Make use of build TypeAliases

There are a lot of spelled out unions for these types, lets reduce that
number

13 files changed, 78 insertions, 85 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index dabc4c10d..a5995e6b1 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -46,7 +46,7 @@ if T.TYPE_CHECKING:
 
     from typing_extensions import TypedDict, NotRequired
 
-    _ALL_SOURCES_TYPE = T.List[T.Union[File, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
+    _ALL_SOURCES_TYPE = T.List[T.Union[File, build.GeneratedTypes]]
 
     class TargetIntrospectionData(TypedDict):
 
@@ -295,7 +295,7 @@ class Backend:
     def generate(self, capture: bool = False, vslite_ctx: T.Optional[T.Dict] = None) -> T.Optional[T.Dict]:
         raise RuntimeError(f'generate is not implemented in {type(self).__name__}')
 
-    def get_target_filename(self, t: T.Union[build.Target, build.CustomTargetIndex], *, warn_multi_output: bool = True) -> str:
+    def get_target_filename(self, t: build.AnyTargetType, *, warn_multi_output: bool = True) -> str:
         if isinstance(t, build.CustomTarget):
             if warn_multi_output and len(t.get_outputs()) != 1:
                 mlog.warning(f'custom_target {t.name!r} has more than one output! '
@@ -308,7 +308,7 @@ class Backend:
             filename = t.get_filename()
         return os.path.join(self.get_target_dir(t), filename)
 
-    def get_target_filename_abs(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
+    def get_target_filename_abs(self, target: build.AnyTargetType) -> str:
         return os.path.join(self.environment.get_build_dir(), self.get_target_filename(target))
 
     def get_target_debug_filename(self, target: build.BuildTarget) -> T.Optional[str]:
@@ -343,7 +343,7 @@ class Backend:
                 curdir = '.'
         return compiler.get_include_args(curdir, False)
 
-    def get_target_filename_for_linking(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> T.Optional[str]:
+    def get_target_filename_for_linking(self, target: build.AnyTargetType) -> T.Optional[str]:
         # On some platforms (msvc for instance), the file that is used for
         # dynamic linking is not the same as the dynamic library itself. This
         # file is called an import library, and we want to link against that.
@@ -368,7 +368,7 @@ class Backend:
         raise AssertionError(f'BUG: Tried to link to {target!r} which is not linkable')
 
     @lru_cache(maxsize=None)
-    def get_target_dir(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
+    def get_target_dir(self, target: build.AnyTargetType) -> str:
         if isinstance(target, build.RunTarget):
             # this produces no output, only a dummy top-level name
             dirname = ''
@@ -394,16 +394,16 @@ class Backend:
             return os.path.join(self.build_to_src, target_dir)
         return self.build_to_src
 
-    def get_target_private_dir(self, target: T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]) -> str:
+    def get_target_private_dir(self, target: build.BuildTargetTypes) -> str:
         return os.path.join(self.get_target_filename(target, warn_multi_output=False) + '.p')
 
-    def get_target_private_dir_abs(self, target: T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]) -> str:
+    def get_target_private_dir_abs(self, target: build.BuildTargetTypes) -> str:
         return os.path.join(self.environment.get_build_dir(), self.get_target_private_dir(target))
 
     @lru_cache(maxsize=None)
     def get_target_generated_dir(
-            self, target: T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex],
-            gensrc: T.Union[build.CustomTarget, build.CustomTargetIndex, build.GeneratedList],
+            self, target: build.BuildTargetTypes,
+            gensrc: build.GeneratedTypes,
             src: str) -> str:
         """
         Takes a BuildTarget, a generator source (CustomTarget or GeneratedList),
@@ -417,7 +417,7 @@ class Backend:
         # target that the GeneratedList is used in
         return os.path.join(self.get_target_private_dir(target), src)
 
-    def get_unity_source_file(self, target: T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex],
+    def get_unity_source_file(self, target: build.BuildTargetTypes,
                               suffix: str, number: int) -> mesonlib.File:
         # There is a potential conflict here, but it is unlikely that
         # anyone both enables unity builds and has a file called foo-unity.cpp.
@@ -1117,8 +1117,8 @@ class Backend:
         return results
 
     def determine_windows_extra_paths(
-            self, target: T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex, programs.ExternalProgram, mesonlib.File, str],
-            extra_bdeps: T.Sequence[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]) -> T.List[str]:
+            self, target: T.Union[build.BuildTargetTypes, programs.ExternalProgram, mesonlib.File, str],
+            extra_bdeps: T.Sequence[build.BuildTargetTypes]) -> T.List[str]:
         """On Windows there is no such thing as an rpath.
 
