Replacing __BEGIN_DECLS in curses

[Roy Marples <roy%marples.name@localhost>]

Hi List

It seems our beloved curses library has been made portable, to work on 
Linux + musl libc.
https://github.com/sabotage-linux/netbsd-curses
I'm in discussions with one of their devs about pushing some of their 
patches into NetBSD so it's easier for them to sync our changes back 
down.

One such change is replacing __BEGIN_DECLS and __END_DECLS with expanded 
macros like
#ifdef cplusplus
extern "C" {
#endif

Which is a lot more portable and very standard.
Suggested patch to curses, forms and panel attached.
Commentary welcome.

Roy

Index: libcurses/curses.h
===================================================================
RCS file: /cvsroot/src/lib/libcurses/curses.h,v
retrieving revision 1.115
diff -u -p -r1.115 curses.h
--- libcurses/curses.h	4 Jan 2017 03:51:29 -0000	1.115
+++ libcurses/curses.h	4 Jan 2017 10:39:12 -0000
@@ -283,11 +283,13 @@ typedef struct __screen SCREEN;
 
 #define	NUM_ACS	128
 
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 extern chtype _acs_char[NUM_ACS];
-__END_DECLS
 #ifdef __cplusplus
 #define __UC_CAST(a)	static_cast<unsigned char>(a)
+}
 #else
 #define __UC_CAST(a)	(unsigned char)(a)
 #endif
@@ -329,9 +331,13 @@ __END_DECLS
 #define	ACS_STERLING	_acs_char[__UC_CAST('}')]
 
 #ifdef HAVE_WCHAR
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 extern cchar_t _wacs_char[NUM_ACS];
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 
 #define	WACS_RARROW     (&_wacs_char[(unsigned char)'+'])
 #define	WACS_LARROW     (&_wacs_char[(unsigned char)','])
@@ -396,6 +402,7 @@ __END_DECLS
 
 #ifdef __cplusplus
 #define __UINT32_CAST(a)	static_cast<u_int32_t>(a)
+extern "C" {
 #else
 #define __UINT32_CAST(a)	(u_int32_t)(a)
 #endif
@@ -403,7 +410,6 @@ __END_DECLS
 #define	PAIR_NUMBER(n)	(((__UINT32_CAST(n)) & A_COLOR) >> 17)
 
 /* Curses external declarations. */
-__BEGIN_DECLS
 extern WINDOW	*curscr;		/* Current screen. */
 extern WINDOW	*stdscr;		/* Standard screen. */
 
@@ -416,7 +422,9 @@ extern int	 COLOR_PAIRS;		/* Max color p
 
 extern int	 ESCDELAY;		/* Delay between keys in esc seq's. */
 extern int	 TABSIZE;		/* Size of a tab. */
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 
 #ifndef OK
 #define	ERR	(-1)			/* Error return. */
@@ -533,7 +541,9 @@ __END_DECLS
 
 #else
 /* Use functions not macros... */
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 int	 addbytes(const char *, int);
 int	 addch(chtype);
 int	 addchnstr(const chtype *, int);
@@ -612,7 +622,9 @@ int	 mvwgetnstr(WINDOW *, int, int, char
 int	 mvwgetstr(WINDOW *, int, int, char *);
 chtype	 mvwinch(WINDOW *, int, int);
 int	 mvwinsch(WINDOW *, int, int, chtype);
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 #endif /* _CURSES_USE_MACROS */
 
 #define	getyx(w, y, x)		(y) = getcury(w), (x) = getcurx(w)
@@ -639,7 +651,9 @@ __END_DECLS
 
 
 /* Public function prototypes. */
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 int	 assume_default_colors(short, short);
 int	 baudrate(void);
 int	 beep(void);
@@ -962,6 +976,9 @@ int	 __waddbytes(WINDOW *, const char *,
 #ifdef HAVE_WCHAR
 int __cputwchar( wchar_t );
 #endif /* HAVE_WCHAR */
-__END_DECLS
+
+#if defined(__cplusplus)
+}
+#endif
 
 #endif /* !_CURSES_H_ */
Index: libform/form.h
===================================================================
RCS file: /cvsroot/src/lib/libform/form.h,v
retrieving revision 1.23
diff -u -p -r1.23 form.h
--- libform/form.h	7 Sep 2015 15:50:49 -0000	1.23
+++ libform/form.h	4 Jan 2017 10:39:12 -0000
@@ -238,16 +238,6 @@ struct _form_field {
 	FORM_STR *buffers; /* array of buffers for the field */
 };
 
-/* define the types of fields we can have */
-extern FIELDTYPE *TYPE_ALNUM;
-extern FIELDTYPE *TYPE_ALPHA;
-extern FIELDTYPE *TYPE_ENUM;
-extern FIELDTYPE *TYPE_INTEGER;
-extern FIELDTYPE *TYPE_NUMERIC;
-extern FIELDTYPE *TYPE_REGEXP;
-extern FIELDTYPE *TYPE_IPV4;
-extern FIELDTYPE *TYPE_IPV6;
-extern FIELDTYPE *TYPE_USER;
 
 /* definition of a field type. */
 struct _form_fieldtype {
@@ -296,9 +286,23 @@ struct _form_struct {
 	FIELD **fields; /* array of fields attached to this form. */
 };
 
-/* Public function prototypes. */
-__BEGIN_DECLS
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* define the types of fields we can have */
+extern FIELDTYPE *TYPE_ALNUM;
+extern FIELDTYPE *TYPE_ALPHA;
+extern FIELDTYPE *TYPE_ENUM;
+extern FIELDTYPE *TYPE_INTEGER;
+extern FIELDTYPE *TYPE_NUMERIC;
+extern FIELDTYPE *TYPE_REGEXP;
+extern FIELDTYPE *TYPE_IPV4;
+extern FIELDTYPE *TYPE_IPV6;
+extern FIELDTYPE *TYPE_USER;
+
+/* Public function prototypes. */
 FIELD       *current_field(FORM *);
 int          data_ahead(FORM *);
 int          data_behind(FORM *);
@@ -377,6 +381,8 @@ int          set_max_field(FIELD *, int)
 int          set_new_page(FIELD *, int);
 int          unpost_form(FORM *);
 
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 
 #endif /* FORM_H */
Index: libpanel/panel.h
===================================================================
RCS file: /cvsroot/src/lib/libpanel/panel.h,v
retrieving revision 1.2
diff -u -p -r1.2 panel.h
--- libpanel/panel.h	2 Nov 2015 01:06:15 -0000	1.2
+++ libpanel/panel.h	4 Jan 2017 10:39:12 -0000
@@ -33,7 +33,10 @@
 
 typedef struct __panel PANEL;
 
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 PANEL  *new_panel(WINDOW *);
 int     del_panel(PANEL *);
 
@@ -56,6 +59,9 @@ PANEL  *panel_below(PANEL *);
 int     move_panel(PANEL *, int, int);
 
 void    update_panels(void);
-__END_DECLS
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif	/* _PANEL_H_ */