Make it easier to override elements in tailwind-merge config

[dcastil]

If someone wants to add classes to the tailwind-merge config, that's no problem.

const twMerge = extendTailwindMerge({
    classGroups: {
        // additions to the config go here
    }
})

But if someone wants to override the config in some places, that gets nasty really fast

const twMerge = createTailwindMerge(() => {
    // Need to import this function and create default config myself
    const config = getDefaultConfig()
    
    // Do I mutate the config?
    config.classGroups.somethingThatExists = []
    
    // Do I mutate arrays? What if arrays are reused?
    config.classGroups.somethingElseThatExists.push({})
    
    // Feels weirdly imperative
    return config
})

It would be really nice if I could override parts of the config declaratively and safely with extendTailwindMerge. I think I could use the same pattern as Tailwind CSS and rely on a extend key in each object to add config to existing one and keep the current config to override elements like this:

const twMerge = extendTailwindMerge({
    classGroups: {
        // overrides to the config go here
        extend: {
            // additions to the config go here
        }
    }
})

This would be a breaking change and therefore only makes sense in a new major version.

[dcastil]

Another idea is to use a different name. extendTailwindMerge doesn't sound very fitting if you can also override. This would also make it possible to ship this as a non-breaking change or make the breaking change more obvious.

[github-actions]

This was addressed in release v2.0.0.