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.

9 files changed, 44 insertions, 23 deletions

diff --git a/mesonbuild/dependencies/dev.py b/mesonbuild/dependencies/dev.py
index 793b38a..c2bef0d 100644
--- a/mesonbuild/dependencies/dev.py
+++ b/mesonbuild/dependencies/dev.py
@@ -29,7 +29,7 @@ from mesonbuild.interpreterbase.decorators import FeatureDeprecated
 from .. import mesonlib, mlog
 from ..compilers import AppleClangCCompiler, AppleClangCPPCompiler, detect_compiler_for
 from ..environment import get_llvm_tool_names
-from ..mesonlib import version_compare, stringlistify, extract_as_list, MachineChoice
+from ..mesonlib import version_compare, stringlistify, extract_as_list
 from .base import DependencyException, DependencyMethods, strip_system_libdirs, SystemDependency
 from .cmake import CMakeDependency
 from .configtool import ConfigToolDependency
@@ -39,7 +39,8 @@ from .pkgconfig import PkgConfigDependency
 
 if T.TYPE_CHECKING:
     from ..envconfig import MachineInfo
-    from .. environment import Environment
+    from ..environment import Environment
+    from ..mesonlib import MachineChoice
     from typing_extensions import TypedDict
 
     class JNISystemDependencyKW(TypedDict):
diff --git a/mesonbuild/interpreter/dependencyfallbacks.py b/mesonbuild/interpreter/dependencyfallbacks.py
index e029854..a252046 100644
--- a/mesonbuild/interpreter/dependencyfallbacks.py
+++ b/mesonbuild/interpreter/dependencyfallbacks.py
@@ -1,5 +1,6 @@
-from .interpreterobjects import SubprojectHolder, extract_required_kwarg
+from __future__ import annotations
 
+from .interpreterobjects import extract_required_kwarg
 from .. import mlog
 from .. import dependencies
 from .. import build
@@ -7,12 +8,13 @@ from ..wrap import WrapMode
 from ..mesonlib import OptionKey, extract_as_list, stringlistify, version_compare_many, listify
 from ..dependencies import Dependency, DependencyException, NotFoundDependency
 from ..interpreterbase import (MesonInterpreterObject, FeatureNew,
-                               InterpreterException, InvalidArguments,
-                               TYPE_nkwargs, TYPE_nvar)
+                               InterpreterException, InvalidArguments)
 
 import typing as T
 if T.TYPE_CHECKING:
     from .interpreter import Interpreter
+    from ..interpreterbase import TYPE_nkwargs, TYPE_nvar
+    from .interpreterobjects import SubprojectHolder
 
 
 class DependencyFallbacksHolder(MesonInterpreterObject):
diff --git a/mesonbuild/interpreter/interpreterobjects.py b/mesonbuild/interpreter/interpreterobjects.py
index bf668f3..6cc636b 100644
--- a/mesonbuild/interpreter/interpreterobjects.py
+++ b/mesonbuild/interpreter/interpreterobjects.py
@@ -16,10 +16,10 @@ from ..modules import ModuleReturnValue, ModuleObject, ModuleState, ExtensionMod
 from ..backend.backends import TestProtocol
 from ..interpreterbase import (
                                ContainerTypeInfo, KwargInfo, MesonOperator,
-                               InterpreterObject, MesonInterpreterObject, ObjectHolder, MutableInterpreterObject,
-                               FeatureCheckBase, FeatureNew, FeatureDeprecated,
+                               MesonInterpreterObject, ObjectHolder, MutableInterpreterObject,
+                               FeatureNew, FeatureDeprecated,
                                typed_pos_args, typed_kwargs, typed_operator,
-                               noArgsFlattening, noPosargs, noKwargs, unholder_return, TYPE_var, TYPE_kwargs, TYPE_nvar, TYPE_nkwargs,
+                               noArgsFlattening, noPosargs, noKwargs, unholder_return,
                                flatten, resolve_second_level_holders, InterpreterException, InvalidArguments, InvalidCode)
 from ..interpreter.type_checking import NoneType, ENV_SEPARATOR_KW
 from ..dependencies import Dependency, ExternalLibrary, InternalDependency
@@ -32,7 +32,7 @@ if T.TYPE_CHECKING:
     from . import kwargs
     from ..cmake.interpreter import CMakeInterpreter
     from ..envconfig import MachineInfo
-    from ..interpreterbase import SubProject
+    from ..interpreterbase import FeatureCheckBase, InterpreterObject, SubProject, TYPE_var, TYPE_kwargs, TYPE_nvar, TYPE_nkwargs
     from .interpreter import Interpreter
 
