c32swidth: New module.

* lib/uchar.in.h (c32swidth): New declaration.
* lib/wcswidth-impl.h: Use macros FUNC, UNIT, CHARACTER_WIDTH.
* lib/wcswidth.c: Define FUNC, UNIT, CHARACTER_WIDTH before including
wcswidth-impl.h.
* lib/c32swidth.c: New file.
* modules/c32swidth: New file.
* m4/uchar_h.m4 (gl_UCHAR_H_REQUIRE_DEFAULTS): Initialize
GNULIB_C32SWIDTH.
* modules/uchar (Makefile.am): Substitute GNULIB_C32SWIDTH.

4 files changed, 72 insertions, 7 deletions

diff --git a/lib/c32swidth.c b/lib/c32swidth.c
new file mode 100644
index 0000000000..2f7adcf74c
--- /dev/null
+++ b/lib/c32swidth.c
@@ -0,0 +1,43 @@
+/* Determine number of screen columns needed for a size-bounded 32-bit wide string.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#define IN_C32SWIDTH
+/* Specification.  */
+#include <uchar.h>
+
+#if _GL_WCHAR_T_IS_UCS4 && !GNULIB_defined_mbstate_t
+
+# include <wchar.h>
+
+_GL_EXTERN_INLINE
+int
+c32swidth (const char32_t *s, size_t n)
+{
+  return wcswidth ((const wchar_t *) s, n);
+}
+
+#else
+
+# include <limits.h>
+
+# define FUNC c32swidth
+# define UNIT char32_t
+# define CHARACTER_WIDTH c32width
+# include "wcswidth-impl.h"
+
+#endif
diff --git a/lib/uchar.in.h b/lib/uchar.in.h
index 3815af4c26..8bf6176b8c 100644
--- a/lib/uchar.in.h
+++ b/lib/uchar.in.h
@@ -494,6 +494,25 @@ _GL_CXXALIASWARN (c32stombs);
 #endif
 
 
+/* Number of screen columns needed for a size-bounded 32-bit wide string.  */
+#if @GNULIB_C32SWIDTH@
+# if (_GL_WCHAR_T_IS_UCS4 && !GNULIB_defined_mbstate_t) && !defined IN_C32SWIDTH
+_GL_BEGIN_C_LINKAGE
+_GL_INLINE _GL_ARG_NONNULL ((1)) int
+c32swidth (const char32_t *s, size_t n)
+{
+  return wcswidth ((const wchar_t *) s, n);
+}
+_GL_END_C_LINKAGE
+# else
+_GL_FUNCDECL_SYS (c32swidth, int, (const char32_t *s, size_t n)
+                                  _GL_ARG_NONNULL ((1)));
+# endif
+_GL_CXXALIAS_SYS (c32swidth, int, (const char32_t *s, size_t n));
+_GL_CXXALIASWARN (c32swidth);
+#endif
+
+
 /* Converts a 32-bit wide character to unibyte character.
    Returns the single-byte representation of WC if it exists,
    or EOF otherwise.  */
diff --git a/lib/wcswidth-impl.h b/lib/wcswidth-impl.h
index a879bfdd93..34cb0b9814 100644
--- a/lib/wcswidth-impl.h
+++ b/lib/wcswidth-impl.h
@@ -16,16 +16,16 @@
    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
 
 int
-wcswidth (const wchar_t *s, size_t n)
+FUNC (const UNIT *s, size_t n)
 {
   int count = 0;
   for (; n > 0; s++, n--)
     {
-      wchar_t c = *s;
-      if (c == (wchar_t)'\0')
+      UNIT c = *s;
+      if (c == (UNIT)'\0')
         break;
       {
-        int width = wcwidth (c);
+        int width = CHARACTER_WIDTH (c);
         if (width < 0)
           goto found_nonprinting;
         if (width > INT_MAX - count)
@@ -39,11 +39,11 @@ wcswidth (const wchar_t *s, size_t n)
      Continue searching for a non-printing wide character.  */
   for (; n > 0; s++, n--)
     {
-      wchar_t c = *s;
-      if (c == (wchar_t)'\0')
+      UNIT c = *s;
+      if (c == (UNIT)'\0')
         break;
       {
-        int width = wcwidth (c);
+        int width = CHARACTER_WIDTH (c);
         if (width < 0)
           goto found_nonprinting;
       }
diff --git a/lib/wcswidth.c b/lib/wcswidth.c
index 8188e380fd..408b826c62 100644
--- a/lib/wcswidth.c
+++ b/lib/wcswidth.c
@@ -22,4 +22,7 @@
 
 #include <limits.h>
 
+#define FUNC wcswidth
+#define UNIT wchar_t
+#define CHARACTER_WIDTH wcwidth
 #include "wcswidth-impl.h"