Extracted a separate class to generate fresh variable names.

5 files changed, 86 insertions, 63 deletions

diff --git a/Source/Dafny/Compiler.cs b/Source/Dafny/Compiler.cs
index 1aa15145..a3312c4a 100644
--- a/Source/Dafny/Compiler.cs
+++ b/Source/Dafny/Compiler.cs
@@ -487,7 +487,7 @@ namespace Microsoft.Dafny {
 

         Indent(indent);  wr.WriteLine("}");

       }

-      constructorIndex ++;

+      constructorIndex++;

     }

 

     void CompileDatatypeStruct(DatatypeDecl dt, int indent) {

@@ -1179,7 +1179,7 @@ namespace Microsoft.Dafny {
               if (!(rhs is HavocRhs)) {

                 lvalues.Add(CreateLvalue(lhs, indent));

 

-                string target = "_rhs" + FreshTmpVarCount();

+                string target = VariableNameGenerator.FreshVariableName("_rhs");

                 rhss.Add(target);

                 TrRhs("var " + target, null, rhs, indent);

               }

@@ -1240,7 +1240,7 @@ namespace Microsoft.Dafny {
           Contract.Assert(s.Bounds != null);  // follows from s.MissingBounds == null

           var n = s.Lhss.Count;

           Contract.Assert(s.Bounds.Count == n);

-          var c = FreshTmpVarCount();

+          var c = VariableNameGenerator.FreshVariableCount();

           var doneLabel = "_ASSIGN_SUCH_THAT_" + c;

           var iterLimit = "_iterLimit_" + c;

 

@@ -1259,7 +1259,7 @@ namespace Microsoft.Dafny {
               Indent(ind);

               wr.WriteLine("var {0}_{1} = {0};", iterLimit, i);

             }

-            var tmpVar = "_assign_such_that_" + FreshTmpVarCount();

+            var tmpVar = VariableNameGenerator.FreshVariableName("_assign_such_that_");

             Indent(ind);

             if (bound is ComprehensionExpr.BoolBoundedPool) {

               wr.WriteLine("foreach (var {0} in Dafny.Helpers.AllBooleans) {{ @{1} = {0};", tmpVar, bv.CompileName);

@@ -1475,7 +1475,7 @@ namespace Microsoft.Dafny {
         // be nested.

 

         // Temporary names

-        var c = FreshTmpVarCount();

+        var c = VariableNameGenerator.FreshVariableCount();

         string ingredients = "_ingredients" + c;

         string tup = "_tup" + c;

 

@@ -1628,7 +1628,7 @@ namespace Microsoft.Dafny {
         //   ...

         // }

         if (s.Cases.Count != 0) {

-          string source = "_source" + FreshTmpVarCount();

+          string source = VariableNameGenerator.FreshVariableName("_source");

           Indent(indent);

           wr.Write("{0} {1} = ", TypeName(cce.NonNull(s.Source.Type)), source);

           TrExpr(s.Source);

@@ -1671,7 +1671,7 @@ namespace Microsoft.Dafny {
         return "@" + ll.Var.CompileName;

       } else if (lhs is MemberSelectExpr) {

         var ll = (MemberSelectExpr)lhs;

-        string obj = "_obj" + FreshTmpVarCount();

+        string obj = VariableNameGenerator.FreshVariableName("_obj");

         Indent(indent);

         wr.Write("var {0} = ", obj);

         TrExpr(ll.Obj);

@@ -1679,7 +1679,7 @@ namespace Microsoft.Dafny {
         return string.Format("{0}.@{1}", obj, ll.Member.CompileName);

       } else if (lhs is SeqSelectExpr) {

         var ll = (SeqSelectExpr)lhs;

-        var c = FreshTmpVarCount();

+        var c = VariableNameGenerator.FreshVariableCount();

         string arr = "_arr" + c;

         string index = "_index" + c;

         Indent(indent);

@@ -1693,7 +1693,7 @@ namespace Microsoft.Dafny {
         return string.Format("{0}[(int){1}]", arr, index);

       } else {

         var ll = (MultiSelectExpr)lhs;

-        var c = FreshTmpVarCount();

+        var c = VariableNameGenerator.FreshVariableCount();

         string arr = "_arr" + c;

         Indent(indent);

         wr.Write("var {0} = ", arr);

