Merge remote-tracking branch 'upstream/master' into issue-16614

mypy/checker.py

@@ -5053,6 +5053,19 @@ def visit_continue_stmt(self, s: ContinueStmt) -> None:
         return
 
     def visit_match_stmt(self, s: MatchStmt) -> None:
+        named_subject: Expression
+        if isinstance(s.subject, CallExpr):
+            # Create a dummy subject expression to handle cases where a match statement's subject
+            # is not a literal value. This lets us correctly narrow types and check exhaustivity
+            # This is hack!
+            id = s.subject.callee.fullname if isinstance(s.subject.callee, RefExpr) else ""
+            name = "dummy-match-" + id
+            v = Var(name)
+            named_subject = NameExpr(name)
+            named_subject.node = v
+        else:
+            named_subject = s.subject
+
         with self.binder.frame_context(can_skip=False, fall_through=0):
             subject_type = get_proper_type(self.expr_checker.accept(s.subject))
 
@@ -5071,7 +5084,7 @@ def visit_match_stmt(self, s: MatchStmt) -> None:
             # The second pass narrows down the types and type checks bodies.
             for p, g, b in zip(s.patterns, s.guards, s.bodies):
                 current_subject_type = self.expr_checker.narrow_type_from_binder(
-                    s.subject, subject_type
+                    named_subject, subject_type
                 )
                 pattern_type = self.pattern_checker.accept(p, current_subject_type)
                 with self.binder.frame_context(can_skip=True, fall_through=2):
@@ -5082,7 +5095,7 @@ def visit_match_stmt(self, s: MatchStmt) -> None:
                         else_map: TypeMap = {}
                     else:
                         pattern_map, else_map = conditional_types_to_typemaps(
-                            s.subject, pattern_type.type, pattern_type.rest_type
+                            named_subject, pattern_type.type, pattern_type.rest_type
                         )
                         self.remove_capture_conflicts(pattern_type.captures, inferred_types)
                         self.push_type_map(pattern_map)
@@ -5110,7 +5123,7 @@ def visit_match_stmt(self, s: MatchStmt) -> None:
                                                 and expr.fullname == case_target.fullname
                                             ):
                                                 continue
-                                            type_map[s.subject] = type_map[expr]
+                                            type_map[named_subject] = type_map[expr]
 
                             self.push_type_map(guard_map)
                             self.accept(b)

mypy/messages.py

@@ -2059,6 +2059,15 @@ def impossible_intersection(
             template.format(formatted_base_class_list, reason), context, code=codes.UNREACHABLE
         )
 
+    def tvar_without_default_type(
+        self, tvar_name: str, last_tvar_name_with_default: str, context: Context
+    ) -> None:
+        self.fail(
+            f'"{tvar_name}" cannot appear after "{last_tvar_name_with_default}" '
+            "in type parameter list because it has no default type",
+            context,
+        )
+
     def report_protocol_problems(
         self,
         subtype: Instance | TupleType | TypedDictType | TypeType | CallableType,

mypy/semanal.py

@@ -226,6 +226,7 @@
     SELF_TYPE_NAMES,
     FindTypeVarVisitor,
     TypeAnalyser,
+    TypeVarDefaultTranslator,
     TypeVarLikeList,
     analyze_type_alias,
     check_for_explicit_any,
@@ -252,6 +253,7 @@
     TPDICT_NAMES,
     TYPE_ALIAS_NAMES,
     TYPE_CHECK_ONLY_NAMES,
+    TYPE_VAR_LIKE_NAMES,
     TYPED_NAMEDTUPLE_NAMES,
     AnyType,
     CallableType,
@@ -1953,17 +1955,19 @@ class Foo(Bar, Generic[T]): ...
             defn.removed_base_type_exprs.append(defn.base_type_exprs[i])
             del base_type_exprs[i]
         tvar_defs: list[TypeVarLikeType] = []
+        last_tvar_name_with_default: str | None = None
         for name, tvar_expr in declared_tvars:
-            tvar_expr_default = tvar_expr.default
-            if isinstance(tvar_expr_default, UnboundType):
-                # TODO: - detect out of order and self-referencing TypeVars
-                #       - nested default types, e.g. list[T1]
-                n = self.lookup_qualified(
-                    tvar_expr_default.name, tvar_expr_default, suppress_errors=True
-                )
-                if n is not None and (default := self.tvar_scope.get_binding(n)) is not None:
-                    tvar_expr.default = default
+            tvar_expr.default = tvar_expr.default.accept(
+                TypeVarDefaultTranslator(self, tvar_expr.name, context)
+            )
             tvar_def = self.tvar_scope.bind_new(name, tvar_expr)
+            if last_tvar_name_with_default is not None and not tvar_def.has_default():
+                self.msg.tvar_without_default_type(
+                    tvar_def.name, last_tvar_name_with_default, context
+                )
+                tvar_def.default = AnyType(TypeOfAny.from_error)
+            elif tvar_def.has_default():
+                last_tvar_name_with_default = tvar_def.name
             tvar_defs.append(tvar_def)
         return base_type_exprs, tvar_defs, is_protocol
 
