258 lines
11 KiB
Python
258 lines
11 KiB
Python
# Copyright (c) 2015-2016 Cara Vinson <ceridwenv@gmail.com>
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# Copyright (c) 2015-2016 Claudiu Popa <pcmanticore@gmail.com>
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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
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# For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
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import six
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from astroid import bases
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from astroid import context as contextmod
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from astroid import exceptions
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from astroid import nodes
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from astroid import util
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class CallSite(object):
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"""Class for understanding arguments passed into a call site
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It needs a call context, which contains the arguments and the
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keyword arguments that were passed into a given call site.
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In order to infer what an argument represents, call
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:meth:`infer_argument` with the corresponding function node
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and the argument name.
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"""
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def __init__(self, callcontext):
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args = callcontext.args
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keywords = callcontext.keywords
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self.duplicated_keywords = set()
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self._unpacked_args = self._unpack_args(args)
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self._unpacked_kwargs = self._unpack_keywords(keywords)
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self.positional_arguments = [
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arg for arg in self._unpacked_args
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if arg is not util.Uninferable
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]
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self.keyword_arguments = {
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key: value for key, value in self._unpacked_kwargs.items()
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if value is not util.Uninferable
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}
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@classmethod
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def from_call(cls, call_node):
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"""Get a CallSite object from the given Call node."""
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callcontext = contextmod.CallContext(call_node.args,
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call_node.keywords)
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return cls(callcontext)
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def has_invalid_arguments(self):
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"""Check if in the current CallSite were passed *invalid* arguments
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This can mean multiple things. For instance, if an unpacking
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of an invalid object was passed, then this method will return True.
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Other cases can be when the arguments can't be inferred by astroid,
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for example, by passing objects which aren't known statically.
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"""
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return len(self.positional_arguments) != len(self._unpacked_args)
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def has_invalid_keywords(self):
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"""Check if in the current CallSite were passed *invalid* keyword arguments
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For instance, unpacking a dictionary with integer keys is invalid
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(**{1:2}), because the keys must be strings, which will make this
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method to return True. Other cases where this might return True if
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objects which can't be inferred were passed.
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"""
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return len(self.keyword_arguments) != len(self._unpacked_kwargs)
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def _unpack_keywords(self, keywords):
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values = {}
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context = contextmod.InferenceContext()
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for name, value in keywords:
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if name is None:
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# Then it's an unpacking operation (**)
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try:
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inferred = next(value.infer(context=context))
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except exceptions.InferenceError:
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values[name] = util.Uninferable
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continue
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if not isinstance(inferred, nodes.Dict):
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# Not something we can work with.
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values[name] = util.Uninferable
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continue
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for dict_key, dict_value in inferred.items:
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try:
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dict_key = next(dict_key.infer(context=context))
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except exceptions.InferenceError:
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values[name] = util.Uninferable
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continue
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if not isinstance(dict_key, nodes.Const):
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values[name] = util.Uninferable
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continue
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if not isinstance(dict_key.value, six.string_types):
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values[name] = util.Uninferable
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continue
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if dict_key.value in values:
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# The name is already in the dictionary
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values[dict_key.value] = util.Uninferable
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self.duplicated_keywords.add(dict_key.value)
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continue
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values[dict_key.value] = dict_value
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else:
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values[name] = value
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return values
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@staticmethod
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def _unpack_args(args):
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values = []
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context = contextmod.InferenceContext()
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for arg in args:
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if isinstance(arg, nodes.Starred):
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try:
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inferred = next(arg.value.infer(context=context))
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except exceptions.InferenceError:
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values.append(util.Uninferable)
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continue
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if inferred is util.Uninferable:
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values.append(util.Uninferable)
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continue
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if not hasattr(inferred, 'elts'):
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values.append(util.Uninferable)
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continue
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values.extend(inferred.elts)
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else:
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values.append(arg)
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return values
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def infer_argument(self, funcnode, name, context):
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"""infer a function argument value according to the call context
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Arguments:
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funcnode: The function being called.
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name: The name of the argument whose value is being inferred.
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context: TODO
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"""
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if name in self.duplicated_keywords:
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raise exceptions.InferenceError('The arguments passed to {func!r} '
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' have duplicate keywords.',
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call_site=self, func=funcnode,
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arg=name, context=context)
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# Look into the keywords first, maybe it's already there.
