Name: vsC45997 Date: 11/27/96


The section "13.4.11 volatile Fields" of The JLS contains the following:

"If a field that is not declared private was not declared volatile and
is changed to be declared volatile, or vice versa, then a linkage time
error, specifically an IncompatibleClassChangeError, may result if the
field is used by a preexisting binary that expected a field of the
opposite volatility. Such changes are not recommended in code that has
been widely distributed."

But I cannot catch IncompatibleClassChangeError on the proper binary
compatibility tests below.

First test consist of two files.

// FILE: binc02201.java
package javasoft.sqe.tests.lang.binc022.binc02201;
import java.io.PrintStream;

class Super { char f = 'f'; }
public class binc02201 extends Super {
  public static void main(String argv[])
  {
    System.exit(run(argv, System.out) + 95/*STATUS_TEMP*/);
  }
  public static int run(String argv[],PrintStream out) {
    char c;
    try {
      c = new Super().f;
      out.println(c);
    }
    catch (IncompatibleClassChangeError e) {
      out.println (e);
      return 0;
    }
    out.println ("failed");
    return 2;
  }
}
    
    
// FILE: binc02201a.java
package javasoft.sqe.tests.lang.binc022.binc02201;

class Super { volatile char f = 'a'; }


After separate compilation and execution with -verify option we have
on both 1.0.2 and 1.1 compilers:
javac -d . binc02201.java
javac -d . binc02201a.java
java -verify javasoft.sqe.tests.lang.binc022.binc02201.binc02201
a
failed


Second test consist of two files.

// FILE: binc02202.java
package javasoft.sqe.tests.lang.binc022.binc02202;
import java.io.PrintStream;

class Super { volatile char f = 'f'; }
public class binc02202 extends Super {
  public static void main(String argv[])
  {
    System.exit(run(argv, System.out) + 95/*STATUS_TEMP*/);
  }
  public static int run(String argv[],PrintStream out) {
    char c;
    try {
      c = new Super().f;
      out.println(c);
    }
    catch (IncompatibleClassChangeError e) {
      out.println (e);
      return 0;
    }
    out.println ("failed");
    return 2;
  }
}
    
    
// FILE: binc02202a.java
package javasoft.sqe.tests.lang.binc022.binc02202;

class Super { char f = 'a'; }


After separate compilation and execution with -verify option we have
on both 1.0.2 and 1.1 compilers:
javac -d . binc02202.java
javac -d . binc02202a.java
java -verify javasoft.sqe.tests.lang.binc022.binc02202.binc02202
a
failed

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