Fix #7494: check type bounds during java joint compilation

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

@@ -89,7 +89,7 @@ class Pickler extends Phase {
 
   override def runOn(units: List[CompilationUnit])(using Context): List[CompilationUnit] = {
     val result = super.runOn(units)
-    if (ctx.settings.YtestPickler.value)
+    if ctx.settings.YtestPickler.value
       testUnpickler(
         using ctx.fresh
             .setPeriod(Period(ctx.runId + 1, FirstPhaseId))

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

@@ -40,11 +40,10 @@ class FrontEnd extends Phase {
 
   def monitor(doing: String)(body: => Unit)(using Context): Unit =
     try body
-    catch {
+    catch
       case NonFatal(ex) =>
         report.echo(s"exception occurred while $doing ${ctx.compilationUnit}")
         throw ex
-    }
 
   def parse(using Context): Unit = monitor("parsing") {
     val unit = ctx.compilationUnit
@@ -84,17 +83,23 @@ class FrontEnd extends Phase {
       case ex: CompilationUnit.SuspendException =>
   }
 
-  private def firstTopLevelDef(trees: List[tpd.Tree])(using Context): Symbol = trees match {
+  def javaCheck(using Context): Unit = monitor("checking java") {
+    val unit = ctx.compilationUnit
+    if unit.isJava then
+      JavaChecks.check(unit.tpdTree)
+  }
+
+
+  private def firstTopLevelDef(trees: List[tpd.Tree])(using Context): Symbol = trees match
     case PackageDef(_, defs) :: _    => firstTopLevelDef(defs)
     case Import(_, _) :: defs        => firstTopLevelDef(defs)
     case (tree @ TypeDef(_, _)) :: _ => tree.symbol
     case _ => NoSymbol
-  }
 
   protected def discardAfterTyper(unit: CompilationUnit)(using Context): Boolean =
     unit.isJava || unit.suspended
 
-  override def runOn(units: List[CompilationUnit])(using Context): List[CompilationUnit] = {
+  override def runOn(units: List[CompilationUnit])(using Context): List[CompilationUnit] =
     val unitContexts =
       for unit <- units yield
         report.inform(s"compiling ${unit.source}")
@@ -106,13 +111,15 @@ class FrontEnd extends Phase {
       enterSyms(using remaining.head)
       remaining = remaining.tail
 
-    if (firstXmlPos.exists && !defn.ScalaXmlPackageClass.exists)
+    if firstXmlPos.exists && !defn.ScalaXmlPackageClass.exists then
       report.error("""To support XML literals, your project must depend on scala-xml.
                   |See https://github.com/scala/scala-xml for more information.""".stripMargin,
         firstXmlPos)
 
     unitContexts.foreach(typeCheck(using _))
     record("total trees after typer", ast.Trees.ntrees)
+    unitContexts.foreach(javaCheck(using _)) // after typechecking to avoid cycles
+
     val newUnits = unitContexts.map(_.compilationUnit).filterNot(discardAfterTyper)
     val suspendedUnits = ctx.run.suspendedUnits
     if newUnits.isEmpty && suspendedUnits.nonEmpty && !ctx.reporter.errorsReported then
@@ -123,14 +130,13 @@ class FrontEnd extends Phase {
                 |  ${suspendedUnits.toList}%, %
                 |"""
       val enableXprintSuspensionHint =
-        if (ctx.settings.XprintSuspension.value) ""
+        if ctx.settings.XprintSuspension.value then ""
         else "\n\nCompiling with  -Xprint-suspension   gives more information."
       report.error(em"""Cyclic macro dependencies $where
                     |Compilation stopped since no further progress can be made.
                     |
                     |To fix this, place macros in one set of files and their callers in another.$enableXprintSuspensionHint""")
     newUnits
-  }
 
   def run(using Context): Unit = unsupported("run")
 }

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

@@ -0,0 +1,26 @@
+package dotty.tools.dotc
+package typer
+
+import core.Contexts._
+import ast.tpd._
+
+/** PostTyper doesn't run on java sources,
+ *  but some checks still need to be applied.
+ */
+object JavaChecks {
+  /** Check the bounds of AppliedTypeTrees. */
+  private object AppliedTypeChecker extends TreeTraverser {
+    def traverse(tree: Tree)(using Context): Unit = tree match
+      case tpt: TypeTree =>
+        Checking.checkAppliedTypesIn(tpt)
+      case tree: AppliedTypeTree =>
+        Checking.checkAppliedType(tree)
+      case _ =>
+        traverseChildren(tree)
+  }
+
+  /** Scan a tree and check it. */
+  def check(tree: Tree)(using Context): Unit =
+    report.debuglog("checking type bounds in " + ctx.compilationUnit.source.name)
+    AppliedTypeChecker.traverse(tree)
+}

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -229,8 +229,10 @@ trait ParallelTesting extends RunnerOrchestration { self =>
      */
     final def checkFile(testSource: TestSource): Option[JFile] = (testSource match {
       case ts: JointCompilationSource =>
-        ts.files.collectFirst { case f if !f.isDirectory => new JFile(f.getPath.replaceFirst("\\.scala$", ".check")) }
-
+        ts.files.collectFirst {
+          case f if !f.isDirectory =>
+            new JFile(f.getPath.replaceFirst("\\.(scala|java)$", ".check"))
+        }
       case ts: SeparateCompilationSource =>
         Option(new JFile(ts.dir.getPath + ".check"))
     }).filter(_.exists)
@@ -679,7 +681,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     def getErrorMapAndExpectedCount(files: Seq[JFile]): (HashMap[String, Integer], Int) = {
       val errorMap = new HashMap[String, Integer]()
       var expectedErrors = 0
-      files.filter(_.getName.endsWith(".scala")).foreach { file =>
+      files.filter(isSourceFile).foreach { file =>
         Using(Source.fromFile(file, "UTF-8")) { source =>
           source.getLines.zipWithIndex.foreach { case (line, lineNbr) =>
             val errors = line.toSeq.sliding("// error".length).count(_.unwrap == "// error")

tests/neg/WrongBounds.java

@@ -0,0 +1,7 @@
+import java.util.*;
+
+class WrongBounds {
+  class LL<T> extends ArrayList<List<T>> {}
+  class Wrap<T extends List<List<?>>> extends ArrayList<T> {}
+  class Wrong<T extends LL<?>> extends Wrap<T> {} // error
+}

tests/neg/java-wrong-bounds/D_1.scala

@@ -0,0 +1,5 @@
+class A
+
+class D[T >: A](v: T) {
+  def getV(): T = v
+}

tests/neg/java-wrong-bounds/J_2.java

@@ -0,0 +1,23 @@
+public class J_2 extends D<String> { // error
+
+  public J_2() {
+    super(null);
+  }
+
+  public static D<String> getDS() { // error
+    return new D<String>("DS");
+  }
+
+  public static final D<String> fieldDS = new D<String>("DS"); // error
+
+  public static void useDS(D<String> ds) {} // error
+
+  public static <A extends D<String>> void genericDS() {} // error
+
+  public static void useOK(D<?> ds) {}
+
+  public static D<?> getOK() {return null;}
+
+  public static <A extends D<?>> D<?> genericOK(A a) {return a;}
+
+}