The Dafny call statement now automatically declares left-hand sides as local variables, if they were not already local variables.

5 files changed, 75 insertions, 15 deletions

diff --git a/Source/Dafny/Dafny.atg b/Source/Dafny/Dafny.atg
index 9ab826ac..022dc912 100644
--- a/Source/Dafny/Dafny.atg
+++ b/Source/Dafny/Dafny.atg
@@ -25,6 +25,28 @@ static Statement! dummyStmt = new ReturnStmt(Token.NoToken);
 static Attributes.Argument! dummyAttrArg = new Attributes.Argument("dummyAttrArg");

 static Scope<string>! parseVarScope = new Scope<string>();

 

+// helper routine for parsing call statements

+private static void RecordCallLhs(IdentifierExpr! e,

+                                  List<IdentifierExpr!>! lhs,

+                                  List<VarDecl!>! newVars) {

+  lhs.Add(e);

+  if (parseVarScope.Find(e.Name) == null) {

+    VarDecl d = new VarDecl(e.tok, e.Name, new InferredTypeProxy(), null);

+    newVars.Add(d);

+    parseVarScope.Push(e.Name, e.Name);

+  }

+}

+

+// helper routine for parsing call statements

+private static Expression! ConvertToLocal(Expression! e)

+{

+  FieldSelectExpr fse = e as FieldSelectExpr;

+  if (fse != null && fse.Obj is ImplicitThisExpr) {

+    return new IdentifierExpr(fse.tok, fse.FieldName);

+  }

+  return e;  // cannot convert to IdentifierExpr (or is already an IdentifierExpr)

+}

+

 ///<summary>

 /// Parses top level declarations from "filename" and appends them to "classes".

 /// Returns the number of parsing errors encountered.

@@ -522,28 +544,31 @@ CallStmt<out Statement! s>
 = (. Token! x, id;

      Expression! e;

      List<IdentifierExpr!> lhs = new List<IdentifierExpr!>();

+     List<VarDecl!> newVars = new List<VarDecl!>();

   .)

   "call"                       (. x = token; .)

   CallStmtSubExpr<out e>

   

   [ ","                        /* call a,b,c,... := ... */

-                               (. if (e is IdentifierExpr) {

-                                    lhs.Add((IdentifierExpr)e);

+                               (. e = ConvertToLocal(e);

+                                  if (e is IdentifierExpr) {

+                                    RecordCallLhs((IdentifierExpr)e, lhs, newVars);

                                   } else if (e is FieldSelectExpr) {

                                     SemErr(e.tok, "each LHS of call statement must be a variable, not a field");

                                   } else {

                                     SemErr(e.tok, "each LHS of call statement must be a variable");

                                   }

                                .)

-    Ident<out id>              (. lhs.Add(new IdentifierExpr(id, id.val)); .)

-    { "," Ident<out id>        (. lhs.Add(new IdentifierExpr(id, id.val)); .)

+    Ident<out id>              (. RecordCallLhs(new IdentifierExpr(id, id.val), lhs, newVars); .)

+    { "," Ident<out id>        (. RecordCallLhs(new IdentifierExpr(id, id.val), lhs, newVars); .)

     }

     ":="

     CallStmtSubExpr<out e>

 

   | ":="                       /* call a := ... */

-                               (. if (e is IdentifierExpr) {

-                                    lhs.Add((IdentifierExpr)e);

+                               (. e = ConvertToLocal(e);

+                                  if (e is IdentifierExpr) {

+                                    RecordCallLhs((IdentifierExpr)e, lhs, newVars);

                                   } else if (e is FieldSelectExpr) {

                                     SemErr(e.tok, "each LHS of call statement must be a variable, not a field");

                                   } else {

@@ -558,10 +583,10 @@ CallStmt<out Statement! s>
      It denotes the RHS, so to be legal it must be a FunctionCallExpr.  */

   (. if (e is FunctionCallExpr) {

        FunctionCallExpr fce = (FunctionCallExpr)e;

-       s = new CallStmt(x, lhs, fce.Receiver, fce.Name, fce.Args);  // this actually does an ownership transfer of fce.Args

+       s = new CallStmt(x, newVars, lhs, fce.Receiver, fce.Name, fce.Args);  // this actually does an ownership transfer of fce.Args

      } else {

        SemErr("RHS of call statement must denote a method invocation");

-       s = new CallStmt(x, lhs, dummyExpr, "dummyMethodName", new List<Expression!>());

+       s = new CallStmt(x, newVars, lhs, dummyExpr, "dummyMethodName", new List<Expression!>());

      }

   .)

   .

diff --git a/Source/Dafny/DafnyAst.ssc b/Source/Dafny/DafnyAst.ssc
index 59d1d0ae..4b97edbd 100644
--- a/Source/Dafny/DafnyAst.ssc
+++ b/Source/Dafny/DafnyAst.ssc
@@ -645,13 +645,15 @@ namespace Microsoft.Dafny
   }

   

   public class CallStmt : Statement {

+    public readonly List<VarDecl!>! NewVars;

     public readonly List<IdentifierExpr!>! Lhs;

     public readonly Expression! Receiver;

     public readonly string! MethodName;

     public readonly List<Expression!>! Args;

     public Method Method;  // filled in by resolution

     

-    public CallStmt(Token! tok, List<IdentifierExpr!>! lhs, Expression! receiver, string! methodName, List<Expression!>! args) {

+    public CallStmt(Token! tok, List<VarDecl!>! newVars, List<IdentifierExpr!>! lhs, Expression! receiver, string! methodName, List<Expression!>! args) {

+      this.NewVars = newVars;

       this.Lhs = lhs;

       this.Receiver = receiver;

       this.MethodName = methodName;

diff --git a/Source/Dafny/Parser.ssc b/Source/Dafny/Parser.ssc
index 0dc7df24..0fd3e612 100644
--- a/Source/Dafny/Parser.ssc
+++ b/Source/Dafny/Parser.ssc
@@ -23,6 +23,28 @@ static Statement! dummyStmt = new ReturnStmt(Token.NoToken);
 static Attributes.Argument! dummyAttrArg = new Attributes.Argument("dummyAttrArg");

 static Scope<string>! parseVarScope = new Scope<string>();

 

+// helper routine for parsing call statements

+private static void RecordCallLhs(IdentifierExpr! e,

+                                  List<IdentifierExpr!>! lhs,

+                                  List<VarDecl!>! newVars) {

+  lhs.Add(e);

+  if (parseVarScope.Find(e.Name) == null) {

+    VarDecl d = new VarDecl(e.tok, e.Name, new InferredTypeProxy(), null);

+    newVars.Add(d);

+    parseVarScope.Push(e.Name, e.Name);

+  }

+}

+

+// helper routine for parsing call statements

+private static Expression! ConvertToLocal(Expression! e)

+{

+  FieldSelectExpr fse = e as FieldSelectExpr;

+  if (fse != null && fse.Obj is ImplicitThisExpr) {

+    return new IdentifierExpr(fse.tok, fse.FieldName);

+  }

+  return e;  // cannot convert to IdentifierExpr (or is already an IdentifierExpr)

+}

+

 ///<summary>

 /// Parses top level declarations from "filename" and appends them to "classes".

 /// Returns the number of parsing errors encountered.

