Merge pull request #10588 from dotty-staging/support-primitive-unliftable-with-precise-types

Allow unlifting precise types for primitives

Author: nicolasstucki

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

@@ -28,58 +28,58 @@ object Unliftable {
    *  - Unlifts `'{false}` into `Some(false)`
    *  - Otherwise unlifts to `None`
    */
-  given BooleanUnliftable as Unliftable[Boolean] = new PrimitiveUnliftable
+  given BooleanUnliftable[T <: Boolean] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Byte
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Byte`
    *  - Otherwise unlifts to `None`
    */
-  given ByteUnliftable as Unliftable[Byte] = new PrimitiveUnliftable
+  given ByteUnliftable[T <: Byte] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Short
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Short`
    *  - Otherwise unlifts to `None`
    */
-  given ShortUnliftable as Unliftable[Short] = new PrimitiveUnliftable
+  given ShortUnliftable[T <: Short] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Int
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Int`
    *  - Otherwise unlifts to `None`
    */
-  given IntUnliftable as Unliftable[Int] = new PrimitiveUnliftable
+  given IntUnliftable[T <: Int] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Long
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Long`
    *  - Otherwise unlifts to `None`
    */
-  given LongUnliftable as Unliftable[Long] = new PrimitiveUnliftable
+  given LongUnliftable[T <: Long] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Float
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Float`
    *  - Otherwise unlifts to `None`
    */
-  given FloatUnliftable as Unliftable[Float] = new PrimitiveUnliftable
+  given FloatUnliftable[T <: Float] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Double
    *  - Unlifts `'{n}` into `Some(n)` for a literal `n` of type `Double`
    *  - Otherwise unlifts to `None`
    */
-  given DoubleUnliftable as Unliftable[Double] = new PrimitiveUnliftable
+  given DoubleUnliftable[T <: Double] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for Char
    *  - Unlifts `'{c}` into `Some(c)` for a literal `c` of type `Char`
    *  - Otherwise unlifts to `None`
    */
-  given CharUnliftable as Unliftable[Char] = new PrimitiveUnliftable
+  given CharUnliftable[T <: Char] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Default unliftable for String
    *  - Unlifts `'{str}` into `Some(str)` for a literal `str` of type `String`
    *  - Otherwise unlifts to `None`
    */
-  given StringUnliftable as Unliftable[String] = new PrimitiveUnliftable
+  given StringUnliftable[T <: String] as Unliftable[T] = new PrimitiveUnliftable
 
   /** Lift a quoted primitive value `'{ x }` into `x` */
-  private class PrimitiveUnliftable[T <: Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String] extends Unliftable[T] {
+  private class PrimitiveUnliftable[T <: Boolean | Byte | Short | Int | Long | Float | Double | Char | String] extends Unliftable[T] {
     def fromExpr(expr: Expr[T]) =
       import quotes.reflect._
       def rec(tree: Term): Option[T] = tree match {

tests/run-macros/expr-map-3.check

@@ -0,0 +1,3 @@
+foo
+foofoo
+apply

tests/run-macros/expr-map-3/Macro_1.scala

@@ -0,0 +1,18 @@
+import scala.quoted._
+
+
+inline def rewrite[T](inline x: Any): Any = ${ stringRewriter('x) }
+
+private def stringRewriter(e: Expr[Any])(using Quotes): Expr[Any] =
+  StringRewriter.transform(e)
+
+private object StringRewriter extends ExprMap {
+
+  def transform[T](e: Expr[T])(using Type[T])(using Quotes): Expr[T] = e match
+    case '{ ${Unlifted(s)}: String } =>
+      // checkIfValid(s)
+      val s2: String & T = s
+      Expr(s2)
+    case _ => transformChildren(e)
+
+}

tests/run-macros/expr-map-3/Test_2.scala

@@ -0,0 +1,12 @@
+object Test {
+
+  def main(args: Array[String]): Unit = {
+    println(rewrite("foo"))
+    println(rewrite("foo" + "foo"))
+
+    rewrite {
+      println("apply")
+    }
+  }
+
+}

tests/run-staging/unliftables.check

@@ -8,8 +8,14 @@ Some(6)
 Some(7.1)
 Some(8.1)
 
+Some(4)
+Some(5)
+Some(8.2)
+
 Some(a)
+Some(b)
 Some(abc)
+Some(def)
 
 Some(List(1, 2, 3))
 Some(List(1, 2, 3))

tests/run-staging/unliftables.scala

@@ -13,8 +13,14 @@ object Test {
     println('{ 7.1: Float }.unlift)
     println('{ 8.1: Double }.unlift)
     println()
+    println(('{ 4 }: Expr[4]).unlift)
+    println(('{ 5L }: Expr[5L]).unlift)
+    println(('{ 8.2 }: Expr[8.2]).unlift)
+    println()
     println('{ 'a' }.unlift)
+    println(('{ 'b' }: Expr['b']).unlift)
     println('{ "abc" }.unlift)
+    println(('{ "def" }: Expr["def"]).unlift)
     println()
     // TODO?
     // println('{ classOf[String] }.unlift)