Fix pretty printer to handle using and erased modifier (#17952)

The existing pretty printer doesn't handle using/erased keyword, making
it a bit misleading when investigating code generated by macros.

This PR add support for those two modifiers

Author: nicolasstucki

compiler/src/scala/quoted/runtime/impl/printers/SourceCode.scala

@@ -158,7 +158,7 @@ object SourceCode {
           for paramClause <- paramss do
             paramClause match
               case TermParamClause(params) =>
-                printArgsDefs(params)
+                printMethdArgsDefs(params)
               case TypeParamClause(params) =>
                 printTargsDefs(stats.collect { case targ: TypeDef => targ  }.filter(_.symbol.isTypeParam).zip(params))
         }
@@ -313,7 +313,7 @@ object SourceCode {
         this += highlightKeyword("def ") += highlightValDef(name1)
         for clause <-  paramss do
           clause match
-            case TermParamClause(params) => printArgsDefs(params)
+            case TermParamClause(params) => printMethdArgsDefs(params)
             case TypeParamClause(params) => printTargsDefs(params.zip(params))
         if (!isConstructor) {
           this += ": "
@@ -460,7 +460,7 @@ object SourceCode {
 
       case tree @ Lambda(params, body) =>  // must come before `Block`
         inParens {
-          printArgsDefs(params)
+          printLambdaArgsDefs(params)
           this += (if tree.tpe.isContextFunctionType then " ?=> " else  " => ")
           printTree(body)
         }
@@ -804,29 +804,37 @@ object SourceCode {
       }
     }
 
-    private def printArgsDefs(args: List[ValDef])(using elideThis: Option[Symbol]): Unit = {
+    private def printSeparatedParamDefs(list: List[ValDef])(using elideThis: Option[Symbol]): Unit = list match {
+      case Nil =>
+      case x :: Nil => printParamDef(x)
+      case x :: xs =>
+        printParamDef(x)
+        this += ", "
+        printSeparatedParamDefs(xs)
+    }
+
+    private def printMethdArgsDefs(args: List[ValDef])(using elideThis: Option[Symbol]): Unit = {
       val argFlags = args match {
         case Nil => Flags.EmptyFlags
         case arg :: _ => arg.symbol.flags
       }
-      if (argFlags.is(Flags.Erased | Flags.Given)) {
-        if (argFlags.is(Flags.Given)) this += " given"
-        if (argFlags.is(Flags.Erased)) this += " erased"
-        this += " "
-      }
       inParens {
         if (argFlags.is(Flags.Implicit) && !argFlags.is(Flags.Given)) this += "implicit "
+        if (argFlags.is(Flags.Given)) this += "using "
 
-        def printSeparated(list: List[ValDef]): Unit = list match {
-          case Nil =>
-          case x :: Nil => printParamDef(x)
-          case x :: xs =>
-            printParamDef(x)
-            this += ", "
-            printSeparated(xs)
-        }
+        printSeparatedParamDefs(args)
+      }
+    }
+
+    private def printLambdaArgsDefs(args: List[ValDef])(using elideThis: Option[Symbol]): Unit = {
+      val argFlags = args match {
+        case Nil => Flags.EmptyFlags
+        case arg :: _ => arg.symbol.flags
+      }
+      inParens {
+        if (argFlags.is(Flags.Implicit) && !argFlags.is(Flags.Given)) this += "implicit "
 
-        printSeparated(args)
+        printSeparatedParamDefs(args)
       }
     }
 
@@ -846,6 +854,9 @@ object SourceCode {
     private def printParamDef(arg: ValDef)(using elideThis: Option[Symbol]): Unit = {
       val name = splicedName(arg.symbol).getOrElse(arg.symbol.name)
       val sym = arg.symbol.owner
+
+      if (arg.symbol.flags.is(Flags.Erased)) this += "erased "
+
       if sym.isDefDef && sym.name == "<init>" then
         val ClassDef(_, _, _, _, body) = sym.owner.tree: @unchecked
         body.collectFirst {

tests/run-macros/term-show.check

@@ -0,0 +1,21 @@
+{
+  class C() {
+    def a: scala.Int = 0
+    private[this] def b: scala.Int = 0
+    private[this] def c: scala.Int = 0
+    private[C] def d: scala.Int = 0
+    protected def e: scala.Int = 0
+    protected[this] def f: scala.Int = 0
+    protected[C] def g: scala.Int = 0
+  }
+  ()
+}
+@scala.annotation.internal.SourceFile("tests/run-macros/term-show/Test_2.scala") trait A() extends java.lang.Object {
+  def imp(x: scala.Int)(implicit str: scala.Predef.String): scala.Int
+  def use(`x₂`: scala.Int)(using `str₂`: scala.Predef.String): scala.Int
+  def era(`x₃`: scala.Int)(erased `str₃`: scala.Predef.String): scala.Int
+  def f1(x1: scala.Int, erased x2: scala.Int): scala.Int
+  def f2(erased `x1₂`: scala.Int, erased `x2₂`: scala.Int): scala.Int
+  def f3(using `x1₃`: scala.Int, erased `x2₃`: scala.Int): scala.Int
+  def f4(using erased `x1₄`: scala.Int, erased `x2₄`: scala.Int): scala.Int
+}

tests/run-macros/term-show/Macro_1.scala

@@ -5,4 +5,11 @@ object TypeToolbox {
   private def showImpl(using Quotes)(v: Expr[Any]): Expr[String] =
     import quotes.reflect.*
     Expr(v.show)
+
+  inline def showTree(inline className: String): String = ${ showTreeImpl('className) }
+  private def showTreeImpl(className: Expr[String])(using Quotes) : Expr[String] =
+    import quotes.reflect.*
+    val name = className.valueOrAbort
+    val res = Symbol.requiredClass(name).tree.show
+    Expr(res)
 }

tests/run-macros/term-show/Test_2.scala

@@ -1,7 +1,19 @@
+import scala.language.experimental.erasedDefinitions
+
+trait A:
+  def imp(x: Int)(implicit str: String): Int
+  def use(x: Int)(using str: String): Int
+  def era(x: Int)(erased str: String): Int
+
+  def f1(x1: Int, erased x2: Int): Int
+  def f2(erased x1: Int, erased x2: Int): Int
+  def f3(using x1: Int, erased x2: Int): Int
+  def f4(using erased x1: Int, erased x2: Int): Int
+
 object Test {
   import TypeToolbox.*
   def main(args: Array[String]): Unit = {
-   assert(show {
+   println(show {
       class C {
         def a = 0
         private def b = 0
@@ -11,19 +23,8 @@ object Test {
         protected[this] def f = 0
         protected[C] def g = 0
       }
-    }
-    ==
-    """{
-      |  class C() {
-      |    def a: scala.Int = 0
-      |    private[this] def b: scala.Int = 0
-      |    private[this] def c: scala.Int = 0
-      |    private[C] def d: scala.Int = 0
-      |    protected def e: scala.Int = 0
-      |    protected[this] def f: scala.Int = 0
-      |    protected[C] def g: scala.Int = 0
-      |  }
-      |  ()
-      |}""".stripMargin)
+    })
+
+    println(showTree("A"))
   }
 }