Pacify --enable-gcc-warnings when no window system is used.

These warnings found that subscript error, so they seem worthwhile.
* composite.c (char_composable_p): Simplify a bit.
* frame.c (x_set_frame_parameters): Add an IF_LINT.
* frame.c (x_set_horizontal_scroll_bars, x_set_scroll_bar_height):
* frame.h (FRAME_HAS_HORIZONTAL_SCROLL_BARS):
* window.c (set_window_scroll_bars):
Use USE_HORIZONTAL_SCROLL_BARS for simplicity.
* frame.h [! USE_HORIZONTAL_SCROLL_BARS]:
Ignore -Wsuggest-attribute=const.
* window.h (USE_HORIZONTAL_SCROLL_BARS): New macro.
(WINDOW_HAS_HORIZONTAL_SCROLL_BAR): Use it.

1 files changed, 8 insertions, 3 deletions

diff --git a/src/frame.h b/src/frame.h
index 0f34770d9b4..c942a9008fa 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -868,9 +868,7 @@ default_pixels_per_inch_y (void)
 #endif /* HAVE_WINDOW_SYSTEM */
 
 /* Whether horizontal scroll bars are currently enabled for frame F.  */
-#if (defined (HAVE_WINDOW_SYSTEM)                                       \
-     && ((defined (USE_TOOLKIT_SCROLL_BARS) && !defined (HAVE_NS))      \
-         || defined (HAVE_NTGUI)))
+#if USE_HORIZONTAL_SCROLL_BARS
 #define FRAME_HAS_HORIZONTAL_SCROLL_BARS(f) \
   ((f)->horizontal_scroll_bars)
 #else
@@ -1501,4 +1499,11 @@ extern Lisp_Object make_monitor_attribute_list (struct MonitorInfo *monitors,
 
 INLINE_HEADER_END
 
+/* Suppress -Wsuggest-attribute=const if there are no scroll bars.
+   This is for functions like x_set_horizontal_scroll_bars that have
+   no effect in this case.  */
+#if ! USE_HORIZONTAL_SCROLL_BARS && 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+# pragma GCC diagnostic ignored "-Wsuggest-attribute=const"
+#endif
+
 #endif /* not EMACS_FRAME_H */