[clean strict optional] Fix another 32 errors (#3265)

* Clean-up treetransform

* Clean-up errors(-2), typeanal, maptype

mypy/errors.py

@@ -27,10 +27,10 @@ class ErrorInfo:
     module = None  # type: Optional[str]
 
     # The name of the type in which this error is located at.
-    type = ''     # Unqualified, may be None
+    type = ''  # type: Optional[str]   # Unqualified, may be None
 
     # The name of the function or member in which this error is located at.
-    function_or_member = ''     # Unqualified, may be None
+    function_or_member = ''  # type: Optional[str]   # Unqualified, may be None
 
     # The line number related to this error within file.
     line = 0     # -1 if unknown
@@ -57,8 +57,8 @@ def __init__(self,
                  import_ctx: List[Tuple[str, int]],
                  file: str,
                  module: Optional[str],
-                 typ: str,
-                 function_or_member: str,
+                 typ: Optional[str],
+                 function_or_member: Optional[str],
                  line: int,
                  column: int,
                  severity: str,
@@ -105,10 +105,10 @@ class Errors:
     file = None  # type: str
 
     # Stack of short names of currents types (or None).
-    type_name = None  # type: List[str]
+    type_name = None  # type: List[Optional[str]]
 
     # Stack of short names of current functions or members (or None).
-    function_or_member = None  # type: List[str]
+    function_or_member = None  # type: List[Optional[str]]
 
     # Ignore errors on these lines of each file.
     ignored_lines = None  # type: Dict[str, Set[int]]
@@ -188,7 +188,7 @@ def set_file(self, file: str, module: Optional[str], ignored_lines: Set[int] = N
             self.target = [module]
 
     def set_file_ignored_lines(self, file: str,
-                               ignored_lines: Set[int] = None,
+                               ignored_lines: Set[int],
                                ignore_all: bool = False) -> None:
         self.ignored_lines[file] = ignored_lines
         if ignore_all:
@@ -265,7 +265,7 @@ def report(self, line: int, column: int, message: str, blocker: bool = False,
             only_once: if True, only report this exact message once per build
             origin_line: if non-None, override current context as origin
         """
-        type = self.type_name[-1]
+        type = self.type_name[-1]  # type: Optional[str]
         if len(self.function_or_member) > 2:
             type = None  # Omit type context if nested function
         if file is None:
@@ -362,7 +362,7 @@ def targets(self) -> Set[str]:
                    for info in self.error_info
                    if info.target)
 
-    def render_messages(self, errors: List[ErrorInfo]) -> List[Tuple[str, int, int,
+    def render_messages(self, errors: List[ErrorInfo]) -> List[Tuple[Optional[str], int, int,
                                                                      str, str]]:
         """Translate the messages into a sequence of tuples.
 
@@ -371,12 +371,12 @@ def render_messages(self, errors: List[ErrorInfo]) -> List[Tuple[str, int, int,
         item may be None. If the line item is negative, the line
         number is not defined for the tuple.
         """
-        result = []  # type: List[Tuple[str, int, int, str, str]]
+        result = []  # type: List[Tuple[Optional[str], int, int, str, str]]
         # (path, line, column, severity, message)
 
         prev_import_context = []  # type: List[Tuple[str, int]]
-        prev_function_or_member = None  # type: str
-        prev_type = None  # type: str
+        prev_function_or_member = None  # type: Optional[str]
+        prev_type = None  # type: Optional[str]
 
         for e in errors:
             # Report module import context, if different from previous message.
@@ -460,10 +460,10 @@ def sort_messages(self, errors: List[ErrorInfo]) -> List[ErrorInfo]:
             result.extend(a)
         return result
 
