lib/string/: Use [0] for end pointers

This helps document the fact that these pointers are pointers to
one-after-the-last element of an array.  GCC currently has a bug by
which it triggers a diagnostic in this code.  However, it works just
fine, and the diagnostic can be ignored.  We're working on removing that
false positive in GCC, so the diagnostic will eventually disappear.

Link: <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108036>
Signed-off-by: Alejandro Colomar <[email protected]>

Author: alejandro-colomar

lib/string/sprintf/seprintf.c

@@ -10,8 +10,8 @@
 
 
 #if !defined(HAVE_SEPRINTF)
-extern inline char *seprintf(char *dst, const char *end,
+extern inline char *seprintf(char *dst, const char end[0],
     const char *restrict fmt, ...);
-extern inline char *vseprintf(char *dst, const char *end,
+extern inline char *vseprintf(char *dst, const char end[0],
     const char *restrict fmt, va_list ap);
 #endif

lib/string/sprintf/seprintf.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024, Alejandro Colomar <[email protected]>
+// SPDX-FileCopyrightText: 2022-2025, Alejandro Colomar <[email protected]>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -18,18 +18,18 @@
 #if !defined(HAVE_SEPRINTF)
 // seprintf - string end-pointer print formatted
 format_attr(printf, 3, 4)
-inline char *seprintf(char *dst, const char *end, const char *restrict fmt,
+inline char *seprintf(char *dst, const char end[0], const char *restrict fmt,
     ...);
 // vseprintf - va_list string end-pointer print formatted
 format_attr(printf, 3, 0)
-inline char *vseprintf(char *dst, const char *end, const char *restrict fmt,
+inline char *vseprintf(char *dst, const char end[0], const char *restrict fmt,
     va_list ap);
 #endif
 
 
 #if !defined(HAVE_SEPRINTF)
 inline char *
-seprintf(char *dst, const char *end, const char *restrict fmt, ...)
+seprintf(char *dst, const char end[0], const char *restrict fmt, ...)
 {
 	char     *p;
 	va_list  ap;
@@ -45,7 +45,7 @@ seprintf(char *dst, const char *end, const char *restrict fmt, ...)
 
 #if !defined(HAVE_SEPRINTF)
 inline char *
-vseprintf(char *dst, const char *end, const char *restrict fmt, va_list ap)
+vseprintf(char *dst, const char end[0], const char *restrict fmt, va_list ap)
 {
 	int        len;
 	ptrdiff_t  size;

lib/string/strcpy/stpecpy.c

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024, Alejandro Colomar <[email protected]>
+// SPDX-FileCopyrightText: 2022-2025, Alejandro Colomar <[email protected]>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -8,6 +8,6 @@
 
 
 #if !defined(HAVE_STPECPY)
-extern inline char *stpecpy(char *dst, const char *end,
+extern inline char *stpecpy(char *dst, const char end[0],
     const char *restrict src);
 #endif

lib/string/strcpy/stpecpy.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024, Alejandro Colomar <[email protected]>
+// SPDX-FileCopyrightText: 2022-2025, Alejandro Colomar <[email protected]>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -20,13 +20,13 @@
 #if !defined(HAVE_STPECPY)
 // stpecpy - string offset-pointer end-pointer copy
 ATTR_STRING(3)
-inline char *stpecpy(char *dst, const char *end, const char *restrict src);
+inline char *stpecpy(char *dst, const char end[0], const char *restrict src);
 #endif
 
 
 #if !defined(HAVE_STPECPY)
 inline char *
-stpecpy(char *dst, const char *end, const char *restrict src)
+stpecpy(char *dst, const char end[0], const char *restrict src)
 {
 	ssize_t  dlen;