[ADT] Use TypeAtIndex in PointerUnion (NFC)

[kazutakahirata]

This patch replaces GetFirstType with TypeAtIndex.

[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Kazu Hirata (kazutakahirata)

Changes

This patch replaces GetFirstType with TypeAtIndex.

---

Full diff: https://github.com/llvm/llvm-project/pull/163036.diff

1 Files Affected:

• (modified) llvm/include/llvm/ADT/PointerUnion.h (+1-7)

diff --git a/llvm/include/llvm/ADT/PointerUnion.h b/llvm/include/llvm/ADT/PointerUnion.h
index 7b66177373011..d9087dd1c516e 100644
--- a/llvm/include/llvm/ADT/PointerUnion.h
+++ b/llvm/include/llvm/ADT/PointerUnion.h
@@ -38,11 +38,6 @@ namespace pointer_union_detail {
     return std::min<int>({PointerLikeTypeTraits<Ts>::NumLowBitsAvailable...});
   }
 
-  /// Find the first type in a list of types.
-  template <typename T, typename...> struct GetFirstType {
-    using type = T;
-  };
-
   /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
   /// for the template arguments.
   template <typename ...PTs> class PointerUnionUIntTraits {
@@ -264,8 +259,7 @@ struct PointerLikeTypeTraits<PointerUnion<PTs...>> {
 // Teach DenseMap how to use PointerUnions as keys.
 template <typename ...PTs> struct DenseMapInfo<PointerUnion<PTs...>> {
   using Union = PointerUnion<PTs...>;
-  using FirstInfo =
-      DenseMapInfo<typename pointer_union_detail::GetFirstType<PTs...>::type>;
+  using FirstInfo = DenseMapInfo<TypeAtIndex<0, PTs...>>;
 
   static inline Union getEmptyKey() { return Union(FirstInfo::getEmptyKey()); }