Remove useless EmptyExternalProgram

It is only used by Environment.get_exe_wrapper() and every callers were
handling None already. Type annotation was wrong, it already could
return None for the case an exe wrapper is needed but none is provided.

mesonbuild/backend/backends.py

@@ -1108,10 +1108,7 @@ class Backend:
                         break
 
             is_cross = self.environment.is_cross_build(test_for_machine)
-            if is_cross and self.environment.need_exe_wrapper():
-                exe_wrapper = self.environment.get_exe_wrapper()
-            else:
-                exe_wrapper = None
+            exe_wrapper = self.environment.get_exe_wrapper()
             machine = self.environment.machines[exe.for_machine]
             if machine.is_windows() or machine.is_cygwin():
                 extra_bdeps: T.List[T.Union[build.BuildTarget, build.CustomTarget]] = []

mesonbuild/environment.py

@@ -25,9 +25,7 @@ from .mesonlib import (
     search_version, MesonBugException
 )
 from . import mlog
-from .programs import (
-    ExternalProgram, EmptyExternalProgram
-)
+from .programs import ExternalProgram
 
 from .envconfig import (
     BinaryTable, MachineInfo, Properties, known_cpu_families, CMakeVariables,
@@ -852,7 +850,7 @@ class Environment:
             return value
         return not machine_info_can_run(self.machines[for_machine])
 
-    def get_exe_wrapper(self) -> ExternalProgram:
+    def get_exe_wrapper(self) -> T.Optional[ExternalProgram]:
         if not self.need_exe_wrapper():
-            return EmptyExternalProgram()
+            return None
         return self.exe_wrapper

mesonbuild/modules/gnome.py

@@ -39,7 +39,7 @@ from ..interpreterbase.decorators import typed_pos_args
 from ..mesonlib import (
     MachineChoice, MesonException, OrderedSet, Popen_safe, join_args,
 )
-from ..programs import OverrideProgram, EmptyExternalProgram
+from ..programs import OverrideProgram
 from ..scripts.gettext import read_linguas
 
 if T.TYPE_CHECKING:
@@ -1464,9 +1464,8 @@ class GnomeModule(ExtensionModule):
             t_args.append(f'--{program_name}={path}')
         if namespace:
             t_args.append('--namespace=' + namespace)
-        # if not need_exe_wrapper, we get an EmptyExternalProgram. If none provided, we get NoneType
         exe_wrapper = state.environment.get_exe_wrapper()
-        if not isinstance(exe_wrapper, (NoneType, EmptyExternalProgram)):
+        if exe_wrapper:
             t_args.append('--run=' + ' '.join(exe_wrapper.get_command()))
         t_args.append(f'--htmlargs={"@@".join(kwargs["html_args"])}')
         t_args.append(f'--scanargs={"@@".join(kwargs["scan_args"])}')

mesonbuild/programs.py

@@ -345,25 +345,6 @@ class NonExistingExternalProgram(ExternalProgram):  # lgtm [py/missing-call-to-i
         return False
 
 
-class EmptyExternalProgram(ExternalProgram):  # lgtm [py/missing-call-to-init]
-    '''
-    A program object that returns an empty list of commands. Used for cases
-    such as a cross file exe_wrapper to represent that it's not required.
-    '''
-
-    def __init__(self) -> None:
-        self.name = None
-        self.command = []
-        self.path = None
-
-    def __repr__(self) -> str:
-        r = '<{} {!r} -> {!r}>'
-        return r.format(self.__class__.__name__, self.name, self.command)
-
-    def found(self) -> bool:
-        return True
-
-
 class OverrideProgram(ExternalProgram):
 
     """A script overriding a program."""