Merge pull request #4623 from retronym/ticket/9392

SI-9392 Avoid crash in GenBCode for incoherent trees

Author: adriaanm

src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala

@@ -351,6 +351,14 @@ class BTypesFromSymbols[G <: Global](val global: G) extends BTypes {
  val isTopLevel = innerClassSym.rawowner.isPackageClass
  // impl classes are considered top-level, see comment in BTypes
  if (isTopLevel || considerAsTopLevelImplementationArtifact(innerClassSym)) None
+ else if (innerClassSym.rawowner.isTerm)
+ // SI-9392 An errant macro might leave a reference to a local class symbol that no longer exists in the tree,
+ // this avoids an assertion error in that case. AFAICT, we don't actually need the `NestedInfo` for all BTypes,
+ // only for ones that describe classes defined in the trees that reach the backend, so this is safe enough.
+ //
+ // TODO Can we avoid creating `NestedInfo` for each type that is referred to, and instead only create if for
+ // symbols of ClassDefs?
+ None
  else {
  // See comment in BTypes, when is a class marked static in the InnerClass table.
  val isStaticNestedClass = isOriginallyStaticOwner(innerClassSym.originalOwner)

test/files/pos/t9392/client_2.scala

@@ -0,0 +1,4 @@
+class Client {
+ Macro()
+}
+

test/files/pos/t9392/macro_1.scala

@@ -0,0 +1,16 @@
+import language.experimental.macros
+
+
+object Macro {
+
+ import reflect.macros.blackbox.Context
+ def impl(c: Context)(): c.Tree = {
+ import c.universe._
+ val tree = q"""class C; new C"""
+ val tree1 = c.typecheck(tree)
+ val tpe = tree1.tpe
+ val tree2 = c.typecheck(c.untypecheck(tree1))
+ q"""$tree2.asInstanceOf[$tpe]"""
+ }
+ def apply(): Any = macro impl
+}