Change the return type of StandardVisitor.VisitExistsExpr() from

ExistsExpr to Expr. Enforcing the return type be ExistsExpr is
too restrictive. For example it prevents anyone from implementing
a visitor that does constant folding of an Expr tree.

There is precedence for this. For example VisitNAryExpr() returns
an Expr not an NAryExpr.

Unfortunately this a breaking API change so anyone who subclasses
the StandardVisitor (or one of its sub classes) and overrides this
method will get compilation errors until they change the return type.
a visitor that does constant folding of an Expr tree

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/VCExpr/Boogie2VCExpr.cs b/Source/VCExpr/Boogie2VCExpr.cs
index f261553b..7cd3d240 100644
--- a/Source/VCExpr/Boogie2VCExpr.cs
+++ b/Source/VCExpr/Boogie2VCExpr.cs
@@ -454,7 +454,7 @@ namespace Microsoft.Boogie.VCExprAST {
       return node;

     }

 

-    public override ExistsExpr VisitExistsExpr(ExistsExpr node) {

+    public override Expr VisitExistsExpr(ExistsExpr node) {

       //Contract.Requires(node != null);

       Contract.Ensures(Contract.Result<ExistsExpr>() != null);

       node = (ExistsExpr)this.VisitQuantifierExpr(node);