[ADT] Modernize type traits in BitmaskEnum.h (NFC)

[kazutakahirata]

This patch replaces std::enable_if_t with std::void_t in two type
traits. Both approaches enable the template specialization if and
only if the LLVM_BITMASK_LARGEST_ENUMERATOR enumerator exists.

[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Kazu Hirata (kazutakahirata)

Changes

This patch replaces std::enable_if_t with std::void_t in two type
traits. Both approaches enable the template specialization if and
only if the LLVM_BITMASK_LARGEST_ENUMERATOR enumerator exists.

---

Full diff: https://github.com/llvm/llvm-project/pull/164567.diff

1 Files Affected:

• (modified) llvm/include/llvm/ADT/BitmaskEnum.h (+2-2)

diff --git a/llvm/include/llvm/ADT/BitmaskEnum.h b/llvm/include/llvm/ADT/BitmaskEnum.h
index d464cbcfcdffd..9555fadda6e47 100644
--- a/llvm/include/llvm/ADT/BitmaskEnum.h
+++ b/llvm/include/llvm/ADT/BitmaskEnum.h
@@ -106,7 +106,7 @@ struct is_bitmask_enum : std::false_type {};
 
 template <typename E>
 struct is_bitmask_enum<
-    E, std::enable_if_t<sizeof(E::LLVM_BITMASK_LARGEST_ENUMERATOR) >= 0>>
+    E, std::void_t<decltype(E::LLVM_BITMASK_LARGEST_ENUMERATOR)>>
     : std::true_type {};
 
 /// Trait class to determine bitmask enumeration largest bit.
@@ -114,7 +114,7 @@ template <typename E, typename Enable = void> struct largest_bitmask_enum_bit;
 
 template <typename E>
 struct largest_bitmask_enum_bit<
-    E, std::enable_if_t<sizeof(E::LLVM_BITMASK_LARGEST_ENUMERATOR) >= 0>> {
+    E, std::void_t<decltype(E::LLVM_BITMASK_LARGEST_ENUMERATOR)>> {
   using UnderlyingTy = std::underlying_type_t<E>;
   static constexpr UnderlyingTy value =
       static_cast<UnderlyingTy>(E::LLVM_BITMASK_LARGEST_ENUMERATOR);