Make src headers idempotent and standalone

Redo src/*.h so that each include file is idempotent (that is, can
be included multiple times with the latter inclusions having no
effect) and standalone (that is, can be included by itself,
with no include file other than config.h needed as a prerequisite).
This is standard practice in GNU programs nowadays.
* lwlib/lwlib-widget.h, src/buffer.h, src/category.h, src/character.h:
* src/charset.h, src/coding.h, src/commands.h, src/disptab.h:
* src/fontset.h, src/gnutls.h, src/indent.h, src/keymap.h, src/macros.h:
* src/regex.h [emacs]:
* src/syntax.h, src/systty.h, src/termhooks.h:
Include lisp.h, for Lisp_Object.
* src/buffer.h, src/category.h, src/cm.h, src/commands.h, src/disptab.h:
* src/indent.h, src/intervals.h, src/keyboard.h, src/macros.h:
* src/process.h, src/puresize.h, src/region-cache.h, src/syntax.h:
* src/syssignal.h, src/sysstdio.h, src/systty.h, src/termchar.h:
* src/termopts.h, src/tparam.h, src/unexec.h:
Protect against multiple inclusion.
* src/buffer.h: Include character.h, for STRING_CHAR.
* src/emacsgtkfixed.h (struct frame):
* src/fontset.h (struct face):
* src/region-cache.h (struct buffer):
* src/termhooks.h (struct glyph):
* src/xsettings.h (struct x_display_info):
Add possibly-forward decl.
* src/syntax.h: Include buffer.h, for BVAR.
* src/sysselect.h: Include lisp.h, for eassume.
* src/termchar.h: Include <stdio.h>, for FILE.
* src/widget.h: Include <X11/IntrinsicP.h>, for Widget.
* src/xsettings.h: Include <X11/Xlib.h>, for XEvent.

lwlib/lwlib-widget.h

@@ -23,6 +23,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef LWLIB_WIDGET_H
 #define LWLIB_WIDGET_H
 
+#include "../src/lisp.h"
+
 typedef enum
 {
   NO_CHANGE = 0,
@@ -96,7 +98,7 @@ typedef struct _widget_value
   /* Whether we should free the toolkit data slot when freeing the
      widget_value itself.  */
   bool free_toolkit_data;
-#endif  
+#endif
 
 } widget_value;
 

src/buffer.h

@@ -18,9 +18,15 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_BUFFER_H
+#define EMACS_BUFFER_H
+
 #include <sys/types.h>
 #include <time.h>
 
+#include "character.h"
+#include "lisp.h"
+
 INLINE_HEADER_BEGIN
 
 /* Accessing the parameters of the current buffer.  */
@@ -1377,3 +1383,5 @@ lowercasep (int c)
 INLINE int upcase (int c) { return uppercasep (c) ? c : upcase1 (c); }
 
 INLINE_HEADER_END
+
+#endif /* EMACS_BUFFER_H */

src/category.h

@@ -22,6 +22,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_CATEGORY_H
+#define EMACS_CATEGORY_H
 
 /* We introduce here three types of object: category, category set,
    and category table.
@@ -53,6 +55,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
    The second extra slot is a version number of the category table.
    But, for the moment, we are not using this slot.  */
 
+#include "lisp.h"
+
 INLINE_HEADER_BEGIN
 
 #define CATEGORYP(x) RANGED_INTEGERP (0x20, x, 0x7E)
@@ -116,3 +120,5 @@ CHAR_HAS_CATEGORY (int ch, int category)
 extern bool word_boundary_p (int, int);
 
 INLINE_HEADER_END
+
+#endif /* EMACS_CATEGORY_H */

src/character.h

@@ -24,6 +24,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #define EMACS_CHARACTER_H
 
 #include <verify.h>
+#include "lisp.h"
 
 INLINE_HEADER_BEGIN
 

src/charset.h

@@ -28,6 +28,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #define EMACS_CHARSET_H
 
 #include <verify.h>
+#include "lisp.h"
 
