build: add editable to dist type (#764)

* build: add `editable` to dist type

Closes #763.

* Merge literals

Author: layday

src/build/_builder.py

@@ -203,7 +203,11 @@ def build_system_requires(self) -> set[str]:
         """
         return set(self._build_system['requires'])
 
-    def get_requires_for_build(self, distribution: Distribution, config_settings: ConfigSettings | None = None) -> set[str]:
+    def get_requires_for_build(
+        self,
+        distribution: Distribution,
+        config_settings: ConfigSettings | None = None,
+    ) -> set[str]:
         """
         Return the dependencies defined by the backend in addition to
         :attr:`build_system_requires` for a given distribution.
@@ -220,7 +224,9 @@ def get_requires_for_build(self, distribution: Distribution, config_settings: Co
             return set(get_requires(config_settings))
 
     def check_dependencies(
-        self, distribution: Distribution, config_settings: ConfigSettings | None = None
+        self,
+        distribution: Distribution,
+        config_settings: ConfigSettings | None = None,
     ) -> set[tuple[str, ...]]:
         """
         Return the dependencies which are not satisfied from the combined set of

src/build/_types.py

@@ -5,7 +5,7 @@
 
 
 ConfigSettings = typing.Mapping[str, typing.Union[str, typing.Sequence[str]]]
-Distribution = typing.Literal['sdist', 'wheel']
+Distribution = typing.Literal['sdist', 'wheel', 'editable']
 StrPath = typing.Union[str, 'os.PathLike[str]']
 SubprocessRunner = typing.Callable[
     [typing.Sequence[str], typing.Optional[str], typing.Optional[typing.Mapping[str, str]]], None