Simplify Implementations registration

Author: edolstra

src/libstore/include/nix/store/store-api.hh

@@ -902,12 +902,15 @@ struct StoreFactory
 
 struct Implementations
 {
-    static std::vector<StoreFactory> * registered;
+    static std::vector<StoreFactory> & registered()
+    {
+        static std::vector<StoreFactory> registered;
+        return registered;
+    }
 
     template<typename T, typename TConfig>
     static void add()
     {
-        if (!registered) registered = new std::vector<StoreFactory>();
         StoreFactory factory{
             .uriSchemes = TConfig::uriSchemes(),
             .create =
@@ -919,7 +922,7 @@ struct Implementations
                  -> std::shared_ptr<StoreConfig>
                  { return std::make_shared<TConfig>(StringMap({})); })
         };
-        registered->push_back(factory);
+        registered().push_back(factory);
     }
 };
 

src/libstore/store-api.cc

@@ -1355,7 +1355,7 @@ ref<Store> openStore(StoreReference && storeURI)
                 return std::make_shared<LocalStore>(params);
         },
         [&](const StoreReference::Specified & g) {
-            for (const auto & implem : *Implementations::registered)
+            for (const auto & implem : Implementations::registered())
                 if (implem.uriSchemes.count(g.scheme))
                     return implem.create(g.scheme, g.authority, params);
 
@@ -1399,6 +1399,4 @@ std::list<ref<Store>> getDefaultSubstituters()
     return stores;
 }
 
-std::vector<StoreFactory> * Implementations::registered = 0;
-
 }

src/nix/main.cc

@@ -193,7 +193,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
         res["args"] = toJSON();
 
         auto stores = nlohmann::json::object();
-        for (auto & implem : *Implementations::registered) {
+        for (auto & implem : Implementations::registered()) {
             auto storeConfig = implem.getConfig();
             auto storeName = storeConfig->name();
             auto & j = stores[storeName];