Fix #5986: Add autolift implicit conversion

docs/docs/reference/other-new-features/principled-meta-programming.md

@@ -600,6 +600,12 @@ Using lifting, we can now give the missing definition of `showExpr` in the intro
 That is, the `showExpr` method converts its `Expr` argument to a string (`code`), and lifts
 the result back to an `Expr[String]` using the `toExpr` wrapper.
 
+**Note**: the `toExpr` extension method can be ommited by importing an implicit
+conversion with `import scala.quoted.autolift._`. The programmer is able to
+declutter slightly the code at the cost of readable _phase distinction_ between
+stages.
+
+
 ## Implementation
 
 ### Syntax

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

@@ -2,6 +2,10 @@ package scala
 
 package object quoted {
 
+  object autolift {
+    implicit def autoToExpr[T: Liftable](x: T): Expr[T] = x.toExpr
+  }
+
   implicit class LiftExprOps[T](val x: T) extends AnyVal {
     def toExpr(implicit ev: Liftable[T]): Expr[T] = ev.toExpr(x)
   }

tests/disabled/run/xml-interpolation-3/XmlQuote_1.scala

@@ -1,5 +1,6 @@
 import scala.quoted._
 import scala.tasty.Tasty
+import scala.quoted.autolift._
 
 import scala.language.implicitConversions
 
@@ -14,6 +15,6 @@ object XmlQuote {
 
   def impl(receiver: StringContext, args: Expr[Seq[Any]]): Expr[Xml] = {
     val string = receiver.parts.mkString("??")
-    '{new Xml(${string.toExpr}, ($args).toList)}
+    '{new Xml(${string}, ($args).toList)}
   }
 }

tests/neg-with-compiler/quote-run-in-macro-1/quoted_1.scala

@@ -1,11 +1,12 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.quoted.Toolbox.Default._
 
 object Macros {
   inline def foo(i: => Int): Int = ${ fooImpl('i) }
   def fooImpl(i: Expr[Int]): Expr[Int] = {
     val y: Int = i.run
-    y.toExpr
+    y
   }
 }

tests/neg-with-compiler/quote-run-in-macro-2/quoted_1.scala

@@ -1,11 +1,11 @@
 import scala.quoted._
-
+import scala.quoted.autolift._
 import scala.quoted.Toolbox.Default._
 
 object Macros {
   inline def foo(i: => Int): Int = ${ fooImpl('i) }
   def fooImpl(i: Expr[Int]): Expr[Int] = {
     val y: Int = i.run
-    y.toExpr
+    y
   }
 }

tests/neg/inline-case-objects/Macro_1.scala

@@ -1,8 +1,9 @@
 
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Macros {
-  def impl(foo: Any): Expr[String] = foo.getClass.getCanonicalName.toExpr
+  def impl(foo: Any): Expr[String] = foo.getClass.getCanonicalName
 }
 
 class Bar {

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

@@ -1,5 +1,6 @@
 
 import scala.quoted._
+import scala.quoted.autolift._
 
 object E {
 
@@ -14,7 +15,7 @@ trait E[T] {
 }
 
 case class I(n: Int) extends E[Int] {
-  def lift: Expr[Int] = n.toExpr
+  def lift: Expr[Int] = n
 }
 
 case class Plus[T](x: E[T], y: E[T])(implicit op: Plus2[T]) extends E[T] {

tests/neg/inline-option/Macro_1.scala

@@ -1,9 +1,10 @@
 
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Macro {
   def impl(opt: Option[Int]): Expr[Int] = opt match {
-    case Some(i) => i.toExpr
+    case Some(i) => i
     case None => '{-1}
   }
 }