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try:
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return self.keyword_arguments[name].infer(context)
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except KeyError:
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pass
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# Too many arguments given and no variable arguments.
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if len(self.positional_arguments) > len(funcnode.args.args):
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if not funcnode.args.vararg:
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raise exceptions.InferenceError('Too many positional arguments '
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'passed to {func!r} that does '
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'not have *args.',
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call_site=self, func=funcnode,
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arg=name, context=context)
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positional = self.positional_arguments[:len(funcnode.args.args)]
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vararg = self.positional_arguments[len(funcnode.args.args):]
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argindex = funcnode.args.find_argname(name)[0]
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kwonlyargs = set(arg.name for arg in funcnode.args.kwonlyargs)
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kwargs = {
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key: value for key, value in self.keyword_arguments.items()
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if key not in kwonlyargs
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}
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# If there are too few positionals compared to
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# what the function expects to receive, check to see
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# if the missing positional arguments were passed
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# as keyword arguments and if so, place them into the
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# positional args list.
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if len(positional) < len(funcnode.args.args):
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for func_arg in funcnode.args.args:
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if func_arg.name in kwargs:
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arg = kwargs.pop(func_arg.name)
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positional.append(arg)
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if argindex is not None:
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# 2. first argument of instance/class method
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if argindex == 0 and funcnode.type in ('method', 'classmethod'):
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if context.boundnode is not None:
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boundnode = context.boundnode
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else:
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# XXX can do better ?
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boundnode = funcnode.parent.frame()
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if isinstance(boundnode, nodes.ClassDef):
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# Verify that we're accessing a method
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# of the metaclass through a class, as in
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# `cls.metaclass_method`. In this case, the
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# first argument is always the class.
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method_scope = funcnode.parent.scope()
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if method_scope is boundnode.metaclass():
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return iter((boundnode, ))
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if funcnode.type == 'method':
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if not isinstance(boundnode, bases.Instance):
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boundnode = bases.Instance(boundnode)
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return iter((boundnode,))
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if funcnode.type == 'classmethod':
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return iter((boundnode,))
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# if we have a method, extract one position
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# from the index, so we'll take in account
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# the extra parameter represented by `self` or `cls`
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if funcnode.type in ('method', 'classmethod'):
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argindex -= 1
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# 2. search arg index
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try:
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return self.positional_arguments[argindex].infer(context)
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except IndexError:
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pass
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if funcnode.args.kwarg == name:
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# It wants all the keywords that were passed into
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# the call site.
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if self.has_invalid_keywords():
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raise exceptions.InferenceError(
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"Inference failed to find values for all keyword arguments "
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"to {func!r}: {unpacked_kwargs!r} doesn't correspond to "
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"{keyword_arguments!r}.",
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keyword_arguments=self.keyword_arguments,
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unpacked_kwargs=self._unpacked_kwargs,
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call_site=self, func=funcnode, arg=name, context=context)
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kwarg = nodes.Dict(lineno=funcnode.args.lineno,
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col_offset=funcnode.args.col_offset,
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parent=funcnode.args)
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kwarg.postinit([(nodes.const_factory(key), value)
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for key, value in kwargs.items()])
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return iter((kwarg, ))
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elif funcnode.args.vararg == name:
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# It wants all the args that were passed into
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# the call site.
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if self.has_invalid_arguments():
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raise exceptions.InferenceError(
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"Inference failed to find values for all positional "
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"arguments to {func!r}: {unpacked_args!r} doesn't "
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"correspond to {positional_arguments!r}.",
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positional_arguments=self.positional_arguments,
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unpacked_args=self._unpacked_args,
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call_site=self, func=funcnode, arg=name, context=context)
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args = nodes.Tuple(lineno=funcnode.args.lineno,
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col_offset=funcnode.args.col_offset,
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parent=funcnode.args)
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args.postinit(vararg)
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return iter((args, ))
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# Check if it's a default parameter.
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try:
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return funcnode.args.default_value(name).infer(context)
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except exceptions.NoDefault:
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pass
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raise exceptions.InferenceError('No value found for argument {name} to '
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'{func!r}', call_site=self,
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func=funcnode, arg=name, context=context)
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