Remove quoted.Const.unapply

This extractor was replaced with the more versatile extractor `quoted.Unlifted.unapply`.
Usually, it is better to use `expr.unlift`/`expr.unliftOrError` when it is simpler to do so.

* Remove definition of `quoted.Const.unapply`
* Replace uses of `Const` with `Unlifted`

**Migration**

* Consider using `expr.unlift` and them match on `Option`
* Consider using `expr.unliftOrError`
* Replace `Const(x)` with `Unlifted(x)` if the type is known
* Replace `Const(x: Int)` with `'{ ${Unlifted(x)}: Int }` if type of expression must be checked at runtime

Author: nicolasstucki

library/src-bootstrapped/scala/quoted/Unliftable.scala

@@ -135,8 +135,8 @@ object Unliftable {
    */
   given StringContextUnliftable as Unliftable[StringContext] = new {
     def fromExpr(x: Expr[StringContext]) = x match {
-      case '{ new StringContext(${Varargs(Consts(args))}: _*) } => Some(StringContext(args: _*))
-      case '{     StringContext(${Varargs(Consts(args))}: _*) } => Some(StringContext(args: _*))
+      case '{ new StringContext(${Varargs(Unlifted(args))}: _*) } => Some(StringContext(args: _*))
+      case '{     StringContext(${Varargs(Unlifted(args))}: _*) } => Some(StringContext(args: _*))
       case _ => None
     }
   }

library/src/scala/quoted/Const.scala

@@ -9,7 +9,7 @@ object Macro {
     var res: Expr[String] = null
     for _ <- 0 to 5_000 do
       (strCtxExpr, argsExpr) match {
-        case ('{ StringContext(${Varargs(Consts(parts))}: _*) }, Varargs(Consts(args))) =>
+        case ('{ StringContext(${Varargs(Unlifted(parts))}: _*) }, Varargs(Unlifted(args))) =>
           res = Expr(StringContext(parts: _*).s(args: _*))
         case _ => ???
       }

library/src/scala/quoted/Consts.scala

@@ -9,7 +9,7 @@ object Macro {
     import quotes.reflect._
     sc match {
       case '{ StringContext(${Varargs(parts)}: _*) } =>
-        for (part @ Const(s) <- parts)
+        for (part @ Unlifted(s) <- parts)
           report.error(s, Term.of(part).pos)
     }
     '{}

tests/bench/string-interpolation-macro/Macro.scala

@@ -9,7 +9,7 @@ object Macro {
     import quotes.reflect._
     sc match {
       case '{ StringContext(${Varargs(parts)}: _*) } =>
-        for (part @ Const(s) <- parts)
+        for (part @ Unlifted(s) <- parts)
           report.error(s, Term.of(part).pos)
     }
     '{}

tests/neg-macros/i6432/Macro_1.scala

@@ -10,7 +10,7 @@ object E {
 
   implicit def ev1[T: Type]: Unliftable[E[T]] = new Unliftable {
     def fromExpr(x: Expr[E[T]]) = x match {
-      case '{ I(${Const(n)}) } => Some(I(n).asInstanceOf[E[T]])
+      case '{ I(${Unlifted(n)}) } => Some(I(n).asInstanceOf[E[T]])
       case '{ Plus[T](${Value(x)}, ${Value(y)})(using $op) } if op.matches('{Plus2.IPlus}) => Some(Plus(x, y)(using Plus2.IPlus.asInstanceOf[Plus2[T]]).asInstanceOf[E[T]])
       case _ => None
     }

tests/neg-macros/i6432b/Macro_1.scala

@@ -4,8 +4,8 @@ import scala.quoted._
 import Even._
 
 object EvenFromDigitsImpl:
-  def apply(digits: Expr[String])(using Quotes): Expr[Even] = digits match {
-    case Const(ds) =>
+  def apply(digits: Expr[String])(using Quotes): Expr[Even] = digits.unlift match {
+    case Some(ds) =>
       val ev =
         try evenFromDigits(ds)
         catch {

tests/neg-macros/inline-macro-staged-interpreter/Macro_1.scala

@@ -9,7 +9,7 @@ private def stringRewriter(e: Expr[Any])(using Quotes): Expr[Any] =
 private object StringRewriter extends ExprMap {
 
   def transform[T](e: Expr[T])(using Type[T])(using Quotes): Expr[T] = e match
-    case Const(s: String) =>
+    case '{ ${Unlifted(s)}: String } =>
       Expr(s.reverse) match
         case '{ $x: T } => x
         case _ => e // e had a singlton String type

tests/neg-with-compiler/GenericNumLits/EvenFromDigitsImpl_1.scala

@@ -26,9 +26,9 @@ private def rewriteMacro[T: Type](x: Expr[T])(using Quotes): Expr[T] = {
             case (_, Some(_)) => '{ $y * $x }
             case _ => '{ $x * $y }
           }
-        case '{ power(${Const(x)}, ${Const(y)}) } =>
+        case '{ power(${Unlifted(x)}, ${Unlifted(y)}) } =>
           Expr(power(x, y))
-        case '{ power($x, ${Const(y)}) } =>
+        case '{ power($x, ${Unlifted(y)}) } =>
           if y == 0 then '{1}
           else '{ times($x, power($x, ${Expr(y-1)})) }
       }),