tests/neg/inline-tuples-1/Macro_1.scala

@@ -1,27 +1,28 @@
 
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Macros {
-  def tup1(tup: Tuple1[Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup2(tup: Tuple2[Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup3(tup: Tuple3[Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup4(tup: Tuple4[Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup5(tup: Tuple5[Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup6(tup: Tuple6[Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup7(tup: Tuple7[Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup8(tup: Tuple8[Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup9(tup: Tuple9[Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup10(tup: Tuple10[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup11(tup: Tuple11[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup12(tup: Tuple12[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup13(tup: Tuple13[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup14(tup: Tuple14[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup15(tup: Tuple15[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup16(tup: Tuple16[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup17(tup: Tuple17[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup18(tup: Tuple18[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup19(tup: Tuple19[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup20(tup: Tuple20[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup21(tup: Tuple21[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
-  def tup22(tup: Tuple22[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum.toExpr
+  def tup1(tup: Tuple1[Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup2(tup: Tuple2[Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup3(tup: Tuple3[Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup4(tup: Tuple4[Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup5(tup: Tuple5[Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup6(tup: Tuple6[Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup7(tup: Tuple7[Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup8(tup: Tuple8[Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup9(tup: Tuple9[Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup10(tup: Tuple10[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup11(tup: Tuple11[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup12(tup: Tuple12[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup13(tup: Tuple13[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup14(tup: Tuple14[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup15(tup: Tuple15[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup16(tup: Tuple16[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup17(tup: Tuple17[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup18(tup: Tuple18[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup19(tup: Tuple19[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup20(tup: Tuple20[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup21(tup: Tuple21[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
+  def tup22(tup: Tuple22[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int]): Expr[Int] = tup.productIterator.map(_.asInstanceOf[Int]).sum
 }

tests/neg/quote-interpolator-core-old.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 // This test checks the correct interpretation of the inlined value class
 
@@ -17,7 +18,7 @@ object FInterpolation {
   }
 
   def fInterpolation(sc: StringContext, args: Seq[Expr[Any]]): Expr[String] = {
-    val str: Expr[String] = sc.parts.mkString("").toExpr
+    val str: Expr[String] = sc.parts.mkString("")
     val args1: Expr[Seq[Any]] = liftSeq(args)
     '{ $str.format($args1: _*) }
   }

tests/neg/quote-macro-splice.scala

@@ -1,15 +1,16 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Test {
 
   inline def foo1: Int = { // error
     println()
-    ${ impl(1.toExpr) }
+    ${ impl(1) }
   }
 
   inline def foo2: Int = { // error
-    ${ impl(1.toExpr) }
-    ${ impl(2.toExpr) }
+    ${ impl(1) }
+    ${ impl(2) }
   }
 
   inline def foo3: Int = { // error

tests/neg/splice-in-top-level-splice-1.scala

@@ -1,7 +1,8 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Foo {
   inline def foo(): Int = ${bar(${x})} // error
   def x: Expr[Int] = '{1}
-  def bar(i: Int): Expr[Int] = i.toExpr
+  def bar(i: Int): Expr[Int] = i
 }

tests/pending/run/tasty-comments/quoted_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.tasty._
 
@@ -12,7 +13,7 @@ object Macros {
 
     val tree = x.unseal
     tree.symbol.comment.map(_.raw) match {
-      case Some(str) => '{ println(${str.toExpr}) }
+      case Some(str) => '{ println(${str}) }
       case None => '{ println() }
     }
   }

tests/pos-with-compiler/quote-0.scala

@@ -1,16 +1,19 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.quoted.Toolbox.Default._
 
 object Macros {
 
+
   inline def assert(expr: => Boolean): Unit =
     ${ assertImpl('expr) }
 
   def assertImpl(expr: Expr[Boolean]) =
     '{ if !($expr) then throw new AssertionError(s"failed assertion: ${${showExpr(expr)}}") }
 
-  def showExpr[T](expr: Expr[T]): Expr[String] = expr.toString.toExpr
+
+  def showExpr[T](expr: Expr[T]): Expr[String] = expr.toString
 
   inline def power(inline n: Int, x: Double) = ${ powerCode(n, 'x) }
 

tests/pos/quote-nested-object/Macro_1.scala

@@ -1,5 +1,6 @@
 
 import scala.quoted._
+import scala.quoted.autolift._
 
 object Macro {
 
@@ -10,15 +11,15 @@ object Macro {
 
     def plus(n: Int, m: Expr[Int]): Expr[Int] =
       if (n == 0) m
-      else '{ ${n.toExpr} + $m }
+      else '{ ${n} + $m }
 