         We must determine all locations of DLLs that this exe
@@ -1184,7 +1184,7 @@ class Backend:
             exe_wrapper = self.environment.get_exe_wrapper()
             machine = self.environment.machines[exe.for_machine]
             if machine.is_windows() or machine.is_cygwin():
-                extra_bdeps: T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]] = []
+                extra_bdeps: T.List[build.BuildTargetTypes] = []
                 if isinstance(exe, build.CustomTarget):
                     extra_bdeps = list(exe.get_transitive_build_target_deps())
                 extra_bdeps.extend(t.depends)
@@ -1252,7 +1252,7 @@ class Backend:
     def write_test_serialisation(self, tests: T.List['Test'], datafile: T.BinaryIO) -> None:
         pickle.dump(self.create_test_serialisation(tests), datafile)
 
-    def construct_target_rel_paths(self, t: T.Union[build.Target, build.CustomTargetIndex], workdir: T.Optional[str]) -> T.List[str]:
+    def construct_target_rel_paths(self, t: build.AnyTargetType, workdir: T.Optional[str]) -> T.List[str]:
         target_dir = self.get_target_dir(t)
         # ensure that test executables can be run when passed as arguments
         if isinstance(t, build.Executable) and workdir is None:
@@ -1452,7 +1452,7 @@ class Backend:
                     deps.append(os.path.join(self.build_to_src, target.subdir, i))
         return deps
 
-    def get_custom_target_output_dir(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
+    def get_custom_target_output_dir(self, target: build.AnyTargetType) -> str:
         # The XCode backend is special. A target foo/bar does
         # not go to ${BUILDDIR}/foo/bar but instead to
         # ${BUILDDIR}/${BUILDTYPE}/foo/bar.
@@ -2025,7 +2025,7 @@ class Backend:
                               compiler: 'Compiler',
                               sources: _ALL_SOURCES_TYPE,
                               output_templ: str,
-                              depends: T.Optional[T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]] = None,
+                              depends: T.Optional[T.List[build.BuildTargetTypes]] = None,
                               ) -> build.GeneratedList:
         '''
         Some backends don't support custom compilers. This is a convenience
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index fde3874b5..adcb2543e 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -153,7 +153,7 @@ class Vs2010Backend(backends.Backend):
     def get_target_private_dir(self, target):
         return os.path.join(self.get_target_dir(target), target.get_id())
 
-    def generate_genlist_for_target(self, genlist: T.Union[build.GeneratedList, build.CustomTarget, build.CustomTargetIndex], target: build.BuildTarget, parent_node: ET.Element, generator_output_files: T.List[str], custom_target_include_dirs: T.List[str], custom_target_output_files: T.List[str]) -> None:
+    def generate_genlist_for_target(self, genlist: build.GeneratedTypes, target: build.BuildTarget, parent_node: ET.Element, generator_output_files: T.List[str], custom_target_include_dirs: T.List[str], custom_target_output_files: T.List[str]) -> None:
         if isinstance(genlist, build.GeneratedList):
             for x in genlist.depends:
                 self.generate_genlist_for_target(x, target, parent_node, [], [], [])
@@ -330,7 +330,7 @@ class Vs2010Backend(backends.Backend):
                 result[o.target.get_id()] = o.target
         return result.items()
 
-    def get_target_deps(self, t: T.Dict[T.Any, T.Union[build.Target, build.CustomTargetIndex]], recursive=False):
+    def get_target_deps(self, t: T.Dict[T.Any, build.AnyTargetType], recursive=False):
         all_deps: T.Dict[str, build.Target] = {}
         for target in t.values():
             if isinstance(target, build.CustomTargetIndex):
@@ -1577,7 +1577,7 @@ class Vs2010Backend(backends.Backend):
     # once a build/compile has generated these sources.
     #
     # This modifies the paths in 'gen_files' in place, as opposed to returning a new list of modified paths.
-    def relocate_generated_file_paths_to_concrete_build_dir(self, gen_files: T.List[str], target: T.Union[build.Target, build.CustomTargetIndex]) -> None:
+    def relocate_generated_file_paths_to_concrete_build_dir(self, gen_files: T.List[str], target: build.AnyTargetType) -> None:
         (_, build_dir_tail) = os.path.split(self.src_to_build)
         meson_build_dir_for_buildtype = build_dir_tail[:-2] + coredata.get_genvs_default_buildtype_list()[0] # Get the first buildtype suffixed dir (i.e. '[builddir]_debug') from '[builddir]_vs'
         # Relative path from this .vcxproj to the directory containing the set of '..._[debug/debugoptimized/release]' setup meson build dirs.
diff --git a/mesonbuild/backend/xcodebackend.py b/mesonbuild/backend/xcodebackend.py
index a0476ca85..ac2126025 100644
--- a/mesonbuild/backend/xcodebackend.py
+++ b/mesonbuild/backend/xcodebackend.py
@@ -280,12 +280,12 @@ class XCodeBackend(backends.Backend):
         return str(uuid.uuid4()).upper().replace('-', '')[:24]
 
