8200199: javac suggests to use var even when var is used

Local var analyzer should use synthetic var type position to decide if analysis is needed

Reviewed-by: jlahoda, vromero

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Analyzer.java

@@ -358,6 +358,10 @@ public class Analyzer {
             super(AnalyzerMode.LOCAL, tag);
         }
 
+        boolean isImplicitlyTyped(JCVariableDecl decl) {
+            return decl.vartype.pos == Position.NOPOS;
+        }
+
         /**
          * Map a variable tree into a new declaration using implicit type.
          */
@@ -390,7 +394,7 @@ public class Analyzer {
 
         boolean match(JCVariableDecl tree){
             return tree.sym.owner.kind == Kind.MTH &&
-                    tree.init != null && !tree.isImplicitlyTyped() &&
+                    tree.init != null && !isImplicitlyTyped(tree) &&
                     attr.canInferLocalVarType(tree) == null;
         }
         @Override
@@ -414,7 +418,7 @@ public class Analyzer {
 
         @Override
         boolean match(JCEnhancedForLoop tree){
-            return !tree.var.isImplicitlyTyped();
+            return !isImplicitlyTyped(tree.var);
         }
         @Override
         List<JCEnhancedForLoop> rewrite(JCEnhancedForLoop oldTree) {

test/langtools/tools/javac/lvti/T8200199.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test /nodynamioccopyright/
+ * @bug 8200199
+ * @summary javac suggests to use var even when var is used
+ * @compile/fail/ref=T8200199.out -Werror -XDfind=local -XDrawDiagnostics T8200199.java
+ */
+
+class T8200199 {
+
+    class Resource implements AutoCloseable {
+        public void close() {};
+    }
+
+    public void implicit() {
+        var i = 33;
+        for (var x = 0 ; x < 10 ; x++) { }
+        try (var r = new Resource()) { }
+    }
+
+    public void explicit() {
+        int i = 33;
+        for (int x = 0 ; x < 10 ; x++) { }
+        try (Resource r = new Resource()) { }
+    }
+}

test/langtools/tools/javac/lvti/T8200199.out

@@ -0,0 +1,6 @@
+T8200199.java:46:13: compiler.warn.local.redundant.type
+T8200199.java:47:18: compiler.warn.local.redundant.type
+T8200199.java:48:23: compiler.warn.local.redundant.type
+- compiler.err.warnings.and.werror
+1 error
+3 warnings