-    def remove_duplicates(self, errors: List[Tuple[str, int, int, str, str]]
-                          ) -> List[Tuple[str, int, int, str, str]]:
+    def remove_duplicates(self, errors: List[Tuple[Optional[str], int, int, str, str]]
+                          ) -> List[Tuple[Optional[str], int, int, str, str]]:
         """Remove duplicates from a sorted error list."""
-        res = []  # type: List[Tuple[str, int, int, str, str]]
+        res = []  # type: List[Tuple[Optional[str], int, int, str, str]]
         i = 0
         while i < len(errors):
             dup = False

mypy/maptype.py

@@ -28,7 +28,9 @@ def map_instance_to_supertypes(instance: Instance,
     # FIX: Currently we should only have one supertype per interface, so no
     #      need to return an array
     result = []  # type: List[Instance]
-    for path in class_derivation_paths(instance.type, supertype):
+    typ = instance.type
+    assert typ is not None, 'Instance.type is not fixed after deserialization'
+    for path in class_derivation_paths(typ, supertype):
         types = [instance]
         for sup in path:
             a = []  # type: List[Instance]
@@ -57,12 +59,14 @@ def class_derivation_paths(typ: TypeInfo,
     result = []  # type: List[List[TypeInfo]]
 
     for base in typ.bases:
-        if base.type == supertype:
-            result.append([base.type])
+        btype = base.type
+        assert btype is not None, 'Instance.type is not fixed after deserialization'
+        if btype == supertype:
+            result.append([btype])
         else:
             # Try constructing a longer path via the base class.
-            for path in class_derivation_paths(base.type, supertype):
-                result.append([base.type] + path)
+            for path in class_derivation_paths(btype, supertype):
+                result.append([btype] + path)
 
     return result
 
@@ -71,6 +75,7 @@ def map_instance_to_direct_supertypes(instance: Instance,
                                       supertype: TypeInfo) -> List[Instance]:
     # FIX: There should only be one supertypes, always.
     typ = instance.type
+    assert typ is not None, 'Instance.type is not fixed after deserialization'
     result = []  # type: List[Instance]
 
     for b in typ.bases:
@@ -98,4 +103,6 @@ def instance_to_type_environment(instance: Instance) -> Dict[TypeVarId, Type]:
     arguments.  The type variables are mapped by their `id`.
 
     """
-    return {binder.id: arg for binder, arg in zip(instance.type.defn.type_vars, instance.args)}
+    typ = instance.type
+    assert typ is not None, 'Instance.type is not fixed after deserialization'
+    return {binder.id: arg for binder, arg in zip(typ.defn.type_vars, instance.args)}

mypy/nodes.py

@@ -872,9 +872,9 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 class WhileStmt(Statement):
     expr = None  # type: Expression
     body = None  # type: Block
-    else_body = None  # type: Block
+    else_body = None  # type: Optional[Block]
 
-    def __init__(self, expr: Expression, body: Block, else_body: Block) -> None:
+    def __init__(self, expr: Expression, body: Block, else_body: Optional[Block]) -> None:
         self.expr = expr
         self.body = body
         self.else_body = else_body
@@ -891,11 +891,11 @@ class ForStmt(Statement):
     # Expression to iterate
     expr = None  # type: Expression
     body = None  # type: Block
-    else_body = None  # type: Block
+    else_body = None  # type: Optional[Block]
     is_async = False  # True if `async for ...` (PEP 492, Python 3.5)
 
     def __init__(self, index: Lvalue, expr: Expression, body: Block,
-                 else_body: Block, index_type: 'mypy.types.Type' = None) -> None:
+                 else_body: Optional[Block], index_type: 'mypy.types.Type' = None) -> None:
         self.index = index
         self.index_type = index_type
         self.expr = expr
@@ -956,10 +956,10 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 class IfStmt(Statement):
     expr = None  # type: List[Expression]
     body = None  # type: List[Block]
-    else_body = None  # type: Block
+    else_body = None  # type: Optional[Block]
 
     def __init__(self, expr: List[Expression], body: List[Block],
-                 else_body: Block) -> None:
+                 else_body: Optional[Block]) -> None:
         self.expr = expr
         self.body = body
         self.else_body = else_body
@@ -969,10 +969,11 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 
 
 class RaiseStmt(Statement):
-    expr = None  # type: Expression
-    from_expr = None  # type: Expression
+    # Plain 'raise' is a valid statement.
+    expr = None  # type: Optional[Expression]
+    from_expr = None  # type: Optional[Expression]
 
-    def __init__(self, expr: Expression, from_expr: Expression = None) -> None:
+    def __init__(self, expr: Optional[Expression], from_expr: Optional[Expression]) -> None:
         self.expr = expr
         self.from_expr = from_expr
 
