Merge branch 'scala:main' into init-global-warning

Author: JasonH53

.github/CODEOWNERS

@@ -0,0 +1,5 @@
+# Any changes to the Scala 3 Standard Library must be approve
+# by one of the officers responsible of maintaining it
+/library/      @scala/stdlib-officers
+/library-aux/  @scala/stdlib-officers
+/library-js/   @scala/stdlib-officers

community-build/community-projects/scodec

@@ -1450,6 +1450,27 @@ object desugar {
       sel
     end match
 
+  case class TuplePatternInfo(arity: Int, varNum: Int, wildcardNum: Int)
+  object TuplePatternInfo:
+    def apply(pat: Tree)(using Context): TuplePatternInfo = pat match
+      case Tuple(pats) =>
+        var arity = 0
+        var varNum = 0
+        var wildcardNum = 0
+        pats.foreach: p =>
+          arity += 1
+          p match
+            case id: Ident if !isBackquoted(id) =>
+              if id.name.isVarPattern then
+                varNum += 1
+                if id.name == nme.WILDCARD then
+                  wildcardNum += 1
+            case _ =>
+        TuplePatternInfo(arity, varNum, wildcardNum)
+      case _ =>
+        TuplePatternInfo(-1, -1, -1)
+  end TuplePatternInfo
+
   /** If `pat` is a variable pattern,
    *
    *    val/var/lazy val p = e
@@ -1483,30 +1504,47 @@ object desugar {
               |please bind to an identifier and use an alias given.""", bind)
         false
 
-      def isTuplePattern(arity: Int): Boolean = pat match {
-        case Tuple(pats) if pats.size == arity =>
-          pats.forall(isVarPattern)
-        case _ => false
-      }
-
-      val isMatchingTuple: Tree => Boolean = {
-        case Tuple(es) => isTuplePattern(es.length) && !hasNamedArg(es)
-        case _ => false
-      }
+      val tuplePatternInfo = TuplePatternInfo(pat)
+
+      // When desugaring a PatDef in general, we use pattern matching on the rhs
+      // and collect the variable values in a tuple, then outside the match,
+      // we destructure the tuple to get the individual variables.
+      // We can achieve two kinds of tuple optimizations if the pattern is a tuple
+      // of simple variables or wildcards:
+      // 1. Full optimization:
+      //    If the rhs is known to produce a literal tuple of the same arity,
+      //    we can directly fetch the values from the tuple.
+      //    For example: `val (x, y) = if ... then (1, "a") else (2, "b")` becomes
+      //    `val $1$ = if ...; val x = $1$._1; val y = $1$._2`.
+      // 2. Partial optimization:
+      //    If the rhs can be typed as a tuple and matched with correct arity, we can
+      //    return the tuple itself in the case if there are no more than one variable
+      //    in the pattern, or return the the value if there is only one variable.
+
+      val fullTupleOptimizable =
+        val isMatchingTuple: Tree => Boolean = {
+          case Tuple(es) => tuplePatternInfo.varNum == es.length && !hasNamedArg(es)
+          case _ => false
+        }
+        tuplePatternInfo.arity > 0
+        && tuplePatternInfo.arity == tuplePatternInfo.varNum
+        && forallResults(rhs, isMatchingTuple)
 
-      // We can only optimize `val pat = if (...) e1 else e2` if:
-      // - `e1` and `e2` are both tuples of arity N
-      // - `pat` is a tuple of N variables or wildcard patterns like `(x1, x2, ..., xN)`
-      val tupleOptimizable = forallResults(rhs, isMatchingTuple)
+      val partialTupleOptimizable =
+        tuplePatternInfo.arity > 0
+        && tuplePatternInfo.arity == tuplePatternInfo.varNum
+        // We exclude the case where there is only one variable,
+        // because it should be handled by `makeTuple` directly.
+        && tuplePatternInfo.wildcardNum < tuplePatternInfo.arity - 1
 
       val inAliasGenerator = original match
         case _: GenAlias => true
         case _ => false
 
-      val vars =
-        if (tupleOptimizable) // include `_`
+      val vars: List[VarInfo] =
+        if fullTupleOptimizable || partialTupleOptimizable then // include `_`
           pat match
-            case Tuple(pats) => pats.map { case id: Ident => id -> TypeTree() }
+            case Tuple(pats) => pats.map { case id: Ident => (id, TypeTree()) }
         else
           getVariables(
             tree = pat,
@@ -1517,12 +1555,27 @@ object desugar {
                 errorOnGivenBinding
           ) // no `_`
 
-      val ids = for ((named, _) <- vars) yield Ident(named.name)
+      val ids = for ((named, tpt) <- vars) yield Ident(named.name)
+
       val matchExpr =
-        if (tupleOptimizable) rhs
+        if fullTupleOptimizable then rhs
         else
-          val caseDef = CaseDef(pat, EmptyTree, makeTuple(ids).withAttachment(ForArtifact, ()))
+          val caseDef =
+            if partialTupleOptimizable then
+              val tmpTuple = UniqueName.fresh()
+              // Replace all variables with wildcards in the pattern
+              val pat1 = pat match
+                case Tuple(pats) =>
+                  val wildcardPats = pats.map(p => Ident(nme.WILDCARD).withSpan(p.span))
+                  Tuple(wildcardPats).withSpan(pat.span)
+              CaseDef(
+                Bind(tmpTuple, pat1),
+                EmptyTree,
+                Ident(tmpTuple).withAttachment(ForArtifact, ())
+              )
+            else CaseDef(pat, EmptyTree, makeTuple(ids).withAttachment(ForArtifact, ()))
           Match(makeSelector(rhs, MatchCheck.IrrefutablePatDef), caseDef :: Nil)
+
       vars match {
         case Nil if !mods.is(Lazy) =>
           matchExpr

community-build/community-projects/specs2

@@ -350,14 +350,16 @@ trait TreeInfo[T <: Untyped] { self: Trees.Instance[T] =>
   }
 
