Summary

Allign java.lang.classfile.Signature.ArrayTypeSig::of constraints check with the javadoc.

Problem

• Javadoc of java.lang.classfile.Signature.ArrayTypeSig::of says: "Throws: IllegalArgumentException - if the resulting array type exceeds 255 dimensions". However the constraint check allows to exceed that limit when the componentSignature argument is already an array.
• The javadoc does not mention the IllegalArgumentException is thrown when dims < 1.

Solution

Fix the constraints check and the javadoc.

Specification

--- a/src/java.base/share/classes/java/lang/classfile/Signature.java
+++ b/src/java.base/share/classes/java/lang/classfile/Signature.java
@@ -417,15 +417,18 @@ public static ArrayTypeSig of(Signature componentSignature) {
          * {@return a signature for an array type}
          * @param dims the dimension of the array
          * @param componentSignature the component type
-         * @throws IllegalArgumentException if the resulting array type exceeds
-         *         255 dimensions
+         * @throws IllegalArgumentException if {@code dims < 1} or the
+         *         resulting array type exceeds 255 dimensions
          */
         public static ArrayTypeSig of(int dims, Signature componentSignature) {
             requireNonNull(componentSignature);
+            if (componentSignature instanceof SignaturesImpl.ArrayTypeSigImpl arr) {
+                if (dims < 1 || dims > 255 - arr.arrayDepth())
+                    throw new IllegalArgumentException("illegal array depth value");
+                return new SignaturesImpl.ArrayTypeSigImpl(dims + arr.arrayDepth(), arr.elemType());
+            }
             if (dims < 1 || dims > 255)
                 throw new IllegalArgumentException("illegal array depth value");
-            if (componentSignature instanceof SignaturesImpl.ArrayTypeSigImpl arr)
-                return new SignaturesImpl.ArrayTypeSigImpl(dims + arr.arrayDepth(), arr.elemType());
             return new SignaturesImpl.ArrayTypeSigImpl(dims, componentSignature);
         }
     }