@@ -982,15 +983,17 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 
 class TryStmt(Statement):
     body = None  # type: Block                # Try body
-    types = None  # type: List[Expression]    # Except type expressions
-    vars = None  # type: List[NameExpr]     # Except variable names
+    # Plain 'except:' also possible
+    types = None  # type: List[Optional[Expression]]    # Except type expressions
+    vars = None  # type: List[Optional[NameExpr]]     # Except variable names
     handlers = None  # type: List[Block]      # Except bodies
-    else_body = None  # type: Block
-    finally_body = None  # type: Block
+    else_body = None  # type: Optional[Block]
+    finally_body = None  # type: Optional[Block]
 
-    def __init__(self, body: Block, vars: List['NameExpr'], types: List[Expression],
-                 handlers: List[Block], else_body: Block,
-                 finally_body: Block) -> None:
+    def __init__(self, body: Block, vars: List[Optional['NameExpr']],
+                 types: List[Optional[Expression]],
+                 handlers: List[Block], else_body: Optional[Block],
+                 finally_body: Optional[Block]) -> None:
         self.body = body
         self.vars = vars
         self.types = types
@@ -1004,13 +1007,13 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 
 class WithStmt(Statement):
     expr = None  # type: List[Expression]
-    target = None  # type: List[Lvalue]
+    target = None  # type: List[Optional[Lvalue]]
     # Type given by type comments for target, can be None
     target_type = None  # type: mypy.types.Type
     body = None  # type: Block
     is_async = False  # True if `async with ...` (PEP 492, Python 3.5)
 
-    def __init__(self, expr: List[Expression], target: List[Lvalue],
+    def __init__(self, expr: List[Expression], target: List[Optional[Lvalue]],
                  body: Block, target_type: 'mypy.types.Type' = None) -> None:
         self.expr = expr
         self.target = target
@@ -1351,7 +1354,7 @@ class UnaryExpr(Expression):
     op = ''
     expr = None  # type: Expression
     # Inferred operator method type
-    method_type = None  # type: mypy.types.Type
+    method_type = None  # type: Optional[mypy.types.Type]
 
     def __init__(self, op: str, expr: Expression) -> None:
         self.op = op
@@ -1433,7 +1436,7 @@ class OpExpr(Expression):
     left = None  # type: Expression
     right = None  # type: Expression
     # Inferred type for the operator method type (when relevant).
-    method_type = None  # type: mypy.types.Type
+    method_type = None  # type: Optional[mypy.types.Type]
 
     def __init__(self, op: str, left: Expression, right: Expression) -> None:
         self.op = op
@@ -1452,7 +1455,7 @@ class ComparisonExpr(Expression):
     operators = None  # type: List[str]
     operands = None  # type: List[Expression]
     # Inferred type for the operator methods (when relevant; None for 'is').
-    method_types = None  # type: List[mypy.types.Type]
+    method_types = None  # type: List[Optional[mypy.types.Type]]
 
     def __init__(self, operators: List[str], operands: List[Expression]) -> None:
         self.operators = operators

mypy/treetransform.py

@@ -3,7 +3,7 @@
 Subclass TransformVisitor to perform non-trivial transformations.
 """
 
-from typing import List, Dict, cast
+from typing import List, Dict, cast, Optional, Iterable
 
 from mypy.nodes import (
     MypyFile, Import, Node, ImportAll, ImportFrom, FuncItem, FuncDef,
@@ -76,7 +76,7 @@ def visit_import_all(self, node: ImportAll) -> ImportAll:
         return ImportAll(node.id, node.relative)
 
     def copy_argument(self, argument: Argument) -> Argument:
-        init_stmt = None  # type: AssignmentStmt
+        init_stmt = None  # type: Optional[AssignmentStmt]
 
         if argument.initialization_statement:
             init_lvalue = cast(
@@ -360,7 +360,7 @@ def visit_yield_from_expr(self, node: YieldFromExpr) -> YieldFromExpr:
         return YieldFromExpr(self.expr(node.expr))
 
     def visit_yield_expr(self, node: YieldExpr) -> YieldExpr:
-        return YieldExpr(self.expr(node.expr))
+        return YieldExpr(self.optional_expr(node.expr))
 
     def visit_await_expr(self, node: AwaitExpr) -> AwaitExpr:
         return AwaitExpr(self.expr(node.expr))
@@ -526,7 +526,7 @@ def stmt(self, stmt: Statement) -> Statement:
     #
     # All the node helpers also propagate line numbers.
 
