simplify array cast a little

external/CMakeLists.txt

@@ -27,3 +27,22 @@ if (NOT TARGET nlohmann_json::nlohmann_json)
 	FetchContent_MakeAvailable(json)
 endif()
 
+if (NOT TARGET zstd::zstd)
+	# TODO: try find_package() first
+	# TODO: try pkg-config next (will work on most distros)
+
+	set(ZSTD_BUILD_STATIC ON)
+	set(ZSTD_BUILD_SHARED OFF)
+	set(ZSTD_BUILD_PROGRAMS OFF)
+	set(ZSTD_BUILD_CONTRIB OFF)
+	set(ZSTD_BUILD_TESTS OFF)
+	FetchContent_Declare(zstd
+		URL "https://github.com/facebook/zstd/releases/download/v1.5.5/zstd-1.5.5.tar.gz"
+		DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+		SOURCE_SUBDIR build/cmake
+		EXCLUDE_FROM_ALL
+	)
+	FetchContent_MakeAvailable(zstd)
+
+	add_library(zstd::zstd ALIAS libzstd_static)
+endif()

flake.nix

@@ -58,8 +58,11 @@
         cmakeFlags = [
           "TOMATO_ASAN=1"
           "CMAKE_BUILD_TYPE=RelWithDebInfo"
+
           "-DFETCHCONTENT_SOURCE_DIR_JSON=${pkgs.nlohmann_json.src}" # we care less about version here
           # do we really care less about the version? do we need a stable abi?
+
+          "-DFETCHCONTENT_SOURCE_DIR_ZSTD=${pkgs.zstd.src}"
         ];
 
         # TODO: replace with install command

src/fragment_store/message_serializer.cpp

@@ -36,7 +36,7 @@ bool MessageSerializerCallbacks::component_emplace_or_replace_json<Message::Comp
 		return true;
 	}
 
-	const auto id = static_cast<std::vector<uint8_t>>(j.is_binary()?j:j["bytes"]);
+	const std::vector<uint8_t> id = j.is_binary()?j:j["bytes"];
 
 	// TODO: id lookup table, this is very inefficent
 	for (const auto& [c_it, id_it] : msc.cr.view<Contact::Components::ID>().each()) {
@@ -79,7 +79,7 @@ bool MessageSerializerCallbacks::component_emplace_or_replace_json<Message::Comp
 		return true;
 	}
 
-	const auto id = static_cast<std::vector<uint8_t>>(j.is_binary()?j:j["bytes"]);
+	const std::vector<uint8_t> id = j.is_binary()?j:j["bytes"];
 
 	// TODO: id lookup table, this is very inefficent
 	for (const auto& [c_it, id_it] : msc.cr.view<Contact::Components::ID>().each()) {