gh-93035: [Enum] Fix IntFlag crash when no single-bit members (GH-93076)

tyehle · web-flow · commit 08cfc3dabf0f · 2022-05-24T18:16:20.000-07:00
`EnumType` attempts to create a custom docstring for each enum/flag, but that was failing with pathological flags that had no members (only multi-bit aliases).
diff --git a/Lib/enum.py b/Lib/enum.py
@@ -538,7 +538,7 @@ def __new__(metacls, cls, bases, classdict, *, boundary=None, _simple=False, **k
         #
         # create a default docstring if one has not been provided
         if enum_class.__doc__ is None:
-            if not member_names:
+            if not member_names or not list(enum_class):
                 enum_class.__doc__ = classdict['__doc__'] = _dedent("""\
                         Create a collection of name/value pairs.
 

Original file line number	Diff line number	Diff line change
`@@ -538,7 +538,7 @@ def __new__(metacls, cls, bases, classdict, , boundary=None, _simple=False, *k`
`538`	`538`	`#`
`539`	`539`	`# create a default docstring if one has not been provided`
`540`	`540`	`if enum_class.__doc__ is None:`
`541`		`- if not member_names:`
	`541`	`+ if not member_names or not list(enum_class):`
`542`	`542`	`enum_class.__doc__ = classdict['__doc__'] = _dedent("""\`
`543`	`543`	`Create a collection of name/value pairs.`
`544`	`544`