 INLINE_HEADER_BEGIN
 

src/cm.h

@@ -16,6 +16,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_CM_H
+#define EMACS_CM_H
+
 /* Holds the minimum and maximum costs for the parameterized capabilities.  */
 struct parmcap
   {
@@ -166,3 +169,5 @@ extern void cmcostinit (struct tty_display_info *);
 extern void cmgoto (struct tty_display_info *, int, int);
 extern void Wcm_clear (struct tty_display_info *);
 extern int Wcm_init (struct tty_display_info *);
+
+#endif /* EMACS_CM_H */

src/coding.h

@@ -26,6 +26,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef EMACS_CODING_H
 #define EMACS_CODING_H
 
+#include "lisp.h"
+
 /* Index to arguments of Fdefine_coding_system_internal.  */
 
 enum define_coding_system_arg_index

src/commands.h

@@ -16,6 +16,10 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_COMMANDS_H
+#define EMACS_COMMANDS_H
+
+#include "lisp.h"
 
 #define Ctl(c) ((c)&037)
 
@@ -39,3 +43,5 @@ extern Lisp_Object unread_switch_frame;
 /* Nonzero if input is coming from the keyboard.  */
 
 #define INTERACTIVE (NILP (Vexecuting_kbd_macro) && !noninteractive)
+
+#endif /* EMACS_COMMANDS_H */

src/disptab.h

@@ -18,6 +18,11 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* Access the slots of a display-table, according to their purpose.  */
 
+#ifndef EMACS_DISPTAB_H
+#define EMACS_DISPTAB_H
+
+#include "lisp.h"
+
 #define DISP_TABLE_P(obj)						    \
   (CHAR_TABLE_P (obj)							    \
    && EQ (XCHAR_TABLE (obj)->purpose, Qdisplay_table)			    \
@@ -92,3 +97,5 @@ extern struct Lisp_Char_Table *buffer_display_table (void);
 
 #define SET_GLYPH_FROM_CHAR(glyph, c) \
   SET_GLYPH (glyph, c, DEFAULT_FACE_ID)
+
+#endif /* EMACS_DISPTAB_H */

src/emacsgtkfixed.h

@@ -23,6 +23,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <gtk/gtk.h>
 
+struct frame;
+
 G_BEGIN_DECLS
 
 extern GtkWidget *emacs_fixed_new (struct frame *f);

src/fontset.h

@@ -26,6 +26,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef EMACS_FONTSET_H
 #define EMACS_FONTSET_H
 
+#include "lisp.h"
+
+struct face;
+
 extern void free_face_fontset (struct frame *, struct face *);
 extern int face_for_char (struct frame *, struct face *, int,
                           ptrdiff_t, Lisp_Object);

src/gnutls.h

@@ -23,6 +23,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <gnutls/gnutls.h>
 #include <gnutls/x509.h>
 
+#include "lisp.h"
+
 /* This limits the attempts to handshake per process (connection).  */
 #define GNUTLS_EMACS_HANDSHAKES_LIMIT 100
 

src/indent.h

@@ -16,6 +16,11 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_INDENT_H
+#define EMACS_INDENT_H
+
+#include "lisp.h"
+
 struct position
   {
     ptrdiff_t bufpos;
@@ -51,3 +56,5 @@ bool disptab_matches_widthtab (struct Lisp_Char_Table *disptab,
 /* Recompute BUF's width table, using the display table DISPTAB.  */
 void recompute_width_table (struct buffer *buf,
                             struct Lisp_Char_Table *disptab);
+
+#endif /* EMACS_INDENT_H */

src/intervals.h

@@ -16,6 +16,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_INTERVALS_H
+#define EMACS_INTERVALS_H
+
 #include "dispextern.h"
 
 INLINE_HEADER_BEGIN
@@ -295,3 +298,5 @@ extern void syms_of_textprop (void);
 #include "composite.h"
 
 INLINE_HEADER_END
+
+#endif /* EMACS_INTERVALS_H */

src/keyboard.h

@@ -17,6 +17,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_KEYBOARD_H
+#define EMACS_KEYBOARD_H
+
 #include "systime.h"		/* for struct timespec, Time */
 #include "coding.h"             /* for ENCODE_UTF_8 and ENCODE_SYSTEM */
 #include "termhooks.h"
@@ -483,3 +486,5 @@ extern const char *const lispy_function_keys[];
 #endif
 
