Use union for the payload of struct Lisp_Vector.

This helps to avoid a few glitches dictated by C's aliasing rules.
* lisp.h (struct Lisp_Vector): Use union for next and
contents member.  Adjust comment.  Change related users.
* alloc.c (next_in_free_list, set_next_in_free_list): Remove.
Related users changed.
* buffer.c, bytecode.c, ccl.c, character.h, chartab.c, composite.c:
* composite.h, disptab.h, fns.c, fontset.c, indent.c, keyboard.c:
* lread.c, msdos.c, process.c, w32menu.c, window.c, xdisp.c:
* xfaces.c, xfont.c, xmenu.c: Related users changed.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 815f3926c55..1570f3831ac 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4534,7 +4534,7 @@ report_overlay_modification (Lisp_Object start, Lisp_Object end, bool after,
     Lisp_Object *copy = alloca (size * sizeof *copy);
     ptrdiff_t i;
 
-    memcpy (copy, XVECTOR (last_overlay_modification_hooks)->contents,
+    memcpy (copy, XVECTOR (last_overlay_modification_hooks)->u.contents,
             size * word_size);
     gcpro1.var = copy;
     gcpro1.nvars = size;