backend: fix type annotation of Backend.generate

`func(value: dict = None)` is invalid, it must be `func(value: dict |
None = None)`, or in our older syntax: `T.Optional[T.Dict] = None`

mesonbuild/backend/backends.py

@@ -287,7 +287,7 @@ class Backend:
     # 'vslite_ctx' is only provided when
     # we expect this backend setup/generation to make use of previously captured
     # compile args (as is the case when using '--genvslite').
-    def generate(self, capture: bool = False, vslite_ctx: dict = None) -> T.Optional[dict]:
+    def generate(self, capture: bool = False, vslite_ctx: T.Optional[T.Dict] = None) -> T.Optional[T.Dict]:
         raise RuntimeError(f'generate is not implemented in {type(self).__name__}')
 
     def get_target_filename(self, t: T.Union[build.Target, build.CustomTargetIndex], *, warn_multi_output: bool = True) -> str:

mesonbuild/backend/ninjabackend.py

@@ -581,7 +581,7 @@ class NinjaBackend(backends.Backend):
 
         raise MesonException(f'Could not determine vs dep dependency prefix string. output: {stderr} {stdout}')
 
-    def generate(self, capture: bool = False, vslite_ctx: dict = None) -> T.Optional[dict]:
+    def generate(self, capture: bool = False, vslite_ctx: T.Optional[T.Dict] = None) -> T.Optional[T.Dict]:
         if vslite_ctx:
             # We don't yet have a use case where we'd expect to make use of this,
             # so no harm in catching and reporting something unexpected.

mesonbuild/backend/nonebackend.py

@@ -2,6 +2,7 @@
 # Copyright 2022 The Meson development team
 
 from __future__ import annotations
+import typing as T
 
 from .backends import Backend
 from .. import mlog
@@ -12,7 +13,7 @@ class NoneBackend(Backend):
 
     name = 'none'
 
-    def generate(self, capture: bool = False, vslite_ctx: dict = None) -> None:
+    def generate(self, capture: bool = False, vslite_ctx: T.Optional[T.Dict] = None) -> None:
         # Check for (currently) unexpected capture arg use cases -
         if capture:
             raise MesonBugException('We do not expect the none backend to generate with \'capture = True\'')

mesonbuild/backend/vs2010backend.py

@@ -221,7 +221,7 @@ class Vs2010Backend(backends.Backend):
 
     def generate(self,
                  capture: bool = False,
-                 vslite_ctx: dict = None) -> T.Optional[dict]:
+                 vslite_ctx: T.Optional[T.Dict] = None) -> T.Optional[T.Dict]:
         # Check for (currently) unexpected capture arg use cases -
         if capture:
             raise MesonBugException('We do not expect any vs backend to generate with \'capture = True\'')

mesonbuild/backend/xcodebackend.py

@@ -255,7 +255,7 @@ class XCodeBackend(backends.Backend):
             result.append(os.path.join(self.environment.get_build_dir(), self.get_target_dir(l)))
         return result
 
-    def generate(self, capture: bool = False, vslite_ctx: dict = None) -> None:
+    def generate(self, capture: bool = False, vslite_ctx: T.Optional[T.Dict] = None) -> None:
         # Check for (currently) unexpected capture arg use cases -
         if capture:
             raise MesonBugException('We do not expect the xcode backend to generate with \'capture = True\'')