Fix issue 118. When iteratively computing bounds, treat RefBoundedPool typed

bound as undetermined so that iteration will continue.

3 files changed, 18 insertions, 1 deletions

diff --git a/Source/Dafny/Resolver.cs b/Source/Dafny/Resolver.cs
index 9dc0f829..79f1e7e1 100644
--- a/Source/Dafny/Resolver.cs
+++ b/Source/Dafny/Resolver.cs
@@ -9771,11 +9771,14 @@ namespace Microsoft.Dafny
         bests = all.ConvertAll(tup => ComprehensionExpr.BoundedPool.GetBest(tup.Item2, onlyFiniteBounds));

         // check to see if we found new bounds in this iteration

         int count = 0;

+        // figure out how many bounds are not determined yet.

         for (int i = 0; i < bests.Count; i++) {

-          if (bests[i] == null) {

+          if (bests[i] == null || (bests[i] is ComprehensionExpr.RefBoundedPool)) {

             count++;

           }

         }

+        // if there are bounds that are not determined yet and the number of undetermined bounds

+        // changed, we will need to do another iteration.

         if (count >0 && count != orgCount) {

           changed = true;

           knownBounds = bests;

diff --git a/Test/dafny4/Bug118.dfy b/Test/dafny4/Bug118.dfy
new file mode 100644
index 00000000..1e2dddeb
--- /dev/null
+++ b/Test/dafny4/Bug118.dfy
@@ -0,0 +1,12 @@
+// RUN: %dafny /compile:0 "%s" > "%t"

+// RUN: %diff "%s.expect" "%t"

+

+class Foo {

+  ghost var Repr: set<object>

+}

+

+function SeqRepr(s:seq<Foo>) : set<object>

+  reads set b | b in s 

+{

+  set o,b | b in s && b != null && o in b.Repr :: o     // Works if you say "set b,o | ..."

+}
\ No newline at end of file
diff --git a/Test/dafny4/Bug118.dfy.expect b/Test/dafny4/Bug118.dfy.expect
new file mode 100644
index 00000000..c0c48e2b
--- /dev/null
+++ b/Test/dafny4/Bug118.dfy.expect
@@ -0,0 +1,2 @@
+

+Dafny program verifier finished with 1 verified, 0 errors