Use tomllib on Python 3.11

docs/installation.rst

@@ -37,8 +37,8 @@ This package can build itself with only the ``toml`` and ``pep517``
 dependencies. The ``--skip-dependency-check`` flag should be used in this
 case.
 
-We have a dependency on tomli_, but toml_ can be used instead, which may make
-bootstrapping easier.
+On Python 3.10 and older, we have a dependency on tomli_, but toml_ can be
+used instead, which may make bootstrapping easier.
 
 
 Compatibility

setup.cfg

@@ -28,9 +28,9 @@ packages = find:
 install_requires =
     packaging>=19.0
     pep517>=0.9.1
-    tomli>=1.0.0 # toml can be used instead -- in case it makes bootstrapping easier
     colorama;os_name == "nt" # not actually a runtime dependency, only supplied as there is not "recommended dependency" support
     importlib-metadata>=0.22;python_version < "3.8"
+    tomli>=1.0.0;python_version < "3.11" # toml can be used instead -- in case it makes bootstrapping easier
 python_requires = >=3.6
 package_dir =
     =src

src/build/__init__.py

@@ -40,13 +40,16 @@
 TOMLDecodeError: Type[Exception]
 toml_loads: Callable[[str], MutableMapping[str, Any]]
 
-
 try:
-    from tomli import TOMLDecodeError
-    from tomli import loads as toml_loads
-except ModuleNotFoundError:  # pragma: no cover
-    from toml import TomlDecodeError as TOMLDecodeError  # type: ignore
-    from toml import loads as toml_loads  # type: ignore
+    from tomllib import TOMLDecodeError  # type: ignore
+    from tomllib import loads as toml_loads  # type: ignore
+except ModuleNotFoundError:
+    try:
+        from tomli import TOMLDecodeError
+        from tomli import loads as toml_loads
+    except ModuleNotFoundError:  # pragma: no cover
+        from toml import TomlDecodeError as TOMLDecodeError  # type: ignore
+        from toml import loads as toml_loads  # type: ignore
 
 
 RunnerType = Callable[[Sequence[str], Optional[str], Optional[Mapping[str, str]]], None]