Improve name argument validation

test/args-test.cc

@@ -144,9 +144,9 @@ TEST(args_test, reserve) {
   fmt::dynamic_format_arg_store<fmt::format_context> store;
   store.reserve(2, 1);
   store.push_back(1.5f);
-  store.push_back(fmt::arg("a1", 42));
-  auto result = fmt::vformat("{a1} and {}", store);
-  EXPECT_EQ("42 and 1.5", result);
+  store.push_back(fmt::arg("a", 42));
+  auto result = fmt::vformat("{} and {a}", store);
+  EXPECT_EQ("1.5 and 42", result);
 }
 
 struct copy_throwable {

test/format-test.cc

@@ -555,6 +555,9 @@ TEST(format_test, named_arg) {
                    "argument not found");
   EXPECT_THROW_MSG((void)fmt::format(runtime("{a}"), 42), format_error,
                    "argument not found");
+  EXPECT_THROW_MSG((void)fmt::format(runtime("{a} {}"), fmt::arg("a", 2), 42),
+                   format_error,
+                   "cannot switch from manual to automatic argument indexing");
 }
 
 TEST(format_test, auto_arg_index) {
@@ -1742,7 +1745,7 @@ TEST(format_test, print) {
 }
 
 TEST(format_test, big_print) {
-  enum {count = 5000};
+  enum { count = 5000 };
   auto big_print = []() {
     for (int i = 0; i < count / 5; ++i) fmt::print("xxxxx");
   };