 INLINE_HEADER_END
+
+#endif /* EMACS_KEYBOARD_H */

src/keymap.h

@@ -19,6 +19,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef KEYMAP_H
 #define KEYMAP_H
 
+#include "lisp.h"
+
 /* The maximum byte size consumed by push_key_description.
    All callers should assure that at least this size of memory is
    allocated at the place pointed by the second argument.

src/macros.h

@@ -16,6 +16,10 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_MACROS_H
+#define EMACS_MACROS_H
+
+#include "lisp.h"
 
 /* Number of successful iterations so far
    for innermost keyboard macro.
@@ -42,3 +46,5 @@ extern void finalize_kbd_macro_chars (void);
 /* Store a character into kbd macro being defined */
 
 extern void store_kbd_macro_char (Lisp_Object);
+
+#endif /* EMACS_MACROS_H */

src/process.h

@@ -16,6 +16,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_PROCESS_H
+#define EMACS_PROCESS_H
+
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
@@ -243,3 +246,5 @@ extern Lisp_Object network_interface_info (Lisp_Object);
 extern Lisp_Object remove_slash_colon (Lisp_Object);
 
 INLINE_HEADER_END
+
+#endif /* EMACS_PROCESS_H */

src/puresize.h

@@ -16,6 +16,11 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_PURESIZE_H
+#define EMACS_PURESIZE_H
+
+#include "lisp.h"
+
 INLINE_HEADER_BEGIN
 
 /* Define PURESIZE, the number of bytes of pure Lisp code to leave space for.
@@ -92,3 +97,5 @@ CHECK_IMPURE (Lisp_Object obj, void *ptr)
 }
 
 INLINE_HEADER_END
+
+#endif /* EMACS_PURESIZE_H */

src/regex.h

@@ -167,6 +167,7 @@ typedef unsigned long reg_syntax_t;
 extern reg_syntax_t re_syntax_options;
 
 #ifdef emacs
+# include "lisp.h"
 /* In Emacs, this is the string or buffer in which we
    are matching.  It is used for looking up syntax properties.  */
 extern Lisp_Object re_match_object;

src/region-cache.h

@@ -18,6 +18,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_REGION_CACHE_H
+#define EMACS_REGION_CACHE_H
 
 /* This code was written by Jim Blandy <jimb@cs.oberlin.edu> to help
    GNU Emacs better support the gene editor written for the University
@@ -60,6 +62,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
    this region has property P" vs. "I don't know if this region has
    property P or not."  */
 
+struct buffer;
 
 /* Allocate, initialize and return a new, empty region cache.  */
 struct region_cache *new_region_cache (void);
@@ -105,3 +108,5 @@ extern int region_cache_forward (struct buffer *buf, struct region_cache *c,
 /* Likewise, except before POS rather than after POS.  */
 extern int region_cache_backward (struct buffer *buf, struct region_cache *c,
 				  ptrdiff_t pos, ptrdiff_t *next);
+
+#endif /* EMACS_REGION_CACHE_H */

src/syntax.h

@@ -18,6 +18,12 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_SYNTAX_H
+#define EMACS_SYNTAX_H
+
+#include "buffer.h"
+#include "lisp.h"
+
 INLINE_HEADER_BEGIN
 
 extern void update_syntax_table (ptrdiff_t, EMACS_INT, bool, Lisp_Object);
@@ -213,3 +219,5 @@ extern ptrdiff_t scan_words (ptrdiff_t, EMACS_INT);
 extern void SETUP_SYNTAX_TABLE_FOR_OBJECT (Lisp_Object, ptrdiff_t, ptrdiff_t);
 
 INLINE_HEADER_END
+
+#endif /* EMACS_SYNTAX_H */

src/sysselect.h

@@ -23,6 +23,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <sys/select.h>
 #endif
 
