environment: make fully type safe

This as much as anything is to stop lying to envconfig about the
potential types it will be given.

mesonbuild/envconfig.py

@@ -13,6 +13,9 @@
 from . import mlog
 from pathlib import Path
 
+if T.TYPE_CHECKING:
+    from .options import ElementaryOptionValues
+
 
 # These classes contains all the data pulled from configuration files (native
 # and cross file currently), and also assists with the reading environment
@@ -152,7 +155,7 @@ class CMakeSkipCompilerTest(Enum):
 class Properties:
     def __init__(
             self,
-            properties: T.Optional[T.Dict[str, T.Optional[T.Union[str, bool, int, T.List[str]]]]] = None,
+            properties: T.Optional[T.Dict[str, ElementaryOptionValues]] = None,
     ):
         self.properties = properties or {}
 
@@ -269,7 +272,9 @@ def __repr__(self) -> str:
         return f'<MachineInfo: {self.system} {self.cpu_family} ({self.cpu})>'
 
     @classmethod
-    def from_literal(cls, literal: T.Dict[str, str]) -> 'MachineInfo':
+    def from_literal(cls, raw: T.Dict[str, ElementaryOptionValues]) -> 'MachineInfo':
+        assert all(isinstance(v, str) for v in raw.values()), 'for mypy'
+        literal = T.cast('T.Dict[str, str]', raw)
         minimum_literal = {'cpu', 'cpu_family', 'endian', 'system'}
         if set(literal) < minimum_literal:
             raise EnvironmentException(
@@ -388,7 +393,7 @@ class BinaryTable:
 
     def __init__(
             self,
-            binaries: T.Optional[T.Dict[str, T.Union[str, T.List[str]]]] = None,
+            binaries: T.Optional[T.Mapping[str, ElementaryOptionValues]] = None,
     ):
         self.binaries: T.Dict[str, T.List[str]] = {}
         if binaries:

mesonbuild/environment.py

@@ -42,9 +42,8 @@
 from mesonbuild import envconfig
 
 if T.TYPE_CHECKING:
-    from configparser import ConfigParser
-
     from .compilers import Compiler
+    from .options import ElementaryOptionValues
     from .wrap.wrap import Resolver
 
     CompilersDict = T.Dict[str, Compiler]
@@ -698,7 +697,8 @@ def __init__(self, source_dir: str, build_dir: str, cmd_options: coredata.Shared
         self.default_pkgconfig = ['pkg-config']
         self.wrap_resolver: T.Optional['Resolver'] = None
 
-    def _load_machine_file_options(self, config: 'ConfigParser', properties: Properties, machine: MachineChoice) -> None:
+    def _load_machine_file_options(self, config: T.Mapping[str, T.Mapping[str, ElementaryOptionValues]],
+                                   properties: Properties, machine: MachineChoice) -> None:
         """Read the contents of a Machine file and put it in the options store."""
 
         # Look for any options in the deprecated paths section, warn about
@@ -708,6 +708,7 @@ def _load_machine_file_options(self, config: 'ConfigParser', properties: Propert
         if paths:
             mlog.deprecation('The [paths] section is deprecated, use the [built-in options] section instead.')
             for k, v in paths.items():
+                assert isinstance(v, (str, list)), 'for mypy'
                 self.options[OptionKey.from_string(k).evolve(machine=machine)] = v
 
         # Next look for compiler options in the "properties" section, this is
@@ -720,6 +721,7 @@ def _load_machine_file_options(self, config: 'ConfigParser', properties: Propert
         for k, v in properties.properties.copy().items():
             if k in deprecated_properties:
                 mlog.deprecation(f'{k} in the [properties] section of the machine file is deprecated, use the [built-in options] section.')
+                assert isinstance(v, (str, list)), 'for mypy'
                 self.options[OptionKey.from_string(k).evolve(machine=machine)] = v
                 del properties.properties[k]
 
@@ -736,6 +738,7 @@ def _load_machine_file_options(self, config: 'ConfigParser', properties: Propert
                         mlog.deprecation('Setting build machine options in cross files, please use a native file instead, this will be removed in meson 2.0', once=True)
                     if key.subproject:
                         raise MesonException('Do not set subproject options in [built-in options] section, use [subproject:built-in options] instead.')
+                    assert isinstance(v, (str, list)), 'for mypy'
                     self.options[key.evolve(subproject=subproject, machine=machine)] = v
             elif section == 'project options' and machine is MachineChoice.HOST:
                 # Project options are only for the host machine, we don't want
@@ -745,6 +748,7 @@ def _load_machine_file_options(self, config: 'ConfigParser', properties: Propert
                     key = OptionKey.from_string(k)
                     if key.subproject:
                         raise MesonException('Do not set subproject options in [built-in options] section, use [subproject:built-in options] instead.')
+                    assert isinstance(v, (str, list)), 'for mypy'
                     self.options[key.evolve(subproject=subproject)] = v
 
     def _set_default_options_from_env(self) -> None:

run_mypy.py

@@ -36,6 +36,7 @@
     'mesonbuild/coredata.py',
     'mesonbuild/depfile.py',
     'mesonbuild/envconfig.py',
+    'mesonbuild/environment.py',
     'mesonbuild/interpreter/compiler.py',
     'mesonbuild/interpreter/mesonmain.py',
     'mesonbuild/interpreter/interpreterobjects.py',