     @functools.lru_cache(maxsize=None)
-    def get_target_dir(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
+    def get_target_dir(self, target: build.AnyTargetType) -> str:
         dirname = os.path.join(target.get_subdir(), T.cast('str', self.environment.coredata.optstore.get_value_for(OptionKey('buildtype'))))
         #os.makedirs(os.path.join(self.environment.get_build_dir(), dirname), exist_ok=True)
         return dirname
 
-    def get_custom_target_output_dir(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
+    def get_custom_target_output_dir(self, target: build.AnyTargetType) -> str:
         dirname = target.get_subdir()
         os.makedirs(os.path.join(self.environment.get_build_dir(), dirname), exist_ok=True)
         return dirname
@@ -525,7 +525,7 @@ class XCodeBackend(backends.Backend):
                 generator_id += 1
 
     def gen_single_target_map(self, genlist: build.GeneratedList, tname: str,
-                              t: T.Union[build.BuildTarget, build.CustomTarget], generator_id: int) -> None:
+                              t: build.AnyTargetType, generator_id: int) -> None:
         k = (tname, generator_id)
         assert k not in self.shell_targets
         self.shell_targets[k] = self.gen_id()
@@ -1439,7 +1439,7 @@ class XCodeBackend(backends.Backend):
                     self.generate_single_generator_phase(tname, t, genlist, generator_id, objects_dict)
                     generator_id += 1
 
-    def generate_single_generator_phase(self, tname: str, t: T.Union[build.BuildTarget, build.CustomTarget],
+    def generate_single_generator_phase(self, tname: str, t: build.AnyTargetType,
                                         genlist: build.GeneratedList, generator_id: int, objects_dict: PbxDict) -> None:
         # TODO: this should be rewritten to use the meson wrapper, like the other generators do
         # Currently it doesn't handle a host binary that requires an exe wrapper correctly.
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 185c1ad42..832e07711 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -494,7 +494,7 @@ class StructuredSources(HoldableObject):
     represent the required filesystem layout.
     """
 
-    sources: T.DefaultDict[str, T.List[T.Union[File, CustomTarget, CustomTargetIndex, GeneratedList]]] = field(
+    sources: T.DefaultDict[str, T.List[T.Union[File, GeneratedTypes]]] = field(
         default_factory=lambda: defaultdict(list))
 
     def __add__(self, other: StructuredSources) -> StructuredSources:
@@ -506,14 +506,14 @@ class StructuredSources(HoldableObject):
     def __bool__(self) -> bool:
         return bool(self.sources)
 
-    def first_file(self) -> T.Union[File, CustomTarget, CustomTargetIndex, GeneratedList]:
+    def first_file(self) -> T.Union[File, GeneratedTypes]:
         """Get the first source in the root
 
         :return: The first source in the root
         """
         return self.sources[''][0]
 
-    def as_list(self) -> T.List[T.Union[File, CustomTarget, CustomTargetIndex, GeneratedList]]:
+    def as_list(self) -> T.List[T.Union[File, GeneratedTypes]]:
         return list(itertools.chain.from_iterable(self.sources.values()))
 
     def needs_copy(self) -> bool:
@@ -724,7 +724,7 @@ class BuildTarget(Target):
         self.link_targets: T.List[LibTypes] = []
         self.link_whole_targets: T.List[T.Union[StaticLibrary, CustomTarget, CustomTargetIndex]] = []
         self.depend_files: T.List[File] = []
-        self.link_depends: T.List[T.Union[File, CustomTarget, CustomTargetIndex, BuildTarget]] = []
+        self.link_depends: T.List[T.Union[File, BuildTargetTypes]] = []
         self.added_deps = set()
         self.name_prefix_set = False
         self.name_suffix_set = False
@@ -1028,7 +1028,7 @@ class BuildTarget(Target):
             langs = ', '.join(self.compilers.keys())
             raise InvalidArguments(f'Cannot mix those languages into a target: {langs}')
 
-    def process_link_depends(self, sources: T.Iterable[T.Union[str, File, CustomTarget, CustomTargetIndex, BuildTarget]]) -> None:
+    def process_link_depends(self, sources: T.Iterable[T.Union[str, File, BuildTargetTypes]]) -> None:
         """Process the link_depends keyword argument.
 
