Run libursa tests on Ubuntu 20.04

Cargo.toml

@@ -21,6 +21,10 @@ crate-type = ["cdylib", "staticlib", "rlib"]
 lto = true
 
 [workspace]
+exclude = [
+    "libursa",
+    "libzmix",
+]
 members = [
     "ursa_accumulators",
     "ursa_core",
@@ -35,4 +39,4 @@ default = ["sharing"]
 sharing = ["ursa_sharing"]
 
 [dependencies]
-ursa_sharing = { version = "0.1", path = "ursa_sharing", optional = true }
+ursa_sharing = { version = "0.1", path = "ursa_sharing", optional = true }

libursa/src/errors/mod.rs

@@ -89,7 +89,7 @@ impl fmt::Display for UrsaCryptoError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut first = true;
 
-        for cause in Fail::iter_chain(&self.inner) {
+        for cause in <dyn Fail>::iter_chain(&self.inner) {
             if first {
                 first = false;
                 writeln!(f, "Error: {}", cause)?;

libursa/src/kex/secp256k1.rs

@@ -130,6 +130,7 @@ mod ecdh_secp256k1 {
     use sha2::digest::generic_array::typenum::U32;
     use sha2::Digest;
     use zeroize::Zeroize;
+    #[allow(dead_code)]
     const PUBLIC_UNCOMPRESSED_KEY_SIZE: usize = 65;
 
     #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]