[llvm] [ADT] Simplify isEqualImpl in DenseMapInfo.h (NFC) (PR #159508)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/159508

This patch replaces the recursive implementation of isEqualImpl with a
C++17 fold expression.


>From 71cff435d1659b5d6493effc845dd7130e959e8b Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Wed, 17 Sep 2025 14:31:52 -0700
Subject: [PATCH] [ADT] Simplify isEqualImpl in DenseMapInfo.h (NFC)

This patch replaces the recursive implementation of isEqualImpl with a
C++17 fold expression.
---
 llvm/include/llvm/ADT/DenseMapInfo.h | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/ADT/DenseMapInfo.h b/llvm/include/llvm/ADT/DenseMapInfo.h
index b91a908d992f8..57a8674e35015 100644
--- a/llvm/include/llvm/ADT/DenseMapInfo.h
+++ b/llvm/include/llvm/ADT/DenseMapInfo.h
@@ -194,20 +194,16 @@ template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
     return getHashValueImpl<0>(values);
   }
 
-  template <unsigned I>
-  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs) {
-    if constexpr (I == sizeof...(Ts)) {
-      return true;
-    } else {
-      using EltType = std::tuple_element_t<I, Tuple>;
-      return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs),
-                                            std::get<I>(rhs)) &&
-             isEqualImpl<I + 1>(lhs, rhs);
-    }
+  template <std::size_t... Is>
+  static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs,
+                          std::index_sequence<Is...>) {
+    return (DenseMapInfo<std::tuple_element_t<Is, Tuple>>::isEqual(
+                std::get<Is>(lhs), std::get<Is>(rhs)) &&
+            ...);
   }
 
   static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
-    return isEqualImpl<0>(lhs, rhs);
+    return isEqualImpl(lhs, rhs, std::index_sequence_for<Ts...>{});
   }
 };