Pacify GCC 10.1.0

Pacify GCC 10.1.0 so that it does not issue false alarms
when Emacs is configured with --enable-gcc-warnings.
* src/dispnew.c (clear_glyph_row):
* src/fns.c (hash_clear):
* src/keyboard.c (append_tab_bar_item):
* src/lisp.h (vcopy):
* src/xfaces.c (get_lface_attributes_no_remap)
(Finternal_copy_lisp_face, realize_default_face):
* src/xmenu.c (set_frame_menubar):
Work around -Warray-bounds false alarm in GCC 10.1.0.
* src/intervals.c (copy_properties):
Avoid -Wnull-dereference false alarm in GCC 10.1.0.
* src/lisp.h (xvector_contents_addr, xvector_contents):
New functions, useful for working around GCC bug 95072.

1 files changed, 22 insertions, 1 deletions

diff --git a/src/lisp.h b/src/lisp.h
index b4ac017dcf5..a55fa32950d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3350,6 +3350,27 @@ struct frame;
 #define HAVE_EXT_TOOL_BAR true
 #endif
 
+/* Return the address of vector A's element at index I.  */
+
+INLINE Lisp_Object *
+xvector_contents_addr (Lisp_Object a, ptrdiff_t i)
+{
+  /* This should return &XVECTOR (a)->contents[i], but that would run
+     afoul of GCC bug 95072.  */
+  void *v = XVECTOR (a);
+  char *p = v;
+  void *w = p + header_size + i * word_size;
+  return w;
+}
+
+/* Return the address of vector A's elements.  */
+
+INLINE Lisp_Object *
+xvector_contents (Lisp_Object a)
+{
+  return xvector_contents_addr (a, 0);
+}
+
 /* Copy COUNT Lisp_Objects from ARGS to contents of V starting from OFFSET.  */
 
 INLINE void
@@ -3357,7 +3378,7 @@ vcopy (Lisp_Object v, ptrdiff_t offset, Lisp_Object const *args,
        ptrdiff_t count)
 {
   eassert (0 <= offset && 0 <= count && offset + count <= ASIZE (v));
-  memcpy (XVECTOR (v)->contents + offset, args, count * sizeof *args);
+  memcpy (xvector_contents_addr (v, offset), args, count * sizeof *args);
 }
 
 /* Functions to modify hash tables.  */