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bpo-40903: Handle multiple '=' in invalid assignment rules in the PEG parser (GH-20697)
Automerge-Triggered-By: @pablogsal
1 parent 843c277 commit 9f49590

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Lines changed: 453 additions & 237 deletions

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‎Grammar/python.gram‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -92,7 +92,7 @@ assignment[stmt_ty]:
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| a=('(' b=single_target ')' { b }
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| single_subscript_attribute_target) ':' b=expression c=['=' d=annotated_rhs { d }] {
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CHECK_VERSION(6, "Variable annotations syntax is", _Py_AnnAssign(a, b, c, 0, EXTRA)) }
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| a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) tc=[TYPE_COMMENT] {
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| a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) !'=' tc=[TYPE_COMMENT] {
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_Py_Assign(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
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| a=single_target b=augassign c=(yield_expr | star_expressions) {
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_Py_AugAssign(a, b->kind, c, EXTRA) }
@@ -646,10 +646,11 @@ invalid_assignment:
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RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "only single target (not tuple) can be annotated") }
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| a=expression ':' expression ['=' annotated_rhs] {
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RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "illegal target for annotation") }
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| a=star_expressions '=' (yield_expr | star_expressions) {
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| (star_targets '=')* a=star_expressions '=' {
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RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
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_PyPegen_get_invalid_target(a),
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"cannot assign to %s", _PyPegen_get_expr_name(_PyPegen_get_invalid_target(a))) }
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| (star_targets '=')* a=yield_expr '=' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "assignment to yield expression not possible") }
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| a=star_expressions augassign (yield_expr | star_expressions) {
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RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
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a,

‎Lib/test/test_syntax.py‎

Lines changed: 20 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -63,6 +63,10 @@
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Traceback (most recent call last):
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SyntaxError: cannot assign to function call
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>>> yield = 1
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Traceback (most recent call last):
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SyntaxError: assignment to yield expression not possible
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>>> del f()
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Traceback (most recent call last):
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SyntaxError: cannot delete function call
@@ -136,6 +140,18 @@
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Traceback (most recent call last):
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SyntaxError: cannot assign to conditional expression
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>>> True = True = 3
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Traceback (most recent call last):
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SyntaxError: cannot assign to True
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>>> x = y = True = z = 3
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Traceback (most recent call last):
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SyntaxError: cannot assign to True
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>>> x = y = yield = 1
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Traceback (most recent call last):
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SyntaxError: assignment to yield expression not possible
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>>> a, b += 1, 2
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Traceback (most recent call last):
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SyntaxError: 'tuple' is an illegal expression for augmented assignment
@@ -148,14 +164,17 @@
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Traceback (most recent call last):
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SyntaxError: 'list' is an illegal expression for augmented assignment
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>>> p = p =
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Traceback (most recent call last):
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SyntaxError: invalid syntax
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From compiler_complex_args():
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>>> def f(None=1):
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... pass
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Traceback (most recent call last):
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SyntaxError: invalid syntax
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From ast_for_arguments():
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>>> def f(x, y=1, z):

‎Misc/NEWS.d/next/Core and Builtins/2020-06-07-22-50-10.bpo-40903.7dWejS.rst‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
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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