This reverts commit af810b35b4.
This is not valid syntax (see bpo-32012).
(cherry picked from commit 4b8a7f51da)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
* Add test capturing failure.
* Honor newlines as present in the original file.
(cherry picked from commit cafaf0447b)
Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>
New tests also added.
I also made the comments in line with the builtin Grammar/Grammar. PEP 306 was
withdrawn, Kees Blom's railroad program has been lost to the sands of time for
at least 16 years now (I found a python-dev post from people looking for it).
(cherry picked from commit b51f5de711)
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Fix two (in my opinion) spurious failure conditions in the lib2to3.tests.test_parser.TestParserIdempotency test_parser test.
Use the same encoding found in the initial file to write a temp file for a diff. This retains the BOM if the encoding was initially utf-8-sig.
If the file cannot be parsed using the normal grammar, try again with no print statement which should succeed for valid files using future print_function
For case (1), the driver was correctly handling a BOM in a utf-8 file, but then the test was not writing a comparison file using 'utf-8-sig' to diff against, so the BOM got removed. I don't think that is the fault of the parser, and lib2to3 will retain the BOM.
For case (2), lib2to3 pre-detects the use of from __future__ import print_function or allows the user to force this interpretation with a -p flag, and then selects a different grammar with the print statement removed. That makes the test cases unfair to this test as the driver itself doesn't know which grammar to use. As a minimal fix, the test will try using a grammar with the print statement, and if that fails fall back on a grammar without it. A more thorough handling of the idempotency test would to be to parse all files using both grammars and ignore if one of the two failed but otherwise check both. I didn't think this was necessary but can change.
This is more complicated than it should be because we need to preserve the
useful mtime-based regeneration feature that lib2to3.pgen2.driver.load_grammar
has. We only look for the pickled grammar file with pkgutil.get_data and only if
the source file does not exist.
Note: this doesn't unpack f-strings into the underlying JoinedStr AST.
Ideally we'd fully implement JoinedStr here but given its additional
complexity, I think this is worth bandaiding as is. This unblocks tools like
https://github.com/google/yapf to format 3.6 syntax using f-strings.
* Allow underscores in numeric literals in lib2to3.
* Stricter literal parsing for Python 3.6 in lib2to3.pgen2.tokenize.
* Add test case for underscores in literals in Python 3.
