[clang] [libclang/python] Refactor enum usage (PR #95608)

[Jannick Kremer via cfe-commits]

================
@@ -611,51 +612,25 @@ def register(value, name):
 
 
 ### Cursor Kinds ###
-class BaseEnumeration:
+class BaseEnumeration(Enum):
     """
     Common base class for named enumerations held in sync with Index.h values.
-
-    Subclasses must define their own _kinds and _name_map members, as:
-    _kinds = []
-    _name_map = None
-    These values hold the per-subclass instances and value-to-name mappings,
-    respectively.
-
     """
 
-    def __init__(self, value):
-        if value >= len(self.__class__._kinds):
-            self.__class__._kinds += [None] * (value - len(self.__class__._kinds) + 1)
-        if self.__class__._kinds[value] is not None:
-            raise ValueError(
-                "{0} value {1} already loaded".format(str(self.__class__), value)
-            )
-        self.value = value
-        self.__class__._kinds[value] = self
-        self.__class__._name_map = None
 
     def from_param(self):
         return self.value
 
-    @property
-    def name(self):
-        """Get the enumeration name of this cursor kind."""
-        if self._name_map is None:
-            self._name_map = {}
-            for key, value in self.__class__.__dict__.items():
-                if isinstance(value, self.__class__):
-                    self._name_map[value] = key
-        return self._name_map[self]
-
     @classmethod
     def from_id(cls, id):
-        if id < 0 or id >= len(cls._kinds) or cls._kinds[id] is None:
-            raise ValueError("Unknown template argument kind %d" % id)
-        return cls._kinds[id]
+        try:
+            return cls(id)
+        except ValueError:
+            raise ValueError("Unknown %s %d" % (cls.__name__, id)) from None
----------------
DeinAlptraum wrote:

Thank you for the feedback! I've removed the `try`-`except` block now so we're just using the `Enum` error message

Irrelevant now, but regarding `from None`:
This effectively removes the previous exception context. Since we are re-raising an exception here, we would get both the exception we raised ourselves _and_  the exception that we caught here.

E.g. currently we get 
```
>>> cindex.TokenKind.from_id(5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/data/shared/programming/repos/llvm-project/clang/bindings/python/clang/cindex.py", line 589, in from_id
    raise ValueError("Unknown %s %d" % (cls.__name__, id)) from None
ValueError: Unknown TokenKind 5
```

and without the `from None` we would get
```
>>> cindex.TokenKind.from_id(5)
Traceback (most recent call last):
  File "/data/shared/programming/repos/llvm-project/clang/bindings/python/clang/cindex.py", line 587, in from_id
    return cls(id)
           ^^^^^^^
  File "/usr/lib/python3.12/enum.py", line 757, in __call__
    return cls.__new__(cls, value)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/enum.py", line 1171, in __new__
    raise ve_exc
ValueError: 5 is not a valid TokenKind

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/data/shared/programming/repos/llvm-project/clang/bindings/python/clang/cindex.py", line 589, in from_id
    raise ValueError("Unknown %s %d" % (cls.__name__, id))
ValueError: Unknown TokenKind 5
```

https://github.com/llvm/llvm-project/pull/95608