include io only if JSON_NO_IO is not set for #2728

include/nlohmann/detail/input/input_adapters.hpp

@@ -2,9 +2,7 @@
 
 #include <array> // array
 #include <cstddef> // size_t
-#include <cstdio> //FILE *
 #include <cstring> // strlen
-#include <istream> // istream
 #include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
 #include <memory> // shared_ptr, make_shared, addressof
 #include <numeric> // accumulate
@@ -12,6 +10,11 @@
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
 #include <utility> // pair, declval
 
+#ifndef JSON_NO_IO
+    #include <cstdio>   //FILE *
+    #include <istream>  // istream
+#endif                  // JSON_NO_IO
+
 #include <nlohmann/detail/iterators/iterator_traits.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 

include/nlohmann/detail/output/output_adapters.hpp

@@ -2,12 +2,16 @@
 
 #include <algorithm> // copy
 #include <cstddef> // size_t
-#include <ios> // streamsize
 #include <iterator> // back_inserter
 #include <memory> // shared_ptr, make_shared
-#include <ostream> // basic_ostream
 #include <string> // basic_string
 #include <vector> // vector
+
+#ifndef JSON_NO_IO
+    #include <ios>      // streamsize
+    #include <ostream>  // basic_ostream
+#endif  // JSON_NO_IO
+
 #include <nlohmann/detail/macro_scope.hpp>
 
 namespace nlohmann

include/nlohmann/json.hpp

@@ -38,7 +38,9 @@ SOFTWARE.
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
 #include <functional> // hash, less
 #include <initializer_list> // initializer_list
-#include <iosfwd> // istream, ostream
+#ifndef JSON_NO_IO
+    #include <iosfwd> // istream, ostream
+#endif  // JSON_NO_IO
 #include <iterator> // random_access_iterator_tag
 #include <memory> // unique_ptr
 #include <numeric> // accumulate
@@ -6882,7 +6884,7 @@ class basic_json
         parser(detail::input_adapter(i)).parse(false, j);
         return i;
     }
-#endif // JSON_NO_IO
+#endif  // JSON_NO_IO
     /// @}
 
     ///////////////////////////