@@ -1720,7 +1720,7 @@ namespace Microsoft.Dafny {
       Contract.Requires((target == null) != (targetExpr == null));

       var tRhs = rhs as TypeRhs;

       if (tRhs != null && tRhs.InitCall != null) {

-        string nw = "_nw" + FreshTmpVarCount();

+        string nw = VariableNameGenerator.FreshVariableName("_nw");

         Indent(indent);

         wr.Write("var {0} = ", nw);

         TrAssignmentRhs(rhs);  // in this case, this call will not require us to spill any let variables first

@@ -1771,7 +1771,7 @@ namespace Microsoft.Dafny {
           // TODO:  What to do here?  When does this happen, what does it mean?

         } else if (!s.Method.IsStatic) {

 

-          string inTmp = "_in" + FreshTmpVarCount();

+          string inTmp = VariableNameGenerator.FreshVariableName("_in");

           inTmps.Add(inTmp);

           Indent(indent);

           wr.Write("var {0} = ", inTmp);

@@ -1781,7 +1781,7 @@ namespace Microsoft.Dafny {
         for (int i = 0; i < s.Method.Ins.Count; i++) {

           Formal p = s.Method.Ins[i];

           if (!p.IsGhost) {

-            string inTmp = "_in" + FreshTmpVarCount();

+            string inTmp = VariableNameGenerator.FreshVariableName("_in");

             inTmps.Add(inTmp);

             Indent(indent);

             wr.Write("var {0} = ", inTmp);

@@ -1823,7 +1823,7 @@ namespace Microsoft.Dafny {
         for (int i = 0; i < s.Method.Outs.Count; i++) {

           Formal p = s.Method.Outs[i];

           if (!p.IsGhost) {

-            string target = "_out" + FreshTmpVarCount();

+            string target = VariableNameGenerator.FreshVariableName("_out");

             outTmps.Add(target);

             Indent(indent);

             wr.WriteLine("{0} {1};", TypeName(s.Lhs[i].Type), target);

@@ -1879,11 +1879,7 @@ namespace Microsoft.Dafny {
       }

     }

 

-    int tmpVarCount = 0;

-    int FreshTmpVarCount()

-    {

-      return tmpVarCount++;

-    }

+    FreshVariableNameGenerator VariableNameGenerator = new FreshVariableNameGenerator();

 

     /// <summary>

     /// Before calling TrAssignmentRhs(rhs), the caller must have spilled the let variables declared in "rhs".

@@ -2249,7 +2245,7 @@ namespace Microsoft.Dafny {
               string arg;

               var fce = actual as FunctionCallExpr;

               if (fce == null || fce.CoCall != FunctionCallExpr.CoCallResolution.Yes) {

-                string varName = "_ac" + FreshTmpVarCount();

+                string varName = VariableNameGenerator.FreshVariableName("_ac");

                 arg = varName;

 

                 wr.Write("var {0} = ", varName);

@@ -2258,7 +2254,7 @@ namespace Microsoft.Dafny {
               } else {

                 var sw = new StringWriter();

                 CompileFunctionCallExpr(fce, sw, (exp) => {

-                  string varName = "_ac" + FreshTmpVarCount();

+                  string varName = VariableNameGenerator.FreshVariableName("_ac");

                   sw.Write(varName);

 

                   wr.Write("var {0} = ", varName);

@@ -2571,7 +2567,7 @@ namespace Microsoft.Dafny {
         //   }

         // }(src)

 

-        string source = "_source" + FreshTmpVarCount();

+        string source = VariableNameGenerator.FreshVariableName("_source");

         wr.Write("new Dafny.Helpers.Function<{0}, {1}>(delegate ({0} {2}) {{ ", TypeName(e.Source.Type), TypeName(e.Type), source);

 

         if (e.Cases.Count == 0) {

diff --git a/Source/Dafny/DafnyAst.cs b/Source/Dafny/DafnyAst.cs
index 18e64b98..7fa8df76 100644
--- a/Source/Dafny/DafnyAst.cs
+++ b/Source/Dafny/DafnyAst.cs
@@ -6195,6 +6195,7 @@ namespace Microsoft.Dafny {
 

   public abstract class QuantifierExpr : ComprehensionExpr, TypeParameter.ParentType {

     public List<TypeParameter> TypeArgs;

