HACKING   [plain text]

Things libgcj hackers should know

If you want to hack on the libgcj files you need to be aware of the
following things. There are probably lots of other things that should be
explained in this HACKING file. Please add them if you discover them :)


A lot of the standard library files come from the GNU Classpath project.
The libgcj and Classpath project have officially merged, but the merge
is not yet complete. Our eventual goal is for Classpath to be an upstream
source provider for libgcj, however it will be some time before this becomes
reality: libgcj and Classpath have different implementations of many core
java classes. In order to merge them, we need to select the best (most
efficient, cleanest) implementation of each method/class/package, resolve
any conflicts created by the merge, and test the final result.

The merged files can be recognized by the standard Classpath copyright
comments at the top of the file. If you make changes to these files
then you should also check in the fix to Classpath.  For small changes
it may be easier to send a patch to the classpath mailinglist.  For
large changes, if you have direct write access to the libgcj tree,
then you will also need to get a Classpath account and do the work

If you merge a libgcj class with a classpath class then you must update the
copyright notice at the top of the file so others can see that this is a
shared libgcj/classpath file.


If you need to add new java files to libgcj then you have to edit the
Makefile.am file in the top (libjava) directory. And run automake.
But note the following (thanks to Bryce McKinlay):

> Do you know the magic dance I have to do when adding files to Makefile.am
> so they will appear in Makefile.in and finally in the user generated
> Makefile?
Yup, you need the magic libgcj automake ;-)


Install that (don't worry, it should still work for other projects), add your
files to the Makefile.am, then just type "automake" and it will regenerate the
Makefile.in. Easy!

Tom Tromey adds:
If you add a class to java.lang, java.io, or java.util
(including sub-packages, like java.lang.ref).

* Edit gcj/javaprims.h

* Go to the `namespace java' line, and delete that entire block (the   
  entire contents of the namespace)

* Then insert the output of `perl ../scripts/classes.pl' into the file
  at that point.

If you're generating a patch there is a program you can get to do an
offline `cvs add' (it will fake an `add' if you don't have write
permission yet).  Then you can use `cvs diff -N' to generate the
patch.  See http://www.red-bean.com/cvsutils/