     from typing_extensions import TypedDict
diff --git a/mesonbuild/modules/fs.py b/mesonbuild/modules/fs.py
index 5faee83..d0f5e2e 100644
--- a/mesonbuild/modules/fs.py
+++ b/mesonbuild/modules/fs.py
@@ -21,7 +21,6 @@ from .. import mlog
 from . import ExtensionModule
 from ..mesonlib import (
     File,
-    FileOrString,
     MesonException,
     path_is_in_root,
 )
@@ -30,6 +29,7 @@ from ..interpreterbase import FeatureNew, KwargInfo, typed_kwargs, typed_pos_arg
 if T.TYPE_CHECKING:
     from . import ModuleState
     from ..interpreter import Interpreter
+    from ..mesonlib import FileOrString
 
     from typing_extensions import TypedDict
 
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index 484938e..5376d00 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -14,6 +14,7 @@
 
 '''This module provides helper functions for Gnome/GLib related
 functionality such as gobject-introspection, gresources and gtk-doc'''
+from __future__ import annotations
 
 import copy
 import itertools
@@ -30,7 +31,7 @@ from .. import build
 from .. import interpreter
 from .. import mesonlib
 from .. import mlog
-from ..build import BuildTarget, CustomTarget, CustomTargetIndex, Executable, GeneratedList, InvalidArguments
+from ..build import CustomTarget, CustomTargetIndex, Executable, GeneratedList, InvalidArguments
 from ..dependencies import Dependency, PkgConfigDependency, InternalDependency
 from ..interpreter.type_checking import DEPENDS_KW, DEPEND_FILES_KW, INSTALL_KW, NoneType, in_set_validator
 from ..interpreterbase import noPosargs, noKwargs, FeatureNew, FeatureDeprecated
@@ -46,6 +47,7 @@ if T.TYPE_CHECKING:
     from typing_extensions import Literal, TypedDict
 
     from . import ModuleState
+    from ..build import BuildTarget
     from ..compilers import Compiler
     from ..interpreter import Interpreter
     from ..interpreterbase import TYPE_var, TYPE_kwargs
diff --git a/mesonbuild/modules/java.py b/mesonbuild/modules/java.py
index 22b8d2c..a8e5062 100644
--- a/mesonbuild/modules/java.py
+++ b/mesonbuild/modules/java.py
@@ -11,17 +11,23 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from __future__ import annotations
 
 import os
 import pathlib
 import typing as T
+
 from mesonbuild import mesonlib
 from mesonbuild.build import CustomTarget, CustomTargetIndex, GeneratedList, Target
-from mesonbuild.compilers import detect_compiler_for, Compiler
-from mesonbuild.interpreter import Interpreter
+from mesonbuild.compilers import detect_compiler_for
 from mesonbuild.interpreterbase.decorators import ContainerTypeInfo, FeatureDeprecated, FeatureNew, KwargInfo, typed_pos_args, typed_kwargs
 from mesonbuild.mesonlib import version_compare, MachineChoice
-from . import NewExtensionModule, ModuleReturnValue, ModuleState
+from . import NewExtensionModule, ModuleReturnValue
+
+if T.TYPE_CHECKING:
+    from . import ModuleState
+    from ..compilers import Compiler
+    from ..interpreter import Interpreter
 
 class JavaModule(NewExtensionModule):
     @FeatureNew('Java Module', '0.60.0')
diff --git a/mesonbuild/modules/qt.py b/mesonbuild/modules/qt.py
index 81dd3e9..99581a4 100644
--- a/mesonbuild/modules/qt.py
+++ b/mesonbuild/modules/qt.py
@@ -12,6 +12,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from __future__ import annotations
 
