Remove some designated initializers

With the switch to C++20, the rules became more strict, and we can no
longer initialize base classes. Make them comments instead.

(BTW
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2287r1.html
this offers some new syntax for this use-case. Hopefully this will be
adopted and we can eventually use it.)

src/libstore/binary-cache-store.cc

@@ -313,7 +313,7 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view n
                     .method = method,
                     .hash = nar.first,
                 },
-                .references = {
+                /* .references = */ {
                     .others = references,
                     .self = false,
                 },
@@ -431,7 +431,7 @@ StorePath BinaryCacheStore::addToStore(
                     .method = method,
                     .hash = h,
                 },
-                .references = {
+                /* .references = */ {
                     .others = references,
                     .self = false,
                 },

src/libstore/build/local-derivation-goal.cc

@@ -2498,7 +2498,7 @@ DrvOutputs LocalDerivationGoal::registerOutputs()
                         .method = outputHash.method,
                         .hash = got,
                     },
-                    .references = rewriteRefs(),
+                    /* .references = */ rewriteRefs(),
                 },
                 Hash::dummy,
             };

src/libstore/content-address.cc

@@ -167,13 +167,13 @@ ContentAddressWithReferences caWithoutRefs(const ContentAddress & ca) {
         [&](const TextHash & h) -> ContentAddressWithReferences {
             return TextInfo {
                 h,
-                .references = {},
+                /* .references = */ {},
             };
         },
         [&](const FixedOutputHash & h) -> ContentAddressWithReferences {
             return FixedOutputInfo {
                 h,
-                .references = {},
+                /* .references = */ {},
             };
         },
     }, ca);

src/libstore/local-store.cc

@@ -1419,7 +1419,7 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
             .method = method,
             .hash = hash,
         },
-        .references = {
+        /* .references = */ {
             .others = references,
             .self = false,
         },

src/libstore/make-content-addressed.cc

@@ -56,7 +56,7 @@ std::map<StorePath, StorePath> makeContentAddressed(
                     .method = FileIngestionMethod::Recursive,
                     .hash = narModuloHash,
                 },
-                .references = std::move(refs),
+                /* .references = */ std::move(refs),
             },
             Hash::dummy,
         };

src/libstore/path-info.cc

@@ -31,7 +31,7 @@ std::optional<ContentAddressWithReferences> ValidPathInfo::contentAddressWithRef
             assert(references.count(path) == 0);
             return TextInfo {
                 th,
-                .references = references,
+                /* .references = */ references,
             };
         },
         [&](const FixedOutputHash & foh) -> ContentAddressWithReferences {
@@ -43,7 +43,7 @@ std::optional<ContentAddressWithReferences> ValidPathInfo::contentAddressWithRef
             }
             return FixedOutputInfo {
                 foh,
-                .references = {
+                /* .references = */ {
                     .others = std::move(refs),
                     .self = hasSelfReference,
                 },

src/libstore/store-api.cc

@@ -234,7 +234,7 @@ std::pair<StorePath, Hash> Store::computeStorePathForPath(std::string_view name,
             .method = method,
             .hash = h,
         },
-        .references = {},
+        /* .references = */ {},
     };
     return std::make_pair(makeFixedOutputPath(name, caInfo), h);
 }
@@ -443,7 +443,7 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
                 .method = method,
                 .hash = hash,
             },
-            .references = {},
+            /* .references = */ {},
         },
         narHash,
     };