[llvm] [STLExtras] Remove incorrect hack to make indexed_accessor_range operator== compatible with C++20 (PR #72220)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-adt

Author: Utkarsh Saxena (usx95)

<details>
<summary>Changes</summary>

This partially reverts c312f025940d79b858166b80c50526558864d54e

The motivation behind this is unclear and the change predates the clang implementation of https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2468r2.html so I am not sure if it was ever intended to work. Rewritten template operators were broken since the beginning.

Moreover, moving away from `friend` would be beneficial as these would only accepted once clang revises its implementation to fix https://github.com/llvm/llvm-project/issues/70210. It also helps in making sure that older compilers still compile LLVM.

---
Full diff: https://github.com/llvm/llvm-project/pull/72220.diff


1 Files Affected:

- (modified) llvm/include/llvm/ADT/STLExtras.h (+5-9) 


``````````diff
diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index 18bc4d108b156bf..e42b0e8d1b27b71 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -1291,15 +1291,11 @@ class indexed_accessor_range_base {
   }
 
   /// Compare this range with another.
-  template <typename OtherT>
-  friend bool operator==(const indexed_accessor_range_base &lhs,
-                         const OtherT &rhs) {
-    return std::equal(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
-  }
-  template <typename OtherT>
-  friend bool operator!=(const indexed_accessor_range_base &lhs,
-                         const OtherT &rhs) {
-    return !(lhs == rhs);
+  template <typename OtherT> bool operator==(const OtherT &rhs) const {
+    return std::equal(begin(), end(), rhs.begin(), rhs.end());
+  }
+  template <typename OtherT> bool operator!=(const OtherT &rhs) const {
+    return !(*this == rhs);
   }
 
   /// Return the size of this range.

``````````

</details>


https://github.com/llvm/llvm-project/pull/72220