/
messages.py
1903 lines (1657 loc) · 85.8 KB
/
messages.py
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"""Facilities for generating error messages during type checking.
Don't add any non-trivial message construction logic to the type
checker, as it can compromise clarity and make messages less
consistent. Add such logic to this module instead. Literal messages, including those
with format args, should be defined as constants in mypy.message_registry.
Historically we tried to avoid all message string literals in the type
checker but we are moving away from this convention.
"""
from collections import OrderedDict
import re
import difflib
from textwrap import dedent
from typing import cast, List, Dict, Any, Sequence, Iterable, Tuple, Set, Optional, Union
from typing_extensions import Final
from mypy.erasetype import erase_type
from mypy.errors import Errors
from mypy.types import (
Type, CallableType, Instance, TypeVarType, TupleType, TypedDictType, LiteralType,
UnionType, NoneType, AnyType, Overloaded, FunctionLike, DeletedType, TypeType,
UninhabitedType, TypeOfAny, UnboundType, PartialType, get_proper_type, ProperType,
get_proper_types
)
from mypy.typetraverser import TypeTraverserVisitor
from mypy.nodes import (
TypeInfo, Context, MypyFile, op_methods, FuncDef, reverse_builtin_aliases,
ARG_POS, ARG_OPT, ARG_NAMED, ARG_NAMED_OPT, ARG_STAR, ARG_STAR2,
ReturnStmt, NameExpr, Var, CONTRAVARIANT, COVARIANT, SymbolNode,
CallExpr
)
from mypy.subtypes import (
is_subtype, find_member, get_member_flags,
IS_SETTABLE, IS_CLASSVAR, IS_CLASS_OR_STATIC,
)
from mypy.sametypes import is_same_type
from mypy.util import unmangle
from mypy.errorcodes import ErrorCode
from mypy import message_registry, errorcodes as codes
ARG_CONSTRUCTOR_NAMES = {
ARG_POS: "Arg",
ARG_OPT: "DefaultArg",
ARG_NAMED: "NamedArg",
ARG_NAMED_OPT: "DefaultNamedArg",
ARG_STAR: "VarArg",
ARG_STAR2: "KwArg",
} # type: Final
class MessageBuilder:
"""Helper class for reporting type checker error messages with parameters.
The methods of this class need to be provided with the context within a
file; the errors member manages the wider context.
IDEA: Support a 'verbose mode' that includes full information about types
in error messages and that may otherwise produce more detailed error
messages.
"""
# Report errors using this instance. It knows about the current file and
# import context.
errors = None # type: Errors
modules = None # type: Dict[str, MypyFile]
# Number of times errors have been disabled.
disable_count = 0
# Hack to deduplicate error messages from union types
disable_type_names = 0
def __init__(self, errors: Errors, modules: Dict[str, MypyFile]) -> None:
self.errors = errors
self.modules = modules
self.disable_count = 0
self.disable_type_names = 0
#
# Helpers
#
def copy(self) -> 'MessageBuilder':
new = MessageBuilder(self.errors.copy(), self.modules)
new.disable_count = self.disable_count
new.disable_type_names = self.disable_type_names
return new
def clean_copy(self) -> 'MessageBuilder':
errors = self.errors.copy()
errors.error_info_map = OrderedDict()
return MessageBuilder(errors, self.modules)
def add_errors(self, messages: 'MessageBuilder') -> None:
"""Add errors in messages to this builder."""
if self.disable_count <= 0:
for errs in messages.errors.error_info_map.values():
for info in errs:
self.errors.add_error_info(info)
def disable_errors(self) -> None:
self.disable_count += 1
def enable_errors(self) -> None:
self.disable_count -= 1
def is_errors(self) -> bool:
return self.errors.is_errors()
def report(self,
msg: str,
context: Optional[Context],
severity: str,
*,
code: Optional[ErrorCode] = None,
file: Optional[str] = None,
origin: Optional[Context] = None,
offset: int = 0) -> None:
"""Report an error or note (unless disabled)."""
if origin is not None:
end_line = origin.end_line
elif context is not None:
end_line = context.end_line
else:
end_line = None
if self.disable_count <= 0:
self.errors.report(context.get_line() if context else -1,
context.get_column() if context else -1,
msg, severity=severity, file=file, offset=offset,
origin_line=origin.get_line() if origin else None,
end_line=end_line,
code=code)
def fail(self,
msg: str,
context: Optional[Context],
*,
code: Optional[ErrorCode] = None,
file: Optional[str] = None,
origin: Optional[Context] = None) -> None:
"""Report an error message (unless disabled)."""
self.report(msg, context, 'error', code=code, file=file, origin=origin)
def note(self,
msg: str,
context: Context,
file: Optional[str] = None,
origin: Optional[Context] = None,
offset: int = 0,
*,
code: Optional[ErrorCode] = None) -> None:
"""Report a note (unless disabled)."""
