storage_proxy: adjust for C++20 std::accumulate() pass-by-value

C++20 passes the input to the binary operation by value (which is sensible), but is not compatible with C++17. Add some #if logic to support both methods. We can remove the logic when we fully transition to C++20. Message-Id: <[email protected]>
sarvex · May 12, 2020 · 89ea879 · 89ea879
1 parent df4b698
commit 89ea879
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/service/storage_proxy.cc b/service/storage_proxy.cc
@@ -3229,7 +3229,12 @@ class data_read_resolver : public abstract_read_resolver {
             auto it = boost::range::find_if(v, [] (auto&& ver) {
                     return bool(ver.par);
             });
-            auto m = boost::accumulate(v, mutation(schema, it->par->mut().key()), [this, schema] (mutation& m, const version& ver) {
+#if __cplusplus <= 201703L
+            using mutation_ref = mutation&;
+#else
+            using mutation_ref = mutation&&;
+#endif
+            auto m = boost::accumulate(v, mutation(schema, it->par->mut().key()), [this, schema] (mutation_ref m, const version& ver) {
                 if (ver.par) {
                     mutation_application_stats app_stats;
                     m.partition().apply(*schema, ver.par->mut().partition(), *schema, app_stats);