FeatureNew: add mypy type annotations for subproject arg

Use a derived type when passing `subproject` around, so that mypy knows
it's actually a SubProject, not a str. This means that passing anything
other than a handle to the interpreter state's subproject attribute
becomes a type violation, specifically when the order of the *four*
different str arguments is typoed.

9 files changed, 28 insertions, 12 deletions

diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 782f59c..27e6d36 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -49,6 +49,7 @@ if T.TYPE_CHECKING:
     from ._typing import ImmutableListProtocol, ImmutableSetProtocol
     from .backend.backends import Backend, ExecutableSerialisation
     from .interpreter.interpreter import Test, SourceOutputs, Interpreter
+    from .interpreterbase import SubProject
     from .mesonlib import FileMode, FileOrString
     from .modules import ModuleState
     from .mparser import BaseNode
@@ -514,7 +515,7 @@ class Target(HoldableObject):
 
     name: str
     subdir: str
-    subproject: str
+    subproject: 'SubProject'
     build_by_default: bool
     for_machine: MachineChoice
 
@@ -675,7 +676,7 @@ class BuildTarget(Target):
 
     install_dir: T.List[T.Union[str, bool]]
 
-    def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
+    def __init__(self, name: str, subdir: str, subproject: 'SubProject', for_machine: MachineChoice,
                  sources: T.List['SourceOutputs'], objects, environment: environment.Environment, kwargs):
         super().__init__(name, subdir, subproject, True, for_machine)
         unity_opt = environment.coredata.get_option(OptionKey('unity'))
diff --git a/mesonbuild/interpreter/interpreterobjects.py b/mesonbuild/interpreter/interpreterobjects.py
index 6b7cbcd..989877e 100644
--- a/mesonbuild/interpreter/interpreterobjects.py
+++ b/mesonbuild/interpreter/interpreterobjects.py
@@ -31,6 +31,7 @@ if T.TYPE_CHECKING:
     from . import kwargs
     from .interpreter import Interpreter
     from ..envconfig import MachineInfo
+    from ..interpreterbase import SubProject
 
     from typing_extensions import TypedDict
 
@@ -40,7 +41,7 @@ if T.TYPE_CHECKING:
 
 
 def extract_required_kwarg(kwargs: 'kwargs.ExtractRequired',
-                           subproject: str,
+                           subproject: 'SubProject',
                            feature_check: T.Optional[FeatureCheckBase] = None,
                            default: bool = True) -> T.Tuple[bool, bool, T.Optional[str]]:
     val = kwargs.get('required', default)
diff --git a/mesonbuild/interpreter/primitives/range.py b/mesonbuild/interpreter/primitives/range.py
index 9054278..a35470c 100644
--- a/mesonbuild/interpreter/primitives/range.py
+++ b/mesonbuild/interpreter/primitives/range.py
@@ -10,8 +10,11 @@ from ...interpreterbase import (
     InvalidArguments,
 )
 
+if T.TYPE_CHECKING:
+    from ...interpreterbase import SubProject
+
 class RangeHolder(MesonInterpreterObject, IterableObject):
-    def __init__(self, start: int, stop: int, step: int, *, subproject: str) -> None:
+    def __init__(self, start: int, stop: int, step: int, *, subproject: 'SubProject') -> None:
         super().__init__(subproject=subproject)
         self.range = range(start, stop, step)
         self.operators.update({
diff --git a/mesonbuild/interpreterbase/__init__.py b/mesonbuild/interpreterbase/__init__.py
index 7c4b1db..13f55e5 100644
--- a/mesonbuild/interpreterbase/__init__.py
+++ b/mesonbuild/interpreterbase/__init__.py
@@ -57,6 +57,8 @@ __all__ = [
 
     'InterpreterBase',
 
+    'SubProject',
+
     'TV_fw_var',
     'TV_fw_args',
     'TV_fw_kwargs',
@@ -91,6 +93,8 @@ from .baseobjects import (
     TYPE_key_resolver,
     TYPE_HoldableTypes,
 
+    SubProject,
+
     HoldableTypes,
 )
 
diff --git a/mesonbuild/interpreterbase/baseobjects.py b/mesonbuild/interpreterbase/baseobjects.py
index ca17481..7186001 100644
--- a/mesonbuild/interpreterbase/baseobjects.py
+++ b/mesonbuild/interpreterbase/baseobjects.py
@@ -39,6 +39,8 @@ TYPE_kwargs = T.Dict[str, TYPE_var]
 TYPE_nkwargs = T.Dict[str, TYPE_nvar]
 TYPE_key_resolver = T.Callable[[mparser.BaseNode], str]
 
+SubProject = T.NewType('SubProject', str)
+
 if T.TYPE_CHECKING:
     from typing_extensions import Protocol
     __T = T.TypeVar('__T', bound=TYPE_var, contravariant=True)
@@ -47,7 +49,7 @@ if T.TYPE_CHECKING:
         def __call__(self, other: __T) -> TYPE_var: ...
 
