[MLIR][Python] MLIR Enum Python bindings infinite recursion (#151584) (#151588)

Fixes an infinite recursion bug when using I32BitEnumAttrCaseGroup with
python bindings.

For more info, see issue:
- #151584

Author: nsmithtt

mlir/test/mlir-tblgen/enums-python-bindings.td

@@ -62,12 +62,15 @@ def MyEnum64 : I64EnumAttr<"MyEnum64", "An example 64-bit enum", [One64, Two64]>
 // CHECK: def _myenum64(x, context):
 // CHECK:     return _ods_ir.IntegerAttr.get(_ods_ir.IntegerType.get_signless(64, context=context), int(x))
 
+def User : I32BitEnumAttrCaseBit<"User", 0, "user">;
+def Group : I32BitEnumAttrCaseBit<"Group", 1, "group">;
+def Other : I32BitEnumAttrCaseBit<"Other", 2, "other">;
+
 def TestBitEnum
-    : I32BitEnumAttr<"TestBitEnum", "", [
-        I32BitEnumAttrCaseBit<"User", 0, "user">,
-        I32BitEnumAttrCaseBit<"Group", 1, "group">,
-        I32BitEnumAttrCaseBit<"Other", 2, "other">,
-      ]> {
+    : I32BitEnumAttr<
+          "TestBitEnum", "",
+          [User, Group, Other,
+           I32BitEnumAttrCaseGroup<"Any", [User, Group, Other], "any">]> {
   let genSpecializedAttr = 0;
   let separator = " | ";
 }
@@ -79,9 +82,10 @@ def TestBitEnum_Attr : EnumAttr<Test_Dialect, TestBitEnum, "testbitenum">;
 // CHECK:     User = 1
 // CHECK:     Group = 2
 // CHECK:     Other = 4
+// CHECK:     Any = 7
 
 // CHECK:     def __iter__(self):
-// CHECK:         return iter([case for case in type(self) if (self & case) is case])
+// CHECK:         return iter([case for case in type(self) if (self & case) is case and self is not case])
 // CHECK:     def __len__(self):
 // CHECK:         return bin(self).count("1")
 
@@ -94,6 +98,8 @@ def TestBitEnum_Attr : EnumAttr<Test_Dialect, TestBitEnum, "testbitenum">;
 // CHECK:             return "group"
 // CHECK:         if self is TestBitEnum.Other:
 // CHECK:             return "other"
+// CHECK:         if self is TestBitEnum.Any:
+// CHECK:             return "any"
 // CHECK:         raise ValueError("Unknown TestBitEnum enum entry.")
 
 // CHECK: @register_attribute_builder("TestBitEnum")

mlir/tools/mlir-tblgen/EnumPythonBindingGen.cpp

@@ -64,7 +64,7 @@ static void emitEnumClass(EnumInfo enumInfo, raw_ostream &os) {
   if (enumInfo.isBitEnum()) {
     os << formatv("    def __iter__(self):\n"
                   "        return iter([case for case in type(self) if "
-                  "(self & case) is case])\n");
+                  "(self & case) is case and self is not case])\n");
     os << formatv("    def __len__(self):\n"
                   "        return bin(self).count(\"1\")\n");
     os << "\n";