Inline operator== and operator!= (#67958)

Avoid triggering -Wnon-template-friend on newer GCC.

---------

Co-authored-by: Richard Smith <[email protected]>

Author: ktf

llvm/include/llvm/ADT/PagedVector.h

@@ -209,35 +209,33 @@ template <typename T, size_t PageSize = 1024 / sizeof(T)> class PagedVector {
       return PagePtr[ElementIdx % PageSize];
     }
 
-    friend bool operator==(MaterializedIterator const &LHS,
-                           MaterializedIterator const &RHS);
-    friend bool operator!=(MaterializedIterator const &LHS,
-                           MaterializedIterator const &RHS);
+    /// Equality operator.
+    friend bool operator==(const MaterializedIterator &LHS,
+                           const MaterializedIterator &RHS) {
+      return LHS.equals(RHS);
+    }
 
     [[nodiscard]] size_t getIndex() const { return ElementIdx; }
-  };
 
-  /// Equality operator.
-  friend bool operator==(MaterializedIterator const &LHS,
-                         MaterializedIterator const &RHS) {
-    assert(LHS.PV == RHS.PV);
-    // Make sure we are comparing either end iterators or iterators pointing
-    // to materialized elements.
-    // It should not be possible to build two iterators pointing to non
-    // materialized elements.
-    assert(LHS.ElementIdx == LHS.PV->Size ||
-           (LHS.ElementIdx < LHS.PV->Size &&
-            LHS.PV->PageToDataPtrs[LHS.ElementIdx / PageSize]));
-    assert(RHS.ElementIdx == RHS.PV->Size ||
-           (RHS.ElementIdx < RHS.PV->Size &&
-            RHS.PV->PageToDataPtrs[RHS.ElementIdx / PageSize]));
-    return LHS.ElementIdx == RHS.ElementIdx;
-  }
+    friend bool operator!=(const MaterializedIterator &LHS,
+                           const MaterializedIterator &RHS) {
+      return !(LHS == RHS);
+    }
 
-  friend bool operator!=(MaterializedIterator const &LHS,
-                         MaterializedIterator const &RHS) {
-    return !(LHS == RHS);
-  }
+  private:
+    void verify() const {
+      assert(
+          ElementIdx == PV->Size ||
+          (ElementIdx < PV->Size && PV->PageToDataPtrs[ElementIdx / PageSize]));
+    }
+
+    bool equals(const MaterializedIterator &Other) const {
+      assert(PV == Other.PV);
+      verify();
+      Other.verify();
+      return ElementIdx == Other.ElementIdx;
+    }
+  };
 
   /// Iterators over the materialized elements of the vector.
   ///