-    def optional_expr(self, expr: Expression) -> Expression:
+    def optional_expr(self, expr: Optional[Expression]) -> Optional[Expression]:
         if expr:
             return self.expr(expr)
         else:
@@ -537,7 +537,7 @@ def block(self, block: Block) -> Block:
         new.line = block.line
         return new
 
-    def optional_block(self, block: Block) -> Block:
+    def optional_block(self, block: Optional[Block]) -> Optional[Block]:
         if block:
             return self.block(block)
         else:
@@ -549,7 +549,8 @@ def statements(self, statements: List[Statement]) -> List[Statement]:
     def expressions(self, expressions: List[Expression]) -> List[Expression]:
         return [self.expr(expr) for expr in expressions]
 
-    def optional_expressions(self, expressions: List[Expression]) -> List[Expression]:
+    def optional_expressions(self, expressions: Iterable[Optional[Expression]]
+                             ) -> List[Optional[Expression]]:
         return [self.optional_expr(expr) for expr in expressions]
 
     def blocks(self, blocks: List[Block]) -> List[Block]:
@@ -558,8 +559,8 @@ def blocks(self, blocks: List[Block]) -> List[Block]:
     def names(self, names: List[NameExpr]) -> List[NameExpr]:
         return [self.duplicate_name(name) for name in names]
 
-    def optional_names(self, names: List[NameExpr]) -> List[NameExpr]:
-        result = []  # type: List[NameExpr]
+    def optional_names(self, names: Iterable[Optional[NameExpr]]) -> List[Optional[NameExpr]]:
+        result = []  # type: List[Optional[NameExpr]]
         for name in names:
             if name:
                 result.append(self.duplicate_name(name))
@@ -571,7 +572,7 @@ def type(self, type: Type) -> Type:
         # Override this method to transform types.
         return type
 
-    def optional_type(self, type: Type) -> Type:
+    def optional_type(self, type: Optional[Type]) -> Optional[Type]:
         if type:
             return self.type(type)
         else:

mypy/typeanal.py

@@ -43,7 +43,7 @@ def analyze_type_alias(node: Expression,
                        lookup_fqn_func: Callable[[str], SymbolTableNode],
                        tvar_scope: TypeVarScope,
                        fail_func: Callable[[str, Context], None],
-                       allow_unnormalized: bool = False) -> Type:
+                       allow_unnormalized: bool = False) -> Optional[Type]:
     """Return type if node is valid as a type alias rvalue.
 
     Return None otherwise. 'node' must have been semantically analyzed.
@@ -139,8 +139,8 @@ def visit_unbound_type(self, t: UnboundType) -> Type:
             if (fullname in nongen_builtins and t.args and
                     not sym.normalized and not self.allow_unnormalized):
                 self.fail(no_subscript_builtin_alias(fullname), t)
-            if sym.kind == TVAR and self.tvar_scope.get_binding(sym) is not None:
-                tvar_def = self.tvar_scope.get_binding(sym)
+            tvar_def = self.tvar_scope.get_binding(sym)
+            if sym.kind == TVAR and tvar_def is not None:
                 if len(t.args) > 0:
                     self.fail('Type variable "{}" used with arguments'.format(
                         t.name), t)
@@ -196,6 +196,7 @@ def visit_unbound_type(self, t: UnboundType) -> Type:
                 return UninhabitedType(is_noreturn=True)
             elif sym.kind == TYPE_ALIAS:
                 override = sym.type_override
+                assert override is not None
                 an_args = self.anal_array(t.args)
                 all_vars = self.get_type_var_names(override)
                 exp_len = len(all_vars)
@@ -453,7 +454,9 @@ def bind_function_type_variables(self,
             if not self.tvar_scope.allow_binding(tvar.fullname()):
                 self.fail("Type variable '{}' is bound by an outer class".format(name), defn)
             self.tvar_scope.bind(name, tvar)
-            defs.append(self.tvar_scope.get_binding(tvar.fullname()))
+            binding = self.tvar_scope.get_binding(tvar.fullname())
+            assert binding is not None
+            defs.append(binding)
 
         return defs