Op

        const Op = union(fuzz_probs.Op) {
            alloc: struct {
                len: usize,
                alignment: Alignment,

                splat: ?u8,
                /// Not embeded directly in the struct as a workaround for tsan since a
                /// switch directly on `Op` loads the entire value non-atomically.
                result: *MemoryDependency,
            },
            free: struct {
                memory: *MemoryDependency,
                alignment: Alignment,

                splat: ?u8,
            },
            resize: Realloc,
            remap: Realloc,

            const Realloc = struct {
                memory: *MemoryDependency,
                alignment: Alignment,
                new_len: usize,

                splat: ?u8,
                /// Not embeded directly in the struct as a workaround for tsan since a
                /// switch directly on `Op` loads the entire value non-atomically.
                result: *MemoryDependency,
            };

            const MemoryDependency = struct {
                ready: std.Io.Event,
                /// Null if the memory failed to be allocated
                memory: ?[]u8,

                const init: MemoryDependency = .{
                    .ready = .unset,
                    .memory = undefined,
                };

                fn get(dep: *MemoryDependency, io: std.Io) ?[]u8 {
                    dep.ready.waitUncancelable(io);
                    return dep.memory;
                }
            };
        }