Update the nightlies doc to mention repo.scala-lang.org

Author: Gedochao

_overviews/core/nightlies.md

@@ -10,57 +10,139 @@ Here's how to find and use these versions.
 
 ## Scala 3
 
-Scala 3 nightly versions are published to Maven Central. If you know the full version number of the nightly you want to use, you can use it just like any other Scala 3 version.
+Scala 3 nightly versions are published to [https://repo.scala-lang.org](https://repo.scala-lang.org). Historically, they used to be published to Maven Central. Old nightly versions of Scala 3 (all the way until `3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY` in August 2025) are still available there, as well as via [https://repo.scala-lang.org](https://repo.scala-lang.org).
 
-One quick way to get that version number is to visit [https://dotty.epfl.ch](https://dotty.epfl.ch) and look in the upper left corner.
+If you know the full version number of the nightly you want to use, you can use it just like any other Scala 3 version.
 
-Another way is to scrape Maven Central, as shown in this script: [https://raw.githubusercontent.com/VirtusLab/community-build3/master/scripts/lastVersionNightly.sc](https://raw.githubusercontent.com/VirtusLab/community-build3/master/scripts/lastVersionNightly.sc)
+There are a number of ways to get that version number, as listed below.
 
-A third way is to use [scala-cli](https://scala-cli.virtuslab.org), as follows. (Since Scala 3.5.0, the `scala` command runs `scala-cli`.)
+### Scala CLI
 
-### scala-cli
+Scala CLI is the official runner of the language and has nightlies available without any extra configuration. From Scala 3.5.0 and on it's available under the `scala` command in Scala 3 installations. It can also be installed separately as `scala-cli`.
+
+Note: The new artifactory is supported since Scala CLI v1.9.0 onwards (or `scala` installed with Scala 3.7.3 or newer).
 
 You can run nightlies with commands such as:
 
-    scala-cli -S 3.nightly
-    scala-cli -S 3.3.nightly
+    scala -e 'println("Hello") -S 3.nightly
+    scala -e 'println("Hello") -S 3.3.nightly
 
-The default command is `repl`, but all the other scala-cli subcommands such as `compile` and `run` work, too. It also works with `//>` directives in your script itself, for example:
+The default command is `repl` (unless sources are passed, in which case it switches to `run`), but all the other scala-cli subcommands such as `compile` and `run` work, too. It also works with `//> using` directives in your script itself, for example:
 
     //> using scala 3.nightly
 
 See this [scala-cli doc page](https://scala-cli.virtuslab.org/docs/commands/compile#scala-nightlies) for details.
 
+### Get it from the nightly website
+
+A quick way to get that version number is to visit [https://nightly.scala-lang.org](https://nightly.scala-lang.org) and look in the upper left corner.
+
+### Check the artifactory, directly
+
+Another way is to scrape the artifactory, as shown in this script: [https://raw.githubusercontent.com/VirtusLab/community-build3/master/scripts/lastVersionNightly.sc](https://raw.githubusercontent.com/VirtusLab/community-build3/master/scripts/lastVersionNightly.sc)
+
+A third way is to use [scala-cli](https://scala-cli.virtuslab.org), as follows. 
+
+### SBT
+
+To use recent nightlies with SBT, adding the appropriate resolver to the build configuration is necessary.
+
+    ThisBuild / scalaVersion := "3.8.0-RC1-bin-20250916-eb1bb73-NIGHTLY"
+    ThisBuild / resolvers += Resolver.scalaNightlyRepository
+    lazy val root = (project in file("."))
+      .settings(name := "sbt-with-scala3-nightlies")
+
+Note that for older nightlies (3.8.0-RC1-bin-20250822-658c8bd-NIGHTLY and before) no such change is necessary, as they were being published to Maven Central. 
+
+Also note that SBT 1.11.5 or newer is necessary.
+
+### Mill
+
+To use recent nightlies with Mill, a custom resolver for the initial bootstrap of the build is needed. 
+Here's an example `build.mill` file:
+
+    package build
+    import mill.*
+    import mill.api.*
+    import scalalib.*
+
+    def scala3NightlyRepo = "https://repo.scala-lang.org/artifactory/maven-nightlies"
+
+    object project extends ScalaModule {
+      def jvmWorker = ModuleRef(CustomJvmWorkerModule)
+      override def scalaVersion = "3.8.0-RC1-bin-20250916-eb1bb73-NIGHTLY"
+      override def repositories = Task { super.repositories() ++ Seq(scala3NightlyRepo)}
+    }
+
+    object CustomJvmWorkerModule extends JvmWorkerModule, CoursierModule {
+      override def repositories = Task { super.repositories() ++ Seq(scala3NightlyRepo)}
+    }
+
+Note how the custom `JvmWorkerModule` is necessary with the added repository. It is not enough to just define it as a repository for the module dependencies.
+
+Also note that Mill 1.0.5 or newer is necessary for this.
+
 ## Scala 2.13 or 2.12
 
 We informally refer to Scala 2 “nightly” versions, but technically it's a misnomer. A so-called “nightly” is built for every merged PR.
 
