Add reflect ClassDef.apply and Symbol.newClass

compiler/src/dotty/tools/dotc/core/Symbols.scala

@@ -577,7 +577,7 @@ object Symbols {
       def complete(denot: SymDenotation)(using Context): Unit = {
         val cls = denot.asClass.classSymbol
         val decls = newScope
-        denot.info = ClassInfo(owner.thisType, cls, parentTypes.map(_.dealias), decls)
+        denot.info = ClassInfo(owner.thisType, cls, parentTypes.map(_.dealias), decls, selfInfo)
       }
     }
     newClassSymbol(owner, name, flags, completer, privateWithin, coord, assocFile)

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

@@ -227,6 +227,11 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
     end ClassDefTypeTest
 
     object ClassDef extends ClassDefModule:
+      def apply(cls: Symbol, parents: List[Tree], body: List[Statement]): ClassDef =
+        val untpdCtr = untpd.DefDef(nme.CONSTRUCTOR, Nil, tpd.TypeTree(dotc.core.Symbols.defn.UnitClass.typeRef), tpd.EmptyTree)
+        val ctr = ctx.typeAssigner.assignType(untpdCtr, cls.primaryConstructor)
+        tpd.ClassDefWithParents(cls.asClass, ctr, parents, body)
+
       def copy(original: Tree)(name: String, constr: DefDef, parents: List[Tree], selfOpt: Option[ValDef], body: List[Statement]): ClassDef = {
         val dotc.ast.Trees.TypeDef(_, originalImpl: tpd.Template) = original
         tpd.cpy.TypeDef(original)(name.toTypeName, tpd.cpy.Template(originalImpl)(constr, parents, derived = Nil, selfOpt.getOrElse(tpd.EmptyValDef), body))
@@ -259,6 +264,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
     object DefDef extends DefDefModule:
       def apply(symbol: Symbol, rhsFn: List[List[Tree]] => Option[Term]): DefDef =
+        assert(symbol.isTerm, s"expected a term symbol but received $symbol")
         withDefaultPos(tpd.DefDef(symbol.asTerm, prefss =>
           xCheckMacroedOwners(xCheckMacroValidExpr(rhsFn(prefss)), symbol).getOrElse(tpd.EmptyTree)
         ))
@@ -1803,7 +1809,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
         (x.prefix, x.name.toString)
     end TermRef
 
-    type TypeRef = dotc.core.Types.NamedType
+    type TypeRef = dotc.core.Types.TypeRef
 
     object TypeRefTypeTest extends TypeTest[TypeRepr, TypeRef]:
       def unapply(x: TypeRepr): Option[TypeRef & x.type] = x match
@@ -2453,6 +2459,20 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       def requiredModule(path: String): Symbol = dotc.core.Symbols.requiredModule(path)
       def requiredMethod(path: String): Symbol = dotc.core.Symbols.requiredMethod(path)
       def classSymbol(fullName: String): Symbol = dotc.core.Symbols.requiredClass(fullName)
+
+      def newClass(owner: Symbol, name: String, parents: List[TypeRepr], decls: Symbol => List[Symbol], selfInfo: Option[TypeRepr]): Symbol =
+        assert(parents.nonEmpty && !parents.head.typeSymbol.is(dotc.core.Flags.Trait), "First parent must be a class")
+        val cls = dotc.core.Symbols.newNormalizedClassSymbol(
+          owner,
+          name.toTypeName,
+          dotc.core.Flags.EmptyFlags,
+          parents,
+          selfInfo.getOrElse(Types.NoType),
+          dotc.core.Symbols.NoSymbol)
+        cls.enter(dotc.core.Symbols.newConstructor(cls, dotc.core.Flags.Synthetic, Nil, Nil))
+        for sym <- decls(cls) do cls.enter(sym)
+        cls
+
       def newMethod(owner: Symbol, name: String, tpe: TypeRepr): Symbol =
         newMethod(owner, name, tpe, Flags.EmptyFlags, noSymbol)
       def newMethod(owner: Symbol, name: String, tpe: TypeRepr, flags: Flags, privateWithin: Symbol): Symbol =
@@ -2621,6 +2641,8 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
         def companionClass: Symbol = self.denot.companionClass
         def companionModule: Symbol = self.denot.companionModule
         def children: List[Symbol] = self.denot.children
+        def typeRef: TypeRef = self.denot.typeRef
+        def termRef: TermRef = self.denot.termRef
 
         def show(using printer: Printer[Symbol]): String = printer.show(self)
 

library/src/scala/quoted/Quotes.scala

@@ -464,6 +464,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
 
     /** Methods of the module object `val ClassDef` */
     trait ClassDefModule { this: ClassDef.type =>
+      @experimental def apply(cls: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): ClassDef
       def copy(original: Tree)(name: String, constr: DefDef, parents: List[Tree /* Term | TypeTree */], selfOpt: Option[ValDef], body: List[Statement]): ClassDef
       def unapply(cdef: ClassDef): (String, DefDef, List[Tree /* Term | TypeTree */], Option[ValDef], List[Statement])
     }
@@ -3533,19 +3534,73 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       /** The class Symbol of a global class definition */
       def classSymbol(fullName: String): Symbol
 
