# Released under the MIT License. See LICENSE for details.
#
"""Plugins for pylint"""
from __future__ import annotations
from typing import TYPE_CHECKING
import astroid
if TYPE_CHECKING:
from typing import Any
from astroid import nodes as nc
VERBOSE = False
[docs]
def register(linter: Any) -> None:
"""Unused here; we're modifying the ast; not linters."""
del linter # Unused.
failed_imports: set[str] = set()
[docs]
def failed_import_hook(modname: str) -> None:
"""Custom failed import callback."""
# We don't actually do anything here except note in our log that
# something couldn't be imported. (may help sanity-check our filtering)
if VERBOSE:
if modname not in failed_imports:
failed_imports.add(modname)
print('GOT FAILED IMPORT OF', modname)
raise astroid.AstroidBuildingError(modname=modname)
[docs]
def ignore_type_check_filter(if_node: nc.NodeNG) -> nc.NodeNG:
"""Ignore stuff under 'if TYPE_CHECKING:' block at module level."""
# Look for a non-nested 'if TYPE_CHECKING:'
if (
isinstance(if_node.test, astroid.Name)
and if_node.test.name == 'TYPE_CHECKING'
and isinstance(if_node.parent, astroid.Module)
):
# Special case: some third party modules are starting to contain
# code that we don't handle cleanly which results in pylint runs
# breaking. For now just ignoring them as they pop up.
# We should try to figure out how to disable this filtering
# for third party modules altogether or make our filtering more
# robust.
if if_node.parent.name in {
'filelock',
'aiohttp.web_app',
'aiohttp.web_response',
}:
return if_node
module_node = if_node.parent
# Remove any locals getting defined under this if statement.
# (ideally should recurse in case we have nested if statements/etc
# but keeping it simple for now).
for name, locations in list(module_node.locals.items()):
# Calc which remaining name locations are outside of the if
# block. Update or delete the list as needed.
new_locs = [l for l in locations if not _under_if(l, if_node)]
if len(new_locs) == len(locations):
continue
if new_locs:
module_node.locals[name] = new_locs
continue
del module_node.locals[name]
# Now replace its children with a simple pass statement.
passnode = astroid.Pass(
parent=if_node,
lineno=if_node.lineno + 1,
end_lineno=if_node.lineno + 1,
col_offset=if_node.col_offset + 1,
end_col_offset=if_node.col_offset + 1,
)
if_node.body = [passnode]
return if_node
def _under_if(node: nc.NodeNG, if_node: nc.NodeNG) -> bool:
"""Return whether the node is under the if statement.
(This returns False if it is under an elif/else portion)
"""
# Quick out:
if node.parent is not if_node:
return False
return node in if_node.body
[docs]
def ignore_reveal_type_call(node: nc.NodeNG) -> nc.NodeNG:
"""Make 'reveal_type()' not trigger an error.
The 'reveal_type()' fake call is used for type debugging types with
mypy and it is annoying having pylint errors pop up alongside the mypy
info.
"""
# Let's just replace any reveal_type(x) call with print(x)..
if isinstance(node.func, astroid.Name) and node.func.name == 'reveal_type':
node.func.name = 'print'
return node
return node
[docs]
def using_future_annotations(node: nc.NodeNG) -> nc.NodeNG:
"""Return whether postponed annotation evaluation is enabled (PEP 563)."""
# Find the module.
mnode = node
while mnode.parent is not None:
mnode = mnode.parent
# Look for 'from __future__ import annotations' to decide
# if we should assume all annotations are defer-eval'ed.
# NOTE: this will become default at some point within a few years..
annotations_set = mnode.locals.get('annotations')
if (
annotations_set
and isinstance(annotations_set[0], astroid.ImportFrom)
and annotations_set[0].modname == '__future__'
):
return True
return False
[docs]
def func_annotations_filter(node: nc.NodeNG) -> nc.NodeNG:
"""Filter annotated function args/retvals.
This accounts for deferred evaluation available in in Python 3.7+
via 'from __future__ import annotations'. In this case we don't
want Pylint to complain about missing symbols in annotations when
they aren't actually needed at runtime.
"""
# Only do this if deferred annotations are on.
if not using_future_annotations(node):
return node
# Wipe out argument annotations.
# Special-case: certain function decorators *do*
# evaluate annotations at runtime so we want to leave theirs intact.
# This includes functools.singledispatch, babase.dispatchmethod, and
# efro.MessageReceiver.
# Lets just look for a @XXX.register or @XXX.handler decorators for
# now; can get more specific if we get false positives.
if node.decorators is not None:
for dnode in node.decorators.nodes:
if isinstance(dnode, astroid.nodes.Name) and dnode.name in {
'dispatchmethod',
'singledispatch',
}:
return node # Leave annotations intact.
if isinstance(
dnode, astroid.nodes.Attribute
) and dnode.attrname in {'register', 'handler'}:
return node # Leave annotations intact.
node.args.annotations = [None for _ in node.args.args]
node.args.varargannotation = None
node.args.kwargannotation = None
node.args.kwonlyargs_annotations = [None for _ in node.args.kwonlyargs]
node.args.posonlyargs_annotations = [None for _ in node.args.kwonlyargs]
# Wipe out return-value annotation.
if node.returns is not None:
node.returns = None
return node
[docs]
def var_annotations_filter(node: nc.NodeNG) -> nc.NodeNG:
"""Filter annotated function variable assigns.
