Fix return value annotations for methods returning copies

These methods always return a new object of the same type as the object
they are bound to, even if this is a subclass. Change the annotations to
reflect that.

CHANGES.rst

@@ -7,6 +7,7 @@ Unreleased
 
 -   Fix compiler error when checking if required blocks in parent templates are
     empty. :pr:`1858`
+-   Fix return value annotations for methods returning copies :pr:`1880`
 
 
 Version 3.1.2

src/jinja2/compiler.py

@@ -216,7 +216,7 @@ def __init__(
         # or compile time.
         self.soft_frame = False
 
-    def copy(self) -> "Frame":
+    def copy(self) -> "te.Self":
         """Create a copy of the current one."""
         rv = object.__new__(self.__class__)
         rv.__dict__.update(self.__dict__)
@@ -229,7 +229,7 @@ def inner(self, isolated: bool = False) -> "Frame":
             return Frame(self.eval_ctx, level=self.symbols.level + 1)
         return Frame(self.eval_ctx, self)
 
-    def soft(self) -> "Frame":
+    def soft(self) -> "te.Self":
         """Return a soft frame.  A soft frame may not be modified as
         standalone thing as it shares the resources with the frame it
         was created of, but it's not a rootlevel frame any longer.

src/jinja2/environment.py

@@ -121,7 +121,7 @@ def load_extensions(
     return result
 
 
-def _environment_config_check(environment: "Environment") -> "Environment":
+def _environment_config_check(environment: _env_bound) -> _env_bound:
     """Perform a sanity check on the environment."""
     assert issubclass(
         environment.undefined, Undefined
@@ -405,7 +405,7 @@ def overlay(
         auto_reload: bool = missing,
         bytecode_cache: t.Optional["BytecodeCache"] = missing,
         enable_async: bool = False,
-    ) -> "Environment":
+    ) -> "te.Self":
         """Create a new overlay environment that shares all the data with the
         current environment except for cache and the overridden attributes.
         Extensions cannot be removed for an overlayed environment.  An overlayed

src/jinja2/ext.py

@@ -88,7 +88,7 @@ def __init_subclass__(cls) -> None:
     def __init__(self, environment: Environment) -> None:
         self.environment = environment
 
-    def bind(self, environment: Environment) -> "Extension":
+    def bind(self, environment: Environment) -> "te.Self":
         """Create a copy of this extension bound to another environment."""
         rv = object.__new__(self.__class__)
         rv.__dict__.update(self.__dict__)

src/jinja2/idtracking.py

@@ -3,6 +3,9 @@
 from . import nodes
 from .visitor import NodeVisitor
 
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
 VAR_LOAD_PARAMETER = "param"
 VAR_LOAD_RESOLVE = "resolve"
 VAR_LOAD_ALIAS = "alias"
@@ -83,7 +86,7 @@ def ref(self, name: str) -> str:
             )
         return rv
 
-    def copy(self) -> "Symbols":
+    def copy(self) -> "te.Self":
         rv = object.__new__(self.__class__)
         rv.__dict__.update(self.__dict__)
         rv.refs = self.refs.copy()

src/jinja2/utils.py

@@ -453,7 +453,7 @@ def __setstate__(self, d: t.Mapping[str, t.Any]) -> None:
     def __getnewargs__(self) -> t.Tuple:
         return (self.capacity,)
 
-    def copy(self) -> "LRUCache":
+    def copy(self) -> "te.Self":
         """Return a shallow copy of the instance."""
         rv = self.__class__(self.capacity)
         rv._mapping.update(self._mapping)