fix cs error too

Cargo.toml

@@ -6,7 +6,7 @@ homepage = "https://github.com/matter-labs/bellman"
 license = "MIT/Apache-2.0"
 name = "bellman_ce"
 repository = "https://github.com/matter-labs/bellman"
-version = "0.3.4"
+version = "0.3.5"
 edition = "2018"
 
 [lib]
@@ -17,8 +17,7 @@ rand = "0.4"
 bit-vec = "0.6"
 cfg-if = "0.1"
 
-#pairing = {package = "pairing_ce", path = "../pairing" }
-pairing = {package = "pairing_ce", version = "0.21" }
+pairing = {package = "pairing_ce", version = "0.21.*" }
 byteorder = "1"
 
 futures= {package = "futures", version = "0.3", default_features = false, features = ["executor"]}
@@ -35,7 +34,6 @@ blake2-rfc = {version = "0.2.18", optional = true}
 [features]
 # default = []
 default = ["multicore"]
-#default = ["wasm"]
 multicore = ["crossbeam", "futures/thread-pool"]
 sonic = ["tiny-keccak", "blake2-rfc"]
 gm17 = []

src/cs.rs

@@ -178,8 +178,8 @@ impl From<io::Error> for SynthesisError {
     }
 }
 
-impl Error for SynthesisError {
-    fn description(&self) -> &str {
+impl SynthesisError {
+    pub fn self_description(&self) -> &str {
         match *self {
             SynthesisError::AssignmentMissing => "an assignment for a variable could not be computed",
             SynthesisError::DivisionByZero => "division by zero",
@@ -193,13 +193,19 @@ impl Error for SynthesisError {
     }
 }
 
+impl Error for SynthesisError {
+    fn description(&self) -> &str {
+        self.self_description()
+    }
+}
+
 impl fmt::Display for SynthesisError {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
         if let &SynthesisError::IoError(ref e) = self {
             write!(f, "I/O error: ")?;
             e.fmt(f)
         } else {
-            write!(f, "{}", self.to_string())
+            write!(f, "{}", self.self_description())
         }
     }
 }