self.report(msg, context, 'note', file=file, origin=origin,
offset=offset, code=code)
def note_multiline(self, messages: str, context: Context, file: Optional[str] = None,
origin: Optional[Context] = None, offset: int = 0,
code: Optional[ErrorCode] = None) -> None:
"""Report as many notes as lines in the message (unless disabled)."""
for msg in messages.splitlines():
self.report(msg, context, 'note', file=file, origin=origin,
offset=offset, code=code)
#
# Specific operations
#
# The following operations are for generating specific error messages. They
# get some information as arguments, and they build an error message based
# on them.
def has_no_attr(self, original_type: Type, typ: Type, member: str, context: Context) -> Type:
"""Report a missing or non-accessible member.
original_type is the top-level type on which the error occurred.
typ is the actual type that is missing the member. These can be
different, e.g., in a union, original_type will be the union and typ
will be the specific item in the union that does not have the member
attribute.
If member corresponds to an operator, use the corresponding operator
name in the messages. Return type Any.
"""
original_type = get_proper_type(original_type)
typ = get_proper_type(typ)
if (isinstance(original_type, Instance) and
original_type.type.has_readable_member(member)):
self.fail('Member "{}" is not assignable'.format(member), context)
elif member == '__contains__':
self.fail('Unsupported right operand type for in ({})'.format(
format_type(original_type)), context, code=codes.OPERATOR)
elif member in op_methods.values():
# Access to a binary operator member (e.g. _add). This case does
# not handle indexing operations.
for op, method in op_methods.items():
if method == member:
self.unsupported_left_operand(op, original_type, context)
break
elif member == '__neg__':
self.fail('Unsupported operand type for unary - ({})'.format(
format_type(original_type)), context, code=codes.OPERATOR)
elif member == '__pos__':
self.fail('Unsupported operand type for unary + ({})'.format(
format_type(original_type)), context, code=codes.OPERATOR)
elif member == '__invert__':
self.fail('Unsupported operand type for ~ ({})'.format(
format_type(original_type)), context, code=codes.OPERATOR)
elif member == '__getitem__':
# Indexed get.
# TODO: Fix this consistently in format_type
if isinstance(original_type, CallableType) and original_type.is_type_obj():
self.fail('The type {} is not generic and not indexable'.format(
format_type(original_type)), context)
else:
self.fail('Value of type {} is not indexable'.format(
format_type(original_type)), context, code=codes.INDEX)
elif member == '__setitem__':
# Indexed set.
self.fail('Unsupported target for indexed assignment', context, code=codes.INDEX)
elif member == '__call__':
if isinstance(original_type, Instance) and \
(original_type.type.fullname() == 'builtins.function'):
# "'function' not callable" is a confusing error message.
# Explain that the problem is that the type of the function is not known.
self.fail('Cannot call function of unknown type', context, code=codes.OPERATOR)
else:
self.fail('{} not callable'.format(format_type(original_type)), context,
code=codes.OPERATOR)
else:
# The non-special case: a missing ordinary attribute.
extra = ''
if member == '__iter__':
extra = ' (not iterable)'
elif member == '__aiter__':
extra = ' (not async iterable)'
if not self.disable_type_names:
failed = False
if isinstance(original_type, Instance) and original_type.type.names:
alternatives = set(original_type.type.names.keys())
matches = [m for m in COMMON_MISTAKES.get(member, []) if m in alternatives]
matches.extend(best_matches(member, alternatives)[:3])
if member == '__aiter__' and matches == ['__iter__']:
matches = [] # Avoid misleading suggestion
if member == '__div__' and matches == ['__truediv__']:
# TODO: Handle differences in division between Python 2 and 3 more cleanly
matches = []
if matches:
self.fail(
'{} has no attribute "{}"; maybe {}?{}'.format(
format_type(original_type), member, pretty_or(matches), extra),
context,
code=codes.ATTR_DEFINED)
failed = True
if not failed:
self.fail(
'{} has no attribute "{}"{}'.format(
format_type(original_type), member, extra),
context,
code=codes.ATTR_DEFINED)
elif isinstance(original_type, UnionType):
# The checker passes "object" in lieu of "None" for attribute
# checks, so we manually convert it back.
typ_format, orig_type_format = format_type_distinctly(typ, original_type)
if typ_format == '"object"' and \
any(type(item) == NoneType for item in original_type.items):
typ_format = '"None"'
self.fail('Item {} of {} has no attribute "{}"{}'.format(
typ_format, orig_type_format, member, extra), context,
code=codes.UNION_ATTR)
return AnyType(TypeOfAny.from_error)
def unsupported_operand_types(self,
op: str,
left_type: Any,
right_type: Any,
context: Context,
*,
code: ErrorCode = codes.OPERATOR) -> None:
"""Report unsupported operand types for a binary operation.
