interpreter: Add type checking for BuildTarget(install_dir: )

This just puts the type checking in the frontend, there's still some
serious cleanup in the build and backend that need to happen.

4 files changed, 15 insertions, 6 deletions

diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 2abe49686..37a437812 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -22,7 +22,7 @@ from . import programs
 from .mesonlib import (
     HoldableObject, SecondLevelHolder,
     File, MesonException, MachineChoice, PerMachine, OrderedSet, listify,
-    extract_as_list, typeslistify, classify_unity_sources,
+    extract_as_list, classify_unity_sources,
     get_filenames_templates_dict, substitute_values, has_path_sep,
     is_parent_path, relpath, PerMachineDefaultable,
     MesonBugException, EnvironmentVariables, pickle_load, lazy_property,
@@ -1291,8 +1291,7 @@ class BuildTarget(Target):
         self.add_deps(deplist)
         # If an item in this list is False, the output corresponding to
         # the list index of that item will not be installed
-        self.install_dir = typeslistify(kwargs.get('install_dir', []),
-                                        (str, bool))
+        self.install_dir = kwargs.get('install_dir', [])
         self.install_mode = kwargs.get('install_mode', None)
         self.install_tag: T.List[T.Optional[str]] = kwargs.get('install_tag') or [None]
         self.extra_files = kwargs.get('extra_files', [])
diff --git a/mesonbuild/interpreter/kwargs.py b/mesonbuild/interpreter/kwargs.py
index 517ccee15..c08ceb759 100644
--- a/mesonbuild/interpreter/kwargs.py
+++ b/mesonbuild/interpreter/kwargs.py
@@ -367,6 +367,7 @@ class _BuildTarget(_BaseBuildTarget):
     d_import_dirs: T.List[T.Union[str, build.IncludeDirs]]
     d_module_versions: T.List[T.Union[str, int]]
     d_unittest: bool
+    install_dir: T.List[T.Union[str, bool]]
     rust_crate_type: T.Optional[Literal['bin', 'lib', 'rlib', 'dylib', 'cdylib', 'staticlib', 'proc-macro']]
     rust_dependency_map: T.Dict[str, str]
     swift_interoperability_mode: Literal['c', 'cpp']
diff --git a/mesonbuild/interpreter/type_checking.py b/mesonbuild/interpreter/type_checking.py
index 7d6b0073a..478924828 100644
--- a/mesonbuild/interpreter/type_checking.py
+++ b/mesonbuild/interpreter/type_checking.py
@@ -614,6 +614,12 @@ _ALL_TARGET_KWS: T.List[KwargInfo] = [
     ),
     INSTALL_MODE_KW,
     INSTALL_TAG_KW,
+    KwargInfo(
+        'install_dir',
+        ContainerTypeInfo(list, (str, bool)),
+        default=[],
+        listify=True,
+    ),
     KwargInfo('implicit_include_directories', bool, default=True, since='0.42.0'),
     NATIVE_KW,
     KwargInfo('resources', ContainerTypeInfo(list, str), default=[], listify=True),
diff --git a/mesonbuild/modules/python.py b/mesonbuild/modules/python.py
index 99602c05a..3d8969f41 100644
--- a/mesonbuild/modules/python.py
+++ b/mesonbuild/modules/python.py
@@ -22,7 +22,7 @@ from ..interpreterbase import (
     InvalidArguments, typed_pos_args, typed_kwargs, KwargInfo,
     FeatureNew, disablerIfNotFound, InterpreterObject
 )
-from ..mesonlib import MachineChoice
+from ..mesonlib import MachineChoice, listify
 from ..options import OptionKey
 from ..programs import ExternalProgram, NonExistingExternalProgram
 
@@ -60,7 +60,8 @@ mod_kwargs = {'subdir', 'limited_api'}
 mod_kwargs.update(known_shmod_kwargs)
 mod_kwargs -= {'name_prefix', 'name_suffix'}
 
-_MOD_KWARGS = [k for k in SHARED_MOD_KWS if k.name not in {'name_prefix', 'name_suffix'}]
+_MOD_KWARGS = [k for k in SHARED_MOD_KWS if
+               k.name not in {'name_prefix', 'name_suffix', 'install_dir'}]
 
 
 class PythonExternalProgram(BasicPythonExternalProgram):
@@ -145,13 +146,15 @@ class PythonInstallation(_ExternalProgramHolder['PythonExternalProgram']):
         if 'install_dir' in kwargs:
             if kwargs['subdir'] is not None:
                 raise InvalidArguments('"subdir" and "install_dir" are mutually exclusive')
+            # the build_target() method now expects this to be correct.
+            kwargs['install_dir'] = listify(kwargs['install_dir'])
         else:
             # We want to remove 'subdir', but it may be None and we want to replace it with ''
             # It must be done this way since we don't allow both `install_dir`
             # and `subdir` to be set at the same time
             subdir = kwargs.pop('subdir') or ''
 
-            kwargs['install_dir'] = self._get_install_dir_impl(False, subdir)
+            kwargs['install_dir'] = [self._get_install_dir_impl(False, subdir)]
 
         target_suffix = self.suffix