Refactoring: make the type of fullname str instead of Bogus[str]

mypy/checker.py

@@ -2178,7 +2178,7 @@ def visit_class_def(self, defn: ClassDef) -> None:
                     temp = self.temp_node(sig, context=decorator)
                     fullname = None
                     if isinstance(decorator, RefExpr):
-                        fullname = decorator.fullname
+                        fullname = decorator.fullname or None
 
                     # TODO: Figure out how to have clearer error messages.
                     # (e.g. "class decorator must be a function that accepts a type."
@@ -4598,7 +4598,7 @@ def visit_decorator(self, e: Decorator) -> None:
             temp = self.temp_node(sig, context=e)
             fullname = None
             if isinstance(d, RefExpr):
-                fullname = d.fullname
+                fullname = d.fullname or None
             # if this is a expression like @b.a where b is an object, get the type of b
             # so we can pass it the method hook in the plugins
             object_type: Type | None = None

mypy/checkexpr.py

@@ -216,8 +216,8 @@ def extract_refexpr_names(expr: RefExpr) -> set[str]:
     Note that currently, the only two subclasses of RefExpr are NameExpr and
     MemberExpr."""
     output: set[str] = set()
-    while isinstance(expr.node, MypyFile) or expr.fullname is not None:
-        if isinstance(expr.node, MypyFile) and expr.fullname is not None:
+    while isinstance(expr.node, MypyFile) or expr.fullname:
+        if isinstance(expr.node, MypyFile) and expr.fullname:
             # If it's None, something's wrong (perhaps due to an
             # import cycle or a suppressed error).  For now we just
             # skip it.
@@ -228,7 +228,7 @@ def extract_refexpr_names(expr: RefExpr) -> set[str]:
             if isinstance(expr.node, TypeInfo):
                 # Reference to a class or a nested class
                 output.update(split_module_names(expr.node.module_name))
-            elif expr.fullname is not None and "." in expr.fullname and not is_suppressed_import:
+            elif "." in expr.fullname and not is_suppressed_import:
                 # Everything else (that is not a silenced import within a class)
                 output.add(expr.fullname.rsplit(".", 1)[0])
             break
@@ -526,7 +526,7 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
             # There are two special cases where plugins might act:
             # * A "static" reference/alias to a class or function;
             #   get_function_hook() will be invoked for these.
-            fullname = e.callee.fullname
+            fullname = e.callee.fullname or None
             if isinstance(e.callee.node, TypeAlias):
                 target = get_proper_type(e.callee.node.target)
                 if isinstance(target, Instance):
@@ -536,7 +536,7 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
             #   get_method_hook() and get_method_signature_hook() will
             #   be invoked for these.
             if (
-                fullname is None
+                not fullname
                 and isinstance(e.callee, MemberExpr)
                 and self.chk.has_type(e.callee.expr)
             ):
@@ -605,7 +605,7 @@ def method_fullname(self, object_type: Type, method_name: str) -> str | None:
         elif isinstance(object_type, TupleType):
             type_name = tuple_fallback(object_type).type.fullname
 
-        if type_name is not None:
+        if type_name:
             return f"{type_name}.{method_name}"
         else:
             return None
@@ -5489,7 +5489,7 @@ def type_info_from_type(typ: Type) -> TypeInfo | None:
 
 
 def is_operator_method(fullname: str | None) -> bool:
-    if fullname is None:
+    if not fullname:
         return False
     short_name = fullname.split(".")[-1]
     return (

mypy/nodes.py

@@ -25,7 +25,6 @@
 from mypy_extensions import trait
 
 import mypy.strconv
-from mypy.bogus_type import Bogus
 from mypy.util import short_type
 from mypy.visitor import ExpressionVisitor, NodeVisitor, StatementVisitor
 
@@ -247,12 +246,10 @@ class SymbolNode(Node):
     def name(self) -> str:
         pass
 
-    # fullname can often be None even though the type system
-    # disagrees. We mark this with Bogus to let mypyc know not to
-    # worry about it.
+    # Fully qualified name
     @property
     @abstractmethod
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         pass
 
     @abstractmethod
@@ -294,7 +291,7 @@ class MypyFile(SymbolNode):
     __match_args__ = ("name", "path", "defs")
 
     # Fully qualified module name
-    _fullname: Bogus[str]
+    _fullname: str
     # Path to the file (empty string if not known)
     path: str
     # Top-level definitions and statements
@@ -361,7 +358,7 @@ def name(self) -> str:
         return "" if not self._fullname else self._fullname.split(".")[-1]
 
     @property
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         return self._fullname
 
     def accept(self, visitor: NodeVisitor[T]) -> T:
@@ -526,16 +523,15 @@ def __init__(self) -> None:
         self.is_static = False
         self.is_final = False
         # Name with module prefix
-        # TODO: Type should be Optional[str]
-        self._fullname = cast(Bogus[str], None)
+        self._fullname = ""
 
     @property
     @abstractmethod
     def name(self) -> str:
         pass
 
     @property
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         return self._fullname
 
 
@@ -871,7 +867,7 @@ def name(self) -> str:
         return self.func.name
 
     @property
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         return self.func.fullname
 
