Fixes the adapter of empty nested responses.

README.md

@@ -684,6 +684,9 @@ https://lists.boost.org/Archives/boost/2023/01/253944.php.
   also changed to return EOF to the user when that error is received
   from the server. That is a breaking change.
 
+* ([Issue 210](https://github.com/boostorg/redis/issues/210))
+  Fixes the adapter of empty nested reposponses.
+
 ### Boost 1.85
 
 * ([Issue 170](https://github.com/boostorg/redis/issues/170))

include/boost/redis/adapter/detail/result_traits.hpp

@@ -102,8 +102,12 @@ class static_aggregate_adapter<result<Tuple>> {
                std::variant>,
          std::tuple_size<Tuple>::value>;
 
+   // Tuple element we are currently on.
    std::size_t i_ = 0;
+
+   // Nested aggregate element counter.
    std::size_t aggregate_size_ = 0;
+
    adapters_array_type adapters_;
    result<Tuple>* res_ = nullptr;
 
@@ -117,36 +121,35 @@ class static_aggregate_adapter<result<Tuple>> {
    }
 
    template <class String>
-   void count(resp3::basic_node<String> const& nd)
+   void count(resp3::basic_node<String> const& elem)
    {
-      if (nd.depth == 1) {
-         if (is_aggregate(nd.data_type))
-            aggregate_size_ = element_multiplicity(nd.data_type) * nd.aggregate_size;
-         else
-            ++i_;
-
-         return;
+      if (elem.depth == 1 && is_aggregate(elem.data_type)) {
+         aggregate_size_ = element_multiplicity(elem.data_type) * elem.aggregate_size;
       }
 
-      if (--aggregate_size_ == 0)
-         ++i_;
+      if (aggregate_size_ == 0) {
+         i_ += 1;
+      } else {
+         aggregate_size_ -= 1;
+      }
    }
 
    template <class String>
-   void operator()(resp3::basic_node<String> const& nd, system::error_code& ec)
+   void operator()(resp3::basic_node<String> const& elem, system::error_code& ec)
    {
       using std::visit;
 
-      if (nd.depth == 0) {
-         auto const real_aggr_size = nd.aggregate_size * element_multiplicity(nd.data_type);
+      if (elem.depth == 0) {
+         auto const multiplicity = element_multiplicity(elem.data_type);
+         auto const real_aggr_size = elem.aggregate_size * multiplicity;
          if (real_aggr_size != std::tuple_size<Tuple>::value)
             ec = redis::error::incompatible_size;
 
          return;
       }
 
-      visit([&](auto& arg){arg(nd, ec);}, adapters_[i_]);
-      count(nd);
+      visit([&](auto& arg){arg(elem, ec);}, adapters_[i_]);
+      count(elem);
    }
 };
 

test/test_low_level_sync_sans_io.cpp

@@ -15,9 +15,11 @@
 using boost::redis::request;
 using boost::redis::config;
 using boost::redis::detail::push_hello;
+using boost::redis::response;
 using boost::redis::adapter::adapt2;
 using boost::redis::adapter::result;
 using boost::redis::resp3::detail::deserialize;
+using boost::redis::ignore_t;
 
