Dedup ADL begin/end lookup

test/ranges-test.cc

@@ -462,18 +462,16 @@ TEST(ranges_test, join_range) {
 }
 
 namespace adl {
-struct vec : std::vector<int> {
-  using std::vector<int>::vector;  // inherit all constructors
+struct vec {
+  int n[2] = {42, 43};
 };
 
-// ADL-found begin() and end() skip the first and last element
-auto begin(vec& v) -> typename vec::iterator { return v.begin() + 1; }
-auto end(vec& v) -> typename vec::iterator { return v.end() - 1; }
+auto begin(const vec& v) -> const int* { return v.n; }
+auto end(const vec& v) -> const int* { return v.n + 2; }
 }
 
 TEST(ranges_test, format_join_adl_begin_end) {
-  auto v = adl::vec{41, 42, 43, 44};
-  EXPECT_EQ(fmt::format("{}", fmt::join(v, "/")), "42/43");
+  EXPECT_EQ(fmt::format("{}", fmt::join(adl::vec(), "/")), "42/43");
 }
 
 #endif  // FMT_RANGES_TEST_ENABLE_JOIN