Merge pull request #7838 from dotty-staging/fix-#7810

Fix #7810: Survive wildcards when summoning a ValueOf

Author: odersky

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -723,10 +723,7 @@ object desugar {
       else if (companionMembers.nonEmpty || companionDerived.nonEmpty || isEnum)
         companionDefs(anyRef, companionMembers)
       else if (isValueClass)
-        impl.constr.vparamss match {
-          case (_ :: Nil) :: _ => companionDefs(anyRef, Nil)
-          case _ => Nil // error will be emitted in typer
-        }
+        companionDefs(anyRef, Nil)
       else Nil
 
     enumCompanionRef match {

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

@@ -1494,6 +1494,7 @@ class TypeComparer(initctx: Context) extends ConstraintHandling[AbsentContext] w
     case tp: SingletonType if tp.isStable => tp
     case tp: ValueType => SkolemType(tp)
     case tp: TypeProxy => ensureStableSingleton(tp.underlying)
+    case tp => assert(ctx.reporter.errorsReported); SkolemType(tp)
   }
 
   /** Skip refinements in `tp2` which match corresponding refinements in `tp1`.

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

@@ -4603,7 +4603,7 @@ object Types {
 
         case tp: AppliedType =>
           def mapArgs(args: List[Type], tparams: List[ParamInfo]): List[Type] = args match {
-            case arg :: otherArgs =>
+            case arg :: otherArgs if tparams.nonEmpty =>
               val arg1 = arg match {
                 case arg: TypeBounds => this(arg)
                 case arg => atVariance(variance * tparams.head.paramVariance)(this(arg))

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -348,7 +348,7 @@ object Erasure {
         tree.symbol.getAnnotation(defn.CompileTimeOnlyAnnot) match {
           case Some(annot) =>
             def defaultMsg =
-              s"""Reference to ${tree.symbol.showLocated} should not have survived,
+              i"""Reference to ${tree.symbol.showLocated} should not have survived,
                  |it should have been processed and eliminated during expansion of an enclosing macro or term erasure."""
             val message = annot.argumentConstant(0).fold(defaultMsg)(_.stringValue)
             ctx.error(message, tree.sourcePos)
@@ -750,8 +750,11 @@ object Erasure {
 
     override def adapt(tree: Tree, pt: Type, locked: TypeVars)(implicit ctx: Context): Tree =
       trace(i"adapting ${tree.showSummary}: ${tree.tpe} to $pt", show = true) {
-        assert(ctx.phase == ctx.erasurePhase || ctx.phase == ctx.erasurePhase.next, ctx.phase)
-        if (tree.isEmpty) tree
+        if ctx.phase != ctx.erasurePhase && ctx.phase != ctx.erasurePhase.next then
+          // this can happen when reading annotations loaded during erasure,
+          // since these are loaded at phase typer.
+          adapt(tree, pt, locked)(given ctx.withPhase(ctx.erasurePhase.next))
+        else if (tree.isEmpty) tree
         else if (ctx.mode is Mode.Pattern) tree // TODO: replace with assertion once pattern matcher is active
         else adaptToType(tree, pt)
       }

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -987,7 +987,10 @@ trait Applications extends Compatibility {
 
   /** Overridden in ReTyper to handle primitive operations that can be generated after erasure */
   protected def handleUnexpectedFunType(tree: untpd.Apply, fun: Tree)(implicit ctx: Context): Tree =
-    throw new Error(i"unexpected type.\n  fun = $fun,\n  methPart(fun) = ${methPart(fun)},\n  methPart(fun).tpe = ${methPart(fun).tpe},\n  tpe = ${fun.tpe}")
+    if ctx.reporter.errorsReported then
+      throw TypeError(i"unexpected function type: ${methPart(fun).tpe}")
+    else
+      throw Error(i"unexpected type.\n  fun = $fun,\n  methPart(fun) = ${methPart(fun)},\n  methPart(fun).tpe = ${methPart(fun).tpe},\n  tpe = ${fun.tpe}")
 
   def typedNamedArgs(args: List[untpd.Tree])(implicit ctx: Context): List[NamedArg] =
     for (arg @ NamedArg(id, argtpt) <- args) yield {

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -859,7 +859,7 @@ trait Implicits { self: Typer =>
     (formal, span) => implicit ctx => {
       def success(t: Tree) = New(defn.ValueOfClass.typeRef.appliedTo(t.tpe), t :: Nil).withSpan(span)
 
-      formal.argTypes match {
+      formal.argInfos match {
         case arg :: Nil =>
           fullyDefinedType(arg.dealias, "ValueOf argument", span) match {
             case ConstantType(c: Constant) =>
@@ -1389,18 +1389,17 @@ trait Implicits { self: Typer =>
               untpd.Apply(untpdConv, untpd.TypedSplice(argument) :: Nil),
               pt, locked)
           }
-          if (cand.isExtension) {
-            val SelectionProto(name: TermName, mbrType, _, _) = pt
-            val result = extMethodApply(untpd.Select(untpdGenerated, name), argument, mbrType)
-            if (!ctx.reporter.hasErrors && cand.isConversion) {
-              val testCtx = ctx.fresh.setExploreTyperState()
-              tryConversion(testCtx)
-              if (testCtx.reporter.hasErrors)
-                ctx.error(em"ambiguous implicit: $generated is eligible both as an implicit conversion and as an extension method container")
-            }
-            result
-          }
-          else tryConversion
+          pt match
+            case SelectionProto(name: TermName, mbrType, _, _) if cand.isExtension =>
+              val result = extMethodApply(untpd.Select(untpdGenerated, name), argument, mbrType)
+              if !ctx.reporter.hasErrors && cand.isConversion then
+                val testCtx = ctx.fresh.setExploreTyperState()
+                tryConversion(testCtx)
+                if testCtx.reporter.hasErrors then
+                  ctx.error(em"ambiguous implicit: $generated is eligible both as an implicit conversion and as an extension method container")
+              result
+            case _ =>
+              tryConversion
         }
       if (ctx.reporter.hasErrors) {
         ctx.reporter.removeBufferedMessages