 BOOST_AUTO_TEST_CASE(low_level_sync_sans_io)
 {
@@ -88,3 +90,113 @@ BOOST_AUTO_TEST_CASE(config_to_hello_cmd_auth)
    std::string_view const expected = "*5\r\n$5\r\nHELLO\r\n$1\r\n3\r\n$4\r\nAUTH\r\n$3\r\nfoo\r\n$3\r\nbar\r\n";
    BOOST_CHECK_EQUAL(req.payload(), expected);
 }
+
+BOOST_AUTO_TEST_CASE(issue_210_empty_set)
+{
+   try {
+      result<
+         std::tuple<
+            result<int>,
+            result<std::vector<std::string>>,
+            result<std::string>,
+            result<int>
+         >
+      > resp;
+
+      char const* wire = "*4\r\n:1\r\n~0\r\n$25\r\nthis_should_not_be_in_set\r\n:2\r\n";
+
+      deserialize(wire, adapt2(resp));
+
+      BOOST_CHECK_EQUAL(std::get<0>(resp.value()).value(), 1);
+      BOOST_CHECK(std::get<1>(resp.value()).value().empty());
+      BOOST_CHECK_EQUAL(std::get<2>(resp.value()).value(), "this_should_not_be_in_set");
+      BOOST_CHECK_EQUAL(std::get<3>(resp.value()).value(), 2);
+
+   } catch (std::exception const& e) {
+      std::cerr << e.what() << std::endl;
+      exit(EXIT_FAILURE);
+   }
+}
+
+BOOST_AUTO_TEST_CASE(issue_210_non_empty_set_size_one)
+{
+   try {
+      result<
+         std::tuple<
+            result<int>,
+            result<std::vector<std::string>>,
+            result<std::string>,
+            result<int>
+         >
+      > resp;
+
+      char const* wire = "*4\r\n:1\r\n~1\r\n$3\r\nfoo\r\n$25\r\nthis_should_not_be_in_set\r\n:2\r\n";
+
+      deserialize(wire, adapt2(resp));
+
+      BOOST_CHECK_EQUAL(std::get<0>(resp.value()).value(), 1);
+      BOOST_CHECK_EQUAL(std::get<1>(resp.value()).value().size(), 1);
+      BOOST_CHECK_EQUAL(std::get<1>(resp.value()).value().at(0), std::string{"foo"});
+      BOOST_CHECK_EQUAL(std::get<2>(resp.value()).value(), "this_should_not_be_in_set");
+      BOOST_CHECK_EQUAL(std::get<3>(resp.value()).value(), 2);
+
+   } catch (std::exception const& e) {
+      std::cerr << e.what() << std::endl;
+      exit(EXIT_FAILURE);
+   }
+}
+
+BOOST_AUTO_TEST_CASE(issue_210_non_empty_set_size_two)
+{
+   try {
+      result<
+         std::tuple<
+            result<int>,
+            result<std::vector<std::string>>,
+            result<std::string>,
+            result<int>
+         >
+      > resp;
+
+      char const* wire = "*4\r\n:1\r\n~2\r\n$3\r\nfoo\r\n$3\r\nbar\r\n$25\r\nthis_should_not_be_in_set\r\n:2\r\n";
+
+      deserialize(wire, adapt2(resp));
+
+      BOOST_CHECK_EQUAL(std::get<0>(resp.value()).value(), 1);
+      BOOST_CHECK_EQUAL(std::get<1>(resp.value()).value().at(0), std::string{"foo"});
+      BOOST_CHECK_EQUAL(std::get<1>(resp.value()).value().at(1), std::string{"bar"});
+      BOOST_CHECK_EQUAL(std::get<2>(resp.value()).value(), "this_should_not_be_in_set");
+
+   } catch (std::exception const& e) {
+      std::cerr << e.what() << std::endl;
+      exit(EXIT_FAILURE);
+   }
+}
+
+BOOST_AUTO_TEST_CASE(issue_210_no_nested)
+{
+   try {
+      result<
+         std::tuple<
+            result<int>,
+            result<std::string>,
+            result<std::string>,
+            result<std::string>
+         >
+      > resp;
+
+      char const* wire = "*4\r\n:1\r\n$3\r\nfoo\r\n$3\r\nbar\r\n$25\r\nthis_should_not_be_in_set\r\n";
+
+      deserialize(wire, adapt2(resp));
+
+      BOOST_CHECK_EQUAL(std::get<0>(resp.value()).value(), 1);
+      BOOST_CHECK_EQUAL(std::get<1>(resp.value()).value(), std::string{"foo"});
+      BOOST_CHECK_EQUAL(std::get<2>(resp.value()).value(), std::string{"bar"});
+      BOOST_CHECK_EQUAL(std::get<3>(resp.value()).value(), "this_should_not_be_in_set");
+
+   } catch (std::exception const& e) {
+      std::cerr << e.what() << std::endl;
+      exit(EXIT_FAILURE);
+   }
+}
+