Upgrade to the latest metaconfig

[olafurpg]

This PR removes the dependency on scalameta/paradise macro annotations and upgrades to the latest metaconfig version (https://olafurpg.github.io/metaconfig/). This is the first step towards having configuration work the same across JVM, JS and Native.

Most of the diff is replacing the @GenerateConfDecoder macro annotation with the semi-automatic metaconfig.generic.{deriveDecoder,deriveSurface} def macros. Amazingly, 1031 out of 1032 tests passed on first compile 💪

The surface macro is nice since it allows automatic generation of all configuration settings with explanation messages, default values and types. Example how we use it in scalafix https://scalacenter.github.io/scalafix/docs/rules/DisableSyntax

The only regression I can't avoid is the "Other" section on the website that did a best-effort to pretty-print all available configuration options as HOCON. The website links to the ScalafmtConfig sources instead now.

[olafurpg]

Appears that we need to upgrade to scalameta v1.8 from v1.7 to complete this PR. The Scala.js linker failures indicate the current classpath is broken on the JVM potentially causing `MethodNotFoundExceptiond due to a binary incompatible change between fastparse 0.4.2 and 0.4.3. The JVM test suite didn't catch it because it is not as exhaustive as the Scala.js closed world optimizer + linker.

The changes for v1.7 to v1.8 are small but enough to cause ~40 test failures. I fixed one incompatibility which brings it down to ~5 test failures.

I'm gonna go ahead and publish a release with the current master before going ahead with this fix.

[olafurpg]

All tests are passing now after upgrading to v1.8 🎉 scalafmt can now format code splices inside of xml literals :)

We are now blocked by the lack of a ConfEncoder[T] in metaconfig for the website to show configuration examples next to code listings. I started working on this in metaconfig, it doesn't seem too hard but stuck on

[error] (metaconfig-coreJVM/test:compileIncremental) scala.reflect.internal.FatalError: Unknown type: <error>, <error> [class scala.reflect.internal.Types$ErrorType$, class scala.reflect.internal.Types$ErrorType$] TypeRef? false

writing the encoder derivation macro

[olafurpg]

Opened https://github.com/olafurpg/metaconfig/pull/43 adding metaconfig.ConfEncoder typeclass to replace toHocon

[olafurpg]

The upgrade to scalameta v1.8 is complete, it took a while since the changes around lambdas were quite big. Overall I think it's a nice improvement, for example it can now force the body of a HOF to be on the same line as the parameter list

// before
(x: Int) =>
  x + 1
// after
(x: Int) => x + 1

Now we are only blocked by lack of toHocon.

[fommil]

if you're using semi automatic derivation in scalameta, maybe there is an opportunity to use the compiler plugin (without the scalaz bits) from https://gitlab.com/fommil/scalaz-deriving/

[olafurpg]

I am indeed using semiauto but with a a twist where I need a base default value passed into the derivation macro. This is required to apply configuration on top of a base setting, for example // scalafmt: { maxColumn = 200} comments are applied on top of the active configuration.

I took a look at scalaz deriving but struggled to figure out what required scalaz and what didn't. It would be helpful to have a section on how to use it without bringing in scalaz.

[fommil]

@olafurpg the entire https://gitlab.com/fommil/scalaz-deriving/#compiler-plugin does not require scalaz.

[mads-hartmann]

Once this is merged I should be able to use metals on this code-base right?

[olafurpg]

@mads-hartmann I haven't tried, there might be other issues but removing scalameta/paradise should definitely improve the situation

[olafurpg]

Almost done 😸 we now have a ConfEncoder typeclass that we can use to pretty print ScalafmtConfig as hocon

This is far cleaner than what we had before which used ugly runtime type matching. The show/hide buttons are still empty for some reason, that's the only remaining blocker to merge this.

[olafurpg]

Released metaconfig v0.7.2 that adds a hocon printer and Conf.patch method to print out minimal configuration examples given two ScalafmtConfig

https://github.com/olafurpg/metaconfig/releases/tag/v0.7.2

• https://olafurpg.github.io/metaconfig/#confprinthocon
• https://olafurpg.github.io/metaconfig/#confpatch

[olafurpg]

OK, this is ready for merge 💪 @mads-hartmann any chance you could take a look at the configuration examples to see if I messed up?

[olafurpg]

Gonna go ahead and merge this to unblock a followup PR that upgrades scalameta to v3.7

[mads-hartmann]

@olafurpg Awesome work. As far as I can tell the show/hide config options works like expected 👍