 import os
 import shutil
@@ -23,17 +24,19 @@ from .. import build
 from .. import coredata
 from .. import mlog
 from ..dependencies import find_external_dependency, Dependency, ExternalLibrary
-from ..mesonlib import MesonException, File, FileOrString, version_compare, Popen_safe
+from ..mesonlib import MesonException, File, version_compare, Popen_safe
 from ..interpreter import extract_required_kwarg
 from ..interpreter.type_checking import NoneType
 from ..interpreterbase import ContainerTypeInfo, FeatureDeprecated, KwargInfo, noPosargs, FeatureNew, typed_kwargs
-from ..programs import ExternalProgram, NonExistingExternalProgram
+from ..programs import NonExistingExternalProgram
 
 if T.TYPE_CHECKING:
     from . import ModuleState
     from ..dependencies.qt import QtPkgConfigDependency, QmakeQtDependency
     from ..interpreter import Interpreter
     from ..interpreter import kwargs
+    from ..mesonlib import FileOrString
+    from ..programs import ExternalProgram
 
     QtDependencyType = T.Union[QtPkgConfigDependency, QmakeQtDependency]
 
diff --git a/mesonbuild/scripts/depscan.py b/mesonbuild/scripts/depscan.py
index 3b26f92..6f92715 100644
--- a/mesonbuild/scripts/depscan.py
+++ b/mesonbuild/scripts/depscan.py
@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from __future__ import annotations
 
 import json
 import os
@@ -20,9 +21,12 @@ import re
 import sys
 import typing as T
 
-from ..backend.ninjabackend import TargetDependencyScannerInfo, ninja_quote
+from ..backend.ninjabackend import ninja_quote
 from ..compilers.compilers import lang_suffixes
 
+if T.TYPE_CHECKING:
+    from ..backend.ninjabackend import TargetDependencyScannerInfo
+
 CPP_IMPORT_RE = re.compile(r'\w*import ([a-zA-Z0-9]+);')
 CPP_EXPORT_RE = re.compile(r'\w*export module ([a-zA-Z0-9]+);')
 
@@ -38,13 +42,13 @@ FORTRAN_USE_RE = re.compile(FORTRAN_USE_PAT, re.IGNORECASE)
 class DependencyScanner:
     def __init__(self, pickle_file: str, outfile: str, sources: T.List[str]):
         with open(pickle_file, 'rb') as pf:
-            self.target_data = pickle.load(pf) # type: TargetDependencyScannerInfo
+            self.target_data: TargetDependencyScannerInfo = pickle.load(pf)
         self.outfile = outfile
         self.sources = sources
-        self.provided_by = {} # type: T.Dict[str, str]
-        self.exports = {} # type: T.Dict[str, str]
-        self.needs = {} # type: T.Dict[str, T.List[str]]
-        self.sources_with_exports = [] # type: T.List[str]
+        self.provided_by: T.Dict[str, str] = {}
+        self.exports: T.Dict[str, str] = {}
+        self.needs: T.Dict[str, T.List[str]] = {}
+        self.sources_with_exports: T.List[str] = []
 
     def scan_file(self, fname: str) -> None:
         suffix = os.path.splitext(fname)[1][1:].lower()
diff --git a/mesonbuild/scripts/run_tool.py b/mesonbuild/scripts/run_tool.py
index 700f459..f120df2 100644
--- a/mesonbuild/scripts/run_tool.py
+++ b/mesonbuild/scripts/run_tool.py
@@ -11,8 +11,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from __future__ import annotations
 
-import subprocess
 import itertools
 import fnmatch
 from pathlib import Path
@@ -22,6 +22,9 @@ from ..compilers import lang_suffixes
 from ..mesonlib import Popen_safe
 import typing as T
 
+if T.TYPE_CHECKING:
+    import subprocess
+
 def parse_pattern_file(fname: Path) -> T.List[str]:
     patterns = []
     try: