bpo-44180: Fix edge cases in invalid assigment rules in the parser#26283
Merged
Conversation
pablogsal
force-pushed
the
other
branch
4 times, most recently
from
267745b to
6b867d0
Compare
The invalid assigment rules are very delicate since the parser can easily raise an invalid assigment when a keyword argument is provided. As they are very deep into the grammar tree, is very difficult to specify in which contexts these rules can be used and in which don't. For that we need to use a different version of the rule that doesn't do error checking in those situations where we don't want the rule to raise (keyword arguments and generator expressions). We also need to check if we are in left-recursive rule, as those can try to eagerly advance the parser even if the parse will fail at the end of the expression. Failing to do this allows the parser to start parsing a call as a tuple and incorrectly identify a keyword argument as an invalid assigment.
Contributor
|
Thanks @pablogsal for the PR 🌮🎉.. I'm working now to backport this PR to: 3.10. |
miss-islington
pushed a commit
to miss-islington/cpython
that referenced
this pull request
May 21, 2021
…ythonGH-26283) The invalid assignment rules are very delicate since the parser can easily raise an invalid assignment when a keyword argument is provided. As they are very deep into the grammar tree, is very difficult to specify in which contexts these rules can be used and in which don't. For that, we need to use a different version of the rule that doesn't do error checking in those situations where we don't want the rule to raise (keyword arguments and generator expressions). We also need to check if we are in left-recursive rule, as those can try to eagerly advance the parser even if the parse will fail at the end of the expression. Failing to do this allows the parser to start parsing a call as a tuple and incorrectly identify a keyword argument as an invalid assignment, before it realizes that it was not a tuple after all. (cherry picked from commit c878a97) Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
|
GH-26292 is a backport of this pull request to the 3.10 branch. |
miss-islington
added a commit
that referenced
this pull request
May 21, 2021
…H-26283) The invalid assignment rules are very delicate since the parser can easily raise an invalid assignment when a keyword argument is provided. As they are very deep into the grammar tree, is very difficult to specify in which contexts these rules can be used and in which don't. For that, we need to use a different version of the rule that doesn't do error checking in those situations where we don't want the rule to raise (keyword arguments and generator expressions). We also need to check if we are in left-recursive rule, as those can try to eagerly advance the parser even if the parse will fail at the end of the expression. Failing to do this allows the parser to start parsing a call as a tuple and incorrectly identify a keyword argument as an invalid assignment, before it realizes that it was not a tuple after all. (cherry picked from commit c878a97) Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The invalid assigment rules are very delicate since the parser can
easily raise an invalid assigment when a keyword argument is provided.
As they are very deep into the grammar tree, is very difficult to
specify in which contexts these rules can be used and in which don't.
For that we need to use a different version of the rule that doesn't do
error checking in those situations where we don't want the rule to raise
(keyword arguments and generator expressions).
We also need to check if we are in left-recursive rule, as those can try
to eagerly advance the parser even if the parse will fail at the end of
the expression. Failing to do this allows the parser to start parsing a
call as a tuple and incorrectly identify a keyword argument as an
invalid assigment.
https://bugs.python.org/issue44180