@@ -2857,6 +2861,10 @@ def visit_assignment_stmt(self, s: AssignmentStmt) -> None:
             with self.allow_unbound_tvars_set():
                 s.rvalue.accept(self)
             self.basic_type_applications = old_basic_type_applications
+        elif self.can_possibly_be_typevarlike_declaration(s):
+            # Allow unbound tvars inside TypeVarLike defaults to be evaluated later
+            with self.allow_unbound_tvars_set():
+                s.rvalue.accept(self)
         else:
             s.rvalue.accept(self)
 
@@ -3033,6 +3041,16 @@ def can_possibly_be_type_form(self, s: AssignmentStmt) -> bool:
         # Something that looks like Foo = Bar[Baz, ...]
         return True
 
+    def can_possibly_be_typevarlike_declaration(self, s: AssignmentStmt) -> bool:
+        """Check if r.h.s. can be a TypeVarLike declaration."""
+        if len(s.lvalues) != 1 or not isinstance(s.lvalues[0], NameExpr):
+            return False
+        if not isinstance(s.rvalue, CallExpr) or not isinstance(s.rvalue.callee, NameExpr):
+            return False
+        ref = s.rvalue.callee
+        ref.accept(self)
+        return ref.fullname in TYPE_VAR_LIKE_NAMES
+
     def is_type_ref(self, rv: Expression, bare: bool = False) -> bool:
         """Does this expression refer to a type?
 
@@ -3522,9 +3540,20 @@ def analyze_alias(
         tvar_defs: list[TypeVarLikeType] = []
         namespace = self.qualified_name(name)
         alias_type_vars = found_type_vars if declared_type_vars is None else declared_type_vars
+        last_tvar_name_with_default: str | None = None
         with self.tvar_scope_frame(self.tvar_scope.class_frame(namespace)):
             for name, tvar_expr in alias_type_vars:
+                tvar_expr.default = tvar_expr.default.accept(
+                    TypeVarDefaultTranslator(self, tvar_expr.name, typ)
+                )
                 tvar_def = self.tvar_scope.bind_new(name, tvar_expr)
+                if last_tvar_name_with_default is not None and not tvar_def.has_default():
+                    self.msg.tvar_without_default_type(
+                        tvar_def.name, last_tvar_name_with_default, typ
+                    )
+                    tvar_def.default = AnyType(TypeOfAny.from_error)
+                elif tvar_def.has_default():
+                    last_tvar_name_with_default = tvar_def.name
                 tvar_defs.append(tvar_def)
 
             analyzed, depends_on = analyze_type_alias(

mypy/stubgen.py

@@ -47,7 +47,7 @@
 import os.path
 import sys
 import traceback
-from typing import Final, Iterable
+from typing import Final, Iterable, Iterator
 
 import mypy.build
 import mypy.mixedtraverser
@@ -114,6 +114,7 @@
 from mypy.stubdoc import ArgSig, FunctionSig
 from mypy.stubgenc import InspectionStubGenerator, generate_stub_for_c_module
 from mypy.stubutil import (
+    TYPING_BUILTIN_REPLACEMENTS,
     BaseStubGenerator,
     CantImport,
     ClassInfo,
@@ -289,20 +290,19 @@ def visit_call_expr(self, node: CallExpr) -> str:
                 raise ValueError(f"Unknown argument kind {kind} in call")
         return f"{callee}({', '.join(args)})"
 
