Don't enable ordinalCount() or bitCount() for bitset enums

Summary:
Bitfield enums are not sequential, so use of these functions on these enums would be invalid.

I looked at whether we could trivially move `bitCount` to template based on `ordinalCount`. `bitCount` must be constexpr, since we use it directly as a bit-field size constant. `log2` and `ceil` to be constexpr, which isn't here until C++ 26.

Reviewed By: javache

Differential Revision: D51518899

fbshipit-source-id: 256f15bbed517be6f90bf43baa43ce96e9259a71

enums.py

@@ -169,19 +169,19 @@ for name, values in sorted(ENUMS.items()):
             ordinal = value[0] if isinstance(value, tuple) else value
             f.write(f"  {ordinal} = YG{name}{ordinal},\n")
         f.write("};\n\n")
-        f.write(
-            f"YG_DEFINE_ENUM_FLAG_OPERATORS({name})\n\n" if name in BITSET_ENUMS else ""
-        )
 
-        f.write("template <>\n")
-        f.write(f"constexpr inline int32_t ordinalCount<{name}>() {{\n")
-        f.write(f"  return {len(values)};\n")
-        f.write("} \n\n")
+        if name in BITSET_ENUMS:
+            f.write(f"YG_DEFINE_ENUM_FLAG_OPERATORS({name})\n\n")
+        else:
+            f.write("template <>\n")
+            f.write(f"constexpr inline int32_t ordinalCount<{name}>() {{\n")
+            f.write(f"  return {len(values)};\n")
+            f.write("} \n\n")
 
-        f.write("template <>\n")
-        f.write(f"constexpr inline int32_t bitCount<{name}>() {{\n")
-        f.write(f"  return {math.ceil(math.log(len(values), 2))};\n")
-        f.write("} \n\n")
+            f.write("template <>\n")
+            f.write(f"constexpr inline int32_t bitCount<{name}>() {{\n")
+            f.write(f"  return {math.ceil(math.log(len(values), 2))};\n")
+            f.write("} \n\n")
 
         f.write(f"constexpr inline {name} scopedEnum(YG{name} unscoped) {{\n")
         f.write(f"  return static_cast<{name}>(unscoped);\n")