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bpo-40903: Handle multiple '=' in invalid assignment rules in the PEG parser #20697

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Merged
miss-islington merged 7 commits into from
Jun 8, 2020
Merged

bpo-40903: Handle multiple '=' in invalid assignment rules in the PEG parser #20697

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a8350d5
bpo-40903: Handle multiple '=' in invalid assignment rules in the PEG…
pablogsal Jun 7, 2020
e994976
📜🤖 Added by blurb_it.
blurb-it[bot] Jun 7, 2020
06ecf9d
Handle clases like 'x = y = z = True'
pablogsal Jun 7, 2020
8c6dafc
Minor cleanup
pablogsal Jun 7, 2020
87b6b75
Don't partially parse chains of assigments
pablogsal Jun 8, 2020
f259e98
Handle assignments to yield expressions
pablogsal Jun 8, 2020
7e61af3
Simplify handling of general invalid assignments
pablogsal Jun 8, 2020
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5 changes: 3 additions & 2 deletions Grammar/python.gram
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,7 @@ assignment[stmt_ty]:
| a=('(' b=single_target ')' { b }
| single_subscript_attribute_target) ':' b=expression c=['=' d=annotated_rhs { d }] {
CHECK_VERSION(6, "Variable annotations syntax is", _Py_AnnAssign(a, b, c, 0, EXTRA)) }
| a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) tc=[TYPE_COMMENT] {
| a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) !'=' tc=[TYPE_COMMENT] {
_Py_Assign(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
| a=single_target b=augassign c=(yield_expr | star_expressions) {
_Py_AugAssign(a, b->kind, c, EXTRA) }
Expand Down Expand Up @@ -646,10 +646,11 @@ invalid_assignment:
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "only single target (not tuple) can be annotated") }
| a=expression ':' expression ['=' annotated_rhs] {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "illegal target for annotation") }
| a=star_expressions '=' (yield_expr | star_expressions) {
| (star_targets '=')* a=star_expressions '=' {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
_PyPegen_get_invalid_target(a),
"cannot assign to %s", _PyPegen_get_expr_name(_PyPegen_get_invalid_target(a))) }
| (star_targets '=')* a=yield_expr '=' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "assignment to yield expression not possible") }
| a=star_expressions augassign (yield_expr | star_expressions) {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
a,
Expand Down
21 changes: 20 additions & 1 deletion Lib/test/test_syntax.py
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Expand Up @@ -63,6 +63,10 @@
Traceback (most recent call last):
SyntaxError: cannot assign to function call

>>> yield = 1
Traceback (most recent call last):
SyntaxError: assignment to yield expression not possible

>>> del f()
Traceback (most recent call last):
SyntaxError: cannot delete function call
Expand Down Expand Up @@ -136,6 +140,18 @@
Traceback (most recent call last):
SyntaxError: cannot assign to conditional expression

>>> True = True = 3
Traceback (most recent call last):
SyntaxError: cannot assign to True

>>> x = y = True = z = 3
Traceback (most recent call last):
SyntaxError: cannot assign to True

>>> x = y = yield = 1
Traceback (most recent call last):
SyntaxError: assignment to yield expression not possible

>>> a, b += 1, 2
Traceback (most recent call last):
SyntaxError: 'tuple' is an illegal expression for augmented assignment
Expand All @@ -148,14 +164,17 @@
Traceback (most recent call last):
SyntaxError: 'list' is an illegal expression for augmented assignment

>>> p = p =
Traceback (most recent call last):
SyntaxError: invalid syntax

From compiler_complex_args():

>>> def f(None=1):
... pass
Traceback (most recent call last):
SyntaxError: invalid syntax


From ast_for_arguments():

>>> def f(x, y=1, z):
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-06-07-22-50-10.bpo-40903.7dWejS.rst
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@@ -0,0 +1 @@
Fixed a possible segfault in the new PEG parser when producing error messages for invalid assignments of the form :code:`p=p=`. Patch by Pablo Galindo
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