+    // TODO(wuestholz): Can we make this non-static?

     private static int quantCount = 0;

     private readonly int quantUnique;

     public string FullName {

@@ -6202,11 +6203,11 @@ namespace Microsoft.Dafny {
         return "q$" + quantUnique;

       }

     }

-    public String Refresh(String s, int counter) {

-      return s + "#" + counter + FullName;

+    public String Refresh(string prefix, FreshVariableNameGenerator freshVarNameGen) {

+      return freshVarNameGen.FreshVariableName(prefix + "#") + FullName;

     }

-    public TypeParameter Refresh(TypeParameter p, int counter) {

-      var cp = new TypeParameter(p.tok, counter + "#" + p.Name, p.EqualitySupport);

+    public TypeParameter Refresh(TypeParameter p, FreshVariableNameGenerator freshVarNameGen) {

+      var cp = new TypeParameter(p.tok, freshVarNameGen.FreshVariableCount() + "#" + p.Name, p.EqualitySupport);

       cp.Parent = this;

       return cp;

     }

@@ -6302,6 +6303,7 @@ namespace Microsoft.Dafny {
 

   public class LambdaExpr : ComprehensionExpr

   {

+    // TODO(wuestholz): Can we make this non-static?

     private static int lamUniques = 0;

 

     public readonly bool OneShot;

diff --git a/Source/Dafny/Resolver.cs b/Source/Dafny/Resolver.cs
index 778138cc..99045b01 100644
--- a/Source/Dafny/Resolver.cs
+++ b/Source/Dafny/Resolver.cs
@@ -492,17 +492,17 @@ namespace Microsoft.Dafny
       return anyChangeToDecreases;

     }

 

-    public static Expression FrameArrowToObjectSet(Expression e, Func<int> freshTmp) {

+    public static Expression FrameArrowToObjectSet(Expression e, FreshVariableNameGenerator freshVarNameGen) {

       var arrTy = e.Type.AsArrowType;

       if (arrTy != null) {

         var bvars = new List<BoundVar>();

         var bexprs = new List<Expression>();

         foreach (var t in arrTy.Args) {

-          var bv = new BoundVar(e.tok, "_x" + freshTmp(), t);

+          var bv = new BoundVar(e.tok, freshVarNameGen.FreshVariableName("_x"), t);

           bvars.Add(bv);

           bexprs.Add(new IdentifierExpr(e.tok, bv.Name) { Type = bv.Type, Var = bv });

         }

-        var oVar = new BoundVar(e.tok, "_o" + freshTmp(), new ObjectType());

+        var oVar = new BoundVar(e.tok, freshVarNameGen.FreshVariableName("_o"), new ObjectType());

         var obj = new IdentifierExpr(e.tok, oVar.Name) { Type = oVar.Type, Var = oVar };

         bvars.Add(oVar);

 

@@ -531,13 +531,13 @@ namespace Microsoft.Dafny
 

       List<Expression> sets = new List<Expression>();

       List<Expression> singletons = null;

-      int tmpVarCount = 0;

+      var freshVarNameGen = new FreshVariableNameGenerator();

       foreach (FrameExpression fe in fexprs) {

         Contract.Assert(fe != null);

         if (fe.E is WildcardExpr) {

           // drop wildcards altogether

         } else {

-          Expression e = FrameArrowToObjectSet(fe.E, () => ++tmpVarCount);  // keep only fe.E, drop any fe.Field designation

+          Expression e = FrameArrowToObjectSet(fe.E, freshVarNameGen);  // keep only fe.E, drop any fe.Field designation

           Contract.Assert(e.Type != null);  // should have been resolved already

           var eType = e.Type.NormalizeExpand();

           if (eType.IsRefType) {

@@ -549,7 +549,7 @@ namespace Microsoft.Dafny
           } else if (eType is SeqType) {

             // e represents a sequence

             // Add:  set x :: x in e

-            var bv = new BoundVar(e.tok, "_s2s_" + (++tmpVarCount), ((SeqType)eType).Arg);

