Merge pull request #7536 from dotty-staging/split-eta-expansion-from-seal

Split eta-expansion from seal

Author: nicolasstucki

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

@@ -237,6 +237,18 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   def Term_underlyingArgument(self: Term)(given Context): Term = self.underlyingArgument
   def Term_underlying(self: Term)(given Context): Term = self.underlying
 
+  def Term_etaExpand(term: Term): Term = term.tpe.widen match {
+    case mtpe: Types.MethodType if !mtpe.isParamDependent =>
+      val closureResType = mtpe.resType match {
+        case t: Types.MethodType => t.toFunctionType()
+        case t => t
+      }
+      val closureTpe = Types.MethodType(mtpe.paramNames, mtpe.paramInfos, closureResType)
+      val closureMethod = ctx.newSymbol(ctx.owner, nme.ANON_FUN, Synthetic | Method, closureTpe)
+      tpd.Closure(closureMethod, tss => Term_etaExpand(new tpd.TreeOps(term).appliedToArgs(tss.head)))
+    case _ => term
+  }
+
   type Ref = tpd.RefTree
 
   def matchRef(tree: Tree)(given Context): Option[Ref] = tree match {
@@ -1591,19 +1603,9 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
     PickledQuotes.quotedTypeToTree(self)
 
   /** Convert `Term` to an `quoted.Expr[Any]`  */
-  def QuotedExpr_seal(self: Term)(given ctx: Context): scala.quoted.Expr[Any] = {
-    def etaExpand(term: Term): Term = term.tpe.widen match {
-      case mtpe: Types.MethodType if !mtpe.isParamDependent =>
-        val closureResType = mtpe.resType match {
-          case t: Types.MethodType => t.toFunctionType()
-          case t => t
-        }
-        val closureTpe = Types.MethodType(mtpe.paramNames, mtpe.paramInfos, closureResType)
-        val closureMethod = ctx.newSymbol(ctx.owner, nme.ANON_FUN, Synthetic | Method, closureTpe)
-        tpd.Closure(closureMethod, tss => etaExpand(new tpd.TreeOps(term).appliedToArgs(tss.head)))
-      case _ => term
-    }
-    new scala.internal.quoted.TastyTreeExpr(etaExpand(self), compilerId)
+  def QuotedExpr_seal(self: Term)(given ctx: Context): scala.quoted.Expr[Any] = self.tpe.widen match {
+    case _: Types.MethodType | _: Types.PolyType => throw new Exception("Cannot seal a partially applied Term. Try eta-expanding the term first.")
+    case _ => new scala.internal.quoted.TastyTreeExpr(self, compilerId)
   }
 
   /** Checked cast to a `quoted.Expr[U]` */

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

@@ -283,6 +283,7 @@ trait CompilerInterface {
   def Term_tpe(self: Term)(given ctx: Context): Type
   def Term_underlyingArgument(self: Term)(given ctx: Context): Term
   def Term_underlying(self: Term)(given ctx: Context): Term
+  def Term_etaExpand(term: Term): Term
 
   /** Tree representing a reference to definition */
   type Ref <: Term

library/src/scala/tasty/reflect/TreeOps.scala

@@ -172,6 +172,7 @@ trait TreeOps extends Core {
     def tpe(given ctx: Context): Type = internal.Term_tpe(self)
     def underlyingArgument(given ctx: Context): Term = internal.Term_underlyingArgument(self)
     def underlying(given ctx: Context): Term = internal.Term_underlying(self)
+    def etaExpand(given ctx: Context): Term = internal.Term_etaExpand(self)
 
     /** A unary apply node with given argument: `tree(arg)` */
     def appliedTo(arg: Term)(given ctx: Context): Term =

tests/run-macros/tasty-seal-method/quoted_1.scala

@@ -14,10 +14,10 @@ object Asserts {
         fn.tpe.widen match {
           case IsMethodType(_) =>
             args.size match {
-              case 0 => Expr.betaReduce(fn.seal.cast[() => Int])()
-              case 1 => Expr.betaReduce(fn.seal.cast[Int => Int])('{0})
-              case 2 => Expr.betaReduce(fn.seal.cast[(Int, Int) => Int])('{0}, '{0})
-              case 3 => Expr.betaReduce(fn.seal.cast[(Int, Int, Int) => Int])('{0}, '{0}, '{0})
+              case 0 => Expr.betaReduce(fn.etaExpand.seal.cast[() => Int])()
+              case 1 => Expr.betaReduce(fn.etaExpand.seal.cast[Int => Int])('{0})
+              case 2 => Expr.betaReduce(fn.etaExpand.seal.cast[(Int, Int) => Int])('{0}, '{0})
+              case 3 => Expr.betaReduce(fn.etaExpand.seal.cast[(Int, Int, Int) => Int])('{0}, '{0}, '{0})
             }
         }
       case _ => x
@@ -35,10 +35,10 @@ object Asserts {
       case Apply(fn, args) =>
         val pre = rec(fn)
         args.size match {
-          case 0 => Expr.betaReduce(pre.seal.cast[() => Any])().unseal
-          case 1 => Expr.betaReduce(pre.seal.cast[Int => Any])('{0}).unseal
-          case 2 => Expr.betaReduce(pre.seal.cast[(Int, Int) => Any])('{0}, '{0}).unseal
-          case 3 => Expr.betaReduce(pre.seal.cast[(Int, Int, Int) => Any])('{0}, '{0}, '{0}).unseal
+          case 0 => Expr.betaReduce(pre.etaExpand.seal.cast[() => Any])().unseal
+          case 1 => Expr.betaReduce(pre.etaExpand.seal.cast[Int => Any])('{0}).unseal
+          case 2 => Expr.betaReduce(pre.etaExpand.seal.cast[(Int, Int) => Any])('{0}, '{0}).unseal
+          case 3 => Expr.betaReduce(pre.etaExpand.seal.cast[(Int, Int, Int) => Any])('{0}, '{0}, '{0}).unseal
         }
       case _ => term
     }