cargo: Move toml implementation into its own module

Author: xclaesse

mesonbuild/cargo/interpreter.py

@@ -11,23 +11,19 @@
 
 from __future__ import annotations
 import dataclasses
-import importlib
-import json
 import os
-import shutil
 import collections
 import urllib.parse
 import itertools
 import typing as T
 
 from . import builder, version, cfg
-from ..mesonlib import MesonException, Popen_safe, MachineChoice
+from .toml import load_toml, TomlImplementationMissing
+from ..mesonlib import MesonException, MachineChoice
 from .. import coredata, mlog
 from ..wrap.wrap import PackageDefinition
 
 if T.TYPE_CHECKING:
-    from types import ModuleType
-
     from typing_extensions import Protocol, Self
 
     from . import manifest
@@ -45,25 +41,6 @@ class DataclassInstance(Protocol):
                               manifest.FixedBuildTarget)
 
 
-# tomllib is present in python 3.11, before that it is a pypi module called tomli,
-# we try to import tomllib, then tomli,
-# TODO: add a fallback to toml2json?
-tomllib: T.Optional[ModuleType] = None
-toml2json: T.Optional[str] = None
-for t in ['tomllib', 'tomli']:
-    try:
-        tomllib = importlib.import_module(t)
-        break
-    except ImportError:
-        pass
-else:
-    # TODO: it would be better to use an Executable here, which could be looked
-    # up in the cross file or provided by a wrap. However, that will have to be
-    # passed in externally, since we don't have (and I don't think we should),
-    # have access to the `Environment` for that in this module.
-    toml2json = shutil.which('toml2json')
-
-
 _EXTRA_KEYS_WARNING = (
     "This may (unlikely) be an error in the cargo manifest, or may be a missing "
     "implementation in Meson. If this issue can be reproduced with the latest "
@@ -72,29 +49,6 @@ class DataclassInstance(Protocol):
     "version that is generating this warning if possible."
 )
 
-class TomlImplementationMissing(MesonException):
-    pass
-
-
-def load_toml(filename: str) -> T.Dict[object, object]:
-    if tomllib:
-        with open(filename, 'rb') as f:
-            raw = tomllib.load(f)
-    else:
-        if toml2json is None:
-            raise TomlImplementationMissing('Could not find an implementation of tomllib, nor toml2json')
-
-        p, out, err = Popen_safe([toml2json, filename])
-        if p.returncode != 0:
-            raise MesonException('toml2json failed to decode output\n', err)
-
-        raw = json.loads(out)
-
-    if not isinstance(raw, dict):
-        raise MesonException("Cargo.toml isn't a dictionary? How did that happen?")
-
-    return raw
-
 
 def fixup_meson_varname(name: str) -> str:
     """Fixup a meson variable name

mesonbuild/cargo/toml.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+import importlib
+import shutil
+import json
+import typing as T
+
+from ..mesonlib import MesonException, Popen_safe
+if T.TYPE_CHECKING:
+    from types import ModuleType
+
+
+# tomllib is present in python 3.11, before that it is a pypi module called tomli,
+# we try to import tomllib, then tomli,
+tomllib: T.Optional[ModuleType] = None
+toml2json: T.Optional[str] = None
+for t in ['tomllib', 'tomli']:
+    try:
+        tomllib = importlib.import_module(t)
+        break
+    except ImportError:
+        pass
+else:
+    # TODO: it would be better to use an Executable here, which could be looked
+    # up in the cross file or provided by a wrap. However, that will have to be
+    # passed in externally, since we don't have (and I don't think we should),
+    # have access to the `Environment` for that in this module.
+    toml2json = shutil.which('toml2json')
+
+class TomlImplementationMissing(MesonException):
+    pass
+
+
+def load_toml(filename: str) -> T.Dict[str, object]:
+    if tomllib:
+        with open(filename, 'rb') as f:
+            raw = tomllib.load(f)
+    else:
+        if toml2json is None:
+            raise TomlImplementationMissing('Could not find an implementation of tomllib, nor toml2json')
+
+        p, out, err = Popen_safe([toml2json, filename])
+        if p.returncode != 0:
+            raise MesonException('toml2json failed to decode output\n', err)
+
+        raw = json.loads(out)
+
+    # tomllib.load() returns T.Dict[str, T.Any] but not other implementations.
+    return T.cast('T.Dict[str, object]', raw)