+            var bv = new BoundVar(e.tok, freshVarNameGen.FreshVariableName("_s2s_"), ((SeqType)eType).Arg);

             var bvIE = new IdentifierExpr(e.tok, bv.Name);

             bvIE.Var = bv;  // resolve here

             bvIE.Type = bv.Type;  // resolve here

diff --git a/Source/Dafny/Translator.cs b/Source/Dafny/Translator.cs
index 4f57d5f9..72a9e752 100644
--- a/Source/Dafny/Translator.cs
+++ b/Source/Dafny/Translator.cs
@@ -14,6 +14,33 @@ using System.Text;
 using Microsoft.Boogie;

 

 namespace Microsoft.Dafny {

+

+  public class FreshVariableNameGenerator

+  {

+    readonly Dictionary<string, int> PrefixToCount = new Dictionary<string, int>();

+

+    public void Reset()

+    {

+      PrefixToCount.Clear();

+    }

+

+    public string FreshVariableName(string prefix = "")

+    {

+      return prefix + FreshVariableCount(prefix);

+    }

+

+    public int FreshVariableCount(string prefix = "")

+    {

+      int old;

+      if (!PrefixToCount.TryGetValue(prefix, out old))

+      {

+        old = 0;

+      }

+      PrefixToCount[prefix] = old + 1;

+      return old;

+    }

+  }

+

   public class Translator {

 

     [NotDelayed]

@@ -1161,7 +1188,7 @@ namespace Microsoft.Dafny {
       args = new List<Bpl.Expr>();

       foreach (Formal arg in formals) {

         Contract.Assert(arg != null);

-        var nm = string.Format("a{0}#{1}", bvs.Count, FreshOtherTmpVarCount());

+        var nm = string.Format("a{0}#{1}", bvs.Count, FreshVarNameGenerator.FreshVariableName());

         Bpl.Variable bv = new Bpl.BoundVariable(arg.tok, new Bpl.TypedIdent(arg.tok, nm, TrType(arg.Type)));

         bvs.Add(bv);

         args.Add(new Bpl.IdentifierExpr(arg.tok, bv));

@@ -1709,7 +1736,7 @@ namespace Microsoft.Dafny {
       currentModule = null;

       codeContext = null;

       loopHeapVarCount = 0;

-      otherTmpVarCount = 0;

+      FreshVarNameGenerator.Reset();

       _tmpIEs.Clear();

     }

 

@@ -2527,16 +2554,15 @@ namespace Microsoft.Dafny {
     ICallable codeContext = null;  // the method/iterator whose implementation is currently being translated or the function whose specification is being checked for well-formedness

     Bpl.LocalVariable yieldCountVariable = null;  // non-null when an iterator body is being translated

     bool assertAsAssume = false; // generate assume statements instead of assert statements

+

     int loopHeapVarCount = 0;

     int FreshLoopHeadVarCount()

     {

       return loopHeapVarCount++;

     }

-    int otherTmpVarCount = 0;

-    int FreshOtherTmpVarCount()

-    {

-      return otherTmpVarCount++;

-    }

+

+    public readonly FreshVariableNameGenerator FreshVarNameGenerator = new FreshVariableNameGenerator();

+

     Dictionary<string, Bpl.IdentifierExpr> _tmpIEs = new Dictionary<string, Bpl.IdentifierExpr>();

     Bpl.IdentifierExpr GetTmpVar_IdExpr(IToken tok, string name, Bpl.Type ty, List<Variable> locals)  // local variable that's shared between statements that need it

     {

@@ -3802,7 +3828,7 @@ namespace Microsoft.Dafny {
           e = Substitute(e, receiverReplacement, substMap);

         }

 

-        e = Resolver.FrameArrowToObjectSet(e, FreshOtherTmpVarCount);

+        e = Resolver.FrameArrowToObjectSet(e, FreshVarNameGenerator);

 

         Bpl.Expr disjunct;

         var eType = e.Type.NormalizeExpand();

@@ -4127,7 +4153,7 @@ namespace Microsoft.Dafny {
       var args = new List<Bpl.Expr>();

       foreach (Formal arg in ctor.Formals) {

         Contract.Assert(arg != null);

-        var nm = string.Format("a{0}#{1}", args.Count, FreshOtherTmpVarCount());

+        var nm = string.Format("a{0}#{1}", args.Count, FreshVarNameGenerator.FreshVariableCount());

         Bpl.Variable bv = new Bpl.LocalVariable(arg.tok, new Bpl.TypedIdent(arg.tok, nm, TrType(arg.Type)));

         locals.Add(bv);

         args.Add(new Bpl.IdentifierExpr(arg.tok, bv));

