src/share/classes/com/sun/tools/javac/comp/Flow.java

*** 263,272 ****
--- 263,276 ----
      /** The list of exceptions that are either caught or declared to be
       *  thrown.
       */
      List<Type> caught;
  
+     /** The list of unreferenced automatic resources.
+      */
+     List<Symbol> unrefdResources;
+ 
      /** Set when processing a loop body the second time for DU analysis. */
      boolean loopPassTwo = false;
  
      /*-------------------- Environments ----------------------*/
  
*** 959,968 ****
--- 963,982 ----
                  }
              }
          }
  
      public void visitTry(JCTry tree) {
+         unrefdResources = List.nil();
+         for (JCTree resource : tree.resources) {
+             if (resource instanceof JCVariableDecl) {
+                 visitVarDef((JCVariableDecl) resource);
+             } else if (resource instanceof JCExpression) {
+                 scanExpr((JCExpression) resource);
+             } else {
+                 throw new AssertionError(tree);  // parser error
+             }
+         }
          List<Type> caughtPrev = caught;
          List<Type> thrownPrev = thrown;
          thrown = List.nil();
          for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
              List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
*** 975,994 ****
--- 989,1028 ----
          Bits uninitsTryPrev = uninitsTry;
          ListBuffer<PendingExit> prevPendingExits = pendingExits;
          pendingExits = new ListBuffer<PendingExit>();
          Bits initsTry = inits.dup();
          uninitsTry = uninits.dup();
+         for (JCTree resource : tree.resources) {
+             MethodSymbol topCloseMethod = (MethodSymbol)syms.autoCloseableType.tsym.members().lookup(names.close).sym;
+             MethodSymbol closeMethod = types.implementation(topCloseMethod, resource.type.tsym, types, true);
+ 
+             for (Type thrownType : closeMethod.getThrownTypes()) {
+                 markThrown(tree.body, thrownType);
+             }
+         }
          scanStat(tree.body);
          List<Type> thrownInTry = thrown;
          thrown = thrownPrev;
          caught = caughtPrev;
          boolean aliveEnd = alive;
          uninitsTry.andSet(uninits);
          Bits initsEnd = inits;
          Bits uninitsEnd = uninits;
          int nextadrCatch = nextadr;
  
+         if (unrefdResources.nonEmpty()) {
+             for (List<JCTree> l = tree.resources; l.nonEmpty(); l = l.tail) {
+                 if (l.head instanceof JCVariableDecl) {
+                     JCVariableDecl v = (JCVariableDecl) l.head;
+                     if (unrefdResources.contains(v.sym)) {
+                         log.warning(v.pos(),
+                                     "automatic.resource.not.referenced", v.sym);
+                     }
+                 }
+             }
+         }
+ 
          List<Type> caughtInTry = List.nil();
          for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) {
              alive = true;
              JCVariableDecl param = l.head.param;
              List<JCExpression> subClauses = TreeInfo.isMultiCatch(l.head) ?
*** 1291,1302 ****
          // annotations don't get scanned
          tree.underlyingType.accept(this);
      }
  
      public void visitIdent(JCIdent tree) {
!         if (tree.sym.kind == VAR)
              checkInit(tree.pos(), (VarSymbol)tree.sym);
      }
  
      public void visitTypeCast(JCTypeCast tree) {
          super.visitTypeCast(tree);
          if (!tree.type.isErroneous()
--- 1325,1348 ----
          // annotations don't get scanned
          tree.underlyingType.accept(this);
      }
  
      public void visitIdent(JCIdent tree) {
!         if (tree.sym.kind == VAR) {
              checkInit(tree.pos(), (VarSymbol)tree.sym);
+             referenced(tree.sym);
+         }
+     }
+ 
+     void referenced(Symbol sym) {
+         if (unrefdResources != null && unrefdResources.contains(sym)) {
+             ListBuffer<Symbol> lb = new ListBuffer<Symbol>();
+             for (List<Symbol> l = unrefdResources; l.nonEmpty(); l = l.tail)
+                 if (l.head != sym)
+                     lb.add(l.head);
+             unrefdResources = lb.toList();
+         }
      }
  
      public void visitTypeCast(JCTypeCast tree) {
          super.visitTypeCast(tree);
          if (!tree.type.isErroneous()