config: change type of rng_seed to int64_t

The old type (a plain int with 32 bits) could overflow easily, which
might cause confusion.

Co-authored-by: Amrita Goswami <[email protected]>

include/config_parser.hpp

@@ -3,6 +3,7 @@
 #include <fmt/ostream.h>
 #include <fmt/ranges.h>
 #include <cstddef>
+#include <cstdint>
 #include <optional>
 #include <random>
 #include <string_view>
@@ -102,7 +103,7 @@ struct SimulationOptions
         = std::variant<DeGrootSettings, ActivityDrivenSettings, ActivityDrivenInertialSettings, DeffuantSettings>;
     Model model;
     std::string model_string;
-    int rng_seed = std::random_device()();
+    int64_t rng_seed = std::random_device()();
     OutputSettings output_settings;
     ModelVariantT model_settings;
     InitialNetworkSettings network_settings;

src/config_parser.cpp

@@ -113,7 +113,7 @@ SimulationOptions parse_config_file( std::string_view config_file_path )
     toml::table tbl;
     tbl = toml::parse_file( config_file_path );
 
-    options.rng_seed = tbl["simulation"]["rng_seed"].value_or( int( options.rng_seed ) );
+    options.rng_seed = tbl["simulation"]["rng_seed"].value_or( int64_t( options.rng_seed ) );
 
     // Parse output settings
     options.output_settings.n_output_network = tbl["io"]["n_output_network"].value<size_t>();