Fix #7204: Use evidence based type testing for unapplies

* Deprecate `IsXYZ` extrators
* Provide `IsInstanceOf[XYZ]` evidences
* Refine the types of arguments of `unapply`s
* Use `_: XYZ` instead of `IsXYZ(_)` in the dotty library

Author: nicolasstucki

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

@@ -57,21 +57,21 @@ trait TreeUtils
           foldTrees(foldTree(x, elemtpt), elems)
         case Inlined(call, bindings, expansion) =>
           foldTree(foldTrees(x, bindings), expansion)
-        case IsDefinition(vdef @ ValDef(_, tpt, rhs)) =>
+        case vdef @ ValDef(_, tpt, rhs) =>
           implicit val ctx = localCtx(vdef)
           foldTrees(foldTree(x, tpt), rhs)
-        case IsDefinition(ddef @ DefDef(_, tparams, vparamss, tpt, rhs)) =>
+        case ddef @ DefDef(_, tparams, vparamss, tpt, rhs) =>
           implicit val ctx = localCtx(ddef)
           foldTrees(foldTree(vparamss.foldLeft(foldTrees(x, tparams))(foldTrees), tpt), rhs)
-        case IsDefinition(tdef @ TypeDef(_, rhs)) =>
+        case tdef @ TypeDef(_, rhs) =>
           implicit val ctx = localCtx(tdef)
           foldTree(x, rhs)
-        case IsDefinition(cdef @ ClassDef(_, constr, parents, derived, self, body)) =>
+        case cdef @ ClassDef(_, constr, parents, derived, self, body) =>
           implicit val ctx = localCtx(cdef)
           foldTrees(foldTrees(foldTrees(foldTrees(foldTree(x, constr), parents), derived), self), body)
         case Import(expr, _) =>
           foldTree(x, expr)
-        case IsPackageClause(clause @ PackageClause(pid, stats)) =>
+        case clause @ PackageClause(pid, stats) =>
           foldTrees(foldTree(x, pid), stats)(given clause.symbol.localContext)
         case Inferred() => x
         case TypeIdent(_) => x
@@ -112,47 +112,47 @@ trait TreeUtils
 
     def transformTree(tree: Tree)(given ctx: Context): Tree = {
       tree match {
-        case IsPackageClause(tree) =>
+        case tree: PackageClause =>
           PackageClause.copy(tree)(transformTerm(tree.pid).asInstanceOf[Ref], transformTrees(tree.stats)(given tree.symbol.localContext))
-        case IsImport(tree) =>
+        case tree: Import =>
           Import.copy(tree)(transformTerm(tree.expr), tree.selectors)
-        case IsStatement(tree) =>
+        case tree: Statement =>
           transformStatement(tree)
-        case IsTypeTree(tree) => transformTypeTree(tree)
-        case IsTypeBoundsTree(tree) => tree // TODO traverse tree
-        case IsWildcardTypeTree(tree) => tree // TODO traverse tree
-        case IsCaseDef(tree) =>
+        case tree: TypeTree => transformTypeTree(tree)
+        case tree: TypeBoundsTree => tree // TODO traverse tree
+        case tree: WildcardTypeTree => tree // TODO traverse tree
+        case tree: CaseDef =>
           transformCaseDef(tree)
-        case IsTypeCaseDef(tree) =>
+        case tree: TypeCaseDef =>
           transformTypeCaseDef(tree)
-        case IsBind(pattern) =>
+        case pattern: Bind =>
           Bind.copy(pattern)(pattern.name, pattern.pattern)
-        case IsUnapply(pattern) =>
+        case pattern: Unapply =>
           Unapply.copy(pattern)(transformTerm(pattern.fun), transformSubTrees(pattern.implicits), transformTrees(pattern.patterns))
-        case IsAlternatives(pattern) =>
+        case pattern: Alternatives =>
           Alternatives.copy(pattern)(transformTrees(pattern.patterns))
       }
     }
 
