dependencies/base: Make MissingCompiler inherit Compiler for mypy

This allows mypy and pyright to correctly determine the return types
from methods, but makes 0 changes at runtime.

mesonbuild/dependencies/base.py

@@ -39,15 +39,34 @@ if T.TYPE_CHECKING:
     )
     from ..interpreter.type_checking import PkgConfigDefineType
 
+    _MissingCompilerBase = Compiler
+else:
+    _MissingCompilerBase = object
+
 
 class DependencyException(MesonException):
     '''Exceptions raised while trying to find dependencies'''
 
 
-class MissingCompiler:
+class MissingCompiler(_MissingCompilerBase):
     """Represent a None Compiler - when no tool chain is found.
     replacing AttributeError with DependencyException"""
 
+    # These are needed in type checking mode to avoid errors, but we don't want
+    # the extra overhead at runtime
+    if T.TYPE_CHECKING:
+        def __init__(self) -> None:
+            pass
+
+        def get_optimization_args(self, optimization_level: str) -> T.List[str]:
+            return []
+
+        def get_output_args(self, outputname: str) -> T.List[str]:
+            return []
+
+        def sanity_check(self, work_dir: str, environment: 'Environment') -> None:
+            return None
+
     def __getattr__(self, item: str) -> T.Any:
         if item.startswith('__'):
             raise AttributeError()