+    def _visit_ref_expr(self, node: NameExpr | MemberExpr) -> str:
+        fullname = self.stubgen.get_fullname(node)
+        if fullname in TYPING_BUILTIN_REPLACEMENTS:
+            return self.stubgen.add_name(TYPING_BUILTIN_REPLACEMENTS[fullname], require=False)
+        qualname = get_qualified_name(node)
+        self.stubgen.import_tracker.require_name(qualname)
+        return qualname
+
     def visit_name_expr(self, node: NameExpr) -> str:
-        self.stubgen.import_tracker.require_name(node.name)
-        return node.name
+        return self._visit_ref_expr(node)
 
     def visit_member_expr(self, o: MemberExpr) -> str:
-        node: Expression = o
-        trailer = ""
-        while isinstance(node, MemberExpr):
-            trailer = "." + node.name + trailer
-            node = node.expr
-        if not isinstance(node, NameExpr):
-            return ERROR_MARKER
-        self.stubgen.import_tracker.require_name(node.name)
-        return node.name + trailer
+        return self._visit_ref_expr(o)
 
     def visit_str_expr(self, node: StrExpr) -> str:
         return repr(node.value)
@@ -351,11 +351,17 @@ def find_defined_names(file: MypyFile) -> set[str]:
     return finder.names
 
 
+def get_assigned_names(lvalues: Iterable[Expression]) -> Iterator[str]:
+    for lvalue in lvalues:
+        if isinstance(lvalue, NameExpr):
+            yield lvalue.name
+        elif isinstance(lvalue, TupleExpr):
+            yield from get_assigned_names(lvalue.items)
+
+
 class DefinitionFinder(mypy.traverser.TraverserVisitor):
     """Find names of things defined at the top level of a module."""
 
-    # TODO: Assignment statements etc.
-
     def __init__(self) -> None:
         # Short names of things defined at the top level.
         self.names: set[str] = set()
@@ -368,6 +374,10 @@ def visit_func_def(self, o: FuncDef) -> None:
         # Don't recurse, as we only keep track of top-level definitions.
         self.names.add(o.name)
 
+    def visit_assignment_stmt(self, o: AssignmentStmt) -> None:
+        for name in get_assigned_names(o.lvalues):
+            self.names.add(name)
+
 
 def find_referenced_names(file: MypyFile) -> set[str]:
     finder = ReferenceFinder()
@@ -1023,10 +1033,15 @@ def is_alias_expression(self, expr: Expression, top_level: bool = True) -> bool:
                 and isinstance(expr.node, (FuncDef, Decorator, MypyFile))
                 or isinstance(expr.node, TypeInfo)
             ) and not self.is_private_member(expr.node.fullname)
-        elif (
-            isinstance(expr, IndexExpr)
-            and isinstance(expr.base, NameExpr)
-            and not self.is_private_name(expr.base.name)
+        elif isinstance(expr, IndexExpr) and (
+            (isinstance(expr.base, NameExpr) and not self.is_private_name(expr.base.name))
+            or (  # Also some known aliases that could be member expression
+                isinstance(expr.base, MemberExpr)
+                and not self.is_private_member(get_qualified_name(expr.base))
+                and self.get_fullname(expr.base).startswith(
+                    ("builtins.", "typing.", "typing_extensions.", "collections.abc.")
+                )
+            )
         ):
             if isinstance(expr.index, TupleExpr):
                 indices = expr.index.items

mypy/stubutil.py

@@ -22,6 +22,26 @@
 # Modules that may fail when imported, or that may have side effects (fully qualified).
 NOT_IMPORTABLE_MODULES = ()
 
+# Typing constructs to be replaced by their builtin equivalents.
+TYPING_BUILTIN_REPLACEMENTS: Final = {
+    # From typing
+    "typing.Text": "builtins.str",
+    "typing.Tuple": "builtins.tuple",
+    "typing.List": "builtins.list",
+    "typing.Dict": "builtins.dict",
+    "typing.Set": "builtins.set",
+    "typing.FrozenSet": "builtins.frozenset",
+    "typing.Type": "builtins.type",
+    # From typing_extensions
+    "typing_extensions.Text": "builtins.str",
+    "typing_extensions.Tuple": "builtins.tuple",
+    "typing_extensions.List": "builtins.list",
+    "typing_extensions.Dict": "builtins.dict",
+    "typing_extensions.Set": "builtins.set",
+    "typing_extensions.FrozenSet": "builtins.frozenset",
+    "typing_extensions.Type": "builtins.type",
+}
+
 
 class CantImport(Exception):
     def __init__(self, module: str, message: str) -> None:
@@ -229,6 +249,8 @@ def visit_unbound_type(self, t: UnboundType) -> str:
             return " | ".join([item.accept(self) for item in t.args])
         if fullname == "typing.Optional":
             return f"{t.args[0].accept(self)} | None"
+        if fullname in TYPING_BUILTIN_REPLACEMENTS:
+            s = self.stubgen.add_name(TYPING_BUILTIN_REPLACEMENTS[fullname], require=True)
         if self.known_modules is not None and "." in s:
             # see if this object is from any of the modules that we're currently processing.
             # reverse sort so that subpackages come before parents: e.g. "foo.bar" before "foo".
@@ -476,7 +498,7 @@ def reexport(self, name: str) -> None:
     def import_lines(self) -> list[str]:
         """The list of required import lines (as strings with python code).
 