     @property
@@ -967,7 +963,7 @@ def __init__(self, name: str, type: mypy.types.Type | None = None) -> None:
         super().__init__()
         self._name = name  # Name without module prefix
         # TODO: Should be Optional[str]
-        self._fullname = cast("Bogus[str]", None)  # Name with module prefix
+        self._fullname = ""  # Name with module prefix
         # TODO: Should be Optional[TypeInfo]
         self.info = VAR_NO_INFO
         self.type: mypy.types.Type | None = type  # Declared or inferred type, or None
@@ -1019,7 +1015,7 @@ def name(self) -> str:
         return self._name
 
     @property
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         return self._fullname
 
     def accept(self, visitor: NodeVisitor[T]) -> T:
@@ -1057,7 +1053,7 @@ class ClassDef(Statement):
 
     __slots__ = (
         "name",
-        "fullname",
+        "_fullname",
         "defs",
         "type_vars",
         "base_type_exprs",
@@ -1075,7 +1071,7 @@ class ClassDef(Statement):
     __match_args__ = ("name", "defs")
 
     name: str  # Name of the class without module prefix
-    fullname: Bogus[str]  # Fully qualified name of the class
+    _fullname: str  # Fully qualified name of the class
     defs: Block
     type_vars: list[mypy.types.TypeVarLikeType]
     # Base class expressions (not semantically analyzed -- can be arbitrary expressions)
@@ -1102,7 +1098,7 @@ def __init__(
     ) -> None:
         super().__init__()
         self.name = name
-        self.fullname = None  # type: ignore[assignment]
+        self._fullname = ""
         self.defs = defs
         self.type_vars = type_vars or []
         self.base_type_exprs = base_type_exprs or []
@@ -1117,6 +1113,14 @@ def __init__(
         self.deco_line: int | None = None
         self.removed_statements = []
 
+    @property
+    def fullname(self) -> str:
+        return self._fullname
+
+    @fullname.setter
+    def fullname(self, v: str) -> None:
+        self._fullname = v
+
     def accept(self, visitor: StatementVisitor[T]) -> T:
         return visitor.visit_class_def(self)
 
@@ -1725,7 +1729,7 @@ class RefExpr(Expression):
     __slots__ = (
         "kind",
         "node",
-        "fullname",
+        "_fullname",
         "is_new_def",
         "is_inferred_def",
         "is_alias_rvalue",
@@ -1739,7 +1743,7 @@ def __init__(self) -> None:
         # Var, FuncDef or TypeInfo that describes this
         self.node: SymbolNode | None = None
         # Fully qualified name (or name if not global)
-        self.fullname: str | None = None
+        self._fullname = ""
         # Does this define a new name?
         self.is_new_def = False
         # Does this define a new name with inferred type?
@@ -1752,6 +1756,14 @@ def __init__(self) -> None:
         # Cache type guard from callable_type.type_guard
         self.type_guard: mypy.types.Type | None = None
 
+    @property
+    def fullname(self) -> str:
+        return self._fullname
+
+    @fullname.setter
+    def fullname(self, v: str) -> None:
+        self._fullname = v
+
 
 class NameExpr(RefExpr):
     """Name expression
@@ -2806,7 +2818,7 @@ class is generic then it will be a type constructor of higher kind.
         "self_type",
     )
 
-    _fullname: Bogus[str]  # Fully qualified name
+    _fullname: str  # Fully qualified name
     # Fully qualified name for the module this type was defined in. This
     # information is also in the fullname, but is harder to extract in the
     # case of nested class definitions.
@@ -3023,7 +3035,7 @@ def name(self) -> str:
         return self.defn.name
 
     @property
-    def fullname(self) -> Bogus[str]:
+    def fullname(self) -> str:
         return self._fullname
 
     def is_generic(self) -> bool:
@@ -3739,11 +3751,7 @@ def serialize(self, prefix: str, name: str) -> JsonDict:
             if prefix is not None:
                 fullname = self.node.fullname
                 if (
-                    # See the comment above SymbolNode.fullname -- fullname can often be None,
-                    # but for complex reasons it's annotated as being `Bogus[str]` instead of `str | None`,
-                    # meaning mypy erroneously thinks the `fullname is not None` check here is redundant
-                    fullname is not None  # type: ignore[redundant-expr]
-                    and "." in fullname
+                    "." in fullname
                     and fullname != prefix + "." + name
                     and not (isinstance(self.node, Var) and self.node.from_module_getattr)
                 ):

mypy/partially_defined.py

@@ -287,7 +287,7 @@ def is_undefined(self, name: str) -> bool:
 
 
 def refers_to_builtin(o: RefExpr) -> bool:
-    return o.fullname is not None and o.fullname.startswith("builtins.")
+    return o.fullname.startswith("builtins.")
 
