PR c++/65051

	* call.c (reference_binding): Don't look for bad conversion
	if TO is incomplete.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@220685 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 13 insertions, 0 deletions

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index f2076c67aee..2b15185a895 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -1694,6 +1694,19 @@ reference_binding (tree rto, tree rfrom, tree expr, bool c_cast_p, int flags,
      difference in top-level cv-qualification is subsumed by the
      initialization itself and does not constitute a conversion.  */
 
+  /* [dcl.init.ref]
+
+     Otherwise, the reference shall be an lvalue reference to a
+     non-volatile const type, or the reference shall be an rvalue
+     reference.
+
+     We try below to treat this as a bad conversion to improve diagnostics,
+     but if TO is an incomplete class, we need to reject this conversion
+     now to avoid unnecessary instantiation.  */
+  if (!CP_TYPE_CONST_NON_VOLATILE_P (to) && !TYPE_REF_IS_RVALUE (rto)
+      && !COMPLETE_TYPE_P (to))
+    return NULL;
+
   /* We're generating a temporary now, but don't bind any more in the
      conversion (specifically, don't slice the temporary returned by a
      conversion operator).  */