Improve error message when writing a class with an oversized constant pool

asm/src/main/java/org/objectweb/asm/ClassTooLargeException.java

+package org.objectweb.asm;
+
+public final class ClassTooLargeException extends IndexOutOfBoundsException {
+    private final String className;
+    private final int constantPoolCount;
+
+    /**
+     * @return The name of the class, or <tt>null</tt> if not known
+     */
+    public String getClassName() {
+        return className;
+    }
+
+    /**
+     * @return The number of byte codes in the method.
+     */
+    public int getConstantPoolCount() {
+        return constantPoolCount;
+    }
+
+    public ClassTooLargeException(String className, int constantPoolCount) {
+        super("Class file too large" + (className == null ? "" : ": " + className));
+        this.className = className;
+        this.constantPoolCount = constantPoolCount;
+    }
+}

asm/src/main/java/org/objectweb/asm/ClassWriter.java

@@ -543,8 +543,9 @@ public class ClassWriter extends ClassVisitor {
     // IMPORTANT: this must be the last part of the ClassFile size computation, because the previous
     // statements can add attribute names to the constant pool, thereby changing its size!
     size += symbolTable.getConstantPoolLength();
-    if (symbolTable.getConstantPoolCount() > 0xFFFF) {
-      throw new IndexOutOfBoundsException("Class file too large!");
+    int constantPoolCount = symbolTable.getConstantPoolCount();
+    if (constantPoolCount > 0xFFFF) {
+      throw new ClassTooLargeException(symbolTable.getClassName(), constantPoolCount);
     }
 
     // Second step: allocate a ByteVector of the correct size (in order to avoid any array copy in

asm/src/test/java/org/objectweb/asm/ClassWriterTest.java

@@ -28,8 +28,7 @@
 package org.objectweb.asm;
 
 import static java.util.stream.Collectors.toSet;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.*;
 import static org.objectweb.asm.test.Assertions.assertThat;
 
 import java.io.FileInputStream;
@@ -129,11 +128,18 @@ public class ClassWriterTest extends AsmTest {
   @ValueSource(ints = {65535, 65536})
   public void testConstantPoolSizeTooLarge(final int constantPoolCount) {
     ClassWriter classWriter = new ClassWriter(0);
-    for (int i = 0; i < constantPoolCount - 1; ++i) {
+    String className = "A";
+    classWriter.visit(Opcodes.V1_7, Opcodes.ACC_PUBLIC, className, null, "java/lang/Object", null);
+    int initConstantPoolCount = 5;
+    // assert(initConstantPoolCount == classWriter.symbolTable.getConstantPoolCount())
+    for (int i = 0; i < constantPoolCount - initConstantPoolCount; ++i) {
       classWriter.newConst(Integer.valueOf(i));
     }
     if (constantPoolCount > 65535) {
-      assertThrows(IndexOutOfBoundsException.class, () -> classWriter.toByteArray());
+      ClassTooLargeException thrown = assertThrows(ClassTooLargeException.class, () -> classWriter.toByteArray());
+      assertEquals(className, thrown.getClassName());
+      assertEquals(constantPoolCount, thrown.getConstantPoolCount());
+      assertEquals("Class file too large: A", thrown.getMessage());
     } else {
       classWriter.toByteArray();
     }
@@ -157,7 +163,7 @@ public class ClassWriterTest extends AsmTest {
     if (methodCodeSize > 65535) {
       MethodTooLargeException thrown = assertThrows(MethodTooLargeException.class, () -> classWriter.toByteArray());
       assertEquals(methodName, thrown.getMethodName());
-      assertEquals(null, thrown.getClassName());
+      assertNull(thrown.getClassName());
       assertEquals(descriptor, thrown.getDescriptor());
       assertEquals(methodCodeSize, thrown.getCodeSize());
       assertEquals("Method code too large: m ()V", thrown.getMessage());