Pass "compilation" object into "basePathTransform"

[mdreizin]

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Issue Details

It would be nice to have ability to access to compilation object under basePathTransform function.

It would be very useful if you would like to use such fields as compilation.fullHash, compilation.hash:

new S3Plugin({
    basePath: 'test',
    basePathTransform: (basePath, compilation) => {
        return basePath + compilation.fullHash;
    },
    s3Options: {
        accessKeyId: process.env.AWS_ACCESS_KEY_ID,
        secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
        region: 'us-west-1'
    },
    s3UploadOptions: {
        Bucket: 'MyBucket'
    }
})

As alternative you can use https://github.com/webpack/loader-utils#interpolatename to interpolate basePath*:

new S3Plugin({
    basePath: 'test/[hash]',
    basePathTransform: basePath => {
        return basePath + '[hash]';
    },
    s3Options: {
        accessKeyId: process.env.AWS_ACCESS_KEY_ID,
        secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
        region: 'us-west-1'
    },
    s3UploadOptions: {
        Bucket: 'MyBucket'
    }
})

[MikaAK]

I don't really like the prospect of passing the compilation object around. I do however like the use of interpolateName. I actually only found out about it a couple days ago so I can definitely look into adding that in

[mdreizin]

@MikaAK Thanks a lot. I will close #46 PR.

[sashako]

Any updates on this? being able to add webpack hash to basePath would be very helpful