     def transformStatement(tree: Statement)(given ctx: Context): Statement = {
       def localCtx(definition: Definition): Context = definition.symbol.localContext
       tree match {
-        case IsTerm(tree) =>
+        case tree: Term =>
           transformTerm(tree)
-        case IsValDef(tree) =>
+        case tree: ValDef =>
           implicit val ctx = localCtx(tree)
           val tpt1 = transformTypeTree(tree.tpt)
           val rhs1 = tree.rhs.map(x => transformTerm(x))
           ValDef.copy(tree)(tree.name, tpt1, rhs1)
-        case IsDefDef(tree) =>
+        case tree: DefDef =>
           implicit val ctx = localCtx(tree)
           DefDef.copy(tree)(tree.name, transformSubTrees(tree.typeParams), tree.paramss mapConserve (transformSubTrees(_)), transformTypeTree(tree.returnTpt), tree.rhs.map(x => transformTerm(x)))
-        case IsTypeDef(tree) =>
+        case tree: TypeDef =>
           implicit val ctx = localCtx(tree)
           TypeDef.copy(tree)(tree.name, transformTree(tree.rhs))
-        case IsClassDef(tree) =>
+        case tree: ClassDef =>
           ClassDef.copy(tree)(tree.name, tree.constructor, tree.parents, tree.derived, tree.self, tree.body)
-        case IsImport(tree) =>
+        case tree: Import =>
           Import.copy(tree)(transformTerm(tree.expr), tree.selectors)
       }
     }
@@ -177,7 +177,7 @@ trait TreeUtils
           New.copy(tree)(transformTypeTree(tpt))
         case Typed(expr, tpt) =>
           Typed.copy(tree)(transformTerm(expr), transformTypeTree(tpt))
-        case IsNamedArg(tree) =>
+        case tree: NamedArg =>
           NamedArg.copy(tree)(tree.name, transformTerm(tree.value))
         case Assign(lhs, rhs) =>
           Assign.copy(tree)(transformTerm(lhs), transformTerm(rhs))
@@ -204,28 +204,28 @@ trait TreeUtils
 
     def transformTypeTree(tree: TypeTree)(given ctx: Context): TypeTree = tree match {
       case Inferred() => tree
-      case IsTypeIdent(tree) => tree
-      case IsTypeSelect(tree) =>
+      case tree: TypeIdent => tree
+      case tree: TypeSelect =>
         TypeSelect.copy(tree)(tree.qualifier, tree.name)
-      case IsProjection(tree) =>
+      case tree: Projection =>
         Projection.copy(tree)(tree.qualifier, tree.name)
-      case IsAnnotated(tree) =>
+      case tree: Annotated =>
         Annotated.copy(tree)(tree.arg, tree.annotation)
-      case IsSingleton(tree) =>
+      case tree: Singleton =>
         Singleton.copy(tree)(transformTerm(tree.ref))
-      case IsRefined(tree) =>
+      case tree: Refined =>
         Refined.copy(tree)(transformTypeTree(tree.tpt), transformTrees(tree.refinements).asInstanceOf[List[Definition]])
-      case IsApplied(tree) =>
+      case tree: Applied =>
         Applied.copy(tree)(transformTypeTree(tree.tpt), transformTrees(tree.args))
-      case IsMatchTypeTree(tree) =>
+      case tree: MatchTypeTree =>
         MatchTypeTree.copy(tree)(tree.bound.map(b => transformTypeTree(b)), transformTypeTree(tree.selector), transformTypeCaseDefs(tree.cases))
-      case IsByName(tree) =>
+      case tree: ByName =>
         ByName.copy(tree)(transformTypeTree(tree.result))
-      case IsLambdaTypeTree(tree) =>
+      case tree: LambdaTypeTree =>
         LambdaTypeTree.copy(tree)(transformSubTrees(tree.tparams), transformTree(tree.body))(given tree.symbol.localContext)
-      case IsTypeBind(tree) =>
+      case tree: TypeBind =>
         TypeBind.copy(tree)(tree.name, tree.body)
-      case IsTypeBlock(tree) =>
+      case tree: TypeBlock =>
         TypeBlock.copy(tree)(tree.aliases, tree.tpt)
     }
 

library/src-bootstrapped/scala/tasty/reflect/TreeUtils.scala

@@ -131,14 +131,14 @@ private[quoted] object Matcher {
         (scrutinee, pattern) match {
 
           // Match a scala.internal.Quoted.patternHole typed as a repeated argument and return the scrutinee tree
-          case (IsTerm(scrutinee @ Typed(s, tpt1)), Typed(TypeApply(patternHole, tpt :: Nil), tpt2))
+          case (scrutinee @ Typed(s, tpt1), Typed(TypeApply(patternHole, tpt :: Nil), tpt2))
               if patternHole.symbol == internal.Definitions_InternalQuoted_patternHole &&
                  s.tpe <:< tpt.tpe &&
                  tpt2.tpe.derivesFrom(defn.RepeatedParamClass) =>
             matched(scrutinee.seal)
 