+      /** Generates a new class symbol for a class with a parameterless constructor.
+       *
+       *  Example usage:
+       *  ```scala
+       *  val name: String = ...
+       *  val parents = List(TypeTree.of[Object], TypeTree.of[Foo])
+       *  def decls(cls: Symbol): List[Symbol] =
+       *    List(Symbol.newMethod(cls, "foo", MethodType(Nil)(_ => Nil, _ => TypeRepr.of[Unit])))
+       *
+       *  val cls = Symbol.newClass(Symbol.spliceOwner, name, parents = parents.map(_.tpe), decls, selfInfo = None)
+       *  val fooSym = cls.declaredMethod("foo").head
+       *
+       *  val fooDef = DefDef(fooSym, argss => Some('{println(s"Calling foo")}.asTerm))
+       *  val clsDef = ClassDef(cls, parents, body = List(fooDef))
+       *  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[Foo])
+       *
+       *  Block(List(clsDef), newCls).asExprOf[Foo]
+       *  ```
+       *  constructs the equivalent to
+       *   ```scala
+       *  '{
+       *    class `name`() extends Object with Foo {
+       *      def foo(): Unit = println("Calling foo")
+       *    }
+       *    new `name`(): Foo
+       *  }
+       *  ```
+       *
+       *  @param parent The owner of the class
+       *  @param name The name of the class
+       *  @param parents The parent classes of the class
+       *  @param decls The member declarations of the class provided the symbol of this class
+       *  @param self The self type of the class if it has one
+       *
+       *  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 ClassDef constructor.
+       *
+       *  @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.
+       */
+      @experimental def newClass(parent: Symbol, name: String, parents: List[TypeRepr], decls: Symbol => List[Symbol], selfInfo: Option[TypeRepr]): Symbol
+
       /** Generates a new method 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 DefDef constructor.
-      *
-      *  @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.
-      */
+       *
+       *  To define a member method of a class, use the `newMethod` within the `decls` function of `newClass`.
+       *
+       *  @param parent The owner of the method
+       *  @param name The name of the method
+       *  @param tpe The type of the method (MethodType, PolyType, ByNameType)
+       *
+       *  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 DefDef constructor.
+       *
+       *  @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 newMethod(parent: Symbol, name: String, tpe: TypeRepr): Symbol
 
       /** Works as the other newMethod, but with additional parameters.
       *
+      *  To define a member method of a class, use the `newMethod` within the `decls` function of `newClass`.
+      *
+      *  @param parent The owner of the method
+      *  @param name The name of the method
+      *  @param tpe The type of the method (MethodType, PolyType, ByNameType)
       *  @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.
       */
@@ -3559,6 +3614,9 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       *
       *  Note: Also see reflect.let
       *
+      *  @param parent The owner of the /var/lazy val
+      *  @param name The name of the val/var/lazy val
+      *  @param tpe The type of the val/var/lazy val
       *  @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
@@ -3572,7 +3630,10 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       *  It is the meta-programmer's responsibility to provide exactly one corresponding definition by passing
       *  this symbol to the BindDef constructor.
       *
+      *  @param parent The owner of the binding
+      *  @param name The name of the binding
       *  @param flags extra flags to with which the symbol should be constructed
+      *  @param tpe The type of the binding
       *  @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.
       */
@@ -3807,6 +3868,14 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
 
         /** Case class or case object children of a sealed trait or cases of an `enum`. */
         def children: List[Symbol]
+
+        /** Type reference to the symbol */
+        @experimental
+        def typeRef: TypeRef
+
+        /** Term reference to the symbol */
+        @experimental
+        def termRef: TermRef
       end extension
     }
 

project/MiMaFilters.scala

@@ -19,6 +19,14 @@ object MiMaFilters {
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#CompilationInfoModule.XmacroSettings"),
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.deriving.Mirror.fromProductTyped"),
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.deriving.Mirror.fromTuple"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ClassDefModule.apply"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#ClassDefModule.apply"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolModule.newClass"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolModule.newClass"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.typeRef"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.typeRef"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.termRef"),
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.quoted.Quotes#reflectModule#SymbolMethods.termRef"),
 
