SI-7582 ClassfileParser: populate privateWithin of Java module class

The `privateWithin` attribute of Java companion module classes was
correctly set under joint compilation (ie, when using JavaParser),
but not under separate compilation.

This commit remedies this. The test covers variety of Java symbols.

2 files changed, 30 insertions, 0 deletions

diff --git a/test/files/run/t7582-private-within/JavaPackagePrivate.java b/test/files/run/t7582-private-within/JavaPackagePrivate.java
new file mode 100644
index 0000000000..672d19b57e
--- /dev/null
+++ b/test/files/run/t7582-private-within/JavaPackagePrivate.java
@@ -0,0 +1,8 @@
+package pack;
+
+class JavaPackagePrivate {
+	int field = 0;
+	static int staticField = 0;
+	void meth() { }
+	static void staticMeth() { }
+}
diff --git a/test/files/run/t7582-private-within/Test.scala b/test/files/run/t7582-private-within/Test.scala
new file mode 100644
index 0000000000..3d581f063b
--- /dev/null
+++ b/test/files/run/t7582-private-within/Test.scala
@@ -0,0 +1,22 @@
+import scala.tools.partest.DirectTest
+
+// Testing that the `privateWithin` field is correctly populated on all
+// the related symbols (e.g. module class) under separate compilation.
+object Test extends DirectTest {
+  def code = ???
+
+  def show(): Unit = {
+    val classpath = List(sys.props("partest.lib"), testOutput.path) mkString sys.props("path.separator")
+    val global = newCompiler("-usejavacp", "-cp", classpath, "-d", testOutput.path)
+    import global._
+    withRun(global) { _ =>
+      def check(sym: Symbol) = {
+        sym.initialize
+        println(f"${sym.accessString}%12s ${sym.accurateKindString} ${sym.name.decode}") // we want to see private[pack] for all of these.
+      }
+      val sym = rootMirror.getRequiredClass("pack.JavaPackagePrivate")
+      val syms = Seq(sym, sym.companionModule, sym.companionModule.moduleClass)
+      (syms ++ syms.flatMap(_.info.decls)).foreach(check)
+    }
+  }
+}