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Merged
merged 1 commit into from
Jul 10, 2018
Merged

Support type aliases in builtins #5338

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5 changes: 4 additions & 1 deletion mypy/checker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@
UnicodeExpr, OpExpr, UnaryExpr, LambdaExpr, TempNode, SymbolTableNode,
Context, Decorator, PrintStmt, BreakStmt, PassStmt, ContinueStmt,
ComparisonExpr, StarExpr, EllipsisExpr, RefExpr, PromoteExpr,
Import, ImportFrom, ImportAll, ImportBase,
Import, ImportFrom, ImportAll, ImportBase, TypeAlias,
ARG_POS, ARG_STAR, LITERAL_TYPE, MDEF, GDEF,
CONTRAVARIANT, COVARIANT, INVARIANT,
)
Expand Down Expand Up @@ -3171,6 +3171,9 @@ def named_type(self, name: str) -> Instance:
# Assume that the name refers to a type.
sym = self.lookup_qualified(name)
node = sym.node
if isinstance(node, TypeAlias):
assert isinstance(node.target, Instance)
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It can't ever be a chain of TypeAliases?

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It can't, chained aliases are collapsed on sight. An alias can target other types (non-Instance) but this function is supposed to be used only with built-in types, that are all instances.

node = node.target.type
assert isinstance(node, TypeInfo)
any_type = AnyType(TypeOfAny.from_omitted_generics)
return Instance(node, [any_type] * len(node.defn.type_vars))
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5 changes: 4 additions & 1 deletion mypy/semanal.py
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Expand Up @@ -1309,7 +1309,10 @@ def named_type_or_none(self, qualified_name: str,
if not sym:
return None
node = sym.node
assert isinstance(node, TypeInfo)
if isinstance(node, TypeAlias):
assert isinstance(node.target, Instance)
node = node.target.type
assert isinstance(node, TypeInfo), node
if args is not None:
# TODO: assert len(args) == len(node.defn.type_vars)
return Instance(node, args)
Expand Down
8 changes: 8 additions & 0 deletions test-data/unit/python2eval.test
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Expand Up @@ -404,3 +404,11 @@ def f(): # no annotation
path = 'test'
path = os.path.join(f(), 'test.py')
[out]

[case testBytesWorkInPython2WithFullStubs_python2]
MYPY = False
if MYPY:
import lib
[file lib.pyi]
x = b'abc'
[out]