Refactor if block to use idiomatic matches

Author: Josh Leeb-du Toit

src/librustc_borrowck/borrowck/check_loans.rs

@@ -395,22 +395,18 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
         assert!(self.bccx.region_scope_tree.scopes_intersect(old_loan.kill_scope,
                                                        new_loan.kill_scope));
 
-        let err_old_new = Result::err(self.report_error_if_loan_conflicts_with_restriction(
-            old_loan, new_loan, old_loan, new_loan
-        ));
-        let err_new_old = Result::err(self.report_error_if_loan_conflicts_with_restriction(
-            new_loan, old_loan, old_loan, new_loan
-        ));
-
-        if let Some(mut err_old) = err_old_new {
-            err_old.emit();
-            if let Some(mut err_new) = err_new_old {
+        let err_old_new = self.report_error_if_loan_conflicts_with_restriction(
+            old_loan, new_loan, old_loan, new_loan).err();
+        let err_new_old = self.report_error_if_loan_conflicts_with_restriction(
+            new_loan, old_loan, old_loan, new_loan).err();
+
+        match (err_old_new, err_new_old) {
+            (Some(mut err), None) | (None, Some(mut err)) => err.emit(),
+            (Some(mut err_old), Some(mut err_new)) => {
+                err_old.emit();
                 err_new.cancel();
             }
-        } else if let Some(mut err_new) = err_new_old {
-            err_new.emit();
-        } else {
-            return true;
+            (None, None) => return true,
         }
 
         false