 class InterpreterObject:
-    def __init__(self, *, subproject: T.Optional[str] = None) -> None:
+    def __init__(self, *, subproject: T.Optional['SubProject'] = None) -> None:
         self.methods: T.Dict[
             str,
             T.Callable[[T.List[TYPE_var], TYPE_kwargs], TYPE_var]
@@ -63,7 +65,7 @@ class InterpreterObject:
         # Current node set during a method call. This can be used as location
         # when printing a warning message during a method call.
         self.current_node:  mparser.BaseNode = None
-        self.subproject: str = subproject or ''
+        self.subproject = subproject or SubProject('')
 
         # Some default operators supported by all objects
         self.operators.update({
diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index c6fcaa0..f104ac6 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -27,8 +27,9 @@ import copy
 import typing as T
 if T.TYPE_CHECKING:
     from .. import mparser
+    from .interpreterbase import SubProject
 
-def get_callee_args(wrapped_args: T.Sequence[T.Any]) -> T.Tuple['mparser.BaseNode', T.List['TYPE_var'], 'TYPE_kwargs', str]:
+def get_callee_args(wrapped_args: T.Sequence[T.Any]) -> T.Tuple['mparser.BaseNode', T.List['TYPE_var'], 'TYPE_kwargs', 'SubProject']:
     # First argument could be InterpreterBase, InterpreterObject or ModuleObject.
     # In the case of a ModuleObject it is the 2nd argument (ModuleState) that
     # contains the needed information.
@@ -600,7 +601,7 @@ class FeatureCheckBase(metaclass=abc.ABCMeta):
     def check_version(target_version: str, feature_version: str) -> bool:
         pass
 
-    def use(self, subproject: str) -> None:
+    def use(self, subproject: 'SubProject') -> None:
         tv = self.get_target_version(subproject)
         # No target version
         if tv == '':
@@ -668,7 +669,7 @@ class FeatureCheckBase(metaclass=abc.ABCMeta):
         return T.cast(TV_func, wrapped)
 
     @classmethod
-    def single_use(cls, feature_name: str, version: str, subproject: str,
+    def single_use(cls, feature_name: str, version: str, subproject: 'SubProject',
                    extra_message: str = '', location: T.Optional['mparser.BaseNode'] = None) -> None:
         """Oneline version that instantiates and calls use()."""
         cls(feature_name, version, extra_message, location).use(subproject)
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index 99f6619..bd7d7f9 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -26,6 +26,8 @@ from .baseobjects import (
     ObjectHolder,
     IterableObject,
 
+    SubProject,
+
     TYPE_var,
     TYPE_kwargs,
 
@@ -73,7 +75,7 @@ FunctionType = T.Dict[
 ]
 
 class InterpreterBase:
-    def __init__(self, source_root: str, subdir: str, subproject: str):
+    def __init__(self, source_root: str, subdir: str, subproject: 'SubProject'):
         self.source_root = source_root
         self.funcs: FunctionType = {}
         self.builtin: T.Dict[str, InterpreterObject] = {}
diff --git a/mesonbuild/optinterpreter.py b/mesonbuild/optinterpreter.py
index 6155c2f..46a4445 100644
--- a/mesonbuild/optinterpreter.py
+++ b/mesonbuild/optinterpreter.py
@@ -22,6 +22,7 @@ from . import mlog
 from .interpreterbase import FeatureNew, typed_pos_args, typed_kwargs, ContainerTypeInfo, KwargInfo, permittedKwargs
 if T.TYPE_CHECKING:
     from .interpreterbase import TYPE_var, TYPE_kwargs
+    from .interpreterbase import SubProject
     from typing_extensions import TypedDict
     FuncOptionArgs = TypedDict('FuncOptionArgs', {
         'type': str,
@@ -50,7 +51,7 @@ optname_regex = re.compile('[^a-zA-Z0-9_-]')
 
 
 class OptionInterpreter:
-    def __init__(self, subproject: str) -> None:
+    def __init__(self, subproject: 'SubProject') -> None:
         self.options: 'coredata.KeyedOptionDictType' = {}
         self.subproject = subproject
         self.option_types = {'string': self.string_parser,
diff --git a/mesonbuild/wrap/wrap.py b/mesonbuild/wrap/wrap.py
index 21eb9d6..51632fd 100644
--- a/mesonbuild/wrap/wrap.py
+++ b/mesonbuild/wrap/wrap.py
@@ -35,6 +35,7 @@ from . import WrapMode
 from .. import coredata
 from ..mesonlib import quiet_git, GIT, ProgressBar, MesonException, windows_proof_rmtree
 from ..interpreterbase import FeatureNew
+from ..interpreterbase import SubProject
 from .. import mesonlib
 
 if T.TYPE_CHECKING:
@@ -95,7 +96,7 @@ class WrapNotFoundException(WrapException):
 class PackageDefinition:
     def __init__(self, fname: str, subproject: str = ''):
         self.filename = fname
-        self.subproject = subproject
+        self.subproject = SubProject(subproject)
         self.type = None  # type: T.Optional[str]
         self.values = {} # type: T.Dict[str, str]
         self.provided_deps = {} # type: T.Dict[str, T.Optional[str]]