This accounts for deferred evaluation.
"""
# pylint: disable=too-many-branches
# pylint: disable=too-many-nested-blocks
if using_future_annotations(node):
# Future behavior:
# Annotated assigns under functions are not evaluated.
# Class and module vars are normally not either. However we
# *do* evaluate if we come across an 'ioprepped' dataclass
# decorator. (the 'ioprepped' decorator explicitly evaluates
# dataclass annotations).
fnode = node
willeval = False
while fnode is not None:
if isinstance(fnode, astroid.FunctionDef):
# Assigns within functions never eval.
break
if isinstance(fnode, astroid.ClassDef):
# Ok; the assign seems to be at the class level.
# See if its an ioprepped dataclass.
if fnode.decorators is not None:
found_ioprepped = False
for dec in fnode.decorators.nodes:
# Look for dataclassio.ioprepped.
if (
isinstance(dec, astroid.nodes.Attribute)
and dec.attrname in {'ioprepped', 'will_ioprep'}
and isinstance(dec.expr, astroid.nodes.Name)
and dec.expr.name == 'dataclassio'
):
found_ioprepped = True
break
# Look for simply 'ioprepped'.
if isinstance(dec, astroid.nodes.Name) and dec.name in {
'ioprepped',
'will_ioprep',
}:
found_ioprepped = True
break
if found_ioprepped:
willeval = True
break
fnode = fnode.parent
else:
# Legacy behavior:
# Annotated assigns under functions are not evaluated,
# but class or module vars are.
fnode = node
willeval = True
while fnode is not None:
if isinstance(
fnode, (astroid.FunctionDef, astroid.AsyncFunctionDef)
):
willeval = False
break
if isinstance(fnode, astroid.ClassDef):
willeval = True
break
fnode = fnode.parent
# If this annotation won't be eval'ed, replace its annotation with
# a dummy value.
if not willeval:
dummyval = astroid.Const(parent=node, value='dummyval')
node.annotation = dummyval
return node
# Stripping subscripts on some generics seems to cause
# more harm than good, so we leave some intact.
# ALLOWED_GENERICS = {'Sequence'}
# def _is_strippable_subscript(node: nc.NodeNG) -> bool:
# if isinstance(node, astroid.Subscript):
# # We can strip if its not in our allowed list.
# if not (
# isinstance(node.value, astroid.Name)
# and node.value.name in ALLOWED_GENERICS
# ):
# return True
# return False
# def class_generics_filter(node: nc.NodeNG) -> nc.NodeNG:
# """Filter generics subscripts out of class declarations."""
# # First, quick-out if nothing here should be filtered.
# found = False
# for base in node.bases:
# if _is_strippable_subscript(base):
# found = True
# if not found:
# return node
# # Now strip subscripts from base classes.
# new_bases: list[nc.NodeNG] = []
# for base in node.bases:
# if _is_strippable_subscript(base):
# new_bases.append(base.value)
# base.value.parent = node
# else:
# new_bases.append(base)
# node.bases = new_bases
# return node
[docs]
def register_plugins(manager: astroid.Manager) -> None:
"""Apply our transforms to a given astroid manager object."""
# Hmm; is this still necessary?
if VERBOSE:
manager.register_failed_import_hook(failed_import_hook)
# Completely ignore everything under an 'if TYPE_CHECKING' conditional.
# That stuff only gets run for mypy, and in general we want to
# check code as if it doesn't exist at all.
manager.register_transform(astroid.If, ignore_type_check_filter)
# We use 'reveal_type()' quite often, which tells mypy to print
# the type of an expression. Let's ignore it in Pylint's eyes so
# we don't see an ugly error there.
manager.register_transform(astroid.Call, ignore_reveal_type_call)
# We make use of 'from __future__ import annotations' which causes Python
# to receive annotations as strings, and also 'if TYPE_CHECKING:' blocks,
# which lets us do imports and whatnot that are limited to type-checking.
# Let's make Pylint understand these.
manager.register_transform(astroid.AnnAssign, var_annotations_filter)
manager.register_transform(astroid.FunctionDef, func_annotations_filter)
manager.register_transform(
astroid.AsyncFunctionDef, func_annotations_filter
)
# Pylint doesn't seem to support Generics much right now, and it seems
# to lead to some buggy behavior and slowdowns. So let's filter them
# out. So instead of this:
# class MyClass(MyType[T]):
# Pylint will see this:
# class MyClass(MyType):
# I've opened a github issue related to the problems I was hitting,
# so we can revisit the need for this if that gets resolved.
# https://github.com/PyCQA/pylint/issues/3605
# UPDATE: As of July 2024 this seems to be no longer necessary; hooray!
# manager.register_transform(astroid.ClassDef, class_generics_filter)
register_plugins(astroid.MANAGER)