为什么 invokevirtual 的目标类型从 javac target 1.1 更改为 1.2？

Question

我知道这些是古老的 Java 版本，但我仍然很好奇。给定以下代码段：

public void test(java.awt.event.MouseEvent e)
{
    System.out.println(e.getID());
}

使用 javac -source 1.3 -target 1.1 编译时生成以下内容：

public void test(java.awt.event.MouseEvent);
 Code:
   0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
   3: aload_1       
   4: invokevirtual #3                  // Method java/awt/AWTEvent.getID:()I
   7: invokevirtual #4                  // Method java/io/PrintStream.println:(I)V
  10: return

使用 javac -source 1.3 -target 1.2 编译时生成以下内容：

public void test(java.awt.event.MouseEvent);
 Code:
   0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
   3: aload_1       
   4: invokevirtual #3                  // Method java/awt/event/MouseEvent.getID:()I
   7: invokevirtual #4                  // Method java/io/PrintStream.println:(I)V
  10: return

为什么 invokevirtual 的目标类型（参见第 4 行）从目标 1.1 更改为目标 1.2？

Answer 1

经过一些研究，似乎从 Java 1.2 开始在 javac 中引入了此更改，以符合 JLS 二进制兼容性规则。以下引用直接来自 the javac source code:

Beginning with -target 1.2 we obey the JLS rules for binary compatibility, emitting as the qualifying type of a reference to a method or field the type of the qualifier. In earlier targets we use as the qualifying type the class in which the member was found.

为什么 invokevirtual 的目标类型从 javac target 1.1 更改为 1.2？

Why did the target type for invokevirtual change from javac target 1.1 to 1.2?

java

javac