 
 class Loop:

mypy/semanal.py

@@ -3022,13 +3022,13 @@ def analyze_lvalues(self, s: AssignmentStmt) -> None:
     def apply_dynamic_class_hook(self, s: AssignmentStmt) -> None:
         if not isinstance(s.rvalue, CallExpr):
             return
-        fname = None
+        fname = ""
         call = s.rvalue
         while True:
             if isinstance(call.callee, RefExpr):
                 fname = call.callee.fullname
             # check if method call
-            if fname is None and isinstance(call.callee, MemberExpr):
+            if not fname and isinstance(call.callee, MemberExpr):
                 callee_expr = call.callee.expr
                 if isinstance(callee_expr, RefExpr) and callee_expr.fullname:
                     method_name = call.callee.name
@@ -4624,7 +4624,7 @@ def bind_name_expr(self, expr: NameExpr, sym: SymbolTableNode) -> None:
         else:
             expr.kind = sym.kind
             expr.node = sym.node
-            expr.fullname = sym.fullname
+            expr.fullname = sym.fullname or ""
 
     def visit_super_expr(self, expr: SuperExpr) -> None:
         if not self.type and not expr.call.args:
@@ -4849,7 +4849,7 @@ def visit_member_expr(self, expr: MemberExpr) -> None:
                     self.process_placeholder(expr.name, "attribute", expr)
                     return
                 expr.kind = sym.kind
-                expr.fullname = sym.fullname
+                expr.fullname = sym.fullname or ""
                 expr.node = sym.node
         elif isinstance(base, RefExpr):
             # This branch handles the case C.bar (or cls.bar or self.bar inside
@@ -4881,7 +4881,7 @@ def visit_member_expr(self, expr: MemberExpr) -> None:
                     if not n:
                         return
                     expr.kind = n.kind
-                    expr.fullname = n.fullname
+                    expr.fullname = n.fullname or ""
                     expr.node = n.node
 
     def visit_op_expr(self, expr: OpExpr) -> None:
@@ -5341,7 +5341,7 @@ def is_overloaded_item(self, node: SymbolNode, statement: Statement) -> bool:
         return False
 
     def is_defined_in_current_module(self, fullname: str | None) -> bool:
-        if fullname is None:
+        if not fullname:
             return False
         return module_prefix(self.modules, fullname) == self.cur_mod_id
 

mypy/server/aststrip.py

@@ -230,7 +230,7 @@ def visit_op_expr(self, node: OpExpr) -> None:
     def strip_ref_expr(self, node: RefExpr) -> None:
         node.kind = None
         node.node = None
-        node.fullname = None
+        node.fullname = ""
         node.is_new_def = False
         node.is_inferred_def = False
 

mypy/server/deps.py

@@ -289,13 +289,9 @@ def visit_decorator(self, o: Decorator) -> None:
             # all call sites, making them all `Any`.
             for d in o.decorators:
                 tname: str | None = None
-                if isinstance(d, RefExpr) and d.fullname is not None:
+                if isinstance(d, RefExpr) and d.fullname:
                     tname = d.fullname
-                if (
-                    isinstance(d, CallExpr)
-                    and isinstance(d.callee, RefExpr)
-                    and d.callee.fullname is not None
-                ):
+                if isinstance(d, CallExpr) and isinstance(d.callee, RefExpr) and d.callee.fullname:
                     tname = d.callee.fullname
                 if tname is not None:
                     self.add_dependency(make_trigger(tname), make_trigger(o.func.fullname))
@@ -500,7 +496,7 @@ def visit_assignment_stmt(self, o: AssignmentStmt) -> None:
             if (
                 isinstance(rvalue, CallExpr)
                 and isinstance(rvalue.callee, RefExpr)
-                and rvalue.callee.fullname is not None
+                and rvalue.callee.fullname
             ):
                 fname: str | None = None
                 if isinstance(rvalue.callee.node, TypeInfo):
@@ -510,7 +506,7 @@ def visit_assignment_stmt(self, o: AssignmentStmt) -> None:
                         fname = init.node.fullname
                 else:
                     fname = rvalue.callee.fullname
-                if fname is None:
+                if not fname:
                     return
                 for lv in o.lvalues:
                     if isinstance(lv, RefExpr) and lv.fullname and lv.is_new_def:
@@ -638,7 +634,7 @@ def visit_del_stmt(self, o: DelStmt) -> None:
     # Expressions
 
     def process_global_ref_expr(self, o: RefExpr) -> None:
-        if o.fullname is not None:
+        if o.fullname:
             self.add_dependency(make_trigger(o.fullname))
 
         # If this is a reference to a type, generate a dependency to its

mypy/strconv.py

@@ -367,7 +367,7 @@ def pretty_name(
             id = ""
         if isinstance(target_node, mypy.nodes.MypyFile) and name == fullname:
             n += id
-        elif kind == mypy.nodes.GDEF or (fullname != name and fullname is not None):
+        elif kind == mypy.nodes.GDEF or (fullname != name and fullname):
             # Append fully qualified name for global references.
             n += f" [{fullname}{id}]"
         elif kind == mypy.nodes.LDEF:

mypy/stubtest.py

@@ -1147,7 +1147,7 @@ def apply_decorator_to_funcitem(
     ) -> nodes.FuncItem | None:
         if not isinstance(decorator, nodes.RefExpr):
             return None
-        if decorator.fullname is None:
+        if not decorator.fullname:
             # Happens with namedtuple
             return None
         if (