dep.name(): return dependency name even if dependency is not found

The dep.name() function schould always return the name of the
dependency as documented. No matter if it was found or not.
https://mesonbuild.com/Reference-manual_returned_dep.html#depfound

mesonbuild/dependencies/base.py

@@ -394,10 +394,10 @@ class ExternalDependency(Dependency, HasNativeKwarg):
 
 
 class NotFoundDependency(Dependency):
-    def __init__(self, environment: 'Environment') -> None:
+    def __init__(self, name: str, environment: 'Environment') -> None:
         super().__init__(DependencyTypeName('not-found'), {})
         self.env = environment
-        self.name = 'not-found'
+        self.name = name
         self.is_found = False
 
     def get_partial_dependency(self, *, compile_args: bool = False,

mesonbuild/dependencies/detect.py

@@ -162,7 +162,7 @@ def find_external_dependency(name: str, env: 'Environment', kwargs: T.Dict[str,
         raise DependencyException('Dependency "%s" not found' % (name) +
                                   (', tried %s' % (tried) if tried else ''))
 
-    return NotFoundDependency(env)
+    return NotFoundDependency(name, env)
 
 
 def _build_external_dependency_list(name: str, env: 'Environment', for_machine: MachineChoice,

mesonbuild/interpreter/dependencyfallbacks.py

@@ -270,7 +270,7 @@ class DependencyFallbacksHolder(MesonInterpreterObject):
             FeatureNew.single_use('OpenMP Dependency', '0.46.0', self.subproject)
 
     def _notfound_dependency(self) -> NotFoundDependency:
-        return NotFoundDependency(self.environment)
+        return NotFoundDependency(self.names[0] if self.names else '', self.environment)
 
     @staticmethod
     def _check_version(wanted: T.Optional[str], found: str) -> bool:

mesonbuild/modules/python.py

@@ -494,10 +494,9 @@ class PythonInstallation(ExternalProgramHolder):
     @noPosargs
     def dependency_method(self, args: T.List['TYPE_var'], kwargs: 'TYPE_kwargs') -> 'Dependency':
         disabled, required, feature = extract_required_kwarg(kwargs, self.subproject)
-
         # it's theoretically (though not practically) possible for the else clse
         # to not bind dep, let's ensure it is.
-        dep: 'Dependency' = NotFoundDependency(self.interpreter.environment)
+        dep: 'Dependency' = NotFoundDependency('python', self.interpreter.environment)
         if disabled:
             mlog.log('Dependency', mlog.bold('python'), 'skipped: feature', mlog.bold(feature), 'disabled')
         else: