How can I merge resource files such as service files and MANIFEST?

[SettingDust]

No description provided.

[martinbonnin]

Woops sorry I managed to miss that issue completely.

For services, I would expect R8 to do it automatically. Just make sure to keep your services interfaces.

Edit: it won't merge if several implementations implement the same interface.

For MANIFEST, I'm not sure, what do you want to merge?

[SettingDust]

For MANIFEST, I'm not sure, what do you want to merge?

The attributes in MANIFEST.MF

[martinbonnin]

I don't think R8 has support for that. You could file a feature request at https://issuetracker.google.com/u/1/issues/new?component=192708&template=840533 but my hunch is that such a feature would require some logic: if 2 attributes conflict, what should be the result? I'm not sure that belongs in R8 or Gr8. You could do a post-processing task for an example to replace the Manifest in the minified jar.

Out of curiosity, what's the use case? What attributes do you need merged?

[SettingDust]

Mainly the MixinConfigs. It's a comma split list of files.

Custom transformer/merge is required

The workaround I'm using in shadow GradleUp/shadow#278 (comment)

[martinbonnin]

I see, thanks for providing this.

Shadow supports Transformers for resources and, because it's a Jar task, it also supports merging manifest using Manifest.from() (source)

Doing the same without writing a 2nd jar in Gr8 would require R8 to accept a callback to modify the jar content on the fly, which is currently not possible.

You can still achieve the same though with a custom task that takes the shadowed jar and rewrites the manifest. Something like so (wildly untested):

val shadowedJar = create("default") {
      // ...
    }

    val rewriteManifest = tasks.register("rewriteManifest", Jar::class.java) {
      from(shadowedJar)

      manifest {
        from(
          configurations
            .flatMap { it.files }
            .map { zipTree(it) }
            .map { zip -> zip.find { it.name.equals("MANIFEST.MF") } }
        )
      }
    }