interpreter: use kwarginfo for build_target(target_type)

Which lets us remove a bunch of validation code

mesonbuild/interpreter/interpreter.py

@@ -1877,17 +1877,12 @@ class Interpreter(InterpreterBase, HoldableObject):
                           kwargs: kwtypes.BuildTarget
                           ) -> T.Union[build.Executable, build.StaticLibrary, build.SharedLibrary,
                                        build.SharedModule, build.BothLibraries, build.Jar]:
-        if 'target_type' not in kwargs:
-            raise InterpreterException('Missing target_type keyword argument')
-        target_type = kwargs.pop('target_type')
+        target_type = kwargs['target_type']
         if target_type == 'executable':
             return self.build_target(node, args, kwargs, build.Executable)
         elif target_type == 'shared_library':
             return self.build_target(node, args, kwargs, build.SharedLibrary)
         elif target_type == 'shared_module':
-            FeatureNew.single_use(
-                'build_target(target_type: \'shared_module\')',
-                '0.51.0', self.subproject, location=node)
             return self.build_target(node, args, kwargs, build.SharedModule)
         elif target_type == 'static_library':
             return self.build_target(node, args, kwargs, build.StaticLibrary)
@@ -1895,10 +1890,7 @@ class Interpreter(InterpreterBase, HoldableObject):
             return self.build_both_libraries(node, args, kwargs)
         elif target_type == 'library':
             return self.build_library(node, args, kwargs)
-        elif target_type == 'jar':
-            return self.build_target(node, args, kwargs, build.Jar)
-        else:
-            raise InterpreterException('Unknown target_type.')
+        return self.build_target(node, args, kwargs, build.Jar)
 
     @noPosargs
     @typed_kwargs(

mesonbuild/interpreter/kwargs.py

@@ -348,7 +348,9 @@ class Library(_BuildTarget):
 
 
 class BuildTarget(Library):
-    pass
+
+    target_type: Literal['executable', 'shared_library', 'static_library',
+                         'shared_module', 'both_libraries', 'library', 'jar']
 
 
 class Jar(_BaseBuildTarget):

mesonbuild/interpreter/type_checking.py

@@ -556,4 +556,16 @@ BUILD_TARGET_KWS = [
     *LIBRARY_KWS,
     *_EXCLUSIVE_EXECUTABLE_KWS,
     *_EXCLUSIVE_JAR_KWS,
+    KwargInfo(
+        'target_type',
+        str,
+        required=True,
+        validator=in_set_validator({
+            'executable', 'shared_library', 'static_library', 'shared_module',
+            'both_libraries', 'library', 'jar'
+        }),
+        since_values={
+            'shared_module': '0.51.0',
+        }
+    )
 ]