 Scala 2 nightly versions are published to a special resolver. Unless you are using scala-cli, you'll need to add that resolver to your build configuration in order to use these versions.
 
-### quick version (sbt)
+### SBT
 
-    Global / resolvers += "scala-integration" at
-      "https://scala-ci.typesafe.com/artifactory/scala-integration/"
-    scalaVersion := "2.13.15-bin-abcd123"
+    ThisBuild / scalaVersion := "2.13.15-bin-abcd123"
+    ThisBuild / resolvers += Resolver.scalaNightlyRepository
+    lazy val root = (project in file("."))
+      .settings(name := "sbt-with-scala2-nightlies")
 
 For a 2.12 nightly, substitute e.g. `2.12.20` for `2.13.15`; in either case, it's the version number of the _next_ release on that branch.
 
 For `abcd123`, substitute the first 7 characters of the SHA of the latest commit to the [2.13.x branch](https://github.com/scala/scala/commits/2.13.x) or [2.12.x branch](https://github.com/scala/scala/commits/2.12.x) that has a green checkmark. (Clicking the checkmark will show a CI job name with the whole version in its name.)
 
 A quick way to find out the full version number of a current nightly is to use [scala-cli](https://scala-cli.virtuslab.org), as follows.
 
-### quick version (scala-cli)
+### Scala CLI
 
-You can run nightlies with:
+Scala CLI is the official runner of the language and has nightlies available without any extra configuration. From Scala 3.5.0 and on it's available under the `scala` command in Scala 3 installations. It can also be installed separately as `scala-cli`.
 
-    scala-cli -S 2.13.nightly
-    scala-cli -S 2.nightly     # same as 2.13.nightly
-    scala-cli -S 2.12.nightly
+Note: The new artifactory is supported since Scala CLI v1.9.0 onwards (or `scala` installed with Scala 3.7.3 or newer).
+
+You can run nightlies with commands such as:
 
-The default command is `repl`, but all the other scala-cli subcommands such as `compile` and `run` work, too. It also works with `//>` directives in your script itself, for example:
+    scala-cli -e 'println("Hello") -S 2.13.nightly
+    scala-cli -e 'println("Hello") -S 2.nightly  # same as 2.13.nightly
+    scala-cli -e 'println("Hello") -S 2.12.nightly
+
+The default command is `repl` (unless sources are passed, in which case it switches to `run`), but all the other scala-cli subcommands such as `compile` and `run` work, too. It also works with `//> using` directives in your script itself, for example:
 
     //> using scala 2.nightly
 
+See this [scala-cli doc page](https://scala-cli.virtuslab.org/docs/commands/compile#scala-nightlies) for details.
+
+### Mill
+
+To use recent nightlies with Mill, a custom resolver for the initial bootstrap of the build is needed.
+Here's an example `build.mill` file:
+
+    package build
+    import mill.*
+    import mill.api.*
+    import scalalib.*
+
+    def scalaNightlyRepo = "https://repo.scala-lang.org/artifactory/maven-nightlies"
+
+    object project extends ScalaModule {
+      def jvmWorker = ModuleRef(CustomJvmWorkerModule)
+      override def scalaVersion = "2.13.17-bin-8b9ec50"
+      override def repositories = Task { super.repositories() ++ Seq(scalaNightlyRepo)}
+    }
+
+    object CustomJvmWorkerModule extends JvmWorkerModule, CoursierModule {
+      override def repositories = Task { super.repositories() ++ Seq(scalaNightlyRepo)}
+    }
+
+Note how the custom `JvmWorkerModule` is necessary with the added repository. It is not enough to just define it as a repository for the module dependencies.
+
 ### Longer explanation
 
 We no longer publish `-SNAPSHOT` versions of Scala 2.
@@ -69,11 +151,15 @@ But the team does publish nightly versions, each with its own fixed version numb
 
 To tell sbt to use one of these nightlies, you need to do three things.
 
-First, add the resolver where the nightlies are kept:
+First, add the direct resolver where the nightlies are kept:
 
     Global / resolvers += "scala-integration" at
       "https://scala-ci.typesafe.com/artifactory/scala-integration/"
 
+Or use the Scala 3 nightly resolver as proxy for the same result:
+
+    Global / resolvers += Resolver.scalaNightlyRepository
+
 Second, specify the Scala version:
 
     scalaVersion := "2.13.1-bin-abcd123"