8246632: StringConcatFactory::makeConcatWithConstants no longer throws NullPointerException when an unexpected constant is null

Reviewed-by: rriggs, mchung

Author: cl4es

src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java

@@ -329,6 +329,10 @@ public static CallSite makeConcatWithConstants(MethodHandles.Lookup lookup,
         Objects.requireNonNull(concatType, "Concat type is null");
         Objects.requireNonNull(constants, "Constants are null");
 
+        for (Object o : constants) {
+            Objects.requireNonNull(o, "Cannot accept null constants");
+        }
+
         if ((lookup.lookupModes() & MethodHandles.Lookup.PRIVATE) == 0) {
             throw new StringConcatException("Invalid caller: " +
                     lookup.lookupClass().getName());
@@ -382,11 +386,11 @@ private static List<String> parseRecipe(MethodType concatType,
             if (c == TAG_CONST) {
                 if (cCount == constants.length) {
                     // Not enough constants
-                    throw constantMismatch(concatType, oCount);
+                    throw constantMismatch(constants, cCount);
                 }
                 // Accumulate constant args along with any constants encoded
                 // into the recipe
-                acc.append(Objects.requireNonNull(constants[cCount++], "Cannot accept null constants"));
+                acc.append(constants[cCount++]);
             } else if (c == TAG_ARG) {
                 // Flush any accumulated characters into a constant
                 if (acc.length() > 0) {
@@ -406,28 +410,32 @@ private static List<String> parseRecipe(MethodType concatType,
         if (acc.length() > 0) {
             elements.add(acc.toString());
         }
-
         if (oCount != concatType.parameterCount()) {
-            throw constantMismatch(concatType, oCount);
+            throw argumentMismatch(concatType, oCount);
         }
-        if (cCount != constants.length) {
-            throw new StringConcatException(
-                    "Mismatched number of concat constants: recipe wants " +
-                            cCount +
-                            " constants, but only " +
-                            constants.length +
-                            " are passed");
+        if (cCount < constants.length) {
+            throw constantMismatch(constants, cCount);
         }
         return elements;
     }
 
-    private static StringConcatException constantMismatch(MethodType concatType,
+    private static StringConcatException argumentMismatch(MethodType concatType,
                                                           int oCount) {
         return new StringConcatException(
                 "Mismatched number of concat arguments: recipe wants " +
-                        oCount +
-                        " arguments, but signature provides " +
-                        concatType.parameterCount());
+                oCount +
+                " arguments, but signature provides " +
+                concatType.parameterCount());
+    }
+
+    private static StringConcatException constantMismatch(Object[] constants,
+            int cCount) {
+        return new StringConcatException(
+                "Mismatched number of concat constants: recipe wants " +
+                        cCount +
+                        " constants, but only " +
+                        constants.length +
+                        " are passed");
     }
 
     /**

test/jdk/java/lang/String/concat/StringConcatFactoryInvariants.java

@@ -220,7 +220,7 @@ public static void main(String[] args) throws Throwable {
         fail("Static arguments and recipe mismatch: too many",
                 () -> StringConcatFactory.makeConcatWithConstants(lookup, methodName, mtThreshold, recipeThreshold, "bar", "baz"));
 
-        fail("Static arguments and recipe mismatch, too many, overflowing constant is null",
+        failNPE("Static arguments and recipe mismatch, too many, overflowing constant is null",
                 () -> StringConcatFactory.makeConcatWithConstants(lookup, methodName, mtThreshold, recipeThreshold, "bar", null));
 
         // Advanced factory: check for mismatched recipe and dynamic arguments