Change doc pages

 - Instead of "Dropped: package objects" have a new doc page "Toplevel Definitions"
   in "other new features".
 - Add a doc page for experimental reference-able package object, which uses some
   wording from the Pre-SIP.

Author: odersky

docs/_docs/reference/experimental/package-object-values.md

@@ -0,0 +1,40 @@
+---
+layout: doc-page
+title: "Reference-able Package Objects"
+redirectFrom: /docs/reference/experimental/package-object-values.html
+nightlyOf: https://docs.scala-lang.org/scala3/reference/experimental/package-object-values.html
+---
+
+One limitation with `package object`s is that we cannot currently assign them to values: `a.b` fails to compile when `b` is a `package object`, even though it succeeds when `b` is a normal `object`. The workaround is to call
+```scala
+  a.b.`package`
+```
+But this is ugly and non-obvious. Or one could use a normal `object`, which is not always possible.
+
+The `packageObjectValues` language extension drops this limitation. The extension is enabled by the language import `import scala.language.experimental.packageObjectValues` or by setting the command line option `-language:experimental.packageObjectValues`.
+
+The extension, turns the following into valid code:
+
+```scala
+package a
+package object b
+
+val z = a.b // Currently fails with "package is not a value"
+```
+
+Currently the workaround is to use a `.package` suffix:
+
+```scala
+val z = a.b.`package`
+```
+
+With the extension, a reference such as `a.b` where `b` is a `package` containing a `package object`, expands to `a.b.package` automatically
+
+## Limitations
+
+* `a.b` only expands to `a.b.package` when used "standalone", i.e. not when part of a larger select chain `a.b.c` or equivalent postfix expression `a.b c`, prefix expression `!a.b`, or infix expression `a.b c d`.
+
+* `a.b` expands to `a.b.package` of the type `a.b.package.type`, and only contains the contents of the `package object`. It does not contain other things in the `package` `a.b` that are outside of the `package object`
+
+Both these requirements are necessary for backwards compatibility, and anyway do not impact the main goal of removing the irregularity between `package object`s and normal `object`s.
+

docs/_docs/reference/other-new-features/toplevel-definitions.md

@@ -0,0 +1,41 @@
+---
+layout: doc-page
+title: "Toplevel Definitions"
+nightlyOf: https://docs.scala-lang.org/scala3/reference/dropped-features/toplevel-definitions.html
+---
+
+All kind of definitions can now be written at the top-level.
+Example:
+```scala
+package p
+type Labelled[T] = (String, T)
+val a: Labelled[Int] = ("count", 1)
+def b = a._2
+
+case class C()
+
+extension (x: C) def pair(y: C) = (x, y)
+```
+Previously, `type`, `val` or `def` definitions had to be wrapped in a package object. Now,
+there may be several source files in a package containing such top-level definitions, and source files can freely mix top-level value, method, and type definitions with classes and objects.
+
+The compiler generates synthetic objects that wrap top-level definitions falling into one of the following categories:
+
+ - all pattern, value, method, and type definitions,
+ - implicit classes and objects,
+ - companion objects of opaque type aliases.
+
+If a source file `src.scala` contains such top-level definitions, they will be put in a synthetic object named `src$package`. The wrapping is transparent, however. The definitions in `src` can still be accessed as members of the enclosing package. The synthetic object will be placed last in the file,
+after any other package clauses, imports, or object and class definitions.
+
+**Note:** This means that
+1. The name of a source file containing wrapped top-level definitions is relevant for binary compatibility. If the name changes, so does the name of the generated object and its class.
+
+2. A top-level main method `def main(args: Array[String]): Unit = ...` is wrapped as any other method. If it appears
+in a source file `src.scala`, it could be invoked from the command line using a command like `scala src$package`. Since the
+"program name" is mangled it is recommended to always put `main` methods in explicitly named objects.
+
+3. The notion of `private` is independent of whether a definition is wrapped or not. A `private` top-level definition is always visible from everywhere in the enclosing package.
+
+4. If several top-level definitions are overloaded variants with the same name,
+they must all come from the same source file.

docs/sidebar.yml

@@ -72,6 +72,8 @@ subsection:
           - page: reference/other-new-features/export.md
           - page: reference/other-new-features/opaques.md
           - page: reference/other-new-features/opaques-details.md
+          - page: reference/other-new-features/toplevel-definitions.md
+          - page: reference/other-new-features/named-tuples.md
           - page: reference/other-new-features/open-classes.md
           - page: reference/other-new-features/parameter-untupling.md
           - page: reference/other-new-features/parameter-untupling-spec.md
@@ -123,7 +125,6 @@ subsection:
           - page: reference/dropped-features/type-projection.md
           - page: reference/dropped-features/do-while.md
           - page: reference/dropped-features/procedure-syntax.md
-          - page: reference/dropped-features/package-objects.md
           - page: reference/dropped-features/early-initializers.md
           - page: reference/dropped-features/class-shadowing.md
           - page: reference/dropped-features/class-shadowing-spec.md
@@ -164,6 +165,7 @@ subsection:
           - page: reference/experimental/runtimeChecked.md
           - page: reference/experimental/better-fors.md
           - page: reference/experimental/unrolled-defs.md
+          - page: reference/experimental/package-object-values.md
       - page: reference/syntax.md
       - title: Language Versions
         index: reference/language-versions/language-versions.md