Fixed a bug related to duplicate bindings (#756)

Author: ankushdesai

Src/PCompiler/CompilerCore/DefaultTranslationErrorHandler.cs

@@ -146,7 +146,8 @@ public Exception BinOpTypeMismatch(
 
         public Exception MoreThanOneParameterForHandlers(ParserRuleContext sourceLocation, int count)
         {
-            return IssueError(sourceLocation, $"functions at entry or exit and do or goto transitions cannot take more than 1 parameter, provided function expects {count} parameters");
+            return IssueError(sourceLocation,
+                $"functions at entry or exit and do or goto transitions cannot take more than 1 parameter, provided function expects {count} parameters");
         }
 
         public Exception ParseFailure(FileInfo file, string message)
@@ -156,12 +157,14 @@ public Exception ParseFailure(FileInfo file, string message)
 
         public Exception IllegalChooseSubExprType(PParser.ChooseExprContext context, PLanguageType subExprType)
         {
-            return IssueError(context, $"choose expects a parameter of type int (max value) or a collection type (seq, set, or map) got a parameter of type {subExprType}");
+            return IssueError(context,
+                $"choose expects a parameter of type int (max value) or a collection type (seq, set, or map) got a parameter of type {subExprType}");
         }
 
         public Exception IllegalChooseSubExprValue(PParser.ChooseExprContext context, int numChoices)
         {
-            return IssueError(context, $"choose expects a parameter with at most 10000 choices, got {numChoices} choices instead.");
+            return IssueError(context,
+                $"choose expects a parameter with at most 10000 choices, got {numChoices} choices instead.");
         }
 
         public Exception IllegalFunctionUsedInSpecMachine(Function function, Machine callerOwner)
@@ -322,7 +325,8 @@ public Exception BareLoopControlFlow(string stmtName, ParserRuleContext context)
 
         public Exception ExitFunctionCannotTakeParameters(ParserRuleContext sourceLocation, int count)
         {
-            return IssueError(sourceLocation, $"Exit functions cannot have input parameters, the provided function expects {count} parameters");
+            return IssueError(sourceLocation,
+                $"Exit functions cannot have input parameters, the provided function expects {count} parameters");
         }
 
         private Exception IssueError(ParserRuleContext location, string message)
@@ -342,7 +346,13 @@ private string DeclarationName(IPDecl method)
 
         public string SpecObservesSetIncompleteWarning(ParserRuleContext ctx, PEvent ev, Machine machine)
         {
-            return $"[!Warning!]\n[{locationResolver.GetLocation(ctx, ctx.start)}] Event {ev.Name} is not in the observes list of the spec machine {machine.Name}. The event-handler is never triggered as the event is not observed by the spec.\n[!Warning!]";
+            return
+                $"[!Warning!]\n[{locationResolver.GetLocation(ctx, ctx.start)}] Event {ev.Name} is not in the observes list of the spec machine {machine.Name}. The event-handler is never triggered as the event is not observed by the spec.\n[!Warning!]";
+        }
+
+        public Exception DuplicateBindings(ParserRuleContext ctx, Interface @interface)
+        {
+            return IssueError(ctx, $"Interface or machine {@interface.Name} is mentioned or bounded multiple times in the module");
         }
     }
 }

Src/PCompiler/CompilerCore/ITranslationErrorHandler.cs

@@ -120,5 +120,6 @@ Exception DuplicateStartState(
         Exception IllegalFunctionUsedInSpecMachine(Function function, Machine callerOwner);
 
         String SpecObservesSetIncompleteWarning(ParserRuleContext loc, PEvent ev, Machine machine);
+        Exception DuplicateBindings(ParserRuleContext loc, Interface @interface);
     }
 }

Src/PCompiler/CompilerCore/TypeChecker/ModuleExprVisitor.cs

@@ -98,6 +98,13 @@ public override IPModuleExpr VisitNamedModule([NotNull] PParser.NamedModuleConte
         public override IPModuleExpr VisitPrimitiveModuleExpr([NotNull] PParser.PrimitiveModuleExprContext context)
         {
             var bindings = context._bindslist.Select(VisitBindExpr).ToList();
+            var seenInterfaces = new List<string>();
+            foreach (var i in bindings.Select(x => x.Item1))
+            {
+                if (seenInterfaces.Contains(i.Name))
+                    throw handler.DuplicateBindings(context, i);
+                seenInterfaces.Add(i.Name);
+            }
             return new BindModuleExpr(context, bindings);
         }