         This is designed to handle strings, Files, and the output of Custom
@@ -1989,12 +1989,12 @@ class Generator(HoldableObject):
                  *,
                  depfile: T.Optional[str] = None,
                  capture: bool = False,
-                 depends: T.Optional[T.List[T.Union[BuildTarget, 'CustomTarget', 'CustomTargetIndex']]] = None,
+                 depends: T.Optional[T.List[BuildTargetTypes]] = None,
                  name: str = 'Generator'):
         self.exe = exe
         self.depfile = depfile
         self.capture = capture
-        self.depends: T.List[T.Union[BuildTarget, 'CustomTarget', 'CustomTargetIndex']] = depends or []
+        self.depends: T.List[BuildTargetTypes] = depends or []
         self.arglist = arguments
         self.outputs = output
         self.name = name
@@ -2024,7 +2024,7 @@ class Generator(HoldableObject):
         basename = os.path.splitext(plainname)[0]
         return [x.replace('@BASENAME@', basename).replace('@PLAINNAME@', plainname) for x in self.arglist]
 
-    def process_files(self, files: T.Iterable[T.Union[str, File, 'CustomTarget', 'CustomTargetIndex', 'GeneratedList']],
+    def process_files(self, files: T.Iterable[T.Union[str, File, GeneratedTypes]],
                       state: T.Union['Interpreter', 'ModuleState'],
                       preserve_path_from: T.Optional[str] = None,
                       extra_args: T.Optional[T.List[str]] = None,
@@ -3078,7 +3078,7 @@ class CompileTarget(BuildTarget):
                  compile_args: T.List[str],
                  include_directories: T.List[IncludeDirs],
                  dependencies: T.List[dependencies.Dependency],
-                 depends: T.List[T.Union[BuildTarget, CustomTarget, CustomTargetIndex]]):
+                 depends: T.List[BuildTargetTypes]):
         compilers = {compiler.get_language(): compiler}
         kwargs = {
             'build_by_default': False,
@@ -3123,7 +3123,7 @@ class RunTarget(Target, CommandBase):
 
     def __init__(self, name: str,
                  command: T.Sequence[T.Union[str, File, BuildTargetTypes, programs.ExternalProgram]],
-                 dependencies: T.Sequence[T.Union[Target, CustomTargetIndex]],
+                 dependencies: T.Sequence[AnyTargetType],
                  subdir: str,
                  subproject: str,
                  environment: environment.Environment,
@@ -3142,7 +3142,7 @@ class RunTarget(Target, CommandBase):
         repr_str = "<{0} {1}: {2}>"
         return repr_str.format(self.__class__.__name__, self.get_id(), self.command[0])
 
-    def get_dependencies(self) -> T.List[T.Union[BuildTarget, CustomTarget, CustomTargetIndex]]:
+    def get_dependencies(self) -> T.List[BuildTargetTypes]:
         return self.dependencies
 
     def get_generated_sources(self) -> T.List[GeneratedTypes]:
diff --git a/mesonbuild/interpreter/compiler.py b/mesonbuild/interpreter/compiler.py
index 57e949961..99204be10 100644
--- a/mesonbuild/interpreter/compiler.py
+++ b/mesonbuild/interpreter/compiler.py
@@ -96,7 +96,7 @@ if T.TYPE_CHECKING:
         compile_args: T.List[str]
         include_directories: T.List[build.IncludeDirs]
         dependencies: T.List[dependencies.Dependency]
-        depends: T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]
+        depends: T.List[build.BuildTargetTypes]
 
 
 class _TestMode(enum.Enum):
@@ -148,7 +148,7 @@ _DEPENDENCIES_KW: KwargInfo[T.List['dependencies.Dependency']] = KwargInfo(
     listify=True,
     default=[],
 )
-_DEPENDS_KW: KwargInfo[T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]] = KwargInfo(
+_DEPENDS_KW: KwargInfo[T.List[build.BuildTargetTypes]] = KwargInfo(
     'depends',
     ContainerTypeInfo(list, (build.BuildTarget, build.CustomTarget, build.CustomTargetIndex)),
     listify=True,
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 73be40eec..b28cc8a76 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -121,13 +121,11 @@ if T.TYPE_CHECKING:
     from .type_checking import SourcesVarargsType
 
     # Input source types passed to Targets
-    SourceInputs = T.Union[mesonlib.File, build.GeneratedList, build.BuildTarget, build.BothLibraries,
-                           build.CustomTargetIndex, build.CustomTarget, build.GeneratedList,
-                           build.ExtractedObjects, str]
+    SourceInputs = T.Union[mesonlib.FileOrString, build.GeneratedTypes, build.BuildTarget,
+                           build.BothLibraries, build.ExtractedObjects]
     # Input source types passed to the build.Target classes
-    SourceOutputs = T.Union[mesonlib.File, build.GeneratedList,
-                            build.BuildTarget, build.CustomTargetIndex, build.CustomTarget,
-                            build.ExtractedObjects, build.GeneratedList, build.StructuredSources]
+    SourceOutputs = T.Union[mesonlib.File, build.GeneratedTypes, build.BuildTarget,
+                            build.ExtractedObjects, build.StructuredSources]
 
     BuildTargetSource = T.Union[mesonlib.FileOrString, build.GeneratedTypes, build.StructuredSources]
 
diff --git a/mesonbuild/interpreter/kwargs.py b/mesonbuild/interpreter/kwargs.py
index f05dd4e12..43e3cb30b 100644
--- a/mesonbuild/interpreter/kwargs.py
+++ b/mesonbuild/interpreter/kwargs.py
@@ -182,16 +182,15 @@ class CustomTarget(TypedDict):
     build_always_stale: T.Optional[bool]
     build_by_default: T.Optional[bool]
     capture: bool
-    command: T.List[T.Union[str, build.BuildTarget, build.CustomTarget,
-                            build.CustomTargetIndex, ExternalProgram, File]]
+    command: T.List[T.Union[str, build.BuildTargetTypes, ExternalProgram, File]]
     console: bool
     depend_files: T.List[FileOrString]
     depends: T.List[T.Union[build.BuildTarget, build.CustomTarget]]
     depfile: T.Optional[str]
     env: EnvironmentVariables
     feed: bool
-    input: T.List[T.Union[str, build.BuildTarget, build.CustomTarget, build.CustomTargetIndex,
-                          build.ExtractedObjects, build.GeneratedList, ExternalProgram, File]]
+    input: T.List[T.Union[str, build.BuildTarget, build.GeneratedTypes,
+                          build.ExtractedObjects, ExternalProgram, File]]
     install: bool
     install_dir: T.List[T.Union[str, T.Literal[False]]]
     install_mode: FileMode
@@ -282,11 +281,10 @@ class ConfigurationDataSet(TypedDict):
 
 class VcsTag(TypedDict):
 
-    command: T.List[T.Union[str, build.BuildTarget, build.CustomTarget,
-                            build.CustomTargetIndex, ExternalProgram, File]]
+    command: T.List[T.Union[str, build.GeneratedTypes, ExternalProgram, File]]
     fallback: T.Optional[str]
-    input: T.List[T.Union[str, build.BuildTarget, build.CustomTarget, build.CustomTargetIndex,
-                          build.ExtractedObjects, build.GeneratedList, ExternalProgram, File]]
+    input: T.List[T.Union[str, build.BuildTarget, build.GeneratedTypes,
+                          build.ExtractedObjects, ExternalProgram, File]]
     output: T.List[str]
     replace_string: str
     install: bool
@@ -343,7 +341,7 @@ class _BaseBuildTarget(TypedDict):
     install_mode: FileMode
     install_rpath: str
     implicit_include_directories: bool
-    link_depends: T.List[T.Union[str, File, build.CustomTarget, build.CustomTargetIndex, build.BuildTarget]]
+    link_depends: T.List[T.Union[str, File, build.GeneratedTypes]]
     link_language: T.Optional[str]
     name_prefix: T.Optional[str]
     name_suffix: T.Optional[str]
@@ -469,7 +467,7 @@ class Jar(_BaseBuildTarget):
 
     main_class: str
     java_resources: T.Optional[build.StructuredSources]
-    sources: T.Union[str, File, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList, build.ExtractedObjects, build.BuildTarget]
+    sources: T.Union[str, File, build.GeneratedTypes, build.ExtractedObjects, build.BuildTarget]
     java_args: T.List[str]
 
 
diff --git a/mesonbuild/interpreter/mesonmain.py b/mesonbuild/interpreter/mesonmain.py
index 602575c57..d22d36bf0 100644
--- a/mesonbuild/interpreter/mesonmain.py
+++ b/mesonbuild/interpreter/mesonmain.py
@@ -129,7 +129,7 @@ class MesonMain(MesonInterpreterObject):
     def add_install_script_method(
             self,
             args: T.Tuple[T.Union[str, mesonlib.File, build.Executable, ExternalProgram],
-                          T.List[T.Union[str, mesonlib.File, build.BuildTarget, build.CustomTarget, build.CustomTargetIndex, ExternalProgram]]],
+                          T.List[T.Union[str, mesonlib.File, build.BuildTargetTypes, ExternalProgram]]],
             kwargs: 'AddInstallScriptKW') -> None:
         script_args = self._process_script_args('add_install_script', args[1])
         script = self._find_source_script('add_install_script', args[0], script_args)
diff --git a/mesonbuild/interpreter/type_checking.py b/mesonbuild/interpreter/type_checking.py
index a551d0f7c..567cd1e59 100644
--- a/mesonbuild/interpreter/type_checking.py
+++ b/mesonbuild/interpreter/type_checking.py
@@ -24,14 +24,14 @@ NoneType: T.Type[None] = type(None)
 if T.TYPE_CHECKING:
     from typing_extensions import Literal
 
-    from ..build import ObjectTypes
+    from ..build import ObjectTypes, GeneratedTypes, BuildTargetTypes
     from ..interpreterbase import TYPE_var
     from ..options import ElementaryOptionValues
     from ..mesonlib import EnvInitValueType
 
