Add Reflection.Symbol.newVal

Part of #8114.

Author: nicolasstucki

compiler/src/dotty/tools/dotc/tastyreflect/ReflectionCompilerInterface.scala

@@ -67,7 +67,7 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   def Context_requiredMethod(self: Context)(path: String): Symbol = self.requiredMethod(path)
   def Context_isJavaCompilationUnit(self: Context): Boolean = self.compilationUnit.isInstanceOf[fromtasty.JavaCompilationUnit]
   def Context_isScala2CompilationUnit(self: Context): Boolean = self.compilationUnit.isInstanceOf[fromtasty.Scala2CompilationUnit]
-  def Context_compilationUnitClassname(self: Context): String = 
+  def Context_compilationUnitClassname(self: Context): String =
     self.compilationUnit match {
       case cu: fromtasty.JavaCompilationUnit => cu.className
       case cu: fromtasty.Scala2CompilationUnit => cu.className
@@ -1758,10 +1758,11 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   def Symbol_of(fullName: String)(using ctx: Context): Symbol =
     ctx.requiredClass(fullName)
 
-  def Symbol_newMethod(parent: Symbol, name: String, flags: Flags, tpe: Type, privateWithin: Symbol)(using ctx: Context): Symbol = {
-    val computedFlags = flags | Flags.Method
-    ctx.newSymbol(parent, name.toTermName, computedFlags, tpe, privateWithin)
-  }
+  def Symbol_newMethod(parent: Symbol, name: String, flags: Flags, tpe: Type, privateWithin: Symbol)(using ctx: Context): Symbol =
+    ctx.newSymbol(parent, name.toTermName, flags | Flags.Method, tpe, privateWithin)
+
+  def Symbol_newVal(parent: Symbol, name: String, flags: Flags, tpe: Type, privateWithin: Symbol)(using ctx: Context): Symbol =
+    ctx.newSymbol(parent, name.toTermName, flags, tpe, privateWithin)
 
   def Symbol_isTypeParam(self: Symbol)(using ctx: Context): Boolean =
     self.isTypeParam

library/src/scala/tasty/Reflection.scala

@@ -2109,6 +2109,20 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
     def newMethod(parent: Symbol, name: String, tpe: Type, flags: Flags, privateWithin: Symbol)(using ctx: Context): Symbol =
       internal.Symbol_newMethod(parent, name, flags, tpe, privateWithin)
 
+    /** Generates a new val/var/lazy val symbol with the given parent, name and type.
+     *
+     *  This symbol starts without an accompanying definition.
+     *  It is the meta-programmer's responsibility to provide exactly one corresponding definition by passing
+     *  this symbol to the ValDef constructor.
+     *
+     *  @param flags extra flags to with which the symbol should be constructed
+     *  @param privateWithin the symbol within which this new method symbol should be private. May be noSymbol.
+     *  @note As a macro can only splice code into the point at which it is expanded, all generated symbols must be
+     *        direct or indirect children of the reflection context's owner.
+     */
+    def newVal(parent: Symbol, name: String, tpe: Type, flags: Flags, privateWithin: Symbol)(using ctx: Context): Symbol =
+      internal.Symbol_newVal(parent, name, flags, tpe, privateWithin)
+
     /** Definition not available */
     def noSymbol(using ctx: Context): Symbol =
       internal.Symbol_noSymbol
@@ -2772,19 +2786,8 @@ class Reflection(private[scala] val internal: CompilerInterface) { self =>
 
   /** Bind the `rhs` to a `val` and use it in `body` */
   def let(rhs: Term)(body: Ident => Term)(using ctx: Context): Term = {
-    import scala.quoted.QuoteContext
-    given QuoteContext = new QuoteContext(this)
-    val expr = (rhs.seal: @unchecked) match {
-      case '{ $rhsExpr: $t } =>
-        '{
-          val x = $rhsExpr
-          ${
-            val id = ('x).unseal.asInstanceOf[Ident]
-            body(id).seal
-          }
-        }
-    }
-    expr.unseal
+    val sym = Symbol.newVal(ctx.owner, "x", rhs.tpe.widen, Flags.EmptyFlags, Symbol.noSymbol)
+    Block(List(ValDef(sym, Some(rhs))), body(Ref(sym).asInstanceOf[Ident]))
   }
 
   /** Bind the given `terms` to names and use them in the `body` */

library/src/scala/tasty/reflect/CompilerInterface.scala

@@ -1309,6 +1309,8 @@ trait CompilerInterface {
 
   def Symbol_newMethod(parent: Symbol, name: String, flags: Flags, tpe: Type, privateWithin: Symbol)(using ctx: Context): Symbol
 
+  def Symbol_newVal(parent: Symbol, name: String, flags: Flags, tpe: Type, privateWithin: Symbol)(using ctx: Context): Symbol
+
   def Symbol_isTypeParam(self: Symbol)(using ctx: Context): Boolean
 
   def Symbol_isPackageDef(symbol: Symbol)(using ctx: Context): Boolean