Backport "Fix a REPL bad symbolic reference" to LTS

.github/workflows/ci.yaml

@@ -47,7 +47,7 @@ jobs:
   test_non_bootstrapped:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -65,8 +65,8 @@ jobs:
            && github.repository == 'scala/scala3'
          )"
     steps:
-      - name: Set JDK 16 as default
-        run: echo "/usr/lib/jvm/java-16-openjdk-amd64/bin" >> $GITHUB_PATH
+      - name: Set JDK 17 as default
+        run: echo "/usr/lib/jvm/java-17-openjdk-amd64/bin" >> $GITHUB_PATH
 
       ## Workaround for https://github.com/actions/runner/issues/2033 (See https://github.com/scala/scala3/pull/19720)
       - name: Reset existing repo
@@ -99,7 +99,7 @@ jobs:
   test:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -119,8 +119,8 @@ jobs:
          )"
 
     steps:
-      - name: Set JDK 16 as default
-        run: echo "/usr/lib/jvm/java-16-openjdk-amd64/bin" >> $GITHUB_PATH
+      - name: Set JDK 17 as default
+        run: echo "/usr/lib/jvm/java-17-openjdk-amd64/bin" >> $GITHUB_PATH
 
       - name: Reset existing repo
         run: |
@@ -229,7 +229,7 @@ jobs:
     name: MiMa
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -248,6 +248,9 @@ jobs:
            && github.repository == 'scala/scala3'
          )"
     steps:
+      - name: Set JDK 17 as default
+        run: echo "/usr/lib/jvm/java-17-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -272,7 +275,7 @@ jobs:
   community_build_a:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -293,6 +296,8 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 8 as default
+        run: echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -324,7 +329,7 @@ jobs:
   community_build_b:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -345,6 +350,8 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 8 as default
+        run: echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -376,7 +383,7 @@ jobs:
   community_build_c:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2020-11-19
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -397,6 +404,8 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 8 as default
+        run: echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -428,7 +437,7 @@ jobs:
   test_sbt:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -447,6 +456,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 17 as default
+        run: echo "/usr/lib/jvm/java-17-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -470,7 +482,7 @@ jobs:
   test_java8:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -526,7 +538,7 @@ jobs:
   publish_nightly:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -542,6 +554,8 @@ jobs:
       SONATYPE_USER: ${{ secrets.SONATYPE_USER_ORGSCALALANG }}
 
     steps:
+      - name: Set JDK 8 as default
+        run: echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -579,7 +593,7 @@ jobs:
   nightly_documentation:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -633,7 +647,7 @@ jobs:
       contents: write  # for actions/create-release to create a release
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
       options: --cpu-shares 4096
       volumes:
         - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
@@ -651,6 +665,8 @@ jobs:
       SONATYPE_USER: ${{ secrets.SONATYPE_USER_ORGSCALALANG }}
 
     steps:
+      - name: Set JDK 8 as default
+        run: echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
       - name: Reset existing repo
         run: |
           git config --global --add safe.directory /__w/scala3/scala3
@@ -723,7 +739,7 @@ jobs:
   open_issue_on_failure:
     runs-on: [self-hosted, Linux]
     container:
-      image: lampepfl/dotty:2021-03-22
+      image: lampepfl/dotty:2023-11-07
     needs: [nightly_documentation, test_windows_full]
     # The `failure()` expression is true iff at least one of the dependencies
     # of this job (including transitive dependencies) has failed.

compiler/src/dotty/tools/dotc/Run.scala

@@ -141,7 +141,7 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
                 |"""
       val enableXprintSuspensionHint =
         if ctx.settings.XprintSuspension.value then ""
-        else "\n\nCompiling with  -Xprint-suspension   gives more information."
+        else "\n\nCompile with -Xprint-suspension for information."
       report.error(em"""Cyclic macro dependencies $where
                     |Compilation stopped since no further progress can be made.
                     |

