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[Python-Dev] bpo-36919: Exception from 'compile' reports a newline char not present in input


Hi,

The following issue arose when implementing IronPython 3. Normally the
behavior of CPython is authoritative, but in this case I started having
doubts.

Since Python 3.2, input in 'exec' mode  of 'compile' does not have to
end in a newline anymore. However, it creates a surprising behavior when
a 'SyntaxError' is reported:

>>> try: compile('try', '<string>', 'exec')
... except SyntaxError as ex: print(repr(ex))
...
SyntaxError('invalid syntax', ('<string>', 1, 4, 'try\n'))

The 'text' field of the exception thrown contains an additional newline
character that was not present in the input. Is it:

a. Proper Python language behavior?
b. CPython implementation artifact?
c. A bug?

The comments on bpo (https://bugs.python.org/issue36919) suggest Case B,
but inconclusive. If case B it is, since IronPython does not exhibit
this behavior, I will submit a patch to StdLib test(s) to make them
implementation independent.

Thanks for comments,
Pavel