Fix which-is-unsatisfied (#394)

Author: Pratyush

relations/examples/non_satisfiable.rs

@@ -37,7 +37,7 @@ fn main() {
     // Build the circuit
     let _result_var =
         generate_constraints(cs.clone(), p1, p2, p3, p4, w1, w2, w3, w4, expected_result).unwrap();
-    let trace = cs.which_predicate_is_unsatisfied().unwrap().unwrap();
+    let trace = cs.which_is_unsatisfied().unwrap().unwrap();
     println!(
         "This is the trace of non-satisfied scenario, Check out the trace:\n{}",
         trace

relations/src/gr1cs/constraint_system_ref.rs

@@ -349,7 +349,7 @@ impl<F: Field> ConstraintSystemRef<F> {
     /// the unsatisfied  prediacate and  `i` is the index of
     /// the first unsatisfied constraint in that  predicate.
     /// If `self.is_in_setup_mode()` or `self == None`, outputs `Err(())`.
-    pub fn which_predicate_is_unsatisfied(&self) -> crate::utils::Result<Option<String>> {
+    pub fn which_is_unsatisfied(&self) -> crate::utils::Result<Option<String>> {
         self.inner()
             .ok_or(SynthesisError::MissingCS)
             .and_then(|cs| cs.borrow().which_is_unsatisfied())