Merge pull request #1936 from retronym/ticket/6891

SI-6891 Fix value class + tailrec crasher.

2 files changed, 27 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index a4287fb181..c274a9e3af 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -1651,6 +1651,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
     @inline final def map(f: Symbol => Symbol): Symbol = if (this eq NoSymbol) this else f(this)
 
+    final def toOption: Option[Symbol] = if (exists) Some(this) else None
+
 // ------ cloneing -------------------------------------------------------------------
 
     /** A clone of this symbol. */
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index 431afd286d..a528a9ced8 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -1440,6 +1440,22 @@ trait Trees extends api.Trees { self: SymbolTable =>
       if (tree.hasSymbol) {
         subst(from, to)
         tree match {
+          case _: DefTree =>
+            val newInfo = symSubst(tree.symbol.info)
+            if (!(newInfo =:= tree.symbol.info)) {
+              debuglog(sm"""
+                |TreeSymSubstituter: updated info of symbol ${tree.symbol}
+                |  Old: ${showRaw(tree.symbol.info, printTypes = true, printIds = true)}
+                |  New: ${showRaw(newInfo, printTypes = true, printIds = true)}""")
+              tree.symbol updateInfo newInfo
+            }
+          case _          =>
+            // no special handling is required for Function or Import nodes here.
+            // as they don't have interesting infos attached to their symbols.
+            // Subsitution of the referenced symbol of Return nodes is handled
+            // in .ChangeOwnerTraverser
+        }
+        tree match {
           case Ident(name0) if tree.symbol != NoSymbol =>
             treeCopy.Ident(tree, tree.symbol.name)
           case Select(qual, name0) if tree.symbol != NoSymbol =>
@@ -1488,6 +1504,15 @@ trait Trees extends api.Trees { self: SymbolTable =>
     }
   }
 
+  trait TreeStackTraverser extends Traverser {
+    import collection.mutable
+    val path: mutable.Stack[Tree] = mutable.Stack()
+    abstract override def traverse(t: Tree) = {
+      path push t
+      try super.traverse(t) finally path.pop()
+    }
+  }
+
   private lazy val duplicator = new Transformer {
     override val treeCopy = newStrictTreeCopier
     override def transform(t: Tree) = {