@@ -671,6 +693,7 @@ public static int Parse (List<ClassDecl!>! classes) {
 		Token! x, id;

 		Expression! e;

 		List<IdentifierExpr!> lhs = new List<IdentifierExpr!>();

+		List<VarDecl!> newVars = new List<VarDecl!>();

 		

 		Expect(42);

 		x = token; 

@@ -678,8 +701,9 @@ public static int Parse (List<ClassDecl!>! classes) {
 		if (t.kind == 8 || t.kind == 35) {

 			if (t.kind == 8) {

 				Get();

+				e = ConvertToLocal(e);

 				if (e is IdentifierExpr) {

-				 lhs.Add((IdentifierExpr)e);

+				  RecordCallLhs((IdentifierExpr)e, lhs, newVars);

 				} else if (e is FieldSelectExpr) {

 				  SemErr(e.tok, "each LHS of call statement must be a variable, not a field");

 				} else {

@@ -687,18 +711,19 @@ public static int Parse (List<ClassDecl!>! classes) {
 				}

 				

 				Ident(out id);

-				lhs.Add(new IdentifierExpr(id, id.val)); 

+				RecordCallLhs(new IdentifierExpr(id, id.val), lhs, newVars); 

 				while (t.kind == 8) {

 					Get();

 					Ident(out id);

-					lhs.Add(new IdentifierExpr(id, id.val)); 

+					RecordCallLhs(new IdentifierExpr(id, id.val), lhs, newVars); 

 				}

 				Expect(35);

 				CallStmtSubExpr(out e);

 			} else {

 				Get();

+				e = ConvertToLocal(e);

 				if (e is IdentifierExpr) {

-				 lhs.Add((IdentifierExpr)e);

+				  RecordCallLhs((IdentifierExpr)e, lhs, newVars);

 				} else if (e is FieldSelectExpr) {

 				  SemErr(e.tok, "each LHS of call statement must be a variable, not a field");

 				} else {

@@ -711,10 +736,10 @@ public static int Parse (List<ClassDecl!>! classes) {
 		Expect(9);

 		if (e is FunctionCallExpr) {

 		 FunctionCallExpr fce = (FunctionCallExpr)e;

-		 s = new CallStmt(x, lhs, fce.Receiver, fce.Name, fce.Args);  // this actually does an ownership transfer of fce.Args

+		 s = new CallStmt(x, newVars, lhs, fce.Receiver, fce.Name, fce.Args);  // this actually does an ownership transfer of fce.Args

 		} else {

 		  SemErr("RHS of call statement must denote a method invocation");

-		  s = new CallStmt(x, lhs, dummyExpr, "dummyMethodName", new List<Expression!>());

+		  s = new CallStmt(x, newVars, lhs, dummyExpr, "dummyMethodName", new List<Expression!>());

 		}

 		

 	}

diff --git a/Source/Dafny/Resolver.ssc b/Source/Dafny/Resolver.ssc
index 2159d3dc..47727562 100644
--- a/Source/Dafny/Resolver.ssc
+++ b/Source/Dafny/Resolver.ssc
@@ -684,6 +684,11 @@ namespace Microsoft.Dafny {
       } else if (stmt is CallStmt) {

         CallStmt s = (CallStmt)stmt;

         

+        // resolve any local variables declared here

+        foreach (VarDecl local in s.NewVars) {

+          ResolveStatement(local);

+        }

+        

         // resolve left-hand side

         Dictionary<string!,object> lhsNameSet = new Dictionary<string!,object>();

         foreach (IdentifierExpr lhs in s.Lhs) {

diff --git a/Source/Dafny/Translator.ssc b/Source/Dafny/Translator.ssc
index 09be93fa..1028058f 100644
--- a/Source/Dafny/Translator.ssc
+++ b/Source/Dafny/Translator.ssc
@@ -1304,6 +1304,9 @@ namespace Microsoft.Dafny {
       } else if (stmt is CallStmt) {

         AddComment(builder, stmt, "call statement");

         CallStmt s = (CallStmt)stmt;

+        foreach (VarDecl local in s.NewVars) {

+          TrStmt(local, builder, locals, etran);

+        }

         Bpl.ExprSeq ins = new Bpl.ExprSeq();

         ins.Add(etran.TrExpr(s.Receiver));

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