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bpo-44180: Fix edge cases in invalid assigment rules in the parser #26283

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Merged
pablogsal merged 1 commit into from
May 21, 2021
Merged

bpo-44180: Fix edge cases in invalid assigment rules in the parser #26283

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38 changes: 24 additions & 14 deletions Grammar/python.gram
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Original file line number Diff line number Diff line change
Expand Up @@ -509,13 +509,13 @@ star_named_expression[expr_ty]:
| '*' a=bitwise_or { _PyAST_Starred(a, Load, EXTRA) }
| named_expression

named_expression[expr_ty]:
| a=NAME ':=' ~ b=expression { _PyAST_NamedExpr(CHECK(expr_ty, _PyPegen_set_expr_context(p, a, Store)), b, EXTRA) }
| invalid_named_expression
| expression !':='

direct_named_expression[expr_ty]:
assigment_expression[expr_ty]:
| a=NAME ':=' ~ b=expression { _PyAST_NamedExpr(CHECK(expr_ty, _PyPegen_set_expr_context(p, a, Store)), b, EXTRA) }

named_expression[expr_ty]:
| assigment_expression
| invalid_named_expression
| expression !':='

annotated_rhs[expr_ty]: yield_expr | star_expressions
Expand Down Expand Up @@ -706,7 +706,7 @@ group[expr_ty]:
| '(' a=(yield_expr | named_expression) ')' { a }
| invalid_group
genexp[expr_ty]:
| '(' a=direct_named_expression b=for_if_clauses ')' { _PyAST_GeneratorExp(a, b, EXTRA) }
| '(' a=( assigment_expression | expression !':=') b=for_if_clauses ')' { _PyAST_GeneratorExp(a, b, EXTRA) }
| invalid_comprehension
set[expr_ty]: '{' a=star_named_expressions '}' { _PyAST_Set(a, EXTRA) }
setcomp[expr_ty]:
Expand Down Expand Up @@ -745,27 +745,29 @@ arguments[expr_ty] (memo):
| a=args [','] &')' { a }
| invalid_arguments
args[expr_ty]:
| a[asdl_expr_seq*]=','.(starred_expression | direct_named_expression !'=')+ b=[',' k=kwargs {k}] { _PyPegen_collect_call_seqs(p, a, b, EXTRA) }
| a[asdl_expr_seq*]=','.(starred_expression | ( assigment_expression | expression !':=') !'=')+ b=[',' k=kwargs {k}] {
_PyPegen_collect_call_seqs(p, a, b, EXTRA) }
| a=kwargs { _PyAST_Call(_PyPegen_dummy_name(p),
CHECK_NULL_ALLOWED(asdl_expr_seq*, _PyPegen_seq_extract_starred_exprs(p, a)),
CHECK_NULL_ALLOWED(asdl_keyword_seq*, _PyPegen_seq_delete_starred_exprs(p, a)),
EXTRA) }

kwargs[asdl_seq*]:
| a=','.kwarg_or_starred+ ',' b=','.kwarg_or_double_starred+ { _PyPegen_join_sequences(p, a, b) }
| ','.kwarg_or_starred+
| ','.kwarg_or_double_starred+
starred_expression[expr_ty]:
| '*' a=expression { _PyAST_Starred(a, Load, EXTRA) }
kwarg_or_starred[KeywordOrStarred*]:
| invalid_kwarg
| a=NAME '=' b=expression {
_PyPegen_keyword_or_starred(p, CHECK(keyword_ty, _PyAST_keyword(a->v.Name.id, b, EXTRA)), 1) }
| a=starred_expression { _PyPegen_keyword_or_starred(p, a, 0) }
| invalid_kwarg
kwarg_or_double_starred[KeywordOrStarred*]:
| invalid_kwarg
| a=NAME '=' b=expression {
_PyPegen_keyword_or_starred(p, CHECK(keyword_ty, _PyAST_keyword(a->v.Name.id, b, EXTRA)), 1) }
| '**' a=expression { _PyPegen_keyword_or_starred(p, CHECK(keyword_ty, _PyAST_keyword(NULL, a, EXTRA)), 1) }
| invalid_kwarg

# NOTE: star_targets may contain *bitwise_or, targets may not.
star_targets[expr_ty]:
Expand Down Expand Up @@ -838,29 +840,37 @@ invalid_arguments:
| a=args ',' '*' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "iterable argument unpacking follows keyword argument unpacking") }
| a=expression b=for_if_clauses ',' [args | expression for_if_clauses] {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, PyPegen_last_item(b, comprehension_ty)->target, "Generator expression must be parenthesized") }
| a=NAME b='=' expression for_if_clauses {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax. Maybe you meant '==' or ':=' instead of '='?")}
| a=args for_if_clauses { _PyPegen_nonparen_genexp_in_call(p, a) }
| args ',' a=expression b=for_if_clauses {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, asdl_seq_GET(b, b->size-1)->target, "Generator expression must be parenthesized") }
| a=args ',' args { _PyPegen_arguments_parsing_error(p, a) }
invalid_kwarg:
| a=NAME b='=' expression for_if_clauses {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax. Maybe you meant '==' or ':=' instead of '='?")}
| !(NAME '=') a=expression b='=' {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(
a, b, "expression cannot contain assignment, perhaps you meant \"==\"?") }

expression_without_invalid[expr_ty]:
| a=disjunction 'if' b=disjunction 'else' c=expression { _PyAST_IfExp(b, a, c, EXTRA) }
| disjunction
| lambdef
invalid_expression:
# !(NAME STRING) is not matched so we don't show this error with some invalid string prefixes like: kf"dsfsdf"
# Soft keywords need to also be ignored because they can be parsed as NAME NAME
| !(NAME STRING | SOFT_KEYWORD) a=disjunction b=expression {
| !(NAME STRING | SOFT_KEYWORD) a=disjunction b=expression_without_invalid {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax. Perhaps you forgot a comma?") }

invalid_named_expression:
| a=expression ':=' expression {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
a, "cannot use assignment expressions with %s", _PyPegen_get_expr_name(a)) }
| a=NAME '=' b=bitwise_or !('='|':='|',') {
RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax. Maybe you meant '==' or ':=' instead of '='?") }
| !(list|tuple|genexp|'True'|'None'|'False') a=bitwise_or b='=' bitwise_or !('='|':='|',') {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot assign to %s here. Maybe you meant '==' instead of '='?",
| a=NAME '=' b=bitwise_or !('='|':=') {
p->in_raw_rule ? NULL : RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax. Maybe you meant '==' or ':=' instead of '='?") }
| !(list|tuple|genexp|'True'|'None'|'False') a=bitwise_or b='=' bitwise_or !('='|':=') {
p->in_raw_rule ? NULL : RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot assign to %s here. Maybe you meant '==' instead of '='?",
_PyPegen_get_expr_name(a)) }

invalid_assignment:
Expand Down
20 changes: 20 additions & 0 deletions Lib/test/test_syntax.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1128,6 +1128,26 @@
Traceback (most recent call last):
SyntaxError: cannot assign to f-string expression here. Maybe you meant '==' instead of '='?

>>> (x, y, z=3, d, e)
Traceback (most recent call last):
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

>>> [x, y, z=3, d, e]
Traceback (most recent call last):
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

>>> [z=3]
Traceback (most recent call last):
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

>>> {x, y, z=3, d, e}
Traceback (most recent call last):
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

>>> {z=3}
Traceback (most recent call last):
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

>>> from t import x,
Traceback (most recent call last):
SyntaxError: trailing comma not allowed without surrounding parentheses
Expand Down
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