Without specifying the resolver in the workspace's Cargo.toml file, there is the following warning:
[user@host gtk-layer-shell-gir]$ cargo build
warning: some crates are on edition 2021 which defaults to `resolver = "2"`, but virtual workspaces default to `resolver = "1"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
Without specifying the resolver in the workspace's Cargo.toml file, there is the following warning:
Resolver 2 was specified to get rid of it.