Zig makes allocation an explicit runtime concern:

   var list = std.ArrayList(i32).init(allocator);

where allocator is a runtime value implementing the allocator interface.

   fn parseJson(allocator: Allocator, input: []const u8) !JsonValue

Zig forces the caller to decide since allocator is part of the function contract. And this is consistent everywhere in Zig. Effectively speaking, this is universal, explicit & mandated dependency injection for memory management as opposed to to classic C++ STL allocators.

Sorry sir, I have a nostalgic fondness for C++ - it was my first language, but it just doesn't compare for flexible allocation convenience compared to Zig.