Patch Drupal core without things ending up in core/core or core/b

If you've ever patched Drupal core with Composer you may have noticed patched files can sometimes end up in the wrong place like core/core or core/b. Thankfully there's a quick fix to ensure the files make it into the correct location.

by saul.willers /

When using cweagans/composer-patches it's easy to include patches in your composer.json

"patches": {
    "drupal/core": {
        "Introduce a batch builder class to make the batch API easier to use": "https://www.drupal.org/files/issues/2018-03-21/2401797-111.patch"
    }
}

However in certain situations patches will get applied incorrectly. This can happen when the patch is only adding new files (not altering existing files), like in the patch above. The result is the patched files end up in a subfolder core/core. If the patch is adding new files and editing existing files the new files will end up in core/b. This is because composer-patches cycle through the -p levels trying to apply them; 1, 0, 2, then 4.

Thankfully there is an easy fix!

"extra": {
   ...
   "patchLevel": {
       "drupal/core": "-p2"
    }
}

Setting the patch level to p2 ensures any patch for core will get applied correctly.

Note that until composer-patches has a 1.6.5 release, specifically this PR, you'll need to use the dev release like:

"require": {
    ...
    "cweagans/composer-patches": "1.x-dev"
}

The 2.x branch of composer-patches also includes this feature.

Big thanks to cweagans for this great tool and jhedstrom for helping to get this into the 1.x branch.

Tagged

Drupal Development, Composer