diff --git a/gcc/doc/gty.texi b/gcc/doc/gty.texi
index 7bd064b57815acc238eb2933861b1de9e57d4b91..15f9fa07405bb66d54a61ec768b733642df23604 100644
--- a/gcc/doc/gty.texi
+++ b/gcc/doc/gty.texi
@@ -217,6 +217,17 @@ struct GTY(()) non_terminated_string @{
 @};
 @end smallexample
 
+Similarly, this is useful for (regular NUL-terminated) strings with
+NUL characters embedded (that the default @code{strlen} use would run
+afoul of):
+
+@smallexample
+struct GTY(()) multi_string @{
+  const char * GTY((string_length ("%h.len + 1"))) str;
+  size_t len;
+@};
+@end smallexample
+
 The @code{string_length} option currently is not supported for (fields
 in) global variables.
 @c <https://inbox.sourceware.org/87bkgqvlst.fsf@euler.schwinge.homeip.net>
diff --git a/libcpp/include/symtab.h b/libcpp/include/symtab.h
index c7ccc6db9f05ad78b54d20704d3452e2399512fd..0c713f2ad30d13d19f5233b9fc660c342ef44962 100644
--- a/libcpp/include/symtab.h
+++ b/libcpp/include/symtab.h
@@ -29,9 +29,7 @@ along with this program; see the file COPYING3.  If not see
 typedef struct ht_identifier ht_identifier;
 typedef struct ht_identifier *ht_identifier_ptr;
 struct GTY(()) ht_identifier {
-  /* This GTY markup arranges that the null-terminated identifier would still
-     stream to PCH correctly, if a null byte were to make its way into an
-     identifier somehow.  */
+  /* We know the 'len'gth of the 'str'ing; use it in the GTY markup.  */
   const unsigned char * GTY((string_length ("1 + %h.len"))) str;
   unsigned int len;
   unsigned int hash_value;