Optimize Unpack for failures (#15967)
This is a small but possibly important PR. Wherever possible we should
represent user error and/or failed type inference as `*tuple[Any,
...]`/`*tuple[<nothing>, ...]`, rather than
`Unpack[Any]`/`Unpack[<nothing>]` or plain `Any`/`<nothing>`. This way
we will not need any special casing for failure conditions in various
places without risking a crash instead of a graceful failure (error
message).
diff --git a/mypy/expandtype.py b/mypy/expandtype.py
index ef8ebe1..26353c0 100644
--- a/mypy/expandtype.py
+++ b/mypy/expandtype.py
@@ -273,7 +273,7 @@
# example is non-normalized types when called from semanal.py.
return UnpackType(t.type.accept(self))
- def expand_unpack(self, t: UnpackType) -> list[Type] | AnyType | UninhabitedType:
+ def expand_unpack(self, t: UnpackType) -> list[Type]:
assert isinstance(t.type, TypeVarTupleType)
repl = get_proper_type(self.variables.get(t.type.id, t.type))
if isinstance(repl, TupleType):
@@ -285,9 +285,9 @@
):
return [UnpackType(typ=repl)]
elif isinstance(repl, (AnyType, UninhabitedType)):
- # tuple[Any, ...] for Any would be better, but we don't have
- # the type info to construct that type here.
- return repl
+ # Replace *Ts = Any with *Ts = *tuple[Any, ...] and some for <nothing>.
+ # These types may appear here as a result of user error or failed inference.
+ return [UnpackType(t.type.tuple_fallback.copy_modified(args=[repl]))]
else:
raise RuntimeError(f"Invalid type replacement to expand: {repl}")
@@ -310,12 +310,7 @@
# We have plain Unpack[Ts]
assert isinstance(var_arg_type, TypeVarTupleType)
fallback = var_arg_type.tuple_fallback
- expanded_items_res = self.expand_unpack(var_arg)
- if isinstance(expanded_items_res, list):
- expanded_items = expanded_items_res
- else:
- # We got Any or <nothing>
- return prefix + [expanded_items_res] + suffix
+ expanded_items = self.expand_unpack(var_arg)
new_unpack = UnpackType(TupleType(expanded_items, fallback))
return prefix + [new_unpack] + suffix
@@ -394,14 +389,8 @@
items: list[Type] = []
for item in typs:
if isinstance(item, UnpackType) and isinstance(item.type, TypeVarTupleType):
- unpacked_items = self.expand_unpack(item)
- if isinstance(unpacked_items, (AnyType, UninhabitedType)):
- # TODO: better error for <nothing>, something like tuple of unknown?
- return unpacked_items
- else:
- items.extend(unpacked_items)
+ items.extend(self.expand_unpack(item))
else:
- # Must preserve original aliases when possible.
items.append(item.accept(self))
return items
diff --git a/mypy/semanal_main.py b/mypy/semanal_main.py
index 51a7014..ec09deb 100644
--- a/mypy/semanal_main.py
+++ b/mypy/semanal_main.py
@@ -381,6 +381,7 @@
errors,
state.options,
is_typeshed_file(state.options.abs_custom_typeshed_dir, state.path or ""),
+ state.manager.semantic_analyzer.named_type,
)
with state.wrap_context():
with mypy.state.state.strict_optional_set(state.options.strict_optional):
@@ -399,6 +400,7 @@
errors,
state.options,
is_typeshed_file(state.options.abs_custom_typeshed_dir, state.path or ""),
+ state.manager.semantic_analyzer.named_type,
)
with state.wrap_context():
with mypy.state.state.strict_optional_set(state.options.strict_optional):
diff --git a/mypy/semanal_typeargs.py b/mypy/semanal_typeargs.py
index 1ae6fad..749b023 100644
--- a/mypy/semanal_typeargs.py
+++ b/mypy/semanal_typeargs.py
@@ -7,7 +7,7 @@
from __future__ import annotations
-from typing import Sequence
+from typing import Callable, Sequence
from mypy import errorcodes as codes, message_registry
from mypy.errorcodes import ErrorCode
@@ -42,11 +42,18 @@
class TypeArgumentAnalyzer(MixedTraverserVisitor):
- def __init__(self, errors: Errors, options: Options, is_typeshed_file: bool) -> None:
+ def __init__(
+ self,
+ errors: Errors,
+ options: Options,
+ is_typeshed_file: bool,
+ named_type: Callable[[str, list[Type]], Instance],
+ ) -> None:
super().__init__()
self.errors = errors
self.options = options
self.is_typeshed_file = is_typeshed_file
+ self.named_type = named_type
self.scope = Scope()
# Should we also analyze function definitions, or only module top-levels?
self.recurse_into_functions = True
@@ -243,16 +250,16 @@
return
if isinstance(proper_type, TypeVarTupleType):
return
+ # TODO: this should probably be .has_base("builtins.tuple"), also elsewhere.
if isinstance(proper_type, Instance) and proper_type.type.fullname == "builtins.tuple":
return
- if isinstance(proper_type, AnyType) and proper_type.type_of_any == TypeOfAny.from_error:
- return
- if not isinstance(proper_type, UnboundType):
- # Avoid extra errors if there were some errors already.
+ if not isinstance(proper_type, (UnboundType, AnyType)):
+ # Avoid extra errors if there were some errors already. Also interpret plain Any
+ # as tuple[Any, ...] (this is better for the code in type checker).
self.fail(
message_registry.INVALID_UNPACK.format(format_type(proper_type, self.options)), typ
)
- typ.type = AnyType(TypeOfAny.from_error)
+ typ.type = self.named_type("builtins.tuple", [AnyType(TypeOfAny.from_error)])
def check_type_var_values(
self, name: str, actuals: list[Type], arg_name: str, valids: list[Type], context: Context
diff --git a/test-data/unit/check-typevar-tuple.test b/test-data/unit/check-typevar-tuple.test
index a36c4d4..c8b33ec 100644
--- a/test-data/unit/check-typevar-tuple.test
+++ b/test-data/unit/check-typevar-tuple.test
@@ -17,8 +17,7 @@
reveal_type(f(varargs)) # N: Revealed type is "builtins.tuple[builtins.int, ...]"
-if object():
- f(0) # E: Argument 1 to "f" has incompatible type "int"; expected <nothing>
+f(0) # E: Argument 1 to "f" has incompatible type "int"; expected "Tuple[<nothing>, ...]"
def g(a: Tuple[Unpack[Ts]], b: Tuple[Unpack[Ts]]) -> Tuple[Unpack[Ts]]:
return a
@@ -26,7 +25,7 @@
reveal_type(g(args, args)) # N: Revealed type is "Tuple[builtins.int, builtins.str]"
reveal_type(g(args, args2)) # N: Revealed type is "Tuple[builtins.int, builtins.str]"
reveal_type(g(args, args3)) # N: Revealed type is "builtins.tuple[builtins.object, ...]"
-reveal_type(g(any, any)) # N: Revealed type is "Any"
+reveal_type(g(any, any)) # N: Revealed type is "builtins.tuple[Any, ...]"
[builtins fixtures/tuple.pyi]
[case testTypeVarTupleMixed]
