Maps

Copy Go Maps with maps.Clone Without Sharing Top-Level State

Copying a Go map is easy to get subtly wrong. Assigning one map variable to another doesn’t duplicate the map, so a write through either variable changes the same underlying map. Since Go 1.21, the standard library’s maps.Clone function gives you a concise way to make a separate top-level map. There is one boundary worth understanding before using it: maps.Clone is a shallow clone. Adding, deleting, or replacing entries in the clone won’t change the original map, but nested maps, slices, pointers, and other reference-bearing values can still refer to the same underlying data.