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

@@ -34,7 +34,10 @@ object ContextOps:
               if (elem.name == name) return elem.sym.denot // return self
             }
             val pre = ctx.owner.thisType
-            if ctx.isJava then javaFindMember(name, pre, required, excluded)
+            if ctx.isJava then
+              // Note: I didn't verify if there exists a code path that would require `lookInCompanion = true`,
+              // it is just to preserve the original behavior.
+              javaFindMember(name, pre, lookInCompanion = true, required, excluded)
             else pre.findMember(name, pre, required, excluded)
           }
           else // we are in the outermost context belonging to a class; self is invisible here. See inClassContext.
@@ -43,7 +46,13 @@ object ContextOps:
           ctx.scope.denotsNamed(name).filterWithFlags(required, excluded).toDenot(NoPrefix)
       }
 
-    final def javaFindMember(name: Name, pre: Type, required: FlagSet = EmptyFlags, excluded: FlagSet = EmptyFlags): Denotation =
+    /** Look in the prefix with Java semantics.
+     * @param lookInCompanion  If true, try in the companion class of a module as a fallback.
+     *                         Note: originally this was used to type Select nodes in Java code,
+     *                         but that is no longer the case.
+     *                         It is preserved in case it is necessary for denotNamed, but this is unverified.
+     */
+    final def javaFindMember(name: Name, pre: Type, lookInCompanion: Boolean, required: FlagSet = EmptyFlags, excluded: FlagSet = EmptyFlags): Denotation =
       assert(ctx.isJava)
       inContext(ctx) {
 
@@ -53,7 +62,7 @@ object ContextOps:
         val directSearch = pre.findMember(name, pre, required, excluded)
 
         // 2. Try to search in companion class if current is an object.
-        def searchCompanionClass = if preSym.is(Flags.Module) then
+        def searchCompanionClass = if lookInCompanion && preSym.is(Flags.Module) then
           preSym.companionClass.thisType.findMember(name, pre, required, excluded)
           else NoDenotation
 

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

@@ -1501,6 +1501,13 @@ object SymDenotations {
     def namedType(using Context): NamedType =
       if (isType) typeRef else termRef
 
+    /** Like typeRef, but the prefix is widened.
+     *
+     *  See tests/neg/i19619/Test.scala
+     */
+    def javaTypeRef(using Context) =
+      TypeRef(maybeOwner.reachablePrefix.widen, symbol)
+
     /** Like typeRef, but objects in the prefix are represented by their singleton type,
      *  this means we output `pre.O.member` rather than `pre.O$.this.member`.
      *

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

@@ -105,17 +105,28 @@ object Symbols extends SymUtils {
     }
 
     private def computeDenot(lastd: SymDenotation)(using Context): SymDenotation = {
+      // Written that way so that it comes in at 32 bytes and is therefore inlineable for
+      // the JIT (reputedly, cutoff is at 35 bytes)
       util.Stats.record("Symbol.computeDenot")
       val now = ctx.period
       checkedPeriod = now
-      if (lastd.validFor contains now) lastd else recomputeDenot(lastd)
+      if lastd.validFor.contains(now) then lastd else recomputeDenot(lastd)
     }
 
     /** Overridden in NoSymbol */
     protected def recomputeDenot(lastd: SymDenotation)(using Context): SymDenotation = {
       util.Stats.record("Symbol.recomputeDenot")
       val newd = lastd.current.asInstanceOf[SymDenotation]
-      lastDenot = newd
+      if newd.exists || lastd.initial.validFor.firstPhaseId <= ctx.phaseId then
+        lastDenot = newd
+      else
+        // We are trying to bring forward a symbol that is defined only at a later phase
+        // (typically, a nested Java class, invisible before erasure).
+        // In that case, keep lastDenot as it was and set the checked period to lastDenot's
+        // previous validity, which means we will try another bring forward when the symbol
+        // is referenced at a later phase. Otherwise we'd get stuck on NoDenotation here.
+        // See #15562 and test i15562b in ReplCompilerTests
+        checkedPeriod = lastd.validFor
       newd
     }
 
@@ -764,7 +775,7 @@ object Symbols extends SymUtils {
       cls: ClassSymbol,
       name: TermName = nme.WILDCARD,
       selfInfo: Type = NoType)(using Context): TermSymbol =
-    newSymbol(cls, name, SelfSymFlags, selfInfo orElse cls.classInfo.selfType, coord = cls.coord)
+    newSymbol(cls, name, SelfSymFlags, selfInfo.orElse(cls.classInfo.selfType), coord = cls.coord)
 