Types can be Type objects or strings.
"""
left_str = ''
if isinstance(left_type, str):
left_str = left_type
else:
left_str = format_type(left_type)
right_str = ''
if isinstance(right_type, str):
right_str = right_type
else:
right_str = format_type(right_type)
if self.disable_type_names:
msg = 'Unsupported operand types for {} (likely involving Union)'.format(op)
else:
msg = 'Unsupported operand types for {} ({} and {})'.format(
op, left_str, right_str)
self.fail(msg, context, code=code)
def unsupported_left_operand(self, op: str, typ: Type,
context: Context) -> None:
if self.disable_type_names:
msg = 'Unsupported left operand type for {} (some union)'.format(op)
else:
msg = 'Unsupported left operand type for {} ({})'.format(
op, format_type(typ))
self.fail(msg, context, code=codes.OPERATOR)
def not_callable(self, typ: Type, context: Context) -> Type:
self.fail('{} not callable'.format(format_type(typ)), context)
return AnyType(TypeOfAny.from_error)
def untyped_function_call(self, callee: CallableType, context: Context) -> Type:
name = callable_name(callee) or '(unknown)'
self.fail('Call to untyped function {} in typed context'.format(name), context,
code=codes.NO_UNTYPED_CALL)
return AnyType(TypeOfAny.from_error)
def incompatible_argument(self,
n: int,
m: int,
callee: CallableType,
arg_type: Type,
arg_kind: int,
context: Context,
outer_context: Context) -> Optional[ErrorCode]:
"""Report an error about an incompatible argument type.
The argument type is arg_type, argument number is n and the
callee type is 'callee'. If the callee represents a method
that corresponds to an operator, use the corresponding
operator name in the messages.
Return the error code that used for the argument (multiple error
codes are possible).
"""
arg_type = get_proper_type(arg_type)
target = ''
callee_name = callable_name(callee)
if callee_name is not None:
name = callee_name
if callee.bound_args and callee.bound_args[0] is not None:
base = format_type(callee.bound_args[0])
else:
base = extract_type(name)
for op, method in op_methods.items():
for variant in method, '__r' + method[2:]:
# FIX: do not rely on textual formatting
if name.startswith('"{}" of'.format(variant)):
if op == 'in' or variant != method:
# Reversed order of base/argument.
self.unsupported_operand_types(op, arg_type, base,
context, code=codes.OPERATOR)
else:
self.unsupported_operand_types(op, base, arg_type,
context, code=codes.OPERATOR)
return codes.OPERATOR
if name.startswith('"__getitem__" of'):
self.invalid_index_type(arg_type, callee.arg_types[n - 1], base, context,
code=codes.INDEX)
return codes.INDEX
if name.startswith('"__setitem__" of'):
if n == 1:
self.invalid_index_type(arg_type, callee.arg_types[n - 1], base, context,
code=codes.INDEX)
return codes.INDEX
else:
msg = '{} (expression has type {}, target has type {})'
arg_type_str, callee_type_str = format_type_distinctly(arg_type,
callee.arg_types[n - 1])
self.fail(msg.format(message_registry.INCOMPATIBLE_TYPES_IN_ASSIGNMENT,
arg_type_str, callee_type_str),
context, code=codes.ASSIGNMENT)
return codes.ASSIGNMENT
target = 'to {} '.format(name)
msg = ''
code = codes.MISC
notes = [] # type: List[str]
if callee_name == '<list>':
name = callee_name[1:-1]
n -= 1
actual_type_str, expected_type_str = format_type_distinctly(arg_type,
callee.arg_types[0])
msg = '{} item {} has incompatible type {}; expected {}'.format(
name.title(), n, actual_type_str, expected_type_str)
code = codes.LIST_ITEM
elif callee_name == '<dict>':
name = callee_name[1:-1]
n -= 1
key_type, value_type = cast(TupleType, arg_type).items
expected_key_type, expected_value_type = cast(TupleType, callee.arg_types[0]).items
# don't increase verbosity unless there is need to do so
if is_subtype(key_type, expected_key_type):
key_type_str = format_type(key_type)
expected_key_type_str = format_type(expected_key_type)
else:
key_type_str, expected_key_type_str = format_type_distinctly(
key_type, expected_key_type)
if is_subtype(value_type, expected_value_type):
value_type_str = format_type(value_type)
expected_value_type_str = format_type(expected_value_type)
else:
value_type_str, expected_value_type_str = format_type_distinctly(
value_type, expected_value_type)
msg = '{} entry {} has incompatible type {}: {}; expected {}: {}'.format(
name.title(), n, key_type_str, value_type_str,
expected_key_type_str, expected_value_type_str)
code = codes.DICT_ITEM
elif callee_name == '<list-comprehension>':
actual_type_str, expected_type_str = map(strip_quotes,
format_type_distinctly(arg_type,
callee.arg_types[0]))
msg = 'List comprehension has incompatible type List[{}]; expected List[{}]'.format(
actual_type_str, expected_type_str)
elif callee_name == '<set-comprehension>':