     // Private to the compiler - needed for forward binary compatibility
     ProblemFilters.exclude[MissingClassProblem]("scala.annotation.since")

tests/neg-macros/newClassExtendsNoParents.check

@@ -0,0 +1,19 @@
+
+-- Error: tests/neg-macros/newClassExtendsNoParents/Test_2.scala:1:25 --------------------------------------------------
+1 |def test: Any = makeClass("foo") // error
+  |                ^^^^^^^^^^^^^^^^
+  |                Exception occurred while executing macro expansion.
+  |                java.lang.AssertionError: assertion failed: First parent must be a class
+  |                	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
+  |                	at scala.quoted.runtime.impl.QuotesImpl$reflect$Symbol$.newClass(QuotesImpl.scala:2464)
+  |                	at scala.quoted.runtime.impl.QuotesImpl$reflect$Symbol$.newClass(QuotesImpl.scala:2463)
+  |                	at Macro_1$package$.makeClassExpr(Macro_1.scala:11)
+  |                	at Macro_1$package$.inline$makeClassExpr(Macro_1.scala:4)
+  |
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |This location contains code that was inlined from Macro_1.scala:3
+3 |inline def makeClass(inline name: String): Any = ${ makeClassExpr('name) }
+  |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+   ---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/newClassExtendsNoParents/Macro_1.scala

@@ -0,0 +1,23 @@
+import scala.quoted.*
+
+inline def makeClass(inline name: String): Any = ${ makeClassExpr('name) }
+private def makeClassExpr(nameExpr: Expr[String])(using Quotes): Expr[Any] = {
+  import quotes.reflect.*
+
+  val name = nameExpr.valueOrAbort
+  val parents = List.empty[Tree] // BUG: first parent is not a class
+  def decls(cls: Symbol): List[Symbol] = Nil
+
+  val cls = Symbol.newClass(Symbol.spliceOwner, name, parents = Nil, decls, selfInfo = None)
+  val clsDef = ClassDef(cls, parents, body = List())
+  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[Object])
+
+  Block(List(clsDef), newCls).asExpr
+
+  // '{
+  //   class `name`() {
+  //     def foo(): Unit = println("Calling `name`.foo")
+  //   }
+  //   new `name`()
+  // }
+}

tests/neg-macros/newClassExtendsNoParents/Test_2.scala

@@ -0,0 +1 @@
+def test: Any = makeClass("foo") // error

tests/neg-macros/newClassExtendsOnlyTrait.check

@@ -0,0 +1,19 @@
+
+-- Error: tests/neg-macros/newClassExtendsOnlyTrait/Test_2.scala:1:25 --------------------------------------------------
+1 |def test: Foo = makeClass("foo") // error
+  |                ^^^^^^^^^^^^^^^^
+  |                Exception occurred while executing macro expansion.
+  |                java.lang.AssertionError: assertion failed: First parent must be a class
+  |                	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
+  |                	at scala.quoted.runtime.impl.QuotesImpl$reflect$Symbol$.newClass(QuotesImpl.scala:2464)
+  |                	at scala.quoted.runtime.impl.QuotesImpl$reflect$Symbol$.newClass(QuotesImpl.scala:2463)
+  |                	at Macro_1$package$.makeClassExpr(Macro_1.scala:12)
+  |                	at Macro_1$package$.inline$makeClassExpr(Macro_1.scala:4)
+  |
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |This location contains code that was inlined from Macro_1.scala:3
+3 |inline def makeClass(inline name: String): Foo = ${ makeClassExpr('name) }
+  |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+   ---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/newClassExtendsOnlyTrait/Macro_1.scala

@@ -0,0 +1,31 @@
+import scala.quoted.*
+
+inline def makeClass(inline name: String): Foo = ${ makeClassExpr('name) }
+private def makeClassExpr(nameExpr: Expr[String])(using Quotes): Expr[Foo] = {
+  import quotes.reflect.*
+
+  val name = nameExpr.valueOrAbort
+  val parents = List(TypeTree.of[Foo]) // BUG: first parent is not a class
+  def decls(cls: Symbol): List[Symbol] =
+    List(Symbol.newMethod(cls, "foo", MethodType(Nil)(_ => Nil, _ => TypeRepr.of[Unit])))
+
+  val cls = Symbol.newClass(Symbol.spliceOwner, name, parents = parents.map(_.tpe), decls, selfInfo = None)
+  val fooSym = cls.declaredMethod("foo").head
+
+  val fooDef = DefDef(fooSym, argss => Some('{println(s"Calling ${$nameExpr}.foo")}.asTerm))
+  val clsDef = ClassDef(cls, parents, body = List(fooDef))
+  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[Foo])
+
+  Block(List(clsDef), newCls).asExprOf[Foo]
+
+  // '{
+  //   class `name`() extends Foo {
+  //     def foo(): Unit = println("Calling `name`.foo")
+  //   }
+  //   new `name`()
+  // }
+}
+
+trait Foo {
+  def foo(): Unit
+}