   /** Create new type parameters with given owner, names, and flags.
    *  @param boundsFn  A function that, given type refs to the newly created
@@ -931,7 +942,7 @@ object Symbols extends SymUtils {
    */
   def getPackageClassIfDefined(path: PreName)(using Context): Symbol =
     staticRef(path.toTypeName, isPackage = true, generateStubs = false)
-      .disambiguate(_ is PackageClass).symbol
+      .disambiguate(_.is(PackageClass)).symbol
 
   def requiredModule(path: PreName)(using Context): TermSymbol = {
     val name = path.toTermName

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -3958,7 +3958,7 @@ object Parsers {
         val tparams = typeParamClauseOpt(ParamOwner.Given)
         newLineOpt()
         val vparamss =
-          if in.token == LPAREN && in.lookahead.isIdent(nme.using)
+          if in.token == LPAREN && (in.lookahead.isIdent(nme.using) || name != EmptyTermName)
           then termParamClauses(ParamOwner.Given)
           else Nil
         newLinesOpt()

compiler/src/dotty/tools/dotc/parsing/xml/MarkupParsers.scala

@@ -372,7 +372,7 @@ object MarkupParsers {
           while {
             xSpaceOpt()
             nextch()
-            ts.append(element)
+            content_LT(ts)
             charComingAfter(xSpaceOpt()) == '<'
           } do ()
           handle.makeXMLseq(Span(start, curOffset, start), ts)

compiler/src/dotty/tools/dotc/reporting/messages.scala

@@ -286,7 +286,7 @@ extends NotFoundMsg(MissingIdentID) {
   }
 }
 
-class TypeMismatch(found: Type, expected: Type, inTree: Option[untpd.Tree], addenda: => String*)(using Context)
+class TypeMismatch(val found: Type, expected: Type, inTree: Option[untpd.Tree], addenda: => String*)(using Context)
   extends TypeMismatchMsg(found, expected)(TypeMismatchID):
 
   def msg(using Context) =
@@ -2749,7 +2749,11 @@ extends SyntaxMsg(TargetNameOnTopLevelClassID):
 class NotClassType(tp: Type)(using Context)
 extends TypeMsg(NotClassTypeID), ShowMatchTrace(tp):
   def msg(using Context) = i"$tp is not a class type"
-  def explain(using Context) = ""
+  def explain(using Context) =
+    i"""A class type includes classes and traits in a specific order. Defining a class, even an anonymous class,
+        |requires specifying a linearization order for the traits it extends. For example, `A & B` is not a class type
+        |because it doesn't specify which trait takes precedence, A or B. For more information about class types, please see the Scala Language Specification.
+        |Class types also can't have refinements."""
 
 class NotConstant(suffix: String, tp: Type)(using Context)
 extends TypeMsg(NotConstantID), ShowMatchTrace(tp):

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

@@ -112,7 +112,8 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
      *  This info is used in phase ParamForwarding
      */
     private def forwardParamAccessors(impl: Template)(using Context): Unit = impl.parents match
-      case superCall @ Apply(fn, superArgs) :: _ if superArgs.nonEmpty =>
+      case superCall @ Apply(fn, superArgs) :: _
+      if superArgs.nonEmpty && fn.symbol.isPrimaryConstructor =>
         fn.tpe.widen match
           case MethodType(superParamNames) =>
             for case stat: ValDef <- impl.body do

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

@@ -620,7 +620,7 @@ trait Applications extends Compatibility {
               defaultArg.tpe.widen match
                 case _: MethodOrPoly if testOnly => matchArgs(args1, formals1, n + 1)
                 case _ => matchArgs(args1, addTyped(treeToArg(defaultArg)), n + 1)
-            else if methodType.isContextualMethod && ctx.mode.is(Mode.ImplicitsEnabled) then
+            else if methodType.isImplicitMethod && ctx.mode.is(Mode.ImplicitsEnabled) then
               matchArgs(args1, addTyped(treeToArg(implicitArg)), n + 1)
             else
               missingArg(n)