@@ -4296,7 +4322,7 @@ namespace Microsoft.Dafny {
 

         List<Bpl.Variable> bvars = new List<Bpl.Variable>();

 

-        Func<string, string> MkName = s => "$l" + FreshOtherTmpVarCount() + "#" + s;

+        Func<string, string> MkName = s => "$l" + FreshVarNameGenerator.FreshVariableCount() + "#" + s;

 

         Bpl.Expr heap; var hVar = BplBoundVar(MkName("heap"), predef.HeapType, out heap);

         bvars.Add(hVar);

@@ -4468,7 +4494,7 @@ namespace Microsoft.Dafny {
       public Action<IToken, Bpl.Expr, string, Bpl.QKeyValue> AssertSink(Translator tran, StmtListBuilder builder) {

         return (t, e, s, qk) => {

           if (Locals != null) {

-            var b = BplLocalVar("b$reqreads#" + tran.FreshOtherTmpVarCount(), Bpl.Type.Bool, Locals);

+            var b = BplLocalVar(tran.FreshVarNameGenerator.FreshVariableName("b$reqreads#"), Bpl.Type.Bool, Locals);

             Asserts.Add(tran.Assert(t, b, s, qk));

             builder.Add(Bpl.Cmd.SimpleAssign(e.tok, (Bpl.IdentifierExpr)b, e));

           } else {

@@ -4933,7 +4959,7 @@ namespace Microsoft.Dafny {
           for (int i = 0; i < e.LHSs.Count; i++) {

             var pat = e.LHSs[i];

             var rhs = e.RHSs[i];

-            var nm = string.Format("let{0}#{1}", i, FreshOtherTmpVarCount());

+            var nm = string.Format("let{0}#{1}", i, FreshVarNameGenerator.FreshVariableCount());

             var r = new Bpl.LocalVariable(pat.tok, new Bpl.TypedIdent(pat.tok, nm, TrType(rhs.Type)));

             locals.Add(r);

             var rIe = new Bpl.IdentifierExpr(pat.tok, r);

@@ -5000,7 +5026,7 @@ namespace Microsoft.Dafny {
         var typeMap = new Dictionary<TypeParameter, Type>();

         var copies = new List<TypeParameter>();

         if (q != null) {

-          copies = Map(q.TypeArgs, tp => q.Refresh(tp, FreshOtherTmpVarCount()));

+          copies = Map(q.TypeArgs, tp => q.Refresh(tp, FreshVarNameGenerator));

           typeMap = Util.Dict(q.TypeArgs, Map(copies, tp => (Type)new UserDefinedType(tp)));

         }

         locals.AddRange(Map(copies,

@@ -5019,7 +5045,7 @@ namespace Microsoft.Dafny {
             // Havoc heap, unless oneShot

             if (!lam.OneShot) {

               Bpl.Expr oldHeap;

-              locals.Add(BplLocalVar("$oldHeap#" + FreshOtherTmpVarCount(), predef.HeapType, out oldHeap));

+              locals.Add(BplLocalVar(FreshVarNameGenerator.FreshVariableName("$oldHeap#"), predef.HeapType, out oldHeap));

               newBuilder.Add(BplSimplestAssign(oldHeap, etran.HeapExpr));

               newBuilder.Add(new HavocCmd(expr.tok, Singleton((Bpl.IdentifierExpr)etran.HeapExpr)));

               newBuilder.Add(new AssumeCmd(expr.tok,

@@ -5028,7 +5054,7 @@ namespace Microsoft.Dafny {
             }

 

             // Set up a new frame

-            var frameName = "$_Frame#l" + FreshOtherTmpVarCount();

+            var frameName = FreshVarNameGenerator.FreshVariableName("$_Frame#l");

             reads = lam.Reads.ConvertAll(s.SubstFrameExpr);

             DefineFrame(e.tok, reads, newBuilder, locals, frameName);

             newEtran = new ExpressionTranslator(newEtran, frameName);

@@ -5170,7 +5196,7 @@ namespace Microsoft.Dafny {
         return;

       }

 

-      var oVar = new Bpl.LocalVariable(tok, new Bpl.TypedIdent(tok, "newtype$check#" + FreshOtherTmpVarCount(), TrType(expr.Type)));

