Issue 18893: invalid exception handling in Lib/ctypes/macholib/dyld.py

The exception handling clauses in framework_find() are weird.


def framework_find(fn, executable_path=None, env=None):
    """
    Find a framework using dyld semantics in a very loose manner.

    Will take input such as:
        Python
        Python.framework
        Python.framework/Versions/Current
    """
    try:
        return dyld_find(fn, executable_path=executable_path, env=env)
    except ValueError as e:
        pass
    fmwk_index = fn.rfind('.framework')
    if fmwk_index == -1:
        fmwk_index = len(fn)
        fn += '.framework'
    fn = os.path.join(fn, os.path.basename(fn[:fmwk_index]))
    try:
        return dyld_find(fn, executable_path=executable_path, env=env)
    except ValueError:
        raise e


My guess is that this is left-over code from Py2.x. Since it doesn't make sense to catch an exception in the second clause just to re-raise it, I think the intention was really to re-raise the original exception caught in the first clause, which no longer works that way in Py3.

The fix would then be to assign the exception to a new variable in the first except clause and re-raise that in the second.

I found this problem because Cython rejected the module with a compile error about "e" being undefined in the last line.

changing title as it doesn't really look like a typo, more a "converto"

Your analysis looks correct to me, that is "raise e" is supposed to raise the exception caught by the first try block.

Seems like a simple fix -- patch attached.

lgtm

New changeset e9f34d382eda by Berker Peksag in branch '3.5':
Issue #18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py
https://hg.python.org/cpython/rev/e9f34d382eda

New changeset 708337cd8e6a by Berker Peksag in branch '3.6':
Issue #18893: Merge from 3.5
https://hg.python.org/cpython/rev/708337cd8e6a

New changeset b9d9c49d5b50 by Berker Peksag in branch 'default':
Issue #18893: Merge from 3.6
https://hg.python.org/cpython/rev/b9d9c49d5b50

Thanks!

versions: + Python 3.7
nosy: + berker.peksag

messages: + msg277456
resolution: fixed
stage: resolved

nosy: + madison.may
messages: + msg196807

keywords: + patch