diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index d566afdfcc591538bd6b591022e58f934df1dd5a..61994787d2dcdf43cdcc350043136d0e08da14e6 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -15422,9 +15422,9 @@ pack_deducible_p (tree parm, tree fn)
    it.  TARGS is a vector into which the deduced template arguments
    are placed.
 
-   Return zero for success, 2 for an incomplete match that doesn't resolve
-   all the types, and 1 for complete failure.  An error message will be
-   printed only for an incomplete match.
+   Returns either a FUNCTION_DECL for the matching specialization of FN or
+   NULL_TREE if no suitable specialization can be found.  If EXPLAIN_P is
+   true, diagnostics will be printed to explain why it failed.
 
    If FN is a conversion operator, or we are trying to produce a specific
    specialization, RETURN_TYPE is the return type desired.