError` message for using ``case ... as ...`` with not a
name.

14
Parser/parser.c generated
View File

@ -24005,7 +24005,7 @@ invalid_case_block_rule(Parser *p)
return _res;
}
// invalid_as_pattern: or_pattern 'as' "_" | or_pattern 'as' !NAME expression
// invalid_as_pattern: or_pattern 'as' "_" | or_pattern 'as' expression
static void *
invalid_as_pattern_rule(Parser *p)
{
@ -24048,12 +24048,12 @@ invalid_as_pattern_rule(Parser *p)
D(fprintf(stderr, "%*c%s invalid_as_pattern[%d-%d]: %s failed!\n", p->level, ' ',
p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "or_pattern 'as' \"_\""));
}
{ // or_pattern 'as' !NAME expression
{ // or_pattern 'as' expression
if (p->error_indicator) {
p->level--;
return NULL;
}
D(fprintf(stderr, "%*c> invalid_as_pattern[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "or_pattern 'as' !NAME expression"));
D(fprintf(stderr, "%*c> invalid_as_pattern[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "or_pattern 'as' expression"));
Token * _keyword;
expr_ty a;
pattern_ty or_pattern_var;
@ -24062,13 +24062,11 @@ invalid_as_pattern_rule(Parser *p)
&&
(_keyword = _PyPegen_expect_token(p, 666)) // token='as'
&&
_PyPegen_lookahead_with_name(0, _PyPegen_name_token, p)
&&
(a = expression_rule(p)) // expression
)
{
D(fprintf(stderr, "%*c+ invalid_as_pattern[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "or_pattern 'as' !NAME expression"));
_res = RAISE_SYNTAX_ERROR_KNOWN_LOCATION ( a , "invalid pattern target" );
D(fprintf(stderr, "%*c+ invalid_as_pattern[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "or_pattern 'as' expression"));
_res = RAISE_SYNTAX_ERROR_KNOWN_LOCATION ( a , "cannot use %s as pattern target" , _PyPegen_get_expr_name ( a ) );
if (_res == NULL && PyErr_Occurred()) {
p->error_indicator = 1;
p->level--;
@ -24078,7 +24076,7 @@ invalid_as_pattern_rule(Parser *p)
}
p->mark = _mark;
D(fprintf(stderr, "%*c%s invalid_as_pattern[%d-%d]: %s failed!\n", p->level, ' ',
p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "or_pattern 'as' !NAME expression"));
p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "or_pattern 'as' expression"));
}
_res = NULL;
done: