Fix some issues

python · ilevkivskyi · Nov 14, 2019 · Nov 8, 2019 · Nov 8, 2019 · Nov 9, 2019
commit ad8f4b4ed40a4b7f525928be589b12465177cbe0
diff --git a/mypy/checkmember.py b/mypy/checkmember.py
@@ -500,7 +500,7 @@ def instance_alias_type(alias: TypeAlias,
     target = get_proper_type(alias.target)  # type: Type
     assert isinstance(get_proper_type(target),
                       Instance), "Must be called only with aliases to classes"
-    target = set_any_tvars(alias, alias.line, alias.column)
+    target = get_proper_type(set_any_tvars(alias, alias.line, alias.column))
     assert isinstance(target, Instance)  # type: ignore[misc]
     tp = type_object_type(target.type, builtin_type)
     return expand_type_by_instance(tp, target)

diff --git a/mypy/semanal_typeargs.py b/mypy/semanal_typeargs.py
@@ -5,10 +5,12 @@
 operations, including subtype checks.
 """
 
-from typing import List, Optional
+from typing import List, Optional, Set
 
 from mypy.nodes import TypeInfo, Context, MypyFile, FuncItem, ClassDef, Block
-from mypy.types import Type, Instance, TypeVarType, AnyType, get_proper_types
+from mypy.types import (
+    Type, Instance, TypeVarType, AnyType, get_proper_types, TypeAliasType, get_proper_type
+)
 from mypy.mixedtraverser import MixedTraverserVisitor
 from mypy.subtypes import is_subtype
 from mypy.sametypes import is_same_type
@@ -27,6 +29,7 @@ def __init__(self, errors: Errors, options: Options, is_typeshed_file: bool) ->
         self.scope = Scope()
         # Should we also analyze function definitions, or only module top-levels?
         self.recurse_into_functions = True
+        self.seen_aliases = set()  # type: Set[TypeAliasType]
 
     def visit_mypy_file(self, o: MypyFile) -> None:
         self.errors.set_file(o.path, o.fullname(), scope=self.scope)
@@ -48,6 +51,13 @@ def visit_block(self, o: Block) -> None:
         if not o.is_unreachable:
             super().visit_block(o)
 
+    def visit_type_alias_type(self, t: TypeAliasType) -> None:
+        super().visit_type_alias_type(t)
+        if t in self.seen_aliases:
+            return
+        self.seen_aliases.add(t)
+        get_proper_type(t).accept(self)
+
     def visit_instance(self, t: Instance) -> None:
         # Type argument counts were checked in the main semantic analyzer pass. We assume
         # that the counts are correct here.

diff --git a/mypy/typeanal.py b/mypy/typeanal.py
@@ -1007,11 +1007,14 @@ def expand_type_alias(node: TypeAlias, args: List[Type],
         fail('Bad number of arguments for type alias, expected: %s, given: %s'
              % (exp_len, act_len), ctx)
         return set_any_tvars(node, ctx.line, ctx.column, from_error=True)
-    typ = TypeAliasType(node, args, ctx.line, ctx.column)  # type: Type
+    typ = TypeAliasType(node, args, ctx.line, ctx.column)
+    assert typ.alias is not None
     # HACK: Implement FlexibleAlias[T, typ] by expanding it to typ here.
-    if (isinstance(typ, Instance)  # type: ignore
-            and typ.type.fullname() == 'mypy_extensions.FlexibleAlias'):
-        typ = typ.args[-1]
+    if (isinstance(typ.alias.target, Instance)  # type: ignore
+            and typ.alias.target.type.fullname() == 'mypy_extensions.FlexibleAlias'):
        exp = get_proper_type(typ)
+        assert isinstance(exp, Instance)
+        return exp.args[-1]
     return typ