Re: [PATCH] uchar-h: <string.h> etc. namespace cleanup

Paul Eggert wrote on 2026-04-24:
> * lib/uchar.in.h: On GNUish platforms, include <stdint.h>,
> <wchar.h>, <wctype.h> only if needed.

This causes a compilation error in a testdir for the modules
  mbrtowc mbsrtowcs mbsnrtowcs mbsrtoc32s mbsnrtoc32s
on a GNU system:

gcc -DHAVE_CONFIG_H -I. -I../../gllib -I..  -DGNULIB_STRICT_CHECKING=1 -I/inst-x86_64-64/include -Wall  -g -O2 -MT mbrtoc32.o -MD -MP -MF .deps/mbrtoc32.Tpo -c -o mbrtoc32.o ../../gllib/mbrtoc32.c
In file included from ../../gllib/mbrtoc32.c:22:
./uchar.h: In function ‘mbsnrtoc32s’:
./uchar.h:1340:10: error: implicit declaration of function ‘mbsnrtowcs’; did you mean ‘mbsnrtoc32s’? [-Wimplicit-function-declaration]
 1340 |          mbsnrtowcs ((wchar_t *) dest, srcp, srclen, len, ps);
      |          ^~~~~~~~~~
      |          mbsnrtoc32s
./uchar.h:1340:23: error: ‘wchar_t’ undeclared (first use in this function)
 1340 |          mbsnrtowcs ((wchar_t *) dest, srcp, srclen, len, ps);
      |                       ^~~~~~~
./uchar.h:46:1: note: ‘wchar_t’ is defined in header ‘<stddef.h>’; this is probably fixable by adding ‘#include <stddef.h>’
   45 | # include_next <uchar.h>
  +++ |+#include <stddef.h>
   46 | #endif
./uchar.h:1340:23: note: each undeclared identifier is reported only once for each function it appears in
 1340 |          mbsnrtowcs ((wchar_t *) dest, srcp, srclen, len, ps);
      |                       ^~~~~~~
./uchar.h:1340:32: error: expected expression before ‘)’ token
 1340 |          mbsnrtowcs ((wchar_t *) dest, srcp, srclen, len, ps);
      |                                ^
./uchar.h: In function ‘mbsrtoc32s’:
./uchar.h:1370:10: error: implicit declaration of function ‘mbsrtowcs’; did you mean ‘mbsrtoc32s’? [-Wimplicit-function-declaration]
 1370 |          mbsrtowcs ((wchar_t *) dest, srcp, len, ps);
      |          ^~~~~~~~~
      |          mbsrtoc32s
./uchar.h:1370:22: error: ‘wchar_t’ undeclared (first use in this function)
 1370 |          mbsrtowcs ((wchar_t *) dest, srcp, len, ps);
      |                      ^~~~~~~
./uchar.h:1370:22: note: ‘wchar_t’ is defined in header ‘<stddef.h>’; this is probably fixable by adding ‘#include <stddef.h>’
./uchar.h:1370:31: error: expected expression before ‘)’ token
 1370 |          mbsrtowcs ((wchar_t *) dest, srcp, len, ps);
      |                               ^
In file included from ./wchar.h:77,
                 from ../../gllib/mbrtoc32.c:89:
/usr/include/wchar.h: At top level:
/usr/include/wchar.h:362:15: error: conflicting types for ‘mbsrtowcs’; have ‘size_t(wchar_t * restrict,  const char ** restrict,  size_t,  mbstate_t * restrict)’ {aka ‘long unsigned int(int * restrict,  const char ** restrict,  long unsigned int,  mbstate_t * restrict)’}
  362 | extern size_t mbsrtowcs (wchar_t *__restrict __dst,
      |               ^~~~~~~~~
./uchar.h:1370:10: note: previous implicit declaration of ‘mbsrtowcs’ with type ‘int()’
 1370 |          mbsrtowcs ((wchar_t *) dest, srcp, len, ps);
      |          ^~~~~~~~~
/usr/include/wchar.h:376:15: error: conflicting types for ‘mbsnrtowcs’; have ‘size_t(wchar_t * restrict,  const char ** restrict,  size_t,  size_t,  mbstate_t * restrict)’ {aka ‘long unsigned int(int * restrict,  const char ** restrict,  long unsigned int,  long unsigned int,  mbstate_t * restrict)’}
  376 | extern size_t mbsnrtowcs (wchar_t *__restrict __dst,
      |               ^~~~~~~~~~
./uchar.h:1340:10: note: previous implicit declaration of ‘mbsnrtowcs’ with type ‘int()’
 1340 |          mbsnrtowcs ((wchar_t *) dest, srcp, srclen, len, ps);
      |          ^~~~~~~~~~
make[3]: *** [Makefile:2347: mbrtoc32.o] Error 1

This patch fixes it.


2026-06-02  Bruno Haible  <[email protected]>

	c32width etc.: Fix compilation error on GNU systems (regr. 2026-04-24).
	* lib/uchar.in.h: Do include <wchar.h> when any of the modules c32width,
	c32snrtombs, c32srtombs, c32swidth, mbsnrtoc32s, mbsrtoc32s is in use.

diff --git a/lib/uchar.in.h b/lib/uchar.in.h
index ed1f1a88f3..3d9f035e6a 100644
--- a/lib/uchar.in.h
+++ b/lib/uchar.in.h
@@ -72,6 +72,9 @@
         defined __cplusplus ? @CXX_HAVE_UCHAR_H@ : @HAVE_UCHAR_H@) \
      || (/* These need wint_t and maybe WEOF and a <wchar.h> function.  */ \
          @GNULIB_BTOC32@ || @GNULIB_C32TOB@) \
+     || (/* These need a <wchar.h> function.  */ \
+         @GNULIB_C32WIDTH@ || @GNULIB_C32SNRTOMBS@ || @GNULIB_C32SRTOMBS@ \
+         || @GNULIB_C32SWIDTH@ || @GNULIB_MBSNRTOC32S@ || @GNULIB_MBSRTOC32S@) \
      || (/* These need mbszero.  */ \
          (@GNULIB_C32STOMBS@ || @GNULIB_MBSTOC32S@)))
 # include <wchar.h>
@@ -91,8 +94,8 @@
      || @GNULIB_C32ISLOWER@ || @GNULIB_C32ISPRINT@ || @GNULIB_C32ISPUNCT@ \
      || @GNULIB_C32ISSPACE@ || @GNULIB_C32ISUPPER@ || @GNULIB_C32ISXDIGIT@ \
      || @GNULIB_C32TOLOWER@ || @GNULIB_C32TOUPPER@ \
-     || @GNULIB_C32_APPLY_MAPPING@ || @GNULIB_C32_APPLY_TYPE_TEST@ \
-     || @GNULIB_C32_GET_MAPPING@ || @GNULIB_C32_GET_TYPE_TEST@)
+     || @GNULIB_C32_GET_TYPE_TEST@ || @GNULIB_C32_APPLY_TYPE_TEST@ \
+     || @GNULIB_C32_GET_MAPPING@ || @GNULIB_C32_APPLY_MAPPING@)
 # include <wctype.h>
 #endif