Tweaks

 - Use Eql derivation in Namer
 - Use end markers in Nullables
 - Fix a link in overview doc

Author: odersky

compiler/src/dotty/tools/dotc/core/Names.scala

@@ -25,8 +25,6 @@ object Names {
     def toTermName: TermName
   }
 
-  implicit def eqName: Eql[Name, Name] = Eql.derived
-
   /** A common superclass of Name and Symbol. After bootstrap, this should be
    *  just the type alias Name | Symbol
    */
@@ -37,7 +35,7 @@ object Names {
    *  in a name table. A derived term name adds a tag, and possibly a number
    *  or a further simple name to some other name.
    */
-  abstract class Name extends Designator with PreName {
+  abstract class Name extends Designator, PreName derives Eql {
 
     /** A type for names of the same kind as this name */
     type ThisName <: Name

compiler/src/dotty/tools/dotc/typer/Nullables.scala

@@ -189,7 +189,7 @@ object Nullables:
       val mutables = infos.foldLeft(Set[TermRef]())((ms, info) =>
         ms.union(info.asserted.filter(_.symbol.is(Mutable))))
       infos.extendWith(NotNullInfo(Set(), mutables))
-  // end notNullInfoOps
+  end notNullInfoOps
 
   extension refOps on (ref: TermRef):
 
@@ -244,6 +244,7 @@ object Nullables:
       refSym.is(Mutable) // if it is immutable, we don't need to check the rest conditions
       && refOwner.isTerm
       && recur(ctx.owner)
+  end refOps
 
   extension treeOps on (tree: Tree):
 
@@ -334,6 +335,7 @@ object Nullables:
           traverseChildren(tree)
           tree.computeNullable()
       }.traverse(tree)
+  end treeOps
 
   extension assignOps on (tree: Assign):
     def computeAssignNullable()(using Context): tree.type = tree.lhs match
@@ -351,6 +353,7 @@ object Nullables:
             tree.withNotNullInfo(NotNullInfo(Set(ref), Set()))
         else tree
       case _ => tree
+  end assignOps
 
   private val analyzedOps = Set(nme.EQ, nme.NE, nme.eq, nme.ne, nme.ZAND, nme.ZOR, nme.UNARY_!)
 
@@ -444,13 +447,16 @@ object Nullables:
    *       xs = xs.next
    */
   def whileContext(whileSpan: Span)(using Context): Context =
+
     def isRetracted(ref: TermRef): Boolean =
       val sym = ref.symbol
       sym.span.exists
       && assignmentSpans.getOrElse(sym.span.start, Nil).exists(whileSpan.contains(_))
       && ctx.notNullInfos.impliesNotNull(ref)
+
     val retractedVars = ctx.notNullInfos.flatMap(_.asserted.filter(isRetracted)).toSet
     ctx.addNotNullInfo(NotNullInfo(Set(), retractedVars))
+  end whileContext
 
   /** Post process all arguments to by-name parameters by removing any not-null
    *  info that was used when typing them. Concretely:

docs/docs/reference/overview.md

@@ -33,7 +33,7 @@ These constructs replace existing constructs with the aim of making the language
  - [Trait Parameters](other-new-features/trait-parameters.md) replace [early initializers](dropped-features/early-initializers.md) with a more generally useful construct.
  - [Given Instances](contextual/delegates.md)
    replace implicit objects and defs, focussing on intent over mechanism.
- - [Given Clauses](contextual/given-clauses.md) replace implicit parameters, avoiding their ambiguities.
+ - [Using Clauses](contextual/using-clauses.md) replace implicit parameters, avoiding their ambiguities.
  - [Extension Methods](contextual/extension-methods.md) replace implicit classes with a clearer and simpler mechanism.
  - [Opaque Type Aliases](other-new-features/opaques.md) replace most uses
    of value classes while guaranteeing absence of boxing.