Add IsNamedTuple compiletime op

Author: bishabosha

compiler/src/dotty/tools/dotc/cc/CheckCaptures.scala

@@ -23,6 +23,7 @@ import CCState.*
 import StdNames.nme
 import NameKinds.{DefaultGetterName, WildcardParamName, UniqueNameKind}
 import reporting.{trace, Message, OverrideError}
+import scala.util.boundary
 
 /** The capture checker */
 object CheckCaptures:
@@ -1290,7 +1291,7 @@ class CheckCaptures extends Recheck, SymTransformer:
      */
     def adaptBoxed(actual: Type, expected: Type, pos: SrcPos, covariant: Boolean, alwaysConst: Boolean, boxErrors: BoxErrors)(using Context): Type =
 
-      def recur(actual: Type, expected: Type, covariant: Boolean): Type =
+      def recur(actual: Type, expected: Type, covariant: Boolean): Type = boundary:
 
         /** Adapt the inner shape type: get the adapted shape type, and the capture set leaked during adaptation
          *  @param boxed   if true we adapt to a boxed expected type
@@ -1384,7 +1385,7 @@ class CheckCaptures extends Recheck, SymTransformer:
               if boxErrors != null then boxErrors += msg
               if ctx.settings.YccDebug.value then
                 println(i"cannot box/unbox $actual vs $expected")
-              return actual
+              boundary.break(actual)
             // Disallow future addition of `cap` to `criticalSet`.
             criticalSet.disallowRootCapability: () =>
               report.error(msg, pos)

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

@@ -962,7 +962,8 @@ class Definitions {
     def TupleXXL_fromIterator(using Context): Symbol = TupleXXLModule.requiredMethod("fromIterator")
     def TupleXXL_unapplySeq(using Context): Symbol = TupleXXLModule.requiredMethod(nme.unapplySeq)
 
-  @tu lazy val NamedTupleModule = requiredModule("scala.NamedTuple")
+  @tu lazy val NamedTupleModule: Symbol = requiredModule("scala.NamedTuple")
+  @tu lazy val NamedTupleModuleClass: Symbol = NamedTupleModule.moduleClass
   @tu lazy val NamedTupleTypeRef: TypeRef = NamedTupleModule.termRef.select(tpnme.NamedTuple).asInstanceOf
 
   @tu lazy val RuntimeTupleMirrorTypeRef: TypeRef = requiredClassRef("scala.runtime.TupleMirror")
@@ -1360,9 +1361,9 @@ class Definitions {
   final def isCompiletime_S(sym: Symbol)(using Context): Boolean =
     sym.name == tpnme.S && sym.owner == CompiletimeOpsIntModuleClass
 
-  final def isNamedTuple_From(sym: Symbol)(using Context): Boolean =
-    sym.name == tpnme.From && sym.owner == NamedTupleModule.moduleClass
-
+  private val namedTupleTypes: Set[Name] = Set(
+    tpnme.From, tpnme.OptFrom, tpnme.IsNamedTuple
+  )
   private val compiletimePackageAnyTypes: Set[Name] = Set(
     tpnme.Equals, tpnme.NotEquals, tpnme.IsConst, tpnme.ToString
   )
@@ -1391,7 +1392,8 @@ class Definitions {
     tpnme.Plus, tpnme.Length, tpnme.Substring, tpnme.Matches, tpnme.CharAt
   )
   private val compiletimePackageOpTypes: Set[Name] =
-    Set(tpnme.S, tpnme.From)
+    Set(tpnme.S)
+    ++ namedTupleTypes
     ++ compiletimePackageAnyTypes
     ++ compiletimePackageIntTypes
     ++ compiletimePackageLongTypes
@@ -1404,7 +1406,7 @@ class Definitions {
     compiletimePackageOpTypes.contains(sym.name)
     && (
          isCompiletime_S(sym)
-      || isNamedTuple_From(sym)
+      || sym.owner == NamedTupleModuleClass && namedTupleTypes.contains(sym.name)
       || sym.owner == CompiletimeOpsAnyModuleClass && compiletimePackageAnyTypes.contains(sym.name)
       || sym.owner == CompiletimeOpsIntModuleClass && compiletimePackageIntTypes.contains(sym.name)
       || sym.owner == CompiletimeOpsLongModuleClass && compiletimePackageLongTypes.contains(sym.name)

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

@@ -367,6 +367,7 @@ object StdNames {
     val Flag : N                = "Flag"
     val Fields: N               = "Fields"
     val From: N                 = "From"
+    val IsNamedTuple: N         = "IsNamedTuple"
     val Ident: N                = "Ident"
     val Import: N               = "Import"
     val Literal: N              = "Literal"
@@ -385,6 +386,7 @@ object StdNames {
     val NoPrefix: N             = "NoPrefix"
     val NoSymbol: N             = "NoSymbol"
     val NoType: N               = "NoType"
+    val OptFrom: N              = "OptFrom"
     val Pair: N                 = "Pair"
     val Ref: N                  = "Ref"
     val RootPackage: N          = "RootPackage"

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

@@ -27,6 +27,7 @@ import parsing.Parsers.OutlineParser
 import dotty.tools.tasty.{TastyHeaderUnpickler, UnpickleException, UnpicklerConfig, TastyVersion}
 import dotty.tools.dotc.core.tasty.TastyUnpickler
 import dotty.tools.tasty.besteffort.BestEffortTastyHeaderUnpickler
+import dotty.tools.dotc.util.SourceFile
 
 object SymbolLoaders {
   import ast.untpd.*
@@ -450,7 +451,7 @@ class TastyLoader(val tastyFile: AbstractFile) extends SymbolLoader {
       val (classRoot, moduleRoot) = rootDenots(root.asClass)
       if (!isBestEffortTasty || ctx.withBestEffortTasty) then
         val tastyBytes = tastyFile.toByteArray
-        unpickler.enter(roots = Set(classRoot, moduleRoot, moduleRoot.sourceModule))(using ctx.withSource(util.NoSource))
+        unpickler.enter(roots = Set(classRoot, moduleRoot, moduleRoot.sourceModule))(using ctx.withSource(util.NoSource : SourceFile))
         if mayLoadTreesFromTasty || isBestEffortTasty then
           classRoot.classSymbol.rootTreeOrProvider = unpickler
           moduleRoot.classSymbol.rootTreeOrProvider = unpickler

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

@@ -54,6 +54,25 @@ object TypeEval:
         case ConstantType(Constant(n: String)) => Some(n)
         case _ => None
 
+      /** is the type concrete? if not then the compiletime op should not reduce */
+      def isKnown(tp: Type): Boolean = tp.dealias match
+        // currently not a concrete known type
+        case TypeRef(NoPrefix,_) => false
+        // currently not a concrete known type
+        case _: TypeParamRef => false
+        // constant if the term is constant
+        case t: TermRef =>
+          if t.denot.symbol.flagsUNSAFE.is(Flags.Param) then
+            // might be substituted later
+            false
+          else
+            isKnown(t.underlying)
+        // an operation type => recursively check all argument compositions
+        case applied: AppliedType if defn.isCompiletimeAppliedType(applied.typeSymbol) =>
+          applied.args.forall(isKnown)
+        // all other types are considered known
+        case _ => true
+
       // Returns Some(true) if the type is a constant.
       // Returns Some(false) if the type is not a constant.
       // Returns None if there is not enough information to determine if the type is a constant.
@@ -113,6 +132,23 @@ object TypeEval:
           case arg @ defn.NamedTuple(_, _) => Some(arg)
           case _ => None
 
+      def optFieldsOf: Option[Type] =
+        if isKnown(tp) then fieldsOf match
+          case Some(tp) => Some(defn.SomeClass.typeRef.appliedTo(tp))
+          case None => Some(defn.NoneModule.termRef)
+        else
+          None
+
+      def isNamedTupleType: Option[Type] =
+        if isKnown(tp) then
+          expectArgsNum(1)
+          val arg = tp.args.head
+          arg.widenDealias match
+            case arg @ defn.NamedTuple(_, _) => Some(ConstantType(Constant(true)))
+            case _ => Some(ConstantType(Constant(false)))
+        else
+          None
+
       def constantFold1[T](extractor: Type => Option[T], op: T => Any): Option[Type] =
         expectArgsNum(1)
         extractor(tp.args.head).map(a => runConstantOp(op(a)))
@@ -147,8 +183,11 @@ object TypeEval:
         val constantType =
           if defn.isCompiletime_S(sym) then
             constantFold1(natValue, _ + 1)
-          else if defn.isNamedTuple_From(sym) then
-            fieldsOf
+          else if owner == defn.NamedTupleModuleClass then name match
+            case tpnme.From => fieldsOf
+            case tpnme.OptFrom => optFieldsOf
+            case tpnme.IsNamedTuple => isNamedTupleType
+            case _ => None
           else if owner == defn.CompiletimeOpsAnyModuleClass then name match
             case tpnme.Equals     => constantFold2(constValue, _ == _)
             case tpnme.NotEquals  => constantFold2(constValue, _ != _)

library/src/scala/NamedTuple.scala

@@ -124,6 +124,12 @@ object NamedTuple:
    */
   type From[T] <: AnyNamedTuple
 
+  @experimental // extra experimental for now
+  type OptFrom[T] <: Option[AnyNamedTuple]
+
+  @experimental // extra experimental for now
+  type IsNamedTuple[T] <: Boolean
+
   /** The type of the empty named tuple */
   type Empty = NamedTuple[EmptyTuple, EmptyTuple]