+#include "lisp.h"
+
 /* The w32 build defines select stuff in w32.h, which is included
    where w32 needs it, but not where sysselect.h is included.  The w32
    definitions in w32.h are incompatible with the below.  */

src/syssignal.h

@@ -17,6 +17,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_SYSSIGNAL_H
+#define EMACS_SYSSIGNAL_H
+
 #include <signal.h>
 
 extern void init_signals (bool);
@@ -72,3 +75,5 @@ char const *safe_strsignal (int) ATTRIBUTE_CONST;
 #endif
 
 void deliver_process_signal (int, signal_handler_t);
+
+#endif /* EMACS_SYSSIGNAL_H */

src/sysstdio.h

@@ -17,6 +17,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_SYSSTDIO_H
+#define EMACS_SYSSTDIO_H
+
 #include <fcntl.h>
 #include <stdio.h>
 
@@ -29,3 +32,5 @@ extern FILE *emacs_fopen (char const *, char const *);
 # define FOPEN_BINARY ""
 # define FOPEN_TEXT ""
 #endif
+
+#endif /* EMACS_SYSSTDIO_H */

src/systty.h

@@ -16,6 +16,9 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_SYSTTY_H
+#define EMACS_SYSTTY_H
+
 /* Include the proper files.  */
 
 #ifndef DOS_NT
@@ -37,6 +40,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <unistd.h>
 
+#include "lisp.h"
+
 
 /* Try to establish the correct character to disable terminal functions
    in a system-independent manner.  Note that USG (at least) define
@@ -85,3 +90,5 @@ extern int emacs_set_tty (int, struct emacs_tty *, bool) EXTERNALLY_VISIBLE;
 extern void suppress_echo_on_tty (int);
 extern int serial_open (Lisp_Object);
 extern void serial_configure (struct Lisp_Process *, Lisp_Object);
+
+#endif /* EMACS_SYSTTY_H */

src/termchar.h

@@ -16,6 +16,10 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_TERMCHAR_H
+#define EMACS_TERMCHAR_H
+
+#include <stdio.h>
 #include "dispextern.h"
 
 /* Each termcap frame points to its own struct tty_output object in
@@ -230,3 +234,5 @@ extern struct tty_display_info *tty_list;
    : (emacs_abort (), (struct tty_display_info *) 0))
 
 #define CURTTY() FRAME_TTY (SELECTED_FRAME())
+
+#endif /* EMACS_TERMCHAR_H */

src/termhooks.h

@@ -23,8 +23,11 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* Miscellanea.   */
 
+#include "lisp.h"
 #include "systime.h" /* for Time */
 
+struct glyph;
+
 INLINE_HEADER_BEGIN
 
 enum scroll_bar_part {

src/termopts.h

@@ -17,9 +17,13 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_TERMOPTS_H
+#define EMACS_TERMOPTS_H
 
 /* Nonzero means use interrupt-driven input.  */
 extern bool interrupt_input;
 
 /* Nonzero while interrupts are temporarily deferred during redisplay.  */
 extern bool interrupts_deferred;
+
+#endif /* EMACS_TERMOPTS_H */

src/tparam.h

@@ -17,6 +17,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef EMACS_TPARAM_H
+#define EMACS_TPARAM_H
 
 /* Don't try to include termcap.h.  On some systems, configure finds a
    non-standard termcap.h that the main build won't find.  */
@@ -33,3 +35,5 @@ char *tparam (const char *, char *, int, int, int, int, int);
 extern char PC;
 extern char *BC;
 extern char *UP;
+
+#endif /* EMACS_TPARAM_H */

src/unexec.h

@@ -1 +1,4 @@
+#ifndef EMACS_UNEXEC_H
+#define EMACS_UNEXEC_H
 void unexec (const char *, const char *);
+#endif /* EMACS_UNEXEC_H */

src/widget.h

@@ -21,6 +21,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef _EmacsFrame_h
 #define _EmacsFrame_h
 
+#include <X11/IntrinsicP.h>
+
 #define XtNminibuffer "minibuffer"
 #define XtCMinibuffer "Minibuffer"
 #define XtNunsplittable "unsplittable"

src/xsettings.h

@@ -20,6 +20,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifndef XSETTINGS_H
 #define XSETTINGS_H
 
+#include <X11/Xlib.h>
+
+struct x_display_info;
+
 extern void xsettings_initialize (struct x_display_info *);
 extern void xft_settings_event (struct x_display_info *, const XEvent *);
 extern const char *xsettings_get_system_font (void);