Mercurial > hg
changeset 30647:1914db1b7d9e stable
demandimport: do not raise ImportError for unknown item in fromlist
This is the behavior of the default __import__() function, which doesn't
validate the existence of the fromlist items. Later on, the missing attribute
is detected while processing the import statement.
https://hg.python.org/cpython/file/v2.7.13/Python/import.c#l2575
The comtypes library relies on this (maybe) undocumented behavior, and we
got a bug report to TortoiseHg, sigh.
https://bitbucket.org/tortoisehg/thg/issues/4647/
The test added at 26a4e46af2bc verifies the behavior of the import statement,
so this patch only adds the test of __import__() function and works around
CPython/PyPy difference.
| author | Yuya Nishihara <yuya@tcha.org> |
|---|---|
| date | Mon, 19 Dec 2016 22:46:00 +0900 |
| parents | 7817df5585db |
| children | 5f33116cd787 |
| files | mercurial/demandimport.py tests/test-demandimport.py tests/test-demandimport.py.out |
| diffstat | 3 files changed, 17 insertions(+), 3 deletions(-) [+] |
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--- a/mercurial/demandimport.py Thu Dec 08 23:59:36 2016 +0800 +++ b/mercurial/demandimport.py Mon Dec 19 22:46:00 2016 +0900 @@ -199,8 +199,11 @@ nonpkg = getattr(mod, '__path__', nothing) is nothing if symbol is nothing: if nonpkg: - # do not try relative import, which would raise ValueError - raise ImportError('cannot import name %s' % attr) + # do not try relative import, which would raise ValueError, + # and leave unknown attribute as the default __import__() + # would do. the missing attribute will be detected later + # while processing the import statement. + return mn = '%s.%s' % (mod.__name__, attr) if mn in ignore: importfunc = _origimport
--- a/tests/test-demandimport.py Thu Dec 08 23:59:36 2016 +0800 +++ b/tests/test-demandimport.py Mon Dec 19 22:46:00 2016 +0900 @@ -70,7 +70,16 @@ print('no demandmod should be created for attribute of non-package ' 'module:\ncontextlib.unknownattr =', f(unknownattr)) except ImportError as inst: - print('contextlib.unknownattr = ImportError: %s' % inst) + print('contextlib.unknownattr = ImportError: %s' + % rsub(r"'", '', str(inst))) + +# Unlike the import statement, __import__() function should not raise +# ImportError even if fromlist has an unknown item +# (see Python/import.c:import_module_level() and ensure_fromlist()) +contextlibimp = __import__('contextlib', globals(), locals(), ['unknownattr']) +print("__import__('contextlib', ..., ['unknownattr']) =", f(contextlibimp)) +print("hasattr(contextlibimp, 'unknownattr') =", + util.safehasattr(contextlibimp, 'unknownattr')) demandimport.disable() os.environ['HGDEMANDIMPORT'] = 'disable'
--- a/tests/test-demandimport.py.out Thu Dec 08 23:59:36 2016 +0800 +++ b/tests/test-demandimport.py.out Mon Dec 19 22:46:00 2016 +0900 @@ -18,4 +18,6 @@ re = <proxied module 'sys'> contextlib = <unloaded module 'contextlib'> contextlib.unknownattr = ImportError: cannot import name unknownattr +__import__('contextlib', ..., ['unknownattr']) = <module 'contextlib' from '?'> +hasattr(contextlibimp, 'unknownattr') = False node = <module 'mercurial.node' from '?'>