   /** Checks whether predicate `p` is true for all result parts of this expression,
-   *  where we zoom into Ifs, Matches, and Blocks.
+   *  where we zoom into Ifs, Matches, Tries, and Blocks.
    */
-  def forallResults(tree: Tree, p: Tree => Boolean): Boolean = tree match {
+  def forallResults(tree: Tree, p: Tree => Boolean): Boolean = tree match
     case If(_, thenp, elsep) => forallResults(thenp, p) && forallResults(elsep, p)
-    case Match(_, cases) => cases forall (c => forallResults(c.body, p))
+    case Match(_, cases) => cases.forall(c => forallResults(c.body, p))
+    case Try(_, cases, finalizer) =>
+      cases.forall(c => forallResults(c.body, p))
+      && (finalizer.isEmpty || forallResults(finalizer, p))
     case Block(_, expr) => forallResults(expr, p)
     case _ => p(tree)
-  }
 
   /** The tree stripped of the possibly nested applications (term and type).
    *  The original tree if it's not an application.

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -31,7 +31,7 @@ enum MigrationVersion(val warnFrom: SourceVersion, val errorFrom: SourceVersion)
   case ImportRename extends MigrationVersion(future, future)
   case ParameterEnclosedByParenthesis extends MigrationVersion(future, future)
   case XmlLiteral extends MigrationVersion(future, future)
-  case GivenSyntax extends MigrationVersion(future, never)
+  case GivenSyntax extends MigrationVersion(future, future)
   case ImplicitParamsWithoutUsing extends MigrationVersion(`3.7`, future)
   case Scala2Implicits extends MigrationVersion(future, future)
 

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -8,7 +8,7 @@ import Feature.isPreviewEnabled
 import util.Property
 
 enum SourceVersion:
-  case `3.0-migration`, `3.0` 
+  case `3.0-migration`, `3.0`
   case `3.1-migration`, `3.1`
   case `3.2-migration`, `3.2`
   case `3.3-migration`, `3.3`
@@ -44,8 +44,10 @@ enum SourceVersion:
   def enablesNamedTuples = isAtLeast(`3.7`)
   def enablesBetterFors(using Context) = isAtLeast(`3.7`) && isPreviewEnabled
 
+  def requiresNewSyntax = isAtLeast(future)
+
 object SourceVersion extends Property.Key[SourceVersion]:
-  
+
   /* The default source version used by the built compiler */
   val defaultSourceVersion = `3.7`
 

compiler/src/dotty/tools/dotc/config/MigrationVersion.scala

@@ -196,7 +196,7 @@ class CheckRealizable(using Context) {
         }
       }
     if sourceVersion.isAtLeast(future) then
-      // check fields only from version 3.x.
+      // check fields only from version 3.future.
       // Reason: An embedded field could well be nullable, which means it
       // should not be part of a path and need not be checked; but we cannot recognize
       // this situation until we have a typesystem that tracks nullability.

compiler/src/dotty/tools/dotc/config/SourceVersion.scala

@@ -14,6 +14,25 @@ import util.Spans.Span
 /** Operations that are shared between Namer and TreeUnpickler */
 object NamerOps:
 
+  /** A completer supporting cleanup actions.
+   *  Needed to break the loop between completion of class and companion object.
+   *  If we try to complete the class first, and completion needs the companion
+   *  object (for instance for processing an import) then the companion object
+   *  completion would consult the companion class info for constructor that
+   *  need a constructor proxy in the object. This can lead to a cyclic reference.
+   *  We break the cycle by delaying adding constructor proxies to be a cleanuo
+   *  action instead.
+   */
+  trait CompleterWithCleanup extends LazyType:
+    private var cleanupActions: List[() => Unit] = Nil
+    def addCleanupAction(op: () => Unit): Unit =
+      cleanupActions = op :: cleanupActions
+    def cleanup(): Unit =
+      if cleanupActions.nonEmpty then
+        cleanupActions.reverse.foreach(_())
+        cleanupActions = Nil
+  end CompleterWithCleanup
+
   /** The type of the constructed instance is returned
    *
    *  @param ctor the constructor
@@ -164,8 +183,14 @@ object NamerOps:
         ApplyProxyCompleter(constr),
         cls.privateWithin,
         constr.coord)
-    for dcl <- cls.info.decls do
+    def doAdd() = for dcl <- cls.info.decls do
       if dcl.isConstructor then scope.enter(proxy(dcl))
+    cls.infoOrCompleter match
+      case completer: CompleterWithCleanup if cls.is(Touched) =>
+        // Taking the info would lead to a cyclic reference here - delay instead until cleanup of `cls`
+        completer.addCleanupAction(doAdd)
+      case _ =>
+        doAdd()
     scope
   end addConstructorApplies
 

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

@@ -410,7 +410,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
         compareErasedValueType
       case ConstantType(v2) =>
         tp1 match {
-          case ConstantType(v1) => v1.value == v2.value && recur(v1.tpe, v2.tpe)
+          case ConstantType(v1) => v1 == v2 && recur(v1.tpe, v2.tpe)
           case _ => secondTry
         }
       case tp2: AnyConstantType =>