Merge pull request #8622 from dotty-staging/fix-#8617

Fix #8617: Check that there is no inheritance/definition shadowing

Author: odersky

community-build/community-projects/scala-xml

@@ -112,7 +112,7 @@ object desugar {
         val originalOwner = sym.owner
         def apply(tp: Type) = tp match {
           case tp: NamedType if tp.symbol.exists && (tp.symbol.owner eq originalOwner) =>
-            val defctx = ctx.outersIterator.dropWhile(_.scope eq ctx.scope).next()
+            val defctx = this.ctx.outersIterator.dropWhile(_.scope eq this.ctx.scope).next()
             var local = defctx.denotNamed(tp.name).suchThat(_.isParamOrAccessor).symbol
             if (local.exists) (defctx.owner.thisType select local).dealiasKeepAnnots
             else {

community-build/community-projects/scalacheck

@@ -1243,7 +1243,7 @@ object Denotations {
       throw new MergeError(sym1, sym2, sym1.info, sym2.info, pre) {
         override def addendum(implicit ctx: Context) =
           i"""
-             |they are both defined in ${sym1.effectiveOwner} but have matching signatures
+             |they are both defined in ${this.sym1.effectiveOwner} but have matching signatures
              |  ${denot1.info} and
              |  ${denot2.info}${super.addendum}"""
       }

community-build/community-projects/scalatest

@@ -3784,7 +3784,7 @@ object Parsers {
             i"refinement cannot have default arguments"
           case tree: ValOrDefDef =>
             if tree.rhs.isEmpty then ""
-            else "refinement in cannot have a right-hand side"
+            else "refinement cannot have a right-hand side"
           case tree: TypeDef =>
             if !tree.isClassDef then ""
             else "refinement cannot be a class or trait"

community-build/community-projects/stdLib213

@@ -57,7 +57,7 @@ enum ErrorMessageID extends java.lang.Enum[ErrorMessageID] {
     CyclicReferenceInvolvingID,
     CyclicReferenceInvolvingImplicitID,
     SuperQualMustBeParentID,
-    AmbiguousImportID,
+    AmbiguousReferenceID,
     MethodDoesNotTakeParametersId,
     AmbiguousOverloadID,
     ReassignmentToValID,

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

@@ -250,13 +250,13 @@ object messages {
     // these are usually easier to analyze.
     object reported extends TypeMap:
       def setVariance(v: Int) = variance = v
-      val constraint = ctx.typerState.constraint
+      val constraint = this.ctx.typerState.constraint
       def apply(tp: Type): Type = tp match
         case tp: TypeParamRef =>
           constraint.entry(tp) match
             case bounds: TypeBounds =>
-              if variance < 0 then apply(ctx.typeComparer.fullUpperBound(tp))
-              else if variance > 0 then apply(ctx.typeComparer.fullLowerBound(tp))
+              if variance < 0 then apply(this.ctx.typeComparer.fullUpperBound(tp))
+              else if variance > 0 then apply(this.ctx.typeComparer.fullLowerBound(tp))
               else tp
             case NoType => tp
             case instType => apply(instType)
@@ -1244,8 +1244,8 @@ object messages {
 
   import typer.Typer.BindingPrec
 
-  class AmbiguousImport(name: Name, newPrec: BindingPrec, prevPrec: BindingPrec, prevCtx: Context)(implicit ctx: Context)
-    extends ReferenceMsg(AmbiguousImportID) {
+  class AmbiguousReference(name: Name, newPrec: BindingPrec, prevPrec: BindingPrec, prevCtx: Context)(implicit ctx: Context)
+    extends ReferenceMsg(AmbiguousReferenceID) {
 
     /** A string which explains how something was bound; Depending on `prec` this is either
       *      imported by <tree>
@@ -1254,6 +1254,7 @@ object messages {
     private def bindingString(prec: BindingPrec, whereFound: Context, qualifier: String = "") = {
       val howVisible = prec match {
         case BindingPrec.Definition => "defined"
+        case BindingPrec.Inheritance => "inherited"
         case BindingPrec.NamedImport => "imported by name"
         case BindingPrec.WildImport => "imported"
         case BindingPrec.PackageClause => "found"
@@ -1266,18 +1267,21 @@ object messages {
     }
 
     def msg =
-      i"""|Reference to ${em"$name"} is ambiguous
+      i"""|Reference to ${em"$name"} is ambiguous,
           |it is both ${bindingString(newPrec, ctx)}
           |and ${bindingString(prevPrec, prevCtx, " subsequently")}"""
 
     def explain =
       em"""|The compiler can't decide which of the possible choices you
-           |are referencing with $name.
+           |are referencing with $name: A definition of lower precedence
+           |in an inner scope, or a definition with higher precedence in
+           |an outer scope.
            |Note:
-           |- Definitions take precedence over imports
-           |- Named imports take precedence over wildcard imports
-           |- You may replace a name when imported using
-           |  ${hl("import")} scala.{ $name => ${name.show + "Tick"} }
+           | - Definitions in an enclosing scope take precedence over inherited definitions
+           | - Definitions take precedence over imports
+           | - Named imports take precedence over wildcard imports
+           | - You may replace a name when imported using
+           |   ${hl("import")} scala.{ $name => ${name.show + "Tick"} }
            |"""
   }
 

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

@@ -138,7 +138,7 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
       tp match {
         case tp: TypeRef if tp.symbol.isSplice =>
           if (tp.isTerm)
-            ctx.error(i"splice outside quotes", pos)
+            this.ctx.error(i"splice outside quotes", pos)
           if level > 0 then getQuoteTypeTags.getTagRef(tp.prefix.asInstanceOf[TermRef])
           else tp
         case tp: TypeRef if tp.symbol == defn.QuotedTypeClass.typeParams.head =>