+      var oVar = new Bpl.LocalVariable(tok, new Bpl.TypedIdent(tok, FreshVarNameGenerator.FreshVariableName("newtype$check#"), TrType(expr.Type)));

       locals.Add(oVar);

       var o = new Bpl.IdentifierExpr(tok, oVar);

       builder.Add(Bpl.Cmd.SimpleAssign(tok, o, etran.TrExpr(expr)));

@@ -5231,7 +5257,7 @@ namespace Microsoft.Dafny {
       Contract.Ensures(Contract.ValueAtReturn(out bv) != null);

       Contract.Ensures(Contract.ValueAtReturn(out ie) != null);

 

-      bv = new BoundVar(tok, prefix + FreshOtherTmpVarCount(), iv.Type); // use this temporary variable counter, but for a Dafny name (the idea being that the number and the initial "_" in the name might avoid name conflicts)

+      bv = new BoundVar(tok, prefix + FreshVarNameGenerator.FreshVariableCount(), iv.Type); // use this temporary variable counter, but for a Dafny name (the idea being that the number and the initial "_" in the name might avoid name conflicts)

       ie = new IdentifierExpr(tok, bv.Name);

       ie.Var = bv;  // resolve here

       ie.Type = bv.Type;  // resolve here

@@ -6158,7 +6184,7 @@ namespace Microsoft.Dafny {
         var bLhs = m.Outs[i];

         if (!ModeledAsBoxType(method.Outs[i].Type) && ModeledAsBoxType(bLhs.Type)) {

           // we need an Box

-          Bpl.LocalVariable var = new Bpl.LocalVariable(bLhs.tok, new Bpl.TypedIdent(bLhs.tok, "$tmp##" + FreshOtherTmpVarCount(), TrType(method.Outs[i].Type)));

+          Bpl.LocalVariable var = new Bpl.LocalVariable(bLhs.tok, new Bpl.TypedIdent(bLhs.tok, FreshVarNameGenerator.FreshVariableName("$tmp##"), TrType(method.Outs[i].Type)));

           localVariables.Add(var);

           Bpl.IdentifierExpr varIdE = new Bpl.IdentifierExpr(bLhs.tok, var.Name, TrType(method.Outs[i].Type));

           tmpOuts.Add(varIdE);

@@ -7920,7 +7946,7 @@ namespace Microsoft.Dafny {
 

       // Now for the other branch, where the postcondition of the call is exported.

       {

-        var initHeapVar = new Bpl.LocalVariable(tok, new Bpl.TypedIdent(tok, "$initHeapForallStmt#" + FreshOtherTmpVarCount(), predef.HeapType));

+        var initHeapVar = new Bpl.LocalVariable(tok, new Bpl.TypedIdent(tok, FreshVarNameGenerator.FreshVariableName("$initHeapForallStmt#"), predef.HeapType));

         locals.Add(initHeapVar);

         var initHeap = new Bpl.IdentifierExpr(tok, initHeapVar);

         var initEtran = new ExpressionTranslator(this, predef, initHeap, etran.Old.HeapExpr);

@@ -7982,7 +8008,7 @@ namespace Microsoft.Dafny {
       Contract.Requires(locals != null);

       Contract.Requires(etran != null);

       // Add all newly allocated objects to the set this._new

-      var updatedSet = new Bpl.LocalVariable(iter.tok, new Bpl.TypedIdent(iter.tok, "$iter_newUpdate" + FreshOtherTmpVarCount(), predef.SetType(iter.tok, predef.BoxType)));

+      var updatedSet = new Bpl.LocalVariable(iter.tok, new Bpl.TypedIdent(iter.tok, FreshVarNameGenerator.FreshVariableName("$iter_newUpdate"), predef.SetType(iter.tok, predef.BoxType)));

       locals.Add(updatedSet);

       var updatedSetIE = new Bpl.IdentifierExpr(iter.tok, updatedSet);

       // call $iter_newUpdate := $IterCollectNewObjects(initHeap, $Heap, this, _new);

@@ -8059,7 +8085,7 @@ namespace Microsoft.Dafny {
 

       // Now for the other branch, where the ensures clauses are exported.