actual_type_str, expected_type_str = map(strip_quotes,
format_type_distinctly(arg_type,
callee.arg_types[0]))
msg = 'Set comprehension has incompatible type Set[{}]; expected Set[{}]'.format(
actual_type_str, expected_type_str)
elif callee_name == '<dictionary-comprehension>':
actual_type_str, expected_type_str = format_type_distinctly(arg_type,
callee.arg_types[n - 1])
msg = ('{} expression in dictionary comprehension has incompatible type {}; '
'expected type {}').format(
'Key' if n == 1 else 'Value',
actual_type_str,
expected_type_str)
elif callee_name == '<generator>':
actual_type_str, expected_type_str = format_type_distinctly(arg_type,
callee.arg_types[0])
msg = 'Generator has incompatible item type {}; expected {}'.format(
actual_type_str, expected_type_str)
else:
try:
expected_type = callee.arg_types[m - 1]
except IndexError: # Varargs callees
expected_type = callee.arg_types[-1]
arg_type_str, expected_type_str = format_type_distinctly(
arg_type, expected_type, bare=True)
if arg_kind == ARG_STAR:
arg_type_str = '*' + arg_type_str
elif arg_kind == ARG_STAR2:
arg_type_str = '**' + arg_type_str
# For function calls with keyword arguments, display the argument name rather than the
# number.
arg_label = str(n)
if isinstance(outer_context, CallExpr) and len(outer_context.arg_names) >= n:
arg_name = outer_context.arg_names[n - 1]
if arg_name is not None:
arg_label = '"{}"'.format(arg_name)
if (arg_kind == ARG_STAR2
and isinstance(arg_type, TypedDictType)
and m <= len(callee.arg_names)
and callee.arg_names[m - 1] is not None
and callee.arg_kinds[m - 1] != ARG_STAR2):
arg_name = callee.arg_names[m - 1]
assert arg_name is not None
arg_type_str, expected_type_str = format_type_distinctly(
arg_type.items[arg_name],
expected_type,
bare=True)
arg_label = '"{}"'.format(arg_name)
msg = 'Argument {} {}has incompatible type {}; expected {}'.format(
arg_label, target, quote_type_string(arg_type_str),
quote_type_string(expected_type_str))
code = codes.ARG_TYPE
expected_type = get_proper_type(expected_type)
if isinstance(expected_type, UnionType):
expected_types = list(expected_type.items)
else:
expected_types = [expected_type]
for type in expected_types:
if isinstance(arg_type, Instance) and isinstance(type, Instance):
notes = append_invariance_notes(notes, arg_type, type)
self.fail(msg, context, code=code)
if notes:
for note_msg in notes:
self.note(note_msg, context, code=code)
return code
def incompatible_argument_note(self,
original_caller_type: ProperType,
callee_type: ProperType,
context: Context,
code: Optional[ErrorCode]) -> None:
if (isinstance(original_caller_type, (Instance, TupleType, TypedDictType)) and
isinstance(callee_type, Instance) and callee_type.type.is_protocol):
self.report_protocol_problems(original_caller_type, callee_type, context, code=code)
if (isinstance(callee_type, CallableType) and
isinstance(original_caller_type, Instance)):
call = find_member('__call__', original_caller_type, original_caller_type)
if call:
self.note_call(original_caller_type, call, context, code=code)
def invalid_index_type(self, index_type: Type, expected_type: Type, base_str: str,
context: Context, *, code: ErrorCode) -> None:
index_str, expected_str = format_type_distinctly(index_type, expected_type)
self.fail('Invalid index type {} for {}; expected type {}'.format(
index_str, base_str, expected_str), context, code=code)
def too_few_arguments(self, callee: CallableType, context: Context,
argument_names: Optional[Sequence[Optional[str]]]) -> None:
if (argument_names is not None and not all(k is None for k in argument_names)
and len(argument_names) >= 1):
num_positional_args = sum(k is None for k in argument_names)
arguments_left = callee.arg_names[num_positional_args:]
diff = [k for k in arguments_left if k not in argument_names]
if len(diff) == 1:
msg = 'Missing positional argument'
else:
msg = 'Missing positional arguments'
callee_name = callable_name(callee)
if callee_name is not None and diff and all(d is not None for d in diff):
args = '", "'.join(cast(List[str], diff))
msg += ' "{}" in call to {}'.format(args, callee_name)
else:
msg = 'Too few arguments' + for_function(callee)
self.fail(msg, context, code=codes.CALL_ARG)
def missing_named_argument(self, callee: CallableType, context: Context, name: str) -> None:
msg = 'Missing named argument "{}"'.format(name) + for_function(callee)
self.fail(msg, context, code=codes.CALL_ARG)
def too_many_arguments(self, callee: CallableType, context: Context) -> None:
msg = 'Too many arguments' + for_function(callee)
self.fail(msg, context, code=codes.CALL_ARG)
def too_many_arguments_from_typed_dict(self,
callee: CallableType,
arg_type: TypedDictType,
context: Context) -> None:
# Try to determine the name of the extra argument.
for key in arg_type.items:
if key not in callee.arg_names:
msg = 'Extra argument "{}" from **args'.format(key) + for_function(callee)
break
else:
self.too_many_arguments(callee, context)
return
self.fail(msg, context)
def too_many_positional_arguments(self, callee: CallableType,
context: Context) -> None:
msg = 'Too many positional arguments' + for_function(callee)
self.fail(msg, context)
def unexpected_keyword_argument(self, callee: CallableType, name: str,
context: Context) -> None:
msg = 'Unexpected keyword argument "{}"'.format(name) + for_function(callee)
self.fail(msg, context, code=codes.CALL_ARG)
module = find_defining_module(self.modules, callee)
if module:
assert callee.definition is not None
fname = callable_name(callee)
if not fname: # an alias to function with a different name
fname = 'Called function'
self.note('{} defined here'.format(fname), callee.definition,
file=module.path, origin=context)
def duplicate_argument_value(self, callee: CallableType, index: int,
context: Context) -> None:
self.fail('{} gets multiple values for keyword argument "{}"'.
format(callable_name(callee) or 'Function', callee.arg_names[index]),
context)
def does_not_return_value(self, callee_type: Optional[Type], context: Context) -> None:
"""Report an error about use of an unusable type."""
name = None # type: Optional[str]
callee_type = get_proper_type(callee_type)
if isinstance(callee_type, FunctionLike):
name = callable_name(callee_type)
if name is not None:
self.fail('{} does not return a value'.format(capitalize(name)), context,
code=codes.FUNC_RETURNS_VALUE)
else:
self.fail('Function does not return a value', context, code=codes.FUNC_RETURNS_VALUE)
def deleted_as_rvalue(self, typ: DeletedType, context: Context) -> None:
"""Report an error about using an deleted type as an rvalue."""
if typ.source is None:
s = ""
else:
s = " '{}'".format(typ.source)
self.fail('Trying to read deleted variable{}'.format(s), context)
def deleted_as_lvalue(self, typ: DeletedType, context: Context) -> None:
"""Report an error about using an deleted type as an lvalue.
Currently, this only occurs when trying to assign to an
exception variable outside the local except: blocks.
"""
if typ.source is None:
s = ""
else:
s = " '{}'".format(typ.source)
self.fail('Assignment to variable{} outside except: block'.format(s), context)
def no_variant_matches_arguments(self,
plausible_targets: List[CallableType],
overload: Overloaded,
arg_types: List[Type],
context: Context) -> None:
name = callable_name(overload)
if name:
name_str = ' of {}'.format(name)
else:
name_str = ''
arg_types_str = ', '.join(format_type(arg) for arg in arg_types)
num_args = len(arg_types)
if num_args == 0:
self.fail('All overload variants{} require at least one argument'.format(name_str),
context, code=codes.CALL_OVERLOAD)
elif num_args == 1:
self.fail('No overload variant{} matches argument type {}'
.format(name_str, arg_types_str), context, code=codes.CALL_OVERLOAD)
else:
self.fail('No overload variant{} matches argument types {}'
.format(name_str, arg_types_str), context, code=codes.CALL_OVERLOAD)
self.pretty_overload_matches(plausible_targets, overload, context, offset=2, max_items=2,
code=codes.CALL_OVERLOAD)
def wrong_number_values_to_unpack(self, provided: int, expected: int,
context: Context) -> None:
if provided < expected:
if provided == 1:
self.fail('Need more than 1 value to unpack ({} expected)'.format(expected),
context)
else:
self.fail('Need more than {} values to unpack ({} expected)'.format(
provided, expected), context)
elif provided > expected:
self.fail('Too many values to unpack ({} expected, {} provided)'.format(
expected, provided), context)
def type_not_iterable(self, type: Type, context: Context) -> None:
self.fail('\'{}\' object is not iterable'.format(type), context)
def incompatible_operator_assignment(self, op: str,
context: Context) -> None:
self.fail('Result type of {} incompatible in assignment'.format(op),
context)
def overload_signature_incompatible_with_supertype(
self, name: str, name_in_super: str, supertype: str,
overload: Overloaded, context: Context) -> None:
target = self.override_target(name, name_in_super, supertype)
