8278863: Add method ClassDesc::ofInternalName

Reviewed-by: jvernee

src/java.base/share/classes/java/lang/constant/ClassDesc.java

@@ -72,12 +72,39 @@ public sealed interface ClassDesc
      * @throws NullPointerException if the argument is {@code null}
      * @throws IllegalArgumentException if the name string is not in the
      * correct format
+     * @see ClassDesc#ofDescriptor(String)
+     * @see ClassDesc#ofInternalName(String)
      */
     static ClassDesc of(String name) {
         ConstantUtils.validateBinaryClassName(requireNonNull(name));
         return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");
     }
 
+    /**
+     * Returns a {@linkplain ClassDesc} for a class or interface type,
+     * given the name of the class or interface in internal form,
+     * such as {@code "java/lang/String"}.
+     *
+     * @apiNote
+     * To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
+     * or {@link #arrayType()}; to create a descriptor for a primitive type, use
+     * {@link #ofDescriptor(String)} or use the predefined constants in
+     * {@link ConstantDescs}.
+     *
+     * @param name the fully qualified class name, in internal (slash-separated) form
+     * @return a {@linkplain ClassDesc} describing the desired class
+     * @throws NullPointerException if the argument is {@code null}
+     * @throws IllegalArgumentException if the name string is not in the
+     * correct format
+     * @jvms 4.2.1 Binary Class and Interface Names
+     * @see ClassDesc#of(String)
+     * @see ClassDesc#ofDescriptor(String)
+     */
+    static ClassDesc ofInternalName(String name) {
+        ConstantUtils.validateInternalClassName(requireNonNull(name));
+        return ClassDesc.ofDescriptor("L" + name + ";");
+    }
+
     /**
      * Returns a {@linkplain ClassDesc} for a class or interface type,
      * given a package name and the unqualified (simple) name for the
@@ -125,6 +152,8 @@ public sealed interface ClassDesc
      * correct format
      * @jvms 4.3.2 Field Descriptors
      * @jvms 4.4.1 The CONSTANT_Class_info Structure
+     * @see ClassDesc#of(String)
+     * @see ClassDesc#ofInternalName(String)
      */
     static ClassDesc ofDescriptor(String descriptor) {
         requireNonNull(descriptor);

src/java.base/share/classes/java/lang/constant/ConstantUtils.java

@@ -58,6 +58,23 @@ class ConstantUtils {
         return name;
     }
 
+    /**
+      * Validates the correctness of an internal class name.
+      * In particular checks for the presence of invalid characters in the name.
+      *
+      * @param name the class name
+      * @return the class name passed if valid
+      * @throws IllegalArgumentException if the class name is invalid
+      */
+     static String validateInternalClassName(String name) {
+         for (int i=0; i<name.length(); i++) {
+             char ch = name.charAt(i);
+             if (ch == ';' || ch == '[' || ch == '.')
+                 throw new IllegalArgumentException("Invalid class name: " + name);
+         }
+         return name;
+     }
+
     /**
      * Validates a member name
      *