Fix per-file strict Optional interaction with default-None args

Author: ddfisher

mypy/fastparse.py

@@ -392,7 +392,7 @@ def do_func_def(self, n: Union[ast3.FunctionDef, ast3.AsyncFunctionDef],
             return func_def
 
     def set_type_optional(self, type: Type, initializer: Expression) -> None:
-        if self.options.no_implicit_optional or not experiments.STRICT_OPTIONAL:
+        if self.options.no_implicit_optional:
             return
         # Indicate that type should be wrapped in an Optional if arg is initialized to None.
         optional = isinstance(initializer, NameExpr) and initializer.name == 'None'

mypy/fastparse2.py

@@ -366,7 +366,7 @@ def visit_FunctionDef(self, n: ast27.FunctionDef) -> Statement:
             return func_def
 
     def set_type_optional(self, type: Type, initializer: Expression) -> None:
-        if self.options.no_implicit_optional or not experiments.STRICT_OPTIONAL:
+        if self.options.no_implicit_optional:
             return
         # Indicate that type should be wrapped in an Optional if arg is initialized to None.
         optional = isinstance(initializer, NameExpr) and initializer.name == 'None'

test-data/unit/check-flags.test

@@ -482,6 +482,23 @@ def f() -> None:
     x = [] # type: Union[List[Optional[str]], str]
 [builtins fixtures/list.pyi]
 
+[case testPerFileStrictOptionalNoneArguments]
+# flags: --config-file tmp/mypy.ini
+import standard, optional
+
+[file standard.py]
+def f(x: int = None) -> None: pass
+[file optional.py]
+def f(x: int = None) -> None: pass
+
+[file mypy.ini]
+[[mypy]
+strict_optional = False
+[[mypy-optional]
+strict_optional = True
+
+
+
 [case testDisallowImplicitTypesIgnoreMissingTypes]
 # flags: --ignore-missing-imports --disallow-any=unimported
 from missing import MyType