[Jastadd] [bug report] bug in establishing throws clauses of anonymous class constructors, and a possible fix

From: Na, Hyunik <hina_at_kaist.ac.kr>
Date: Sat, 25 Feb 2012 18:39:33 +0900

I'm sorry. I pressed Ctrl+Enter by mistake.

The following is the whole thing that I intended to send.

 

---------------------------------------------------

 

 

Hello JastAdd developers,

 

I found a minor bug of JastAddJ in establishing throws clauses of anonymous
class constructors, and a possible fix.

It is minor in that it is extremely rare that this bug causes a problem. (in
only one .java file, java/security/KeyStore.java, in OpenJDK6 class
library)

But, due to this bug (and two others), I couldn't compile OpenJDK6 class
library using JastAddJ, as I reported 3 months ago.

 

The bug manifests itself in the following simple example:

 

-=-=-=

 

           class C { }

           class D { }

           class MyException extends Exception { }

 

           public class Test {

             public static void main( String [] args ) {

               new C() {

                 D d = new D() { void m() throws MyException { throw new
MyException(); } };

               };

             }

           }

 

-=-=-=

 

Running JastAddJ compiler (rev. 9210) on this example produces the following
error message:

 

-=-=-=

 

[hina_at_hyunikLinux temp]$ java -cp JastAddJ/Java1.5Backend/ JavaCompiler
Test.java

Errors:

Test.java:7:

  Semantic Error: new C() {

        D d = new D() {

            void m() throws MyException {

              throw new MyException();

            }

        };

    } may throw uncaught exception MyException; it must be caught or
declared as being thrown

[hina_at_hyunikLinux temp]$

 

-=-=-=

 

The problem is that JastAddJ adds MyException in the throws clause of the
anonymous constructor, "new C() {.}",

which should not be the case.

 

I made a slight modification of the JastAddJ source code at this problem:

The last line

 

           return super.reachedException(catchType);

 

of ClassInstanceExpr.reachedException() in
Java1.4Frontend/ExceptionHandling.jrag was replaced by the following four
lines.

 

           for ( int i = 0 ; i < getNumArg() ; i++ ) {

              if ( getArg(i).reachedException(catchType) )

                 return true;

           }

           return false;

 

This is to prevent JastAddJ from wrongly recognizing the exceptions thrown
in the TypeDecl subtree of a ClassInstanceExpr

as the exceptions that the ClassInstanceExpr throws.

 

Now, I can compile java/security/KeyStore.java

 

I hope this modification is appropriate.

 

- Hyunik.

 

 
Received on Sat Feb 25 2012 - 10:39:47 CET