move a bunch of imports into TYPE_CHECKING blocks

These are only used for type checking, so don't bother importing them at
runtime.

Generally add future annotations at the same time, to make sure that
existing uses of these imports don't need to be quoted.

6 files changed, 13 insertions, 11 deletions

diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 8eca0b3..bc238c7 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -33,10 +33,9 @@ from ..interpreterbase import InterpreterException, InvalidArguments, InvalidCod
 from ..interpreterbase import Disabler, disablerIfNotFound
 from ..interpreterbase import FeatureNew, FeatureDeprecated, FeatureNewKwargs, FeatureDeprecatedKwargs
 from ..interpreterbase import ObjectHolder
-from ..interpreterbase.baseobjects import InterpreterObject, TYPE_var, TYPE_kwargs
 from ..modules import ExtensionModule, ModuleObject, MutableModuleObject, NewExtensionModule, NotFoundExtensionModule
 from ..cmake import CMakeInterpreter
-from ..backend.backends import Backend, ExecutableSerialisation
+from ..backend.backends import ExecutableSerialisation
 
 from . import interpreterobjects as OBJ
 from . import compiler as compilerOBJ
@@ -96,6 +95,8 @@ if T.TYPE_CHECKING:
     from typing_extensions import Literal
 
     from . import kwargs
+    from ..backend.backends import Backend
+    from ..interpreterbase.baseobjects import InterpreterObject, TYPE_var, TYPE_kwargs
     from ..programs import OverrideProgram
 
     # Input source types passed to Targets
diff --git a/mesonbuild/interpreter/primitives/array.py b/mesonbuild/interpreter/primitives/array.py
index e48e1c2..eeea112 100644
--- a/mesonbuild/interpreter/primitives/array.py
+++ b/mesonbuild/interpreter/primitives/array.py
@@ -1,5 +1,6 @@
 # Copyright 2021 The Meson development team
 # SPDX-license-identifier: Apache-2.0
+from __future__ import annotations
 
 import typing as T
 
@@ -15,7 +16,6 @@ from ...interpreterbase import (
     FeatureNew,
 
     TYPE_var,
-    TYPE_kwargs,
 
     InvalidArguments,
 )
@@ -24,6 +24,7 @@ from ...mparser import PlusAssignmentNode
 if T.TYPE_CHECKING:
     # Object holders need the actual interpreter
     from ...interpreter import Interpreter
+    from ...interpreterbase import TYPE_kwargs
 
 class ArrayHolder(ObjectHolder[T.List[TYPE_var]], IterableObject):
     def __init__(self, obj: T.List[TYPE_var], interpreter: 'Interpreter') -> None:
diff --git a/mesonbuild/interpreter/primitives/dict.py b/mesonbuild/interpreter/primitives/dict.py
index 24f4d21..ac7c99b 100644
--- a/mesonbuild/interpreter/primitives/dict.py
+++ b/mesonbuild/interpreter/primitives/dict.py
@@ -1,5 +1,6 @@
 # Copyright 2021 The Meson development team
 # SPDX-license-identifier: Apache-2.0
+from __future__ import annotations
 
 import typing as T
 
@@ -14,7 +15,6 @@ from ...interpreterbase import (
     typed_pos_args,
 
     TYPE_var,
-    TYPE_kwargs,
 
     InvalidArguments,
 )
@@ -22,6 +22,7 @@ from ...interpreterbase import (
 if T.TYPE_CHECKING:
     # Object holders need the actual interpreter
     from ...interpreter import Interpreter
+    from ...interpreterbase import TYPE_kwargs
 
 class DictHolder(ObjectHolder[T.Dict[str, TYPE_var]], IterableObject):
     def __init__(self, obj: T.Dict[str, TYPE_var], interpreter: 'Interpreter') -> None:
diff --git a/mesonbuild/interpreter/primitives/integer.py b/mesonbuild/interpreter/primitives/integer.py
index 6563ee9..f433f57 100644
--- a/mesonbuild/interpreter/primitives/integer.py
+++ b/mesonbuild/interpreter/primitives/integer.py
@@ -1,5 +1,6 @@
 # Copyright 2021 The Meson development team
 # SPDX-license-identifier: Apache-2.0
+from __future__ import annotations
 
 from ...interpreterbase import (
     ObjectHolder,
@@ -8,9 +9,6 @@ from ...interpreterbase import (
     noKwargs,
     noPosargs,
 
-    TYPE_var,
-    TYPE_kwargs,
-
     InvalidArguments
 )
 
@@ -19,6 +17,7 @@ import typing as T
 if T.TYPE_CHECKING:
     # Object holders need the actual interpreter
     from ...interpreter import Interpreter
+    from ...interpreterbase import TYPE_var, TYPE_kwargs
 
 class IntegerHolder(ObjectHolder[int]):
     def __init__(self, obj: int, interpreter: 'Interpreter') -> None:
diff --git a/mesonbuild/interpreter/primitives/string.py b/mesonbuild/interpreter/primitives/string.py
index 9cd51b4..9129303 100644
--- a/mesonbuild/interpreter/primitives/string.py
+++ b/mesonbuild/interpreter/primitives/string.py
@@ -1,5 +1,6 @@
 # Copyright 2021 The Meson development team
 # SPDX-license-identifier: Apache-2.0
+from __future__ import annotations
 
 import re
 import os
@@ -17,9 +18,6 @@ from ...interpreterbase import (
     noPosargs,
     typed_pos_args,
 
-    TYPE_var,
-    TYPE_kwargs,
-
     InvalidArguments,
 )
 
@@ -27,6 +25,7 @@ from ...interpreterbase import (
 if T.TYPE_CHECKING:
     # Object holders need the actual interpreter
     from ...interpreter import Interpreter
+    from ...interpreterbase import TYPE_var, TYPE_kwargs
 
 class StringHolder(ObjectHolder[str]):
     def __init__(self, obj: str, interpreter: 'Interpreter') -> None:
diff --git a/mesonbuild/interpreter/type_checking.py b/mesonbuild/interpreter/type_checking.py
index cce0024..37ab192 100644
--- a/mesonbuild/interpreter/type_checking.py
+++ b/mesonbuild/interpreter/type_checking.py
@@ -11,7 +11,6 @@ from .. import compilers
 from ..build import (EnvironmentVariables, EnvInitValueType, CustomTarget, BuildTarget,
                      CustomTargetIndex, ExtractedObjects, GeneratedList, IncludeDirs)
 from ..coredata import UserFeatureOption
-from ..interpreterbase import TYPE_var
 from ..interpreterbase.decorators import KwargInfo, ContainerTypeInfo
 from ..mesonlib import File, FileMode, MachineChoice, listify, has_path_sep, OptionKey
 from ..programs import ExternalProgram
@@ -22,6 +21,8 @@ NoneType: T.Type[None] = type(None)
 if T.TYPE_CHECKING:
     from typing_extensions import Literal
 
+    from ..interpreterbase import TYPE_var
+
 def in_set_validator(choices: T.Set[str]) -> T.Callable[[str], T.Optional[str]]:
     """Check that the choice given was one of the given set."""