Upgrade vergen 3

Author: dynaxis

Cargo.lock

@@ -54,7 +54,7 @@ toml = "0.4"
 cidr = "0.0.4"
 
 [build-dependencies]
-vergen = "2"
+vergen = "3"
 
 [[bin]]
 path = "codechain/main.rs"

Cargo.toml

@@ -14,20 +14,8 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-extern crate vergen;
-
-use vergen::{ConstantsFlags, Result, Vergen};
+use vergen::{generate_cargo_keys, ConstantsFlags};
 
 fn main() {
-    gen_constants().expect("Unable to generate vergen constants!");
-}
-
-fn gen_constants() -> Result<()> {
-    let vergen = Vergen::new(ConstantsFlags::all())?;
-
-    for (k, v) in vergen.build_info() {
-        println!("cargo:rustc-env={}={}", k.name(), v);
-    }
-
-    Ok(())
+    generate_cargo_keys(ConstantsFlags::all()).expect("Unable to generate vergen constants!");
 }