7.7 Finding the cause of a regression

Note: This is not a “simple” task; it requires a fair amount of technical knowledge.

Git has special functionality to help tracking down the exact commit which causes a problem. See the git manual page for git bisect. This is a job that non-programmers can do, although it requires familiarity with git, ability to compile LilyPond, and generally a fair amount of technical knowledge. An in-depth explanation of this process will not be given here.

Even if you are not familiar with git or are not able to compile LilyPond you can still help to narrow down the cause of a regression simply by downloading the binary releases of different LilyPond versions and testing them for the regression. Knowing which version of LilyPond first exhibited the regression is helpful to a developer as it shortens the git bisect procedure described above.

Once a problematic commit is identified, the programmers’ job is much easier. In fact, for most regression bugs, the majority of the time is spent simply finding the problematic commit.

More information is in Regression tests.


LilyPond — Contributor’s Guide