8156180: javac accepts code that violates JLS chapter 16

DA/DU analysis should skip parenthesis around variable references

Reviewed-by: vromero

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

@@ -2345,10 +2345,11 @@ public class Flow {
         // assigned before reading their value
         public void visitSelect(JCFieldAccess tree) {
             super.visitSelect(tree);
+            JCTree sel = TreeInfo.skipParens(tree.selected);
             if (enforceThisDotInit &&
-                tree.selected.hasTag(IDENT) &&
-                ((JCIdent)tree.selected).name == names._this &&
-                tree.sym.kind == VAR) {
+                    sel.hasTag(IDENT) &&
+                    ((JCIdent)sel).name == names._this &&
+                    tree.sym.kind == VAR) {
                 checkInit(tree.pos(), (VarSymbol)tree.sym);
             }
         }

langtools/test/tools/javac/DefiniteAssignment/8156180/T8156180.java

@@ -0,0 +1,23 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8156180
+ * @summary javac accepts code that violates JLS chapter 16
+ *
+ * @compile/fail/ref=T8156180.out -XDrawDiagnostics T8156180.java
+ */
+
+class T8156180 {
+    public final int a1, b1, c1, d1;
+    public int a2, b2, c2, d2;
+
+    T8156180(int value) {
+        a2 = this.a1;
+        b2 = (this).b1;
+        c2 = ((this)).c1;
+        d2 = (((this))).d1;
+        a1 = value;
+        b1 = value;
+        c1 = value;
+        d1 = value;
+    }
+}

langtools/test/tools/javac/DefiniteAssignment/8156180/T8156180.out

@@ -0,0 +1,5 @@
+T8156180.java:14:18: compiler.err.var.might.not.have.been.initialized: a1
+T8156180.java:15:20: compiler.err.var.might.not.have.been.initialized: b1
+T8156180.java:16:22: compiler.err.var.might.not.have.been.initialized: c1
+T8156180.java:17:24: compiler.err.var.might.not.have.been.initialized: d1
+4 errors