-        In order for a module be included in this output, an indentifier must be both
+        In order for a module be included in this output, an identifier must be both
         'required' via require_name() and 'imported' via add_import_from()
         or add_import()
         """
@@ -585,9 +607,9 @@ def __init__(
         # a corresponding import statement.
         self.known_imports = {
             "_typeshed": ["Incomplete"],
-            "typing": ["Any", "TypeVar", "NamedTuple"],
+            "typing": ["Any", "TypeVar", "NamedTuple", "TypedDict"],
             "collections.abc": ["Generator"],
-            "typing_extensions": ["TypedDict", "ParamSpec", "TypeVarTuple"],
+            "typing_extensions": ["ParamSpec", "TypeVarTuple"],
         }
 
     def get_sig_generators(self) -> list[SignatureGenerator]:
@@ -613,7 +635,10 @@ def add_name(self, fullname: str, require: bool = True) -> str:
         """
         module, name = fullname.rsplit(".", 1)
         alias = "_" + name if name in self.defined_names else None
-        self.import_tracker.add_import_from(module, [(name, alias)], require=require)
+        while alias in self.defined_names:
+            alias = "_" + alias
+        if module != "builtins" or alias:  # don't import from builtins unless needed
+            self.import_tracker.add_import_from(module, [(name, alias)], require=require)
         return alias or name
 
     def add_import_line(self, line: str) -> None:

mypy/typeanal.py

@@ -38,7 +38,12 @@
 )
 from mypy.options import Options
 from mypy.plugin import AnalyzeTypeContext, Plugin, TypeAnalyzerPluginInterface
-from mypy.semanal_shared import SemanticAnalyzerCoreInterface, paramspec_args, paramspec_kwargs
+from mypy.semanal_shared import (
+    SemanticAnalyzerCoreInterface,
+    SemanticAnalyzerInterface,
+    paramspec_args,
+    paramspec_kwargs,
+)
 from mypy.state import state
 from mypy.tvar_scope import TypeVarLikeScope
 from mypy.types import (
@@ -2520,3 +2525,32 @@ def process_types(self, types: list[Type] | tuple[Type, ...]) -> None:
         else:
             for t in types:
                 t.accept(self)
+
+
+class TypeVarDefaultTranslator(TrivialSyntheticTypeTranslator):
+    """Type translate visitor that replaces UnboundTypes with in-scope TypeVars."""
+
+    def __init__(
+        self, api: SemanticAnalyzerInterface, tvar_expr_name: str, context: Context
+    ) -> None:
+        self.api = api
+        self.tvar_expr_name = tvar_expr_name
+        self.context = context
+
+    def visit_unbound_type(self, t: UnboundType) -> Type:
+        sym = self.api.lookup_qualified(t.name, t, suppress_errors=True)
+        if sym is not None:
+            if type_var := self.api.tvar_scope.get_binding(sym):
+                return type_var
+            if isinstance(sym.node, TypeVarLikeExpr):
+                self.api.fail(
+                    f'Type parameter "{self.tvar_expr_name}" has a default type '
+                    "that refers to one or more type variables that are out of scope",
+                    self.context,
+                )
+                return AnyType(TypeOfAny.from_error)
+        return super().visit_unbound_type(t)
+
+    def visit_type_alias_type(self, t: TypeAliasType) -> Type:
+        # TypeAliasTypes are analyzed separately already, just return it
+        return t

mypy/types.py

@@ -85,6 +85,15 @@
         TypeVisitor as TypeVisitor,
     )
 
+TYPE_VAR_LIKE_NAMES: Final = (
+    "typing.TypeVar",
+    "typing_extensions.TypeVar",
+    "typing.ParamSpec",
+    "typing_extensions.ParamSpec",
+    "typing.TypeVarTuple",
+    "typing_extensions.TypeVarTuple",
+)
+
 TYPED_NAMEDTUPLE_NAMES: Final = ("typing.NamedTuple", "typing_extensions.NamedTuple")
 
 # Supported names of TypedDict type constructors.