Working with Git

This page assumes that you are already familiar with the basic workings of git and have obtained the development version of Carpet. Please contribute to this page.

Finding an Offending Patch

It happens that you notice that something that used to work in a previous version of your code does not work any more in the current version. Git offers the command git bisect to help find the particular patch which broke your code.

This is what you can do:

• Go to the git tree directory
• Run: git log
• In the output of the above command select a version that you think is "good" (i.e. still works); the version format is something like 6b93d4531de10266355867d0d04e093b13aa8bda and follows the keyword commit in the above output
• Run: git bisect start
• Run: git bisect good b93d4531de10266355867d0d04e093b13aa8bda (for example)
• Run: git bisect bad master
• This will make git remove half of the commits from the most recent version to version 6b93d4531de10266355867d0d04e093b13aa8bda
• (*) Recompile your code and test it
• (**) If the test is OK, run: git bisect good; if the test still fails, run: git bisect bad
• Repeat steps (*) and (**) until git tells you something like:

  1dd96e20cb7a87d294c5298b46f01dff97b0da53 is first bad commit
  commit 1dd96e20cb7a87d294c5298b46f01dff97b0da53
  [...]

• You have found the first "bad" commit!
• (The following are words of the on-line documentation.) You can then examine the commit with git-show(1), find out who wrote it, and mail them your bug report with the commit id
• In order to go back to the most recent version, run: git bisect reset

(Thanks to Luca Baiotti for this description.)

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