     object Implementation2 {
 
       inline def plus(inline n: Int, m: Int): Int = ${ plus(n, 'm) }
 
       def plus(n: Int, m: Expr[Int]): Expr[Int] =
         if (n == 0) m
-        else '{ ${n.toExpr} + $m }
+        else '{ ${n} + $m }
     }
   }
 

tests/run-custom-args/Yretain-trees/tasty-definitions-2/Macro_1.scala

@@ -1,5 +1,6 @@
 import scala.quoted._
 import scala.tasty._
+import scala.quoted.autolift._
 
 object Foo {
 
@@ -9,9 +10,9 @@ object Foo {
   def inspectBodyImpl(x: Expr[Int])(implicit reflect: Reflection): Expr[String] = {
     import reflect._
     def definitionString(tree: Tree): Expr[String] = tree.symbol match {
-      case IsDefDefSymbol(sym) => sym.tree.show.toExpr
-      case IsValDefSymbol(sym) => sym.tree.show.toExpr
-      case IsBindSymbol(sym) => sym.tree.show.toExpr
+      case IsDefDefSymbol(sym) => sym.tree.show
+      case IsValDefSymbol(sym) => sym.tree.show
+      case IsBindSymbol(sym) => sym.tree.show
     }
     x.unseal match {
       case Term.Inlined(None, Nil, arg) => definitionString(arg)

tests/run-custom-args/Yretain-trees/tasty-definitions-3/Macro_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 import scala.tasty._
 
 object Foo {
@@ -9,9 +10,9 @@ object Foo {
   def inspectBodyImpl(x: Expr[Int])(implicit reflect: Reflection): Expr[String] = {
     import reflect._
     def definitionString(tree: Tree): Expr[String] = tree.symbol match {
-      case IsDefDefSymbol(sym) => sym.tree.show.toExpr
-      case IsValDefSymbol(sym) => sym.tree.show.toExpr
-      case IsBindSymbol(sym) => sym.tree.show.toExpr
+      case IsDefDefSymbol(sym) => sym.tree.show
+      case IsValDefSymbol(sym) => sym.tree.show
+      case IsBindSymbol(sym) => sym.tree.show
     }
     x.unseal match {
       case Term.Inlined(None, Nil, arg) => definitionString(arg)

tests/run-custom-args/Yretain-trees/tasty-extractors-owners/quoted_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.tasty._
 
@@ -42,7 +43,7 @@ object Macros {
 
     val tree = x.unseal
     output.traverseTree(tree)
-    '{print(${buff.result().toExpr})}
+    '{print(${buff.result()})}
   }
 
 }

tests/run-with-compiler-custom-args/staged-streams_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 /**
   * Port of the strymonas library as described in O. Kiselyov et al., Stream fusion, to completeness (POPL 2017)
@@ -598,7 +599,7 @@ object Test {
 
         def init(k: St => Expr[Unit]): Expr[Unit] = {
           Var('{($arr).length}) { n =>
-            Var(0.toExpr){ i =>
+            Var(0){ i =>
               k((i, n, arr))
             }
           }

tests/run-with-compiler/quote-impure-by-name/quoted_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.quoted.Toolbox.Default._
 
@@ -13,6 +14,6 @@ object Index {
 
   def succImpl[K, H, T](prev: Expr[Index[K, T]])(implicit k: Type[K], h: Type[H], t: Type[T]): Expr[Index[K, (H, T)]] = {
     val value = s"1 + {${prev.show}}"
-    '{new Index(${value.toExpr})}
+    '{new Index(${value})}
   }
 }

tests/run-with-compiler/quote-inline-function/quoted_1.scala

@@ -1,4 +1,5 @@
 import scala.quoted._
+import scala.quoted.autolift._
 
 import scala.quoted.Toolbox.Default._
 
@@ -20,6 +21,6 @@ object Macros {
         i += 1
       } while (i < j)
     }
-    res.show.toExpr
+    res.show
   }
 }