Review changes + mypyc fix

mypy/fastparse.py

@@ -1431,7 +1431,7 @@ def visit_BinOp(self, n: ast3.BinOp) -> Type:
         return UnionType([left, right],
                          line=self.line,
                          column=self.convert_column(n.col_offset),
-                         is_binary_op=True)
+                         uses_pep604_syntax=True)
 
     def visit_NameConstant(self, n: NameConstant) -> Type:
         if isinstance(n.value, bool):

mypy/semanal.py

@@ -206,7 +206,7 @@ class SemanticAnalyzer(NodeVisitor[None],
     patches = None  # type: List[Tuple[int, Callable[[], None]]]
     loop_depth = 0         # Depth of breakable loops
     cur_mod_id = ''        # Current module id (or None) (phase 2)
-    is_stub_file = False   # Are we analyzing a stub file?
+    _is_stub_file = False   # Are we analyzing a stub file?
     _is_typeshed_stub_file = False  # Are we analyzing a typeshed stub file?
     imports = None  # type: Set[str]  # Imported modules (during phase 2 analysis)
     # Note: some imports (and therefore dependencies) might
@@ -280,6 +280,10 @@ def __init__(self,
 
     # mypyc doesn't properly handle implementing an abstractproperty
     # with a regular attribute so we make them properties
+    @property
+    def is_stub_file(self) -> bool:
+        return self._is_stub_file
+
     @property
     def is_typeshed_stub_file(self) -> bool:
         return self._is_typeshed_stub_file
@@ -507,7 +511,7 @@ def file_context(self,
         self.cur_mod_node = file_node
         self.cur_mod_id = file_node.fullname
         scope.enter_file(self.cur_mod_id)
-        self.is_stub_file = file_node.path.lower().endswith('.pyi')
+        self._is_stub_file = file_node.path.lower().endswith('.pyi')
         self._is_typeshed_stub_file = is_typeshed_file(file_node.path)
         self.globals = file_node.names
         self.tvar_scope = TypeVarLikeScope()

mypy/semanal_shared.py

@@ -78,6 +78,11 @@ def is_future_flag_set(self, flag: str) -> bool:
         """Is the specific __future__ feature imported"""
         raise NotImplementedError
 
+    @property
+    @abstractmethod
+    def is_stub_file(self) -> bool:
+        raise NotImplementedError
+
 
 @trait
 class SemanticAnalyzerInterface(SemanticAnalyzerCoreInterface):

mypy/typeanal.py

@@ -605,11 +605,11 @@ def visit_star_type(self, t: StarType) -> Type:
         return StarType(self.anal_type(t.type), t.line)
 
     def visit_union_type(self, t: UnionType) -> Type:
-        if (t.is_binary_op is True
+        if (t.uses_pep604_syntax is True
                 and self.api.is_stub_file is False
                 and self.options.python_version < (3, 10)
                 and self.api.is_future_flag_set('annotations') is False):
-            self.fail("Alternative syntax for unions requires Python 3.10 or newer", t)
+            self.fail("X | Y syntax for unions requires Python 3.10", t)
         return UnionType(self.anal_array(t.items), t.line)
 
     def visit_partial_type(self, t: PartialType) -> Type:

mypy/types.py

@@ -1725,12 +1725,12 @@ class UnionType(ProperType):
     __slots__ = ('items',)
 
     def __init__(self, items: Sequence[Type], line: int = -1, column: int = -1,
-                 is_binary_op: bool = False) -> None:
+                 uses_pep604_syntax: bool = False) -> None:
         super().__init__(line, column)
         self.items = flatten_nested_unions(items)
         self.can_be_true = any(item.can_be_true for item in items)
         self.can_be_false = any(item.can_be_false for item in items)
-        self.is_binary_op = is_binary_op
+        self.uses_pep604_syntax = uses_pep604_syntax
 
     def __hash__(self) -> int:
         return hash(frozenset(self.items))

test-data/unit/check-union-or-syntax.test

@@ -72,7 +72,7 @@ x: int | None
 
 [case testUnionOrSyntaxMissingFutureImport]
 # flags: --python-version 3.9
-x: int | None  # E: Alternative syntax for unions requires Python 3.10 or newer
+x: int | None  # E: X | Y syntax for unions requires Python 3.10
 
 [case testUnionOrSyntaxInStubFile]
 # flags: --python-version 3.6