tests/neg-macros/newClassExtendsOnlyTrait/Test_2.scala

@@ -0,0 +1 @@
+def test: Foo = makeClass("foo") // error

tests/run-macros/newClass.check

@@ -0,0 +1,4 @@
+Constructing foo
+class Test_2$package$foo$1
+Constructing bar
+class Test_2$package$bar$1

tests/run-macros/newClass/Macro_1.scala

@@ -0,0 +1,21 @@
+import scala.quoted.*
+
+inline def makeClass(inline name: String): Any = ${ makeClassExpr('name) }
+private def makeClassExpr(nameExpr: Expr[String])(using Quotes): Expr[Any] = {
+  import quotes.reflect.*
+
+  val name = nameExpr.valueOrAbort
+  val parents = List(TypeTree.of[Object])
+  def decls(cls: Symbol): List[Symbol] = Nil
+
+  val cls = Symbol.newClass(Symbol.spliceOwner, name, parents = parents.map(_.tpe), decls, selfInfo = None)
+
+  val clsDef = ClassDef(cls, parents, body = List('{println(s"Constructing ${$nameExpr}")}.asTerm))
+  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[Object])
+
+  Block(List(clsDef), newCls).asExpr
+  // '{
+  //   class `name`() { println("Constructing `name`") }
+  //   new `name`()
+  // }
+}

tests/run-macros/newClass/Test_2.scala

@@ -0,0 +1,6 @@
+@main def Test: Unit = {
+  val foo = makeClass("foo")
+  println(foo.getClass)
+  val bar = makeClass("bar")
+  println(bar.getClass)
+}

tests/run-macros/newClassExtends.check

@@ -0,0 +1,4 @@
+Calling foo.foo
+class Test_2$package$foo$1
+Calling bar.foo
+class Test_2$package$bar$1

tests/run-macros/newClassExtends/Macro_1.scala

@@ -0,0 +1,31 @@
+import scala.quoted.*
+
+inline def makeClass(inline name: String): Foo = ${ makeClassExpr('name) }
+private def makeClassExpr(nameExpr: Expr[String])(using Quotes): Expr[Foo] = {
+  import quotes.reflect.*
+
+  val name = nameExpr.valueOrAbort
+  val parents = List(TypeTree.of[Object], TypeTree.of[Foo])
+  def decls(cls: Symbol): List[Symbol] =
+    List(Symbol.newMethod(cls, "foo", MethodType(Nil)(_ => Nil, _ => TypeRepr.of[Unit])))
+
+  val cls = Symbol.newClass(Symbol.spliceOwner, name, parents = parents.map(_.tpe), decls, selfInfo = None)
+  val fooSym = cls.declaredMethod("foo").head
+
+  val fooDef = DefDef(fooSym, argss => Some('{println(s"Calling ${$nameExpr}.foo")}.asTerm))
+  val clsDef = ClassDef(cls, parents, body = List(fooDef))
+  val newCls = Typed(Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil), TypeTree.of[Foo])
+
+  Block(List(clsDef), newCls).asExprOf[Foo]
+
+  // '{
+  //   class `name`() extends Object, Foo {
+  //     def foo(): Unit = println("Calling `name`.foo")
+  //   }
+  //   new `name`()
+  // }
+}
+
+trait Foo {
+  def foo(): Unit
+}

tests/run-macros/newClassExtends/Test_2.scala

@@ -0,0 +1,8 @@
+@main def Test: Unit = {
+  val foo: Foo = makeClass("foo")
+  foo.foo()
+  println(foo.getClass)
+  val bar: Foo = makeClass("bar")
+  bar.foo()
+  println(bar.getClass)
+}

tests/run-macros/newClassSelf.check

@@ -0,0 +1,8 @@
+Calling Bar.bar
+Calling Foo.foo
+Calling Bar.bar
+class Test_2$package$A$1
+Calling Bar.bar
+Calling Foo.foo
+Calling Bar.bar
+class Test_2$package$B$1