Re: printf, wchar

[Bruno Haible]

Simon Josefsson wrote:
> On uClinux I got:
> 
> /bin/sh ../libtool --tag=CC   --mode=compile ucfront-gcc m68k-elf-gcc -m5200 
> -DCONFIG_COLDFIRE -DHAVE_CONFIG_H -I. -I.. -I../../../lib/gl  -I../intl 
> -I/data/fast/uclinux/uClinux-dist/lib/libgcrypt/inst/include 
> -I/data/fast/uclinux/uClinux-dist/lib/libgpg-error/inst/include  -g 
> -fomit-frame-pointer -pipe -fno-common -fno-builtin -Wall -DEMBED -msep-data 
> -Dlinux -D__linux__ -Dunix -D__uClinux__ -MT printf-parse.lo -MD -MP -MF 
> .deps/printf-parse.Tpo -c -o printf-parse.lo ../../../lib/gl/printf-parse.c
>  ucfront-gcc m68k-elf-gcc -m5200 -DCONFIG_COLDFIRE -DHAVE_CONFIG_H -I. -I.. 
> -I../../../lib/gl -I../intl 
> -I/data/fast/uclinux/uClinux-dist/lib/libgcrypt/inst/include 
> -I/data/fast/uclinux/uClinux-dist/lib/libgpg-error/inst/include -g 
> -fomit-frame-pointer -pipe -fno-common -fno-builtin -Wall -DEMBED -msep-data 
> -Dlinux -D__linux__ -Dunix -D__uClinux__ -MT printf-parse.lo -MD -MP -MF 
> .deps/printf-parse.Tpo -c ../../../lib/gl/printf-parse.c -o printf-parse.o
> In file included from ./wchar.h:42,
>                  from ./stdint.h:94,
>                  from ../../../lib/gl/printf-parse.c:39:
> /data/fast/uclinux/uClinux-dist/uClibc/include/wchar.h:32:2: error: #error 
> Attempted to include wchar.h when uClibc built without wide char support.
> make[7]: *** [printf-parse.lo] Error 1
> 
> Configure says:
> 
> checking wchar.h usability... no
> checking wchar.h presence... no
> checking for wchar.h... no
> 
> The tests fail because:
> 
> configure:24279: checking wchar.h usability
> configure:24296: ucfront-gcc m68k-elf-gcc -m5200 -DCONFIG_COLDFIRE -c  -g 
> -fomit-frame-pointer -pipe -fno-common -fno-builtin -Wall -DEMBED -msep-data 
> -Dlinux -D__linux__ -Dunix -D__uClinux__  conftest.c >&5
> In file included from conftest.c:82:
> /data/fast/uclinux/uClinux-dist/uClibc/include/wchar.h:32:2: error: #error 
> Attempted to include wchar.h when uClibc built without wide char support.
> configure:24302: $? = 1

OK, so the assumption that we made in January, that <wchar.h> is universally
present, is not valid.

> 2007-06-07  Simon Josefsson  <address@hidden>
> 
>       * lib/wchar_.h: Don't include wchar.h if missing.
> 
> --- wchar_.h  30 May 2007 15:01:38 +0200      1.5
> +++ wchar_.h  07 Jun 2007 11:31:38 +0200      
> @@ -35,6 +35,7 @@
>  #include <stdio.h>
>  #include <time.h>
>  
> +#if HAVE_WCHAR_H
>  /* Include the original <wchar.h>.  */
>  /* The include_next requires a split double-inclusion guard.  */
>  #if @HAVE_INCLUDE_NEXT@
> @@ -42,6 +43,7 @@
>  #else
>  # include @ABSOLUTE_WCHAR_H@
>  #endif
> +#endif
>  
>  #ifndef _GL_WCHAR_H
>  #define _GL_WCHAR_H

There is a little more than this, because - as you know - we want the
replacement *.h files to be independent of <config.h> as far as possible.

I applied the appended patch.

> Alternatively, stdint_.h could avoid including wchar.h, but this fix
> seems cleaner because printf can always assume wchar.h, and the wchar
> module is responsible for making it appear as if the wchar.h intefaces
> works.

Yes, this is the purpose of the modules: that you don't need to change much
when we notice yet another portability problem. The 'wchar' module is a
dependency of the 'stdint' module, therefore lib/stdint_.h does not need to
be changed - it can assume a working <wchar.h> file.

But m4/stdint.m4 has to be changed, because it runs at a moment when the
replacement <wchar.h> is not yet in place.

Bruno


2007-06-07  Bruno Haible  <address@hidden>

        Work around the lack of <wchar.h> on some builds of uClibc.
        * doc/headers/wchar.texi: Update.
        * lib/wchar_.h: Include <wchar.h> only if it exists.
        * m4/wchar.m4 (gl_WCHAR_H): Check for <wchar.h>. Set HAVE_WCHAR_H.
        * m4/stdint.m4 (gl_STDINT_H): Check for <wchar.h>.
        (gl_STDINT_TYPE_PROPERTIES): Don't try to include <wchar.h> if it
        doesn't exist.
        * modules/wchar (wchar.h): Substitute HAVE_WCHAR_H.
        * modules/mbfile (Depends-on): Add wchar.
        * modules/mbiter (Depends-on): Likewise.
        * modules/mbuiter (Depends-on): Likewise.

*** lib/wchar_.h        30 May 2007 02:16:53 -0000      1.5
--- lib/wchar_.h        7 Jun 2007 13:25:51 -0000
***************
*** 35,46 ****
  #include <stdio.h>
  #include <time.h>
  
! /* Include the original <wchar.h>.  */
  /* The include_next requires a split double-inclusion guard.  */
! #if @HAVE_INCLUDE_NEXT@
! # include_next <wchar.h>
! #else
! # include @ABSOLUTE_WCHAR_H@
  #endif
  
  #ifndef _GL_WCHAR_H
--- 35,49 ----
  #include <stdio.h>
  #include <time.h>
  
! /* Include the original <wchar.h> if it exists.
!    Some builds of uClibc lack it.  */
  /* The include_next requires a split double-inclusion guard.  */
! #if @HAVE_WCHAR_H@
! # if @HAVE_INCLUDE_NEXT@
! #  include_next <wchar.h>
! # else
! #  include @ABSOLUTE_WCHAR_H@
! # endif
  #endif
  
  #ifndef _GL_WCHAR_H
*** m4/stdint.m4        2 Jun 2007 20:45:23 -0000       1.31
--- m4/stdint.m4        7 Jun 2007 13:25:51 -0000
***************
*** 1,4 ****
! # stdint.m4 serial 25
  dnl Copyright (C) 2001-2007 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
--- 1,4 ----
! # stdint.m4 serial 26
  dnl Copyright (C) 2001-2007 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
***************
*** 222,227 ****
--- 222,231 ----
      fi
      AC_SUBST([HAVE_SYS_BITYPES_H])
  
+     dnl Check for <wchar.h> (missing in Linux uClibc when built without wide
+     dnl character support).
+     AC_CHECK_HEADERS_ONCE([wchar.h])
+ 
      gl_STDINT_TYPE_PROPERTIES
      STDINT_H=stdint.h
    fi
***************
*** 357,365 ****
       included before <wchar.h>.  