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -1233,7 +1233,10 @@ class Typer extends Namer
     def caseRest(implicit ctx: Context) = {
       val pat1 = checkSimpleKinded(typedType(cdef.pat)(ctx.addMode(Mode.Pattern)))
       val pat2 = indexPattern(cdef).transform(pat1)
-      val body1 = typedType(cdef.body, pt)
+      var body1 = typedType(cdef.body, pt)
+      if !body1.isType then
+        assert(ctx.reporter.errorsReported)
+        body1 = TypeTree(errorType("<error: not a type>", cdef.sourcePos))
       assignType(cpy.CaseDef(cdef)(pat2, EmptyTree, body1), pat2, body1)
     }
     caseRest(ctx.fresh.setFreshGADTBounds.setNewScope)
@@ -1548,7 +1551,13 @@ class Typer extends Namer
 
   def typedAlternative(tree: untpd.Alternative, pt: Type)(implicit ctx: Context): Alternative = {
     val nestedCtx = ctx.addMode(Mode.InPatternAlternative)
+    def ensureValueTypeOrWildcard(tree: Tree) =
+      if tree.tpe.isValueTypeOrWildcard then tree
+      else
+        assert(ctx.reporter.errorsReported)
+        tree.withType(defn.AnyType)
     val trees1 = tree.trees.mapconserve(typed(_, pt)(nestedCtx))
+      .mapconserve(ensureValueTypeOrWildcard)
     assignType(cpy.Alternative(tree)(trees1), trees1)
   }
 
@@ -1924,13 +1933,17 @@ class Typer extends Namer
     val annot1 = typedExpr(tree.annot, defn.AnnotationClass.typeRef)
     val arg1 = typed(tree.arg, pt)
     if (ctx.mode is Mode.Type) {
-      val result = assignType(cpy.Annotated(tree)(arg1, annot1), arg1, annot1)
-      result.tpe match {
-        case AnnotatedType(rhs, Annotation.WithBounds(bounds)) =>
-          if (!bounds.contains(rhs)) ctx.error(em"type $rhs outside bounds $bounds", tree.sourcePos)
-        case _ =>
-      }
-      result
+      if arg1.isType then
+        val result = assignType(cpy.Annotated(tree)(arg1, annot1), arg1, annot1)
+        result.tpe match {
+          case AnnotatedType(rhs, Annotation.WithBounds(bounds)) =>
+            if (!bounds.contains(rhs)) ctx.error(em"type $rhs outside bounds $bounds", tree.sourcePos)
+          case _ =>
+        }
+        result
+      else
+        assert(ctx.reporter.errorsReported)
+        TypeTree(UnspecifiedErrorType)
     }
     else {
       val arg2 = arg1 match {

docs/docs/reference/contextual/extension-methods-new.md

@@ -0,0 +1 @@
+val a = implicitly[ValueOf[_]] // error

tests/neg/i7810.scala

@@ -0,0 +1,8 @@
+trait A {
+    type Type[X,]  // error
+    def a[X]: Type[X,]  // error
+}
+class B extends A {
+    type Type[X]
+    var a = 1
+}

tests/neg/i7811.scala

@@ -0,0 +1,3 @@
+def f(): Any = ???
+var f: (UndefinedA & UndefinedB) { val x: Int } = ??? // error // error
+val a = f // error

tests/neg/i7812.scala

@@ -0,0 +1,3 @@
+implicit def f[X <: Undefined](implicit a: Int): X = ??? // error
+def g(arg: h.NonExistent): Int = ???
+val h: Int = ???

tests/neg/i7813.scala

@@ -0,0 +1 @@
+def i0 = Unit  // error

tests/neg/i7814.scala

@@ -0,0 +1,3 @@
+trait A {
+    val a: Int match { case Int => this } // error
+}

tests/neg/i7815.scala

@@ -0,0 +1,4 @@
+object A {
+    def f()(>) = ???     // error
+    import f.NonExistent // error
+}

tests/neg/i7816.scala

@@ -0,0 +1,8 @@
+trait Foo[A]
+class A {
+    def F[x : Foo]() = ???
+
+    Int match {
+        case Int | F => ()  // error
+    }
+}

tests/neg/i7817.scala

@@ -0,0 +1 @@
+def foo = (x: @) => ()  // error

tests/neg/i7818.scala

@@ -0,0 +1 @@
+object A { type F[X >: F, Y] }

tests/pending/neg/i7820.scala

@@ -0,0 +1,3 @@
+trait F[x]
+implicit def foo[f[_], y, x <: f[y]](implicit ev: F[y]): F[x] = ???
+val test = implicitly

tests/pending/pos/i7745.scala

@@ -0,0 +1,5 @@
+object Example extends App {
+
+  final case class Foo[A](run: (given A) => Int)
+
+}