     _FullEnvInitValueType = T.Union[EnvironmentVariables, T.List[str], T.List[T.List[str]], EnvInitValueType, str, None]
     PkgConfigDefineType = T.Optional[T.Tuple[T.Tuple[str, str], ...]]
-    SourcesVarargsType = T.List[T.Union[str, File, CustomTarget, CustomTargetIndex, GeneratedList, StructuredSources, ExtractedObjects, BuildTarget]]
+    SourcesVarargsType = T.List[T.Union[str, File, GeneratedTypes, StructuredSources, ExtractedObjects, BuildTarget]]
 
 
 def in_set_validator(choices: T.Set[str]) -> T.Callable[[str], T.Optional[str]]:
@@ -269,7 +269,7 @@ DEPFILE_KW: KwargInfo[T.Optional[str]] = KwargInfo(
     validator=lambda x: 'Depfile must be a plain filename with a subdirectory' if has_path_sep(x) else None
 )
 
-DEPENDS_KW: KwargInfo[T.List[T.Union[BuildTarget, CustomTarget, CustomTargetIndex]]] = KwargInfo(
+DEPENDS_KW: KwargInfo[T.List[BuildTargetTypes]] = KwargInfo(
     'depends',
     ContainerTypeInfo(list, (BuildTarget, CustomTarget, CustomTargetIndex)),
     listify=True,
@@ -284,7 +284,7 @@ DEPEND_FILES_KW: KwargInfo[T.List[T.Union[str, File]]] = KwargInfo(
     default=[],
 )
 
-COMMAND_KW: KwargInfo[T.List[T.Union[str, BuildTarget, CustomTarget, CustomTargetIndex, ExternalProgram, File]]] = KwargInfo(
+COMMAND_KW: KwargInfo[T.List[T.Union[str, BuildTargetTypes, ExternalProgram, File]]] = KwargInfo(
     'command',
     ContainerTypeInfo(list, (str, BuildTarget, CustomTarget, CustomTargetIndex, ExternalProgram, File), allow_empty=False),
     required=True,
@@ -349,7 +349,7 @@ OUTPUT_KW: KwargInfo[str] = KwargInfo(
     validator=lambda x: _output_validator([x])
 )
 
-CT_INPUT_KW: KwargInfo[T.List[T.Union[str, File, ExternalProgram, BuildTarget, CustomTarget, CustomTargetIndex, ExtractedObjects, GeneratedList]]] = KwargInfo(
+CT_INPUT_KW: KwargInfo[T.List[T.Union[str, File, ExternalProgram, BuildTarget, GeneratedTypes, ExtractedObjects]]] = KwargInfo(
     'input',
     ContainerTypeInfo(list, (str, File, ExternalProgram, BuildTarget, CustomTarget, CustomTargetIndex, ExtractedObjects, GeneratedList)),
     listify=True,
@@ -461,7 +461,7 @@ LINK_WHOLE_KW: KwargInfo[T.List[T.Union[BothLibraries, StaticLibrary, CustomTarg
     validator=link_whole_validator,
 )
 
-DEPENDENCY_SOURCES_KW: KwargInfo[T.List[T.Union[str, File, CustomTarget, CustomTargetIndex, GeneratedList]]] = KwargInfo(
+DEPENDENCY_SOURCES_KW: KwargInfo[T.List[T.Union[str, File, GeneratedTypes]]] = KwargInfo(
     'sources',
     ContainerTypeInfo(list, (str, File, CustomTarget, CustomTargetIndex, GeneratedList)),
     listify=True,
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index b4505fdb9..aeda4837e 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -378,7 +378,7 @@ def list_deps_from_source(intr: IntrospectionInterpreter) -> T.List[T.Dict[str,
 def list_deps(coredata: cdata.CoreData, backend: backends.Backend) -> T.List[T.Dict[str, T.Union[str, T.List[str]]]]:
     result: T.Dict[str, T.Dict[str, T.Union[str, T.List[str]]]] = {}
 
-    def _src_to_str(src_file: T.Union[mesonlib.FileOrString, build.CustomTarget, build.StructuredSources, build.CustomTargetIndex, build.GeneratedList]) -> T.List[str]:
+    def _src_to_str(src_file: T.Union[mesonlib.FileOrString, build.GeneratedTypes, build.StructuredSources]) -> T.List[str]:
         if isinstance(src_file, str):
             return [src_file]
         if isinstance(src_file, mesonlib.File):
diff --git a/mesonbuild/modules/_qt.py b/mesonbuild/modules/_qt.py
index 7d52842f9..675c174a7 100644
--- a/mesonbuild/modules/_qt.py
+++ b/mesonbuild/modules/_qt.py
@@ -39,7 +39,7 @@ if T.TYPE_CHECKING:
         """Keyword arguments for the Resource Compiler method."""
 
         name: T.Optional[str]
-        sources: T.Sequence[T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
+        sources: T.Sequence[T.Union[FileOrString, build.GeneratedTypes]]
         extra_args: T.List[str]
         method: str
 
@@ -47,7 +47,7 @@ if T.TYPE_CHECKING:
 
         """Keyword arguments for the Ui Compiler method."""
 
