Fix issue 139. Allow bound variables in nested case patterns to shadow variables

declared outside the enclosing match.

1 files changed, 11 insertions, 1 deletions

diff --git a/Source/Dafny/Resolver.cs b/Source/Dafny/Resolver.cs
index 5a63b4e3..d3b59b51 100644
--- a/Source/Dafny/Resolver.cs
+++ b/Source/Dafny/Resolver.cs
@@ -6376,7 +6376,12 @@ namespace Microsoft.Dafny
         if (topLevel) {

           ScopePushAndReport(scope, v, "parameter");

         } else {

-          if (scope.Find(v.Name) != null) {

+          // For cons(a, const(b, c)):

+          // this handles check to see if 'b' or 'c' is duplicate with 'a',

+          // the duplication check between 'b' and 'c' is handled in the desugared

+          // form (to avoid reporting the same error twice), that is why we don't 

+          // push 'b' and 'c' onto the scope, only find.

+          if (scope.FindInCurrentScope(v.Name) != null) {

             reporter.Error(MessageSource.Resolver, v, "Duplicate parameter name: {0}", v.Name);

           }

         }

@@ -11069,6 +11074,11 @@ namespace Microsoft.Dafny
       return Find(name, false);

     }

 

+    public Thing FindInCurrentScope(string name) {

+      Contract.Requires(name != null);

+      return Find(name, true);

+    }

+

     public bool ContainsDecl(Thing t) {

       return things.Exists(thing => thing == t);

     }