Change the return type of StandardVisitor.VisitLiteralExpr() from

LiteralExpr to Expr. Enforcing the return type be LiteralExpr is
too restrictive.

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/AbsInt/IntervalDomain.cs b/Source/AbsInt/IntervalDomain.cs
index 5a4c606f..1ac80970 100644
--- a/Source/AbsInt/IntervalDomain.cs
+++ b/Source/AbsInt/IntervalDomain.cs
@@ -659,7 +659,7 @@ namespace Microsoft.Boogie.AbstractInterpretation
         Lo = Hi = null;

         return base.VisitExpr(node);

       }

-      public override LiteralExpr VisitLiteralExpr(LiteralExpr node) {

+      public override Expr VisitLiteralExpr(LiteralExpr node) {

         if (node.Val is BigNum) {

           var n = ((BigNum)node.Val).ToBigInteger;

           Lo = n;