-        sources: T.Sequence[T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
+        sources: T.Sequence[T.Union[FileOrString, build.GeneratedTypes]]
         extra_args: T.List[str]
         method: str
         preserve_paths: bool
@@ -56,8 +56,8 @@ if T.TYPE_CHECKING:
 
         """Keyword arguments for the Moc Compiler method."""
 
-        sources: T.Sequence[T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
-        headers: T.Sequence[T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
+        sources: T.Sequence[T.Union[FileOrString, build.GeneratedTypes]]
+        headers: T.Sequence[T.Union[FileOrString, build.GeneratedTypes]]
         extra_args: T.List[str]
         method: str
         include_directories: T.List[T.Union[str, build.IncludeDirs]]
@@ -94,7 +94,7 @@ if T.TYPE_CHECKING:
         method: str
         qresource: T.Optional[str]
         rcc_extra_arguments: T.List[str]
-        ts_files: T.List[T.Union[str, File, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]]
+        ts_files: T.List[T.Union[str, File, build.GeneratedTypes]]
 
     class GenQrcKwArgs(TypedDict):
 
@@ -325,7 +325,7 @@ class QtBaseModule(ExtensionModule):
             raise MesonException(f'Unable to parse resource file {abspath}')
 
     def _parse_qrc_deps(self, state: ModuleState,
-                        rcc_file_: T.Union[FileOrString, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]) -> T.List[File]:
+                        rcc_file_: T.Union[FileOrString, build.GeneratedTypes]) -> T.List[File]:
         result: T.List[File] = []
         inputs: T.Sequence['FileOrString'] = []
         if isinstance(rcc_file_, (str, File)):
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index 6a7685390..9e525601e 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -648,7 +648,7 @@ class GnomeModule(ExtensionModule):
         return link_command, new_depends
 
     def _get_dependencies_flags_raw(
-            self, deps: T.Sequence[T.Union['Dependency', build.BuildTarget, CustomTarget, CustomTargetIndex]],
+            self, deps: T.Sequence[T.Union['Dependency', build.BuildTargetTypes]],
             state: 'ModuleState',
             depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]],
             include_rpath: bool,
@@ -741,7 +741,7 @@ class GnomeModule(ExtensionModule):
         return cflags, internal_ldflags, external_ldflags, gi_includes, depends
 
     def _get_dependencies_flags(
-            self, deps: T.Sequence[T.Union['Dependency', build.BuildTarget, CustomTarget, CustomTargetIndex]],
+            self, deps: T.Sequence[T.Union['Dependency', build.BuildTargetTypes]],
             state: 'ModuleState',
             depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]],
             include_rpath: bool = False,
@@ -895,8 +895,8 @@ class GnomeModule(ExtensionModule):
 
     @staticmethod
     def _get_gir_targets_deps(girtargets: T.Sequence[build.BuildTarget]
-                              ) -> T.List[T.Union[build.BuildTarget, CustomTarget, CustomTargetIndex, Dependency]]:
-        ret: T.List[T.Union[build.BuildTarget, CustomTarget, CustomTargetIndex, Dependency]] = []
+                              ) -> T.List[T.Union[build.BuildTargetTypes, Dependency]]:
+        ret: T.List[T.Union[build.BuildTargetTypes, Dependency]] = []
         for girtarget in girtargets:
             ret += girtarget.get_all_link_deps()
             ret += girtarget.get_external_deps()
@@ -972,7 +972,7 @@ class GnomeModule(ExtensionModule):
             state: 'ModuleState',
             girfile: str,
             scan_command: T.Sequence[T.Union['FileOrString', Executable, ExternalProgram, OverrideProgram]],
-            generated_files: T.Sequence[T.Union[str, mesonlib.File, CustomTarget, CustomTargetIndex, GeneratedList]],
+            generated_files: T.Sequence[T.Union[str, mesonlib.File, build.GeneratedTypes]],
             depends: T.Sequence[T.Union['FileOrString', build.BuildTarget, 'build.GeneratedTypes', build.StructuredSources]],
             env_flags: T.Sequence[str],
             kwargs: T.Dict[str, T.Any]) -> GirTarget:
@@ -1021,7 +1021,7 @@ class GnomeModule(ExtensionModule):
     @staticmethod
     def _make_typelib_target(state: 'ModuleState', typelib_output: str,
                              typelib_cmd: T.Sequence[T.Union[str, Executable, ExternalProgram, CustomTarget]],
-                             generated_files: T.Sequence[T.Union[str, mesonlib.File, CustomTarget, CustomTargetIndex, GeneratedList]],
+                             generated_files: T.Sequence[T.Union[str, mesonlib.File, build.GeneratedTypes]],
                              kwargs: T.Dict[str, T.Any]) -> TypelibTarget:
         install = kwargs['install_typelib']
         if install is None:
@@ -1051,7 +1051,7 @@ class GnomeModule(ExtensionModule):
     @staticmethod
     def _gather_typelib_includes_and_update_depends(
             state: 'ModuleState',
-            deps: T.Sequence[T.Union[Dependency, build.BuildTarget, CustomTarget, CustomTargetIndex]],
+            deps: T.Sequence[T.Union[Dependency, build.BuildTargetTypes]],
             depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]
             ) -> T.Tuple[T.List[str], T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]]:
         # Need to recursively add deps on GirTarget sources from our
@@ -2041,13 +2041,13 @@ class GnomeModule(ExtensionModule):
     def _make_mkenum_impl(
             self,
             state: 'ModuleState',
-            sources: T.Sequence[T.Union[str, mesonlib.File, CustomTarget, CustomTargetIndex, GeneratedList]],
+            sources: T.Sequence[T.Union[str, mesonlib.File, build.GeneratedTypes]],
             output: str,
             cmd: T.List[str],
             *,
             install: bool = False,
             install_dir: T.Optional[T.Sequence[T.Union[str, bool]]] = None,
-            depends: T.Optional[T.Sequence[T.Union[CustomTarget, CustomTargetIndex, BuildTarget]]] = None
+            depends: T.Optional[T.Sequence[build.BuildTargetTypes]] = None
             ) -> build.CustomTarget:
         real_cmd: T.List[T.Union[str, 'ToolType']] = [self._find_tool(state, 'glib-mkenums')]
         real_cmd.extend(cmd)
diff --git a/mesonbuild/modules/i18n.py b/mesonbuild/modules/i18n.py
index 8b8306584..2d8d04d3e 100644
--- a/mesonbuild/modules/i18n.py
+++ b/mesonbuild/modules/i18n.py
@@ -56,16 +56,15 @@ if T.TYPE_CHECKING:
     class ItsJoinFile(TypedDict):
 
