Make ostream operators opt in to reduce the risk of ODR violations

test/printf-test.cc

@@ -11,7 +11,6 @@
 #include <climits>
 #include <cstring>
 
-#include "fmt/ostream.h"
 #include "fmt/xchar.h"
 #include "gtest-extra.h"
 #include "util.h"
@@ -533,10 +532,6 @@ TEST(printf_test, wide_string) {
   EXPECT_EQ(L"abc", fmt::sprintf(L"%s", L"abc"));
 }
 
-TEST(printf_test, printf_custom) {
-  EXPECT_EQ("abc", test_sprintf("%s", test_string("abc")));
-}
-
 TEST(printf_test, vprintf) {
   fmt::format_arg_store<fmt::printf_context, int> as{42};
   fmt::basic_format_args<fmt::printf_context> args(as);