 

-      var initHeapVar = new Bpl.LocalVariable(s.Tok, new Bpl.TypedIdent(s.Tok, "$initHeapForallStmt#" + FreshOtherTmpVarCount(), predef.HeapType));

+      var initHeapVar = new Bpl.LocalVariable(s.Tok, new Bpl.TypedIdent(s.Tok, FreshVarNameGenerator.FreshVariableName("$initHeapForallStmt#"), predef.HeapType));

       locals.Add(initHeapVar);

       var initHeap = new Bpl.IdentifierExpr(s.Tok, initHeapVar);

       var initEtran = new ExpressionTranslator(this, predef, initHeap, etran.Old.HeapExpr);

@@ -8341,7 +8367,7 @@ namespace Microsoft.Dafny {
         builder.Add(new CommentCmd("TrCallStmt: Adding lhs " + lhs + " with type " + lhs.Type));

         if (bLhss[i] == null) {  // (in the current implementation, the second parameter "true" to ProcessLhss implies that all bLhss[*] will be null)

           // create temporary local and assign it to bLhss[i]

-          string nm = "$rhs##" + FreshOtherTmpVarCount();

+          string nm = FreshVarNameGenerator.FreshVariableName("$rhs##");

           var ty = TrType(lhs.Type);

           Bpl.Expr wh = GetWhereClause(lhs.tok, new Bpl.IdentifierExpr(lhs.tok, nm, ty), lhs.Type, etran);

           Bpl.LocalVariable var = new Bpl.LocalVariable(lhs.tok, new Bpl.TypedIdent(lhs.tok, nm, ty, wh));

@@ -8352,7 +8378,7 @@ namespace Microsoft.Dafny {
       Bpl.IdentifierExpr initHeap = null;

       if (codeContext is IteratorDecl) {

         // var initHeap := $Heap;

-        var initHeapVar = new Bpl.LocalVariable(s.Tok, new Bpl.TypedIdent(s.Tok, "$initHeapCallStmt#" + FreshOtherTmpVarCount(), predef.HeapType));

+        var initHeapVar = new Bpl.LocalVariable(s.Tok, new Bpl.TypedIdent(s.Tok, FreshVarNameGenerator.FreshVariableName("$initHeapCallStmt#"), predef.HeapType));

         locals.Add(initHeapVar);

         initHeap = new Bpl.IdentifierExpr(s.Tok, initHeapVar);

         // initHeap := $Heap;

@@ -8525,7 +8551,7 @@ namespace Microsoft.Dafny {
         var bLhs = Lhss[i];

         if (ModeledAsBoxType(callee.Outs[i].Type) && !ModeledAsBoxType(LhsTypes[i])) {

           // we need an Unbox

-          Bpl.LocalVariable var = new Bpl.LocalVariable(bLhs.tok, new Bpl.TypedIdent(bLhs.tok, "$tmp##" + FreshOtherTmpVarCount(), predef.BoxType));

+          Bpl.LocalVariable var = new Bpl.LocalVariable(bLhs.tok, new Bpl.TypedIdent(bLhs.tok, FreshVarNameGenerator.FreshVariableName("$tmp##"), predef.BoxType));

           locals.Add(var);

           Bpl.IdentifierExpr varIdE = new Bpl.IdentifierExpr(bLhs.tok, var.Name, predef.BoxType);

           tmpOuts.Add(varIdE);

@@ -9455,7 +9481,7 @@ namespace Microsoft.Dafny {
       Contract.Requires(predef != null);

 

       if (bLhs == null) {

-        var nm = string.Format("$rhs#{0}", FreshOtherTmpVarCount());

+        var nm = FreshVarNameGenerator.FreshVariableName("$rhs#");

         var v = new Bpl.LocalVariable(tok, new Bpl.TypedIdent(tok, nm, lhsType == null ? predef.BoxType : TrType(lhsType)));

         locals.Add(v);

         bLhs = new Bpl.IdentifierExpr(tok, v);

@@ -10940,12 +10966,12 @@ namespace Microsoft.Dafny {
 

           if (Attributes.ContainsBool(e.Attributes, "layerQuantifier", ref _scratch)) {

             // If this is a layer quantifier, quantify over layers here, and use $LS(ly) layers in the translation of the body

-            var ly = BplBoundVar(e.Refresh("$ly", translator.FreshOtherTmpVarCount()), predef.LayerType, bvars);

+            var ly = BplBoundVar(e.Refresh("$ly", translator.FreshVarNameGenerator), predef.LayerType, bvars);

             Expr layer = translator.LayerSucc(ly);

             bodyEtran = new ExpressionTranslator(translator, predef, HeapExpr, This, applyLimited_CurrentFunction, layer, layer, modifiesFrame);

           }

           if (Attributes.ContainsBool(e.Attributes, "heapQuantifier", ref _scratch)) {

-            var h = BplBoundVar(e.Refresh("$heap", translator.FreshOtherTmpVarCount()), predef.HeapType, bvars);

+            var h = BplBoundVar(e.Refresh("$heap", translator.FreshVarNameGenerator), predef.HeapType, bvars);

             bodyEtran = new ExpressionTranslator(bodyEtran, h);

             antecedent = BplAnd(new List<Bpl.Expr> {

               antecedent,

@@ -10986,7 +11012,7 @@ namespace Microsoft.Dafny {
           Bpl.Expr typeAntecedent = TrBoundVariables(e.BoundVars, bvars);

           Bpl.QKeyValue kv = TrAttributes(e.Attributes, null);

 

-          var yVar = new Bpl.BoundVariable(expr.tok, new Bpl.TypedIdent(expr.tok, "$y#" + translator.FreshOtherTmpVarCount(), predef.BoxType));

+          var yVar = new Bpl.BoundVariable(expr.tok, new Bpl.TypedIdent(expr.tok, translator.FreshVarNameGenerator.FreshVariableName("$y#"), predef.BoxType));

           Bpl.Expr y = new Bpl.IdentifierExpr(expr.tok, yVar);

 

           var eq = Bpl.Expr.Eq(y, BoxIfNecessary(expr.tok, TrExpr(e.Term), e.Term.Type));

@@ -11006,7 +11032,7 @@ namespace Microsoft.Dafny {
 

           Bpl.QKeyValue kv = TrAttributes(e.Attributes, null);

 

-          var yVar = new Bpl.BoundVariable(expr.tok, new Bpl.TypedIdent(expr.tok, "$y#" + translator.FreshOtherTmpVarCount(), predef.BoxType));

+          var yVar = new Bpl.BoundVariable(expr.tok, new Bpl.TypedIdent(expr.tok, translator.FreshVarNameGenerator.FreshVariableName("$y#"), predef.BoxType));

 

           Bpl.Expr unboxy = translator.UnboxIfBoxed(new Bpl.IdentifierExpr(expr.tok, yVar), bv.Type);

           Bpl.Expr typeAntecedent = translator.GetWhereClause(bv.tok, unboxy, bv.Type, this);

@@ -12277,7 +12303,7 @@ namespace Microsoft.Dafny {
           foreach (var n in inductionVariables) {

             toks.Add(n.tok);

             types.Add(n.Type.NormalizeExpand());

-            BoundVar k = new BoundVar(n.tok, n.Name + "$ih#" + FreshOtherTmpVarCount(), n.Type);

+            BoundVar k = new BoundVar(n.tok, n.Name + "$ih#" + FreshVarNameGenerator.FreshVariableCount(), n.Type);

             kvars.Add(k);

 

             IdentifierExpr ieK = new IdentifierExpr(k.tok, k.AssignUniqueName(currentDeclaration));

diff --git a/Test/VSI-Benchmarks/b3.dfy b/Test/VSI-Benchmarks/b3.dfy
index 91044397..5a2b6e13 100644
--- a/Test/VSI-Benchmarks/b3.dfy
+++ b/Test/VSI-Benchmarks/b3.dfy
@@ -86,8 +86,8 @@ class Benchmark3 {
    

     while (j < n)

       invariant j <= n;

+      invariant 0 <= k < n && old(q.contents)[k] == m;

       invariant q.contents == old(q.contents)[j..] + old(q.contents)[..j]; //i.e. rotated

-      invariant 0 <= k < |old(q.contents)| && old(q.contents)[k] == m;

       invariant forall i :: 0 <= i < j ==> m <= old(q.contents)[i]; //m is min so far

     {

       var x := q.Dequeue();

@@ -104,7 +104,6 @@ class Benchmark3 {
       var x := q.Dequeue();

       q.Enqueue(x);

       j := j+1;

-      assert q.contents == old(q.contents)[j..] + old(q.contents)[..j];

     }

 

     m := q.Dequeue();