         input: T.List[T.Union[
-            str, build.BuildTarget, build.CustomTarget, build.CustomTargetIndex,
-            build.ExtractedObjects, build.GeneratedList, ExternalProgram,
-            mesonlib.File]]
+            str, build.BuildTarget, build.GeneratedTypes,
+            build.ExtractedObjects, ExternalProgram, mesonlib.File]]
         output: str
         build_by_default: bool
         install: bool
         install_dir: T.Optional[str]
         install_tag: T.Optional[str]
         its_files: T.List[str]
-        mo_targets: T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]
+        mo_targets: T.List[build.BuildTargetTypes]
 
     class XgettextProgramT(TypedDict):
 
@@ -75,7 +74,7 @@ if T.TYPE_CHECKING:
         install_dir: T.Optional[str]
         install_tag: T.Optional[str]
 
-    SourcesType = T.Union[str, mesonlib.File, build.BuildTarget, build.BothLibraries, build.CustomTarget, build.CustomTargetIndex]
+    SourcesType = T.Union[str, mesonlib.File, build.BuildTargetTypes, build.BothLibraries]
 
 
 _ARGS: KwargInfo[T.List[str]] = KwargInfo(
@@ -239,7 +238,7 @@ class XgettextProgram:
         return mesonlib.File.from_built_file(self.interpreter.subdir, rsp_file.name)
 
     @staticmethod
-    def _get_source_id(sources: T.Iterable[T.Union[SourcesType, build.CustomTargetIndex]]) -> T.Iterable[str]:
+    def _get_source_id(sources: T.Iterable[SourcesType]) -> T.Iterable[str]:
         for source in sources:
             if isinstance(source, build.Target):
                 yield source.get_id()
@@ -309,8 +308,7 @@ class I18nModule(ExtensionModule):
         ddirs = self._get_data_dirs(state, kwargs['data_dirs'])
         datadirs = '--datadirs=' + ':'.join(ddirs) if ddirs else None
 
-        command: T.List[T.Union[str, build.BuildTarget, build.CustomTarget,
-                                build.CustomTargetIndex, 'ExternalProgram', mesonlib.File]] = []
+        command: T.List[T.Union[str, build.BuildTargetTypes, ExternalProgram, mesonlib.File]] = []
         command.extend(state.environment.get_build_command())
         command.extend([
             '--internal', 'msgfmthelper',
@@ -489,8 +487,7 @@ class I18nModule(ExtensionModule):
         for target in mo_targets:
             mo_fnames.append(path.join(target.get_subdir(), target.get_outputs()[0]))
 
-        command: T.List[T.Union[str, build.BuildTarget, build.CustomTarget,
-                                build.CustomTargetIndex, 'ExternalProgram', mesonlib.File]] = []
+        command: T.List[T.Union[str, build.BuildTargetTypes, ExternalProgram, mesonlib.File]] = []
         command.extend(state.environment.get_build_command())
 
         itstool_cmd = self.tools['itstool'].get_command()