Apply suggestions from code review

Co-authored-by: philnik777 <[email protected]>

Author: wdunicornpro

libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill.pass.cpp

@@ -120,13 +120,13 @@ constexpr bool test() {
     {
       std::array<std::string, 10> a;
       auto ret = std::ranges::fill(a.begin(), a.end(), "long long string so no SSO");
-      assert(ret == a.begin() + a.size());
+      assert(ret == a.end());
       assert(std::all_of(a.begin(), a.end(), [](auto& s) { return s == "long long string so no SSO"; }));
     }
     {
       std::array<std::string, 10> a;
       auto ret = std::ranges::fill(a, "long long string so no SSO");
-      assert(ret == a.begin() + a.size());
+      assert(ret == a.end());
       assert(std::all_of(a.begin(), a.end(), [](auto& s) { return s == "long long string so no SSO"; }));
     }
   }