           // Match a scala.internal.Quoted.patternHole and return the scrutinee tree
-          case (IsTerm(scrutinee), TypeApply(patternHole, tpt :: Nil))
+          case (scrutinee: Term, TypeApply(patternHole, tpt :: Nil))
               if patternHole.symbol == internal.Definitions_InternalQuoted_patternHole &&
                  scrutinee.tpe <:< tpt.tpe =>
             matched(scrutinee.seal)
@@ -162,7 +162,7 @@ private[quoted] object Matcher {
           case (Select(qual1, _), Select(qual2, _)) if scrutinee.symbol == pattern.symbol =>
             qual1 =?= qual2
 
-          case (IsRef(_), IsRef(_)) if scrutinee.symbol == pattern.symbol =>
+          case (_: Ref, _: Ref) if scrutinee.symbol == pattern.symbol =>
             matched
 
           case (Apply(fn1, args1), Apply(fn2, args2)) if fn1.symbol == fn2.symbol =>
@@ -209,7 +209,7 @@ private[quoted] object Matcher {
           case (Repeated(elems1, _), Repeated(elems2, _)) if elems1.size == elems2.size =>
             elems1 =?= elems2
 
-          case (IsTypeTree(scrutinee), IsTypeTree(pattern)) if scrutinee.tpe <:< pattern.tpe =>
+          case (scrutinee: TypeTree, pattern: TypeTree) if scrutinee.tpe <:< pattern.tpe =>
             matched
 
           case (Applied(tycon1, args1), Applied(tycon2, args2)) =>
@@ -306,7 +306,7 @@ private[quoted] object Matcher {
       *          `None` if it did not match or `Some(tup: Tuple)` if it matched where `tup` contains the contents of the holes.
       */
     private def patternsMatches(scrutinee: Tree, pattern: Tree)(given Context, Env): (Env, Matching) = (scrutinee, pattern) match {
-      case (IsTerm(v1), Unapply(TypeApply(Select(patternHole @ Ident("patternHole"), "unapply"), List(tpt)), Nil, Nil))
+      case (v1: Term, Unapply(TypeApply(Select(patternHole @ Ident("patternHole"), "unapply"), List(tpt)), Nil, Nil))
         if patternHole.symbol.owner.fullName == "scala.runtime.quoted.Matcher$" =>
         (summon[Env], matched(v1.seal))
 
@@ -327,7 +327,7 @@ private[quoted] object Matcher {
       case (Typed(Ident("_"), tpt1), Typed(Ident("_"), tpt2)) =>
         (summon[Env], tpt1 =?= tpt2)
 
-      case (IsTerm(v1), IsTerm(v2)) =>
+      case (v1: Term, v2: Term) =>
         (summon[Env], v1 =?= v2)
 
       case _ =>
@@ -360,7 +360,7 @@ private[quoted] object Matcher {
     }
 
     private def isTypeBinding(tree: Tree): Boolean = tree match {
-      case IsTypeDef(tree) => hasBindAnnotation(tree.symbol)
+      case tree: TypeDef => hasBindAnnotation(tree.symbol)
       case _ => false
     }
   }

library/src/scala/internal/quoted/Matcher.scala

@@ -22,7 +22,7 @@ object Sym {
   def unapply[T](expr: Expr[T])(given qctx: QuoteContext): Option[Sym[T]] = {
     import qctx.tasty.{_, given}
     expr.unseal match {
-      case IsIdent(ref) =>
+      case ref: Ident =>
         val sym = ref.symbol
         Some(new Sym[T](sym.name, sym))
       case _ => None

library/src/scala/quoted/matching/Sym.scala

@@ -13,8 +13,8 @@ package object matching {
   def searchImplicitExpr[T](given tpe: Type[T], qctx: QuoteContext): Option[Expr[T]] = {
     import qctx.tasty.{_, given}
     searchImplicit(tpe.unseal.tpe) match {
-      case IsImplicitSearchSuccess(iss) => Some(iss.tree.seal.asInstanceOf[Expr[T]])
-      case IsImplicitSearchFailure(isf) => None
+      case iss: ImplicitSearchSuccess => Some(iss.tree.seal.asInstanceOf[Expr[T]])
+      case isf: ImplicitSearchFailure => None
     }
   }