src/jdk.compiler/share/classes/com/sun/tools/javac/code/Lint.java

@@ -120,10 +120,11 @@
             }
             values.add(LintCategory.REQUIRES_TRANSITIVE_AUTOMATIC);
             values.add(LintCategory.OPENS);
             values.add(LintCategory.MODULE);
             values.add(LintCategory.REMOVAL);
+            values.add(LintCategory.FUTURE);
         }
 
         // Look for specific overrides
         for (LintCategory lc : LintCategory.values()) {
             if (options.isSet(Option.XLINT_CUSTOM, lc.option)) {

@@ -283,10 +284,16 @@
          * Warn about unchecked operations on raw types.
          */
         UNCHECKED("unchecked"),
 
         /**
+         * Warn about source structures that may be illegal or
+         * questionable in future source versions.
+         */
+        FUTURE("future"),
+
+        /**
          * Warn about potentially unsafe vararg methods
          */
         VARARGS("varargs");
 
         LintCategory(String option) {