[3.10] bpo-44368: Improve syntax errors with invalid as pattern targets (GH-26632) (GH-26792)
(cherry picked from commit 05073036dcecefc00b0c3e7397601809da41e2f1)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Grammar/python.gram b/Grammar/python.gram
index 0ccdc3e..56daca0 100644
--- a/Grammar/python.gram
+++ b/Grammar/python.gram
@@ -244,6 +244,7 @@
as_pattern[pattern_ty]:
| pattern=or_pattern 'as' target=pattern_capture_target {
_PyAST_MatchAs(pattern, target->v.Name.id, EXTRA) }
+ | invalid_as_pattern
or_pattern[pattern_ty]:
| patterns[asdl_pattern_seq*]='|'.closed_pattern+ {
asdl_seq_LEN(patterns) == 1 ? asdl_seq_GET(patterns, 0) : _PyAST_MatchOr(patterns, EXTRA) }
@@ -974,6 +975,9 @@
| "case" patterns guard? !':' { RAISE_SYNTAX_ERROR("expected ':'") }
| a="case" patterns guard? ':' NEWLINE !INDENT {
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") }
invalid_if_stmt:
| 'if' named_expression NEWLINE { RAISE_SYNTAX_ERROR("expected ':'") }
| a='if' a=named_expression ':' NEWLINE !INDENT {