PR c++/58678

	* search.c (dfs_get_pure_virtuals): Treat the destructor of an
	abstract class as pure.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@208573 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 16 insertions, 0 deletions

diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index c3eed90f6c3..66c6df5215e 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -2096,6 +2096,22 @@ dfs_get_pure_virtuals (tree binfo, void *data)
 	if (DECL_PURE_VIRTUAL_P (BV_FN (virtuals)))
 	  vec_safe_push (CLASSTYPE_PURE_VIRTUALS (type), BV_FN (virtuals));
     }
+  /* Treat a virtual destructor in an abstract class as pure even if it
+     isn't declared as pure; there is no way it would be called through the
+     vtable except during construction, which causes undefined behavior.  */
+  if (binfo == TYPE_BINFO (type)
+      && CLASSTYPE_PURE_VIRTUALS (type)
+      && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type))
+    {
+      tree dtor = CLASSTYPE_DESTRUCTORS (type);
+      if (DECL_VIRTUAL_P (dtor) && !DECL_PURE_VIRTUAL_P (dtor))
+	{
+	  tree clone;
+	  DECL_PURE_VIRTUAL_P (dtor) = true;
+	  FOR_EACH_CLONE (clone, dtor)
+	    DECL_PURE_VIRTUAL_P (clone) = true;
+	}
+    }
 
   return NULL_TREE;
 }