self.fail('Signature of "{}" incompatible with {}'.format(
name, target), context, code=codes.OVERRIDE)
note_template = 'Overload variants must be defined in the same order as they are in "{}"'
self.note(note_template.format(supertype), context, code=codes.OVERRIDE)
def signature_incompatible_with_supertype(
self, name: str, name_in_super: str, supertype: str,
context: Context) -> None:
target = self.override_target(name, name_in_super, supertype)
self.fail('Signature of "{}" incompatible with {}'.format(
name, target), context, code=codes.OVERRIDE)
def argument_incompatible_with_supertype(
self, arg_num: int, name: str, type_name: Optional[str],
name_in_supertype: str, arg_type_in_supertype: Type, supertype: str,
context: Context) -> None:
target = self.override_target(name, name_in_supertype, supertype)
arg_type_in_supertype_f = format_type_bare(arg_type_in_supertype)
self.fail('Argument {} of "{}" is incompatible with {}; '
'supertype defines the argument type as "{}"'
.format(arg_num, name, target, arg_type_in_supertype_f),
context,
code=codes.OVERRIDE)
if name == "__eq__" and type_name:
multiline_msg = self.comparison_method_example_msg(class_name=type_name)
self.note_multiline(multiline_msg, context, code=codes.OVERRIDE)
def comparison_method_example_msg(self, class_name: str) -> str:
return dedent('''\
It is recommended for "__eq__" to work with arbitrary objects, for example:
def __eq__(self, other: object) -> bool:
if not isinstance(other, {class_name}):
return NotImplemented
return <logic to compare two {class_name} instances>
'''.format(class_name=class_name))
def return_type_incompatible_with_supertype(
self, name: str, name_in_supertype: str, supertype: str,
original: Type, override: Type,
context: Context) -> None:
target = self.override_target(name, name_in_supertype, supertype)
override_str, original_str = format_type_distinctly(override, original)
self.fail('Return type {} of "{}" incompatible with return type {} in {}'
.format(override_str, name, original_str, target),
context,
code=codes.OVERRIDE)
def override_target(self, name: str, name_in_super: str,
supertype: str) -> str:
target = 'supertype "{}"'.format(supertype)
if name_in_super != name:
target = '"{}" of {}'.format(name_in_super, target)
return target
def incompatible_type_application(self, expected_arg_count: int,
actual_arg_count: int,
context: Context) -> None:
if expected_arg_count == 0:
self.fail('Type application targets a non-generic function or class',
context)
elif actual_arg_count > expected_arg_count:
self.fail('Type application has too many types ({} expected)'
.format(expected_arg_count), context)
else:
self.fail('Type application has too few types ({} expected)'
.format(expected_arg_count), context)
def alias_invalid_in_runtime_context(self, item: ProperType, ctx: Context) -> None:
kind = (' to Callable' if isinstance(item, CallableType) else
' to Tuple' if isinstance(item, TupleType) else
' to Union' if isinstance(item, UnionType) else
' to Literal' if isinstance(item, LiteralType) else
'')
self.fail('The type alias{} is invalid in runtime context'.format(kind), ctx)
def could_not_infer_type_arguments(self, callee_type: CallableType, n: int,
context: Context) -> None:
callee_name = callable_name(callee_type)
if callee_name is not None and n > 0:
self.fail('Cannot infer type argument {} of {}'.format(n, callee_name), context)
else:
self.fail('Cannot infer function type argument', context)
def invalid_var_arg(self, typ: Type, context: Context) -> None:
self.fail('List or tuple expected as variable arguments', context)
def invalid_keyword_var_arg(self, typ: Type, is_mapping: bool, context: Context) -> None:
typ = get_proper_type(typ)
if isinstance(typ, Instance) and is_mapping:
self.fail('Keywords must be strings', context)
else:
suffix = ''
if isinstance(typ, Instance):
suffix = ', not {}'.format(format_type(typ))
self.fail(
'Argument after ** must be a mapping{}'.format(suffix),
context)
def undefined_in_superclass(self, member: str, context: Context) -> None:
self.fail('"{}" undefined in superclass'.format(member), context)
def first_argument_for_super_must_be_type(self, actual: Type, context: Context) -> None:
actual = get_proper_type(actual)
if isinstance(actual, Instance):
# Don't include type of instance, because it can look confusingly like a type
# object.
type_str = 'a non-type instance'
else:
type_str = format_type(actual)
self.fail('Argument 1 for "super" must be a type object; got {}'.format(type_str), context)
def too_few_string_formatting_arguments(self, context: Context) -> None:
self.fail('Not enough arguments for format string', context)
def too_many_string_formatting_arguments(self, context: Context) -> None:
self.fail('Not all arguments converted during string formatting', context)
def unsupported_placeholder(self, placeholder: str, context: Context) -> None:
self.fail('Unsupported format character \'%s\'' % placeholder, context)
def string_interpolation_with_star_and_key(self, context: Context) -> None:
self.fail('String interpolation contains both stars and mapping keys', context)
def requires_int_or_char(self, context: Context) -> None:
self.fail('%c requires int or char', context)
def key_not_in_mapping(self, key: str, context: Context) -> None:
self.fail('Key \'%s\' not found in mapping' % key, context)
def string_interpolation_mixing_key_and_non_keys(self, context: Context) -> None:
self.fail('String interpolation mixes specifier with and without mapping keys', context)
def cannot_determine_type(self, name: str, context: Context) -> None:
self.fail("Cannot determine type of '%s'" % name, context, code=codes.HAS_TYPE)
def cannot_determine_type_in_base(self, name: str, base: str, context: Context) -> None:
self.fail("Cannot determine type of '%s' in base class '%s'" % (name, base), context)
def no_formal_self(self, name: str, item: CallableType, context: Context) -> None:
self.fail('Attribute function "%s" with type %s does not accept self argument'
% (name, format_type(item)), context)
def incompatible_self_argument(self, name: str, arg: Type, sig: CallableType,
is_classmethod: bool, context: Context) -> None:
kind = 'class attribute function' if is_classmethod else 'attribute function'
self.fail('Invalid self argument %s to %s "%s" with type %s'
% (format_type(arg), kind, name, format_type(sig)), context)
def incompatible_conditional_function_def(self, defn: FuncDef) -> None:
self.fail('All conditional function variants must have identical '
'signatures', defn)
def cannot_instantiate_abstract_class(self, class_name: str,
abstract_attributes: List[str],
context: Context) -> None:
attrs = format_string_list(["'%s'" % a for a in abstract_attributes])
self.fail("Cannot instantiate abstract class '%s' with abstract "
"attribute%s %s" % (class_name, plural_s(abstract_attributes),
attrs),
context, code=codes.ABSTRACT)
def base_class_definitions_incompatible(self, name: str, base1: TypeInfo,
base2: TypeInfo,
context: Context) -> None:
self.fail('Definition of "{}" in base class "{}" is incompatible '
'with definition in base class "{}"'.format(
name, base1.name(), base2.name()), context)
def cant_assign_to_method(self, context: Context) -> None:
self.fail(message_registry.CANNOT_ASSIGN_TO_METHOD, context,
code=codes.ASSIGNMENT)
def cant_assign_to_classvar(self, name: str, context: Context) -> None:
self.fail('Cannot assign to class variable "%s" via instance' % name, context)
def final_cant_override_writable(self, name: str, ctx: Context) -> None:
self.fail('Cannot override writable attribute "{}" with a final one'.format(name), ctx)
def cant_override_final(self, name: str, base_name: str, ctx: Context) -> None:
self.fail('Cannot override final attribute "{}"'
' (previously declared in base class "{}")'.format(name, base_name), ctx)
def cant_assign_to_final(self, name: str, attr_assign: bool, ctx: Context) -> None:
"""Warn about a prohibited assignment to a final attribute.
Pass `attr_assign=True` if the assignment assigns to an attribute.
"""
kind = "attribute" if attr_assign else "name"
self.fail('Cannot assign to final {} "{}"'.format(kind, unmangle(name)), ctx)
def protocol_members_cant_be_final(self, ctx: Context) -> None:
self.fail("Protocol member cannot be final", ctx)
def final_without_value(self, ctx: Context) -> None:
self.fail("Final name must be initialized with a value", ctx)
def read_only_property(self, name: str, type: TypeInfo,
context: Context) -> None:
self.fail('Property "{}" defined in "{}" is read-only'.format(
name, type.name()), context)
def incompatible_typevar_value(self,
callee: CallableType,
typ: Type,
typevar_name: str,
context: Context) -> None:
self.fail(message_registry.INCOMPATIBLE_TYPEVAR_VALUE
.format(typevar_name, callable_name(callee) or 'function', format_type(typ)),
context,
code=codes.TYPE_VAR)
def dangerous_comparison(self, left: Type, right: Type, kind: str, ctx: Context) -> None:
left_str = 'element' if kind == 'container' else 'left operand'
right_str = 'container item' if kind == 'container' else 'right operand'
message = 'Non-overlapping {} check ({} type: {}, {} type: {})'
left_typ, right_typ = format_type_distinctly(left, right)
self.fail(message.format(kind, left_str, left_typ, right_str, right_typ), ctx,
code=codes.COMPARISON_OVERLAP)
def overload_inconsistently_applies_decorator(self, decorator: str, context: Context) -> None:
self.fail(
'Overload does not consistently use the "@{}" '.format(decorator)
+ 'decorator on all function signatures.',
context)
def overloaded_signatures_overlap(self, index1: int, index2: int, context: Context) -> None:
self.fail('Overloaded function signatures {} and {} overlap with '
'incompatible return types'.format(index1, index2), context)
def overloaded_signature_will_never_match(self, index1: int, index2: int,
context: Context) -> None:
self.fail(
'Overloaded function signature {index2} will never be matched: '
'signature {index1}\'s parameter type(s) are the same or broader'.format(
index1=index1,
index2=index2),
context)
def overloaded_signatures_typevar_specific(self, index: int, context: Context) -> None:
self.fail('Overloaded function implementation cannot satisfy signature {} '.format(index) +
'due to inconsistencies in how they use type variables', context)
def overloaded_signatures_arg_specific(self, index: int, context: Context) -> None:
self.fail('Overloaded function implementation does not accept all possible arguments '
'of signature {}'.format(index), context)
def overloaded_signatures_ret_specific(self, index: int, context: Context) -> None:
self.fail('Overloaded function implementation cannot produce return type '
'of signature {}'.format(index), context)
def warn_both_operands_are_from_unions(self, context: Context) -> None:
self.note('Both left and right operands are unions', context)
def warn_operand_was_from_union(self, side: str, original: Type, context: Context) -> None:
self.note('{} operand is of type {}'.format(side, format_type(original)), context)
def operator_method_signatures_overlap(
self, reverse_class: TypeInfo, reverse_method: str, forward_class: Type,
forward_method: str, context: Context) -> None:
self.fail('Signatures of "{}" of "{}" and "{}" of {} '
'are unsafely overlapping'.format(
reverse_method, reverse_class.name(),
forward_method, format_type(forward_class)),
context)
def forward_operator_not_callable(
self, forward_method: str, context: Context) -> None:
self.fail('Forward operator "{}" is not callable'.format(
forward_method), context)
def signatures_incompatible(self, method: str, other_method: str,
context: Context) -> None:
self.fail('Signatures of "{}" and "{}" are incompatible'.format(
method, other_method), context)
def yield_from_invalid_operand_type(self, expr: Type, context: Context) -> Type:
text = format_type(expr) if format_type(expr) != 'object' else expr
self.fail('"yield from" can\'t be applied to {}'.format(text), context)
return AnyType(TypeOfAny.from_error)
def invalid_signature(self, func_type: Type, context: Context) -> None:
self.fail('Invalid signature "{}"'.format(func_type), context)
def invalid_signature_for_special_method(
self, func_type: Type, context: Context, method_name: str) -> None:
self.fail('Invalid signature "{}" for "{}"'.format(func_type, method_name), context)
def reveal_type(self, typ: Type, context: Context) -> None:
self.note('Revealed type is \'{}\''.format(typ), context)
def reveal_locals(self, type_map: Dict[str, Optional[Type]], context: Context) -> None:
# To ensure that the output is predictable on Python < 3.6,
# use an ordered dictionary sorted by variable name
sorted_locals = OrderedDict(sorted(type_map.items(), key=lambda t: t[0]))
self.note("Revealed local types are:", context)
for line in [' {}: {}'.format(k, v) for k, v in sorted_locals.items()]:
self.note(line, context)
def unsupported_type_type(self, item: Type, context: Context) -> None:
self.fail('Unsupported type Type[{}]'.format(format_type(item)), context)
def redundant_cast(self, typ: Type, context: Context) -> None:
self.fail('Redundant cast to {}'.format(format_type(typ)), context,
code=codes.REDUNDANT_CAST)
def unimported_type_becomes_any(self, prefix: str, typ: Type, ctx: Context) -> None:
self.fail("{} becomes {} due to an unfollowed import".format(prefix, format_type(typ)),
ctx, code=codes.NO_ANY_UNIMPORTED)
def need_annotation_for_var(self, node: SymbolNode, context: Context,
python_version: Optional[Tuple[int, int]] = None) -> None:
hint = ''
has_variable_annotations = not python_version or python_version >= (3, 6)
# Only gives hint if it's a variable declaration and the partial type is a builtin type
if (python_version and isinstance(node, Var) and isinstance(node.type, PartialType) and
node.type.type and node.type.type.fullname() in reverse_builtin_aliases):
alias = reverse_builtin_aliases[node.type.type.fullname()]
alias = alias.split('.')[-1]
type_dec = '<type>'
if alias == 'Dict':
type_dec = '{}, {}'.format(type_dec, type_dec)
if has_variable_annotations:
hint = ' (hint: "{}: {}[{}] = ...")'.format(node.name(), alias, type_dec)
else:
hint = ' (hint: "{} = ... # type: {}[{}]")'.format(node.name(), alias, type_dec)
if has_variable_annotations:
needed = 'annotation'
else:
needed = 'comment'
self.fail("Need type {} for '{}'{}".format(needed, unmangle(node.name()), hint), context,