[very much a wip] pep 612

mypy/applytype.py

@@ -4,7 +4,8 @@
 import mypy.sametypes
 from mypy.expandtype import expand_type
 from mypy.types import (
-    Type, TypeVarId, TypeVarType, CallableType, AnyType, PartialType, get_proper_types
+    Type, TypeVarId, TypeVarType, CallableType, AnyType, PartialType, get_proper_types,
+    TypeVarDef, TypeVarLikeDef, ProperType
 )
 from mypy.nodes import Context
 
@@ -29,20 +30,22 @@ def apply_generic_arguments(
     # Check that inferred type variable values are compatible with allowed
     # values and bounds.  Also, promote subtype values to allowed values.
     types = get_proper_types(orig_types)
-    for i, type in enumerate(types):
-        assert not isinstance(type, PartialType), "Internal error: must never apply partial type"
-        values = get_proper_types(callable.variables[i].values)
-        if type is None:
-            continue
+
+    # Create a map from type variable id to target type.
+    id_to_type = {}  # type: Dict[TypeVarId, Type]
+
+    def get_target_type(tvar: TypeVarLikeDef, type: ProperType) -> Optional[Type]:
+        assert isinstance(tvar, TypeVarDef), "TODO(shantanu) paramspec"
+        values = get_proper_types(tvar.values)
         if values:
             if isinstance(type, AnyType):
-                continue
+                return type
             if isinstance(type, TypeVarType) and type.values:
                 # Allow substituting T1 for T if every allowed value of T1
                 # is also a legal value of T.
                 if all(any(mypy.sametypes.is_same_type(v, v1) for v in values)
                        for v1 in type.values):
-                    continue
+                    return type
             matching = []
             for value in values:
                 if mypy.subtypes.is_subtype(type, value):
@@ -53,28 +56,26 @@ def apply_generic_arguments(
                 for match in matching[1:]:
                     if mypy.subtypes.is_subtype(match, best):
                         best = match
-                types[i] = best
-            else:
-                if skip_unsatisfied:
-                    types[i] = None
-                else:
-                    report_incompatible_typevar_value(callable, type, callable.variables[i].name,
-                                                      context)
+                return best
+            if skip_unsatisfied:
+                return None
+            report_incompatible_typevar_value(callable, type, tvar.name, context)
         else:
-            upper_bound = callable.variables[i].upper_bound
+            upper_bound = tvar.upper_bound
             if not mypy.subtypes.is_subtype(type, upper_bound):
                 if skip_unsatisfied:
-                    types[i] = None
-                else:
-                    report_incompatible_typevar_value(callable, type, callable.variables[i].name,
-                                                      context)
+                    return None
+                report_incompatible_typevar_value(callable, type, tvar.name, context)
+        return type
 
-    # Create a map from type variable id to target type.
-    id_to_type = {}  # type: Dict[TypeVarId, Type]
-    for i, tv in enumerate(tvars):
-        typ = types[i]
-        if typ:
-            id_to_type[tv.id] = typ
+    for tvar, type in zip(tvars, types):
+        assert not isinstance(type, PartialType), "Internal error: must never apply partial type"
+        if type is None:
+            continue
+
+        target_type = get_target_type(tvar, type)
+        if target_type is not None:
+            id_to_type[tvar.id] = target_type
 
     # Apply arguments to argument types.
     arg_types = [expand_type(at, id_to_type) for at in callable.arg_types]

mypy/checker.py

@@ -50,7 +50,7 @@
     erase_def_to_union_or_bound, erase_to_union_or_bound, coerce_to_literal,
     try_getting_str_literals_from_type, try_getting_int_literals_from_type,
     tuple_fallback, is_singleton_type, try_expanding_enum_to_union,
-    true_only, false_only, function_type, TypeVarExtractor, custom_special_method,
+    true_only, false_only, function_type, get_type_vars, custom_special_method,
     is_literal_type_like,
 )
 from mypy import message_registry
@@ -1389,15 +1389,14 @@ def expand_typevars(self, defn: FuncItem,
                         typ: CallableType) -> List[Tuple[FuncItem, CallableType]]:
         # TODO use generator
         subst = []  # type: List[List[Tuple[TypeVarId, Type]]]
-        tvars = typ.variables or []
-        tvars = tvars[:]
+        tvars = list(typ.variables) or []
         if defn.info:
             # Class type variables
             tvars += defn.info.defn.type_vars or []
+        # TODO(shantanu): audit for paramspec
         for tvar in tvars:
-            if tvar.values:
-                subst.append([(tvar.id, value)
-                              for value in tvar.values])
+            if isinstance(tvar, TypeVarDef) and tvar.values:
+                subst.append([(tvar.id, value) for value in tvar.values])
         # Make a copy of the function to check for each combination of
         # value restricted type variables. (Except when running mypyc,
         # where we need one canonical version of the function.)
@@ -5325,7 +5324,7 @@ def detach_callable(typ: CallableType) -> CallableType:
 
     appear_map = {}  # type: Dict[str, List[int]]
     for i, inner_type in enumerate(type_list):
-        typevars_available = inner_type.accept(TypeVarExtractor())
+        typevars_available = get_type_vars(inner_type)
         for var in typevars_available:
             if var.fullname not in appear_map:
                 appear_map[var.fullname] = []
@@ -5335,7 +5334,7 @@ def detach_callable(typ: CallableType) -> CallableType:
     for var_name, appearances in appear_map.items():
         used_type_var_names.add(var_name)
 
-    all_type_vars = typ.accept(TypeVarExtractor())
+    all_type_vars = get_type_vars(typ)
     new_variables = []
     for var in set(all_type_vars):
         if var.fullname not in used_type_var_names:

mypy/checkexpr.py

@@ -31,6 +31,7 @@
     DictionaryComprehension, ComplexExpr, EllipsisExpr, StarExpr, AwaitExpr, YieldExpr,
     YieldFromExpr, TypedDictExpr, PromoteExpr, NewTypeExpr, NamedTupleExpr, TypeVarExpr,
     TypeAliasExpr, BackquoteExpr, EnumCallExpr, TypeAlias, SymbolNode, PlaceholderNode,
+    ParamSpecExpr,
     ARG_POS, ARG_OPT, ARG_NAMED, ARG_STAR, ARG_STAR2, LITERAL_TYPE, REVEAL_TYPE,
 )
 from mypy.literals import literal
@@ -3969,6 +3970,9 @@ def visit_temp_node(self, e: TempNode) -> Type:
     def visit_type_var_expr(self, e: TypeVarExpr) -> Type:
         return AnyType(TypeOfAny.special_form)
 
+    def visit_paramspec_var_expr(self, e: ParamSpecExpr) -> Type:
+        return AnyType(TypeOfAny.special_form)
+
     def visit_newtype_expr(self, e: NewTypeExpr) -> Type:
         return AnyType(TypeOfAny.special_form)
 

mypy/checkmember.py

@@ -1,11 +1,11 @@
 """Type checking of attribute access"""
 
-from typing import cast, Callable, Optional, Union, List
+from typing import cast, Callable, Optional, Union, List, Sequence
 from typing_extensions import TYPE_CHECKING
 
 from mypy.types import (
     Type, Instance, AnyType, TupleType, TypedDictType, CallableType, FunctionLike, TypeVarDef,
-    Overloaded, TypeVarType, UnionType, PartialType, TypeOfAny, LiteralType,
+    TypeVarLikeDef, Overloaded, TypeVarType, UnionType, PartialType, TypeOfAny, LiteralType,
     DeletedType, NoneType, TypeType, has_type_vars, get_proper_type, ProperType
 )
 from mypy.nodes import (
@@ -676,7 +676,7 @@ def analyze_class_attribute_access(itype: Instance,
                                    name: str,
                                    mx: MemberContext,
                                    override_info: Optional[TypeInfo] = None,
-                                   original_vars: Optional[List[TypeVarDef]] = None
+                                   original_vars: Optional[Sequence[TypeVarLikeDef]] = None
                                    ) -> Optional[Type]:
     """Analyze access to an attribute on a class object.
 
@@ -839,7 +839,7 @@ def analyze_enum_class_attribute_access(itype: Instance,
 def add_class_tvars(t: ProperType, isuper: Optional[Instance],
                     is_classmethod: bool,
                     original_type: Type,
-                    original_vars: Optional[List[TypeVarDef]] = None) -> Type:
+                    original_vars: Optional[Sequence[TypeVarLikeDef]] = None) -> Type:
     """Instantiate type variables during analyze_class_attribute_access,
     e.g T and Q in the following:
 
@@ -883,7 +883,7 @@ class B(A[str]): pass
             assert isuper is not None
             t = cast(CallableType, expand_type_by_instance(t, isuper))
             freeze_type_vars(t)
-        return t.copy_modified(variables=tvars + t.variables)
+        return t.copy_modified(variables=list(tvars) + list(t.variables))
     elif isinstance(t, Overloaded):
         return Overloaded([cast(CallableType, add_class_tvars(item, isuper,
                                                               is_classmethod, original_type,

mypy/expandtype.py

@@ -5,7 +5,7 @@
     NoneType, TypeVarType, Overloaded, TupleType, TypedDictType, UnionType,
     ErasedType, PartialType, DeletedType, UninhabitedType, TypeType, TypeVarId,
     FunctionLike, TypeVarDef, LiteralType, get_proper_type, ProperType,
-    TypeAliasType)
+    TypeAliasType, ParamSpecDef, ParamSpecType)
 
 
 def expand_type(typ: Type, env: Mapping[TypeVarId, Type]) -> Type:
@@ -40,9 +40,15 @@ def freshen_function_type_vars(callee: F) -> F:
         tvdefs = []
         tvmap = {}  # type: Dict[TypeVarId, Type]
         for v in callee.variables:
-            tvdef = TypeVarDef.new_unification_variable(v)
+            tvdef = v.new_unification_variable()
             tvdefs.append(tvdef)
-            tvmap[v.id] = TypeVarType(tvdef)
+            if isinstance(tvdef, TypeVarDef):
+                tvtype = TypeVarType(tvdef)  # type: Type
+            elif isinstance(tvdef, ParamSpecDef):
+                tvtype = ParamSpecType(tvdef)
+            else:
+                assert False
+            tvmap[v.id] = tvtype
         fresh = cast(CallableType, expand_type(callee, tvmap)).copy_modified(variables=tvdefs)
         return cast(F, fresh)
     else:

mypy/fixup.py

@@ -11,7 +11,8 @@
 from mypy.types import (
     CallableType, Instance, Overloaded, TupleType, TypedDictType,
     TypeVarType, UnboundType, UnionType, TypeVisitor, LiteralType,
-    TypeType, NOT_READY, TypeAliasType, AnyType, TypeOfAny)
+    TypeType, NOT_READY, TypeAliasType, AnyType, TypeOfAny, TypeVarDef
+)
 from mypy.visitor import NodeVisitor
 from mypy.lookup import lookup_fully_qualified
 
@@ -183,10 +184,13 @@ def visit_callable_type(self, ct: CallableType) -> None:
         if ct.ret_type is not None:
             ct.ret_type.accept(self)
         for v in ct.variables:
-            if v.values:
-                for val in v.values:
-                    val.accept(self)
-            v.upper_bound.accept(self)
+            if isinstance(v, TypeVarDef):
+                if v.values:
+                    for val in v.values:
+                        val.accept(self)
+                v.upper_bound.accept(self)
+            else:
+                assert False  # TODO(shantanu): add param spec
         for arg in ct.bound_args:
             if arg:
                 arg.accept(self)

mypy/literals.py

@@ -8,7 +8,7 @@
     ConditionalExpr, EllipsisExpr, YieldFromExpr, YieldExpr, RevealExpr, SuperExpr,
     TypeApplication, LambdaExpr, ListComprehension, SetComprehension, DictionaryComprehension,
     GeneratorExpr, BackquoteExpr, TypeVarExpr, TypeAliasExpr, NamedTupleExpr, EnumCallExpr,
-    TypedDictExpr, NewTypeExpr, PromoteExpr, AwaitExpr, TempNode, AssignmentExpr,
+    TypedDictExpr, NewTypeExpr, PromoteExpr, AwaitExpr, TempNode, AssignmentExpr, ParamSpecExpr
 )
 from mypy.visitor import ExpressionVisitor
 
@@ -213,6 +213,9 @@ def visit_backquote_expr(self, e: BackquoteExpr) -> None:
     def visit_type_var_expr(self, e: TypeVarExpr) -> None:
         return None
 
+    def visit_paramspec_var_expr(self, e: ParamSpecExpr) -> None:
+        return None
+
     def visit_type_alias_expr(self, e: TypeAliasExpr) -> None:
         return None
 

mypy/messages.py

@@ -21,7 +21,7 @@
 from mypy.errors import Errors
 from mypy.types import (
     Type, CallableType, Instance, TypeVarType, TupleType, TypedDictType, LiteralType,
-    UnionType, NoneType, AnyType, Overloaded, FunctionLike, DeletedType, TypeType,
+    UnionType, NoneType, AnyType, Overloaded, FunctionLike, DeletedType, TypeType, TypeVarDef,
     UninhabitedType, TypeOfAny, UnboundType, PartialType, get_proper_type, ProperType,
     get_proper_types
 )
@@ -1868,16 +1868,20 @@ def [T <: int] f(self, x: int, y: T) -> None
     if tp.variables:
         tvars = []
         for tvar in tp.variables:
-            upper_bound = get_proper_type(tvar.upper_bound)
-            if (isinstance(upper_bound, Instance) and
-                    upper_bound.type.fullname != 'builtins.object'):
-                tvars.append('{} <: {}'.format(tvar.name, format_type_bare(upper_bound)))
-            elif tvar.values:
-                tvars.append('{} in ({})'
-                             .format(tvar.name, ', '.join([format_type_bare(tp)
-                                                           for tp in tvar.values])))
+            if isinstance(tvar, TypeVarDef):
+                upper_bound = get_proper_type(tvar.upper_bound)
+                if (isinstance(upper_bound, Instance) and
+                        upper_bound.type.fullname != 'builtins.object'):
+                    tvars.append('{} <: {}'.format(tvar.name, format_type_bare(upper_bound)))
+                elif tvar.values:
+                    tvars.append('{} in ({})'
+                                 .format(tvar.name, ', '.join([format_type_bare(tp)
+                                                               for tp in tvar.values])))
+                else:
+                    tvars.append(tvar.name)
             else:
-                tvars.append(tvar.name)
+                # For other TypeVarLikeDefs, just use the repr
+                tvars.append(repr(tvar))
         s = '[{}] {}'.format(', '.join(tvars), s)
     return 'def {}'.format(s)