Creating A Patch
If you want to submit improvements to the FPC or Lazarus code, you need to submit a patch which developers can easily merge.
- .po translation files should be sent as whole files
- new files should be sent as whole files, with instructions where they should be placed
- 1 Requirements
- 2 Platform differences
- 3 Creating a patch using SVN
- 4 Creating a patch using Git
- 5 Submitting the patch
- 6 Git
- 7 Applying a patch
- 8 See also
You need the main/development version of Lazarus (or FPC). You can get Lazarus using either Git or SVN.
- Git: Getting Lazarus development version. This is the native repository.
- SVN: Read-only mirror of the official GitLab repository requires some svn gymnastics due to a bug in many versions of svn:
svn checkout --depth files https://github.com/fpc/Lazarus/branches all cd all svn update --set-depth infinity main
svn checkout --depth files https://github.com/fpc/FPCSource/branches all cd all svn update --set-depth infinity main
The instructions later assume you have opened a command prompt and moved (cd) to the directory of the repository. Here are the details :
Assuming you checked out Lazarus into C:\lazarus, open command prompt (cmd.exe) and type "cd \lazarus".
Assuming you checked out Lazarus into ~/lazarus, open terminal and type "cd ~/lazarus".
Creating a patch using SVN
svn diff > mypatch.diff
This includes all changed files in the whole SVN repository.
You can also define the individual files, to make sure no garbage is included, eg. :
svn diff ide/main.pp ideintf/objectinspector.pp > mypatch.diff
See also TortoiseSvn#Troubleshooting if you have problems.
Creating a patch using Git
First, develop your code in a separate branch! While your development branch is active, you can create patches of all your local commits by :
git format-patch master
It creates a set of patches named like "0001-CommitMsg.patch", "0002-CommitMsg.patch" and so on.
If you want all the changes in one patch, either combine the commits using "git rebase -i ..." or use the following command :
git format-patch master --stdout > mypatch.patch
Submitting the patch
Now you have a patch. I'd suggest to look the file over to see if it looks ok (no unexpected changes).
The recommended way to submit a patch is through the bug tracker, see How do I create a bug report for details. If there is a report for the issue your patch fixes, use that, otherwise create a new issue. Upload the file to attach it to the issue.
The GitHub repository  is only a mirror and does not accept pull-requests.
Applying a patch
This explains how to apply somebody else's patch to your local repository. You can test the patch by using the --dry-run toggle switch like this:
patch --dry-run < somepatch.diff
The output of the patch program will be identical to the actual patching, only it does not alter the sourcecode files. Very handy for testing, without the possibility to screw up your source.
A patch made with "svn diff"
To do the final patching, use the following commandline:
patch < somepatch.diff
If that doesn't work because the path layout of your environment is different from the environment where the patch was created, you can tell patch to strip out all path information:
patch -p0 < somepatch.diff
Any GUI tool for diffs on Windows can handle these patches, too, including TortoiseMerge.
A patch made with "git format-patch"
Git itself applies the patch like this :
git apply 0001-gitpatch.patch
The "patch" command now supports git format patches with -p1. This is tested with patch v.2.6.1 on Linux, old versions may not support it.
patch -p1 < 0001-gitpatch.patch
"patch" is available for Windows, too, but there are also GUI tools for the job.
TortoiseMerge supports the Git format patch without problems. It is installed together with Tortoise SVN but is not integrated in explorer. It must be opened from the Start menu.
ToDo: add more GUI tools that support Git format patches
Finally, patches may have a Unix/Linux line ending (LF) while your local file has Windows (CR+LF) line endings or vice versa. You'll have to convert the patch file before applying on Windows at least, as the supplied patch.exe is picky about line endings.
On Windows, the patch.exe supplied with FPC/Lazarus is very picky; you may have better luck with the patch.exe supplied by Git:
"C:\Program Files (x86)\Git\bin\patch.exe" -p0 < mypatch.diff
... or the svn patch command available since SVN 1.7.
- How do I create a bug report general information on submitting bugs, what should be covered in a bug report, and using the bug tracker.
- Tips on writing bug reports detailed information on what should be covered in a bug report.
- Database bug reporting Specific info and sample programs for database bugs
- Moderating the bug tracker