Add reflect newMethodOverride and newValOverride

Closes #15035

Author: nicolasstucki

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -2485,8 +2485,20 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
         newMethod(owner, name, tpe, Flags.EmptyFlags, noSymbol)
       def newMethod(owner: Symbol, name: String, tpe: TypeRepr, flags: Flags, privateWithin: Symbol): Symbol =
         dotc.core.Symbols.newSymbol(owner, name.toTermName, flags | dotc.core.Flags.Method, tpe, privateWithin)
+
+      def newMethodOverride(owner: Symbol, overridden: Symbol): Symbol =
+        assert(isMethod(overridden), "not a method symbol: " + overridden) // TODO check that is is a member of a class
+        val flags = overridden.flags &~ dotc.core.Flags.Deferred | dotc.core.Flags.Override
+        dotc.core.Symbols.newSymbol(owner, overridden.name, flags, overridden.info, dotc.core.Symbols.NoSymbol)
+
       def newVal(owner: Symbol, name: String, tpe: TypeRepr, flags: Flags, privateWithin: Symbol): Symbol =
         dotc.core.Symbols.newSymbol(owner, name.toTermName, flags, tpe, privateWithin)
+
+      def newValOverride(owner: Symbol, overridden: Symbol): Symbol =
+        assert(isField(overridden) || isMethod(overridden), "not a method or field symbol: " + overridden) // TODO check that is is a member of a class
+        val flags = overridden.flags &~ dotc.core.Flags.Deferred &~ dotc.core.Flags.Method | dotc.core.Flags.Override
+        dotc.core.Symbols.newSymbol(owner, overridden.name, flags, overridden.info, dotc.core.Symbols.NoSymbol)
+
       def newBind(owner: Symbol, name: String, flags: Flags, tpe: TypeRepr): Symbol =
         dotc.core.Symbols.newSymbol(owner, name.toTermName, flags | Case, tpe)
       def noSymbol: Symbol = dotc.core.Symbols.NoSymbol
@@ -2661,13 +2673,14 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       private def appliedTypeRef(sym: Symbol): TypeRepr =
         sym.typeRef.appliedTo(sym.typeParams.map(_.typeRef))
 
-      private def isMethod(sym: Symbol): Boolean =
-        sym.isTerm && sym.is(dotc.core.Flags.Method) && !sym.isConstructor
-
-      private def isField(sym: Symbol): Boolean =
-        sym.isTerm && !sym.is(dotc.core.Flags.Method)
     end SymbolMethods
 
+    private def isMethod(sym: Symbol): Boolean =
+      sym.isTerm && sym.is(dotc.core.Flags.Method) && !sym.isConstructor
+
+    private def isField(sym: Symbol): Boolean =
+      sym.isTerm && !sym.is(dotc.core.Flags.Method)
+
     type Signature = dotc.core.Signature
 
     object Signature extends SignatureModule:

library/src/scala/quoted/Quotes.scala

@@ -3669,7 +3669,16 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       */
       def newMethod(parent: Symbol, name: String, tpe: TypeRepr, flags: Flags, privateWithin: Symbol): Symbol
 
-      /** Generates a new val/var/lazy val symbol with the given parent, name and type.
+      /** Generates a new method symbol that overrides another definition.
+       *  The signature will be the same as the overridden symbol.
+       *
+       *  @param parent The owner of the method
+       *  @param overridden The symbol being overridden
+       */
+      @experimental
+      def newMethodOverride(parent: Symbol, overridden: Symbol): Symbol
+
+      /** 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
@@ -3687,6 +3696,15 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       */
       def newVal(parent: Symbol, name: String, tpe: TypeRepr, flags: Flags, privateWithin: Symbol): Symbol
 
+      /** Generates a new `val` or `lazy val` symbol that overrides another definition.
+       *  The signature will be the same as the overridden symbol.
+       *
+       *  @param parent The owner of the method
+       *  @param overridden The symbol being overridden
+       */
+      @experimental
+      def newValOverride(parent: Symbol, overridden: Symbol): Symbol
+
       /** Generates a pattern bind symbol with the given parent, name and type.
       *
       *  This symbol starts without an accompanying definition.

tests/run-custom-args/tasty-inspector/stdlibExperimentalDefinitions.scala

@@ -66,6 +66,9 @@ val experimentalDefinitionInLibrary = Set(
   // Can be stabilized in 3.3.0 (unsure) or later
   "scala.quoted.Quotes.reflectModule.CompilationInfoModule.XmacroSettings",
   "scala.quoted.Quotes.reflectModule.FlagsModule.JavaAnnotation",
+  "scala.quoted.Quotes.reflectModule.SymbolModule.newValOverride",
+  "scala.quoted.Quotes.reflectModule.SymbolModule.newMethodgitOverride",
+
   // Cant be stabilized yet.
   // Need newClass variant that can add constructor parameters.
   // Need experimental annotation macros to check that design works.

tests/run-macros/i15035.check

@@ -0,0 +1,10 @@
+1
+1
+1
+1
+1
+3
+3
+3
+3
+3

tests/run-macros/i15035/Macro_1.scala

@@ -0,0 +1,24 @@
+import scala.quoted.*
+
+inline def make[T](inline value: Int): T = ${impl[T]('value)}
+
+def impl[T: Type](value: Expr[Int])(using Quotes): Expr[T] = {
+  import quotes.reflect.*
+
+  val className = "Foo"
+  val parents = List(TypeTree.of[Object], TypeTree.of[T])
+
+  val parentMethods = TypeRepr.of[T].typeSymbol.declaredMethods
+
+  def decls(cls: Symbol): List[Symbol] =
+    TypeRepr.of[T].typeSymbol.declaredFields.map(field => Symbol.newValOverride(cls, field)) ++
+    TypeRepr.of[T].typeSymbol.declaredMethods.map(method => Symbol.newMethodOverride(cls, method))
+
+  val cls = Symbol.newClass(Symbol.spliceOwner, className, parents = parents.map(_.tpe), decls, selfType = None)
+  val body =
+    cls.declaredFields.map { method => ValDef(method, Some(value.asTerm)) } ++
+    cls.declaredMethods.map { method => DefDef(method, argss => Some(value.asTerm)) }
+  val clsDef = ClassDef(cls, parents, body = body)
+  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[T])
+  Block(List(clsDef), newCls).asExprOf[T]
+}

tests/run-macros/i15035/Test_2.scala

@@ -0,0 +1,33 @@
+trait A {
+  val v1: Int
+  lazy val v2: Int
+  def f1(): Int
+  def f2(foo: String): Int
+  def f3: Int
+}
+
+trait B {
+  val v1: Int = 2
+  lazy val v2: Int = 2
+  def f1(): Int = 2
+  def f2(foo: String): Int = 2
+  def f3: Int = 2
+}
+
+
+@main
+def Test = {
+  val a: A = make[A](1)
+  println(a.v1)
+  println(a.v2)
+  println(a.f1())
+  println(a.f2("test"))
+  println(a.f3)
+
+  val b: B = make[B](3)
+  println(b.v1)
+  println(b.v2)
+  println(b.f1())
+  println(b.f2("test"))
+  println(b.f3)
+}