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 :) -- libgcj uses GNU Classpath as an upstream provider. Snapshots of Classpath are imported into the libgcj source tree. Some classes are overridden by local versions; these files still appear in the libgcj tree. To import a new release: - Check out a classpath snapshot I use 'cvs export' for this. Make a tag to ensure future hackers know exactly what revision was checked out; tags are of the form 'libgcj-import-DATE'. - Use auto* to create configure, Makefile.in, etc You have to make sure to use the gcc libtool.m4 and gcc lt* scripts cd .../classpath cp ../../lt* . cp ../../config.sub ../../config.guess . aclocal -I m4 -I ../.. autoconf autoheader automake rm -rf autom4te.cache - Test everything first. The simplest way to do this is by overlaying the checked out classpath on your gcc tree and then doing a build. - Use 'cvs import' to import. The vendor tag is 'CLASSPATH'. For the release tag, if this is a released classpath version, use something like 'classpath-import-VERSION'; otherwise something like 'classpath-import-DATE'. Be sure to use -ko and -I\! - Remove any files that were deleted in Classpath - Run 'scripts/makemake.tcl > sources.am' in the source tree - Run automake for libgcj Over time we plan to remove as many of the remaining divergences as possible. File additions and deletions require running scripts/makemake.tcl before running automake. -- In general you should not make any changes in the classpath/ directory. Changes here should come via imports from upstream. However, there are two (known) exceptions to this rule: * In an emergency, such as a bootstrap breakage, it is ok to commit a patch provided that the problem is resolved (by fixing a compiler bug or fixing the Classpath bug upstream) somehow and the resolution is later checked in (erasing the local diff). * On a release branch to fix a bug, where a full-scale import of Classpath is not advisable. -- You can develop in a GCC tree using a CVS checkout of Classpath, most of the time. (The exceptions are when an incompatible change has been made in Classpath and some core part of libgcj has not yet been updated.) The way to set this up is very similar to importing a new version of Classpath into the libgcj tree. In your working tree: * cd gcc/libjava; rm -rf classpath * cvs co classpath * cd classpath Now run the auto tools as specified in the import process; then cd .. * Run 'scripts/makemake.tcl > sources.am' in the source tree * Run automake for libgcj Now you should be ready to go. If you are working in a tree like this, you must remember to run makemake.tcl and automake whenever you update your embedded classpath tree. -- 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. This must be run from the build tree, in /classpath/lib; it uses the .class file name to determine what to print. 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/