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.
# A dummy extension that installs an hgweb command that throws an Exception.
from __future__ import absolute_import
from mercurial.hgweb import (
webcommands,
)
def raiseerror(web, req, tmpl):
'''Dummy web command that raises an uncaught Exception.'''
# Simulate an error after partial response.
if 'partialresponse' in req.form:
req.respond(200, 'text/plain')
req.write('partial content\n')
raise AttributeError('I am an uncaught error!')
def extsetup(ui):
setattr(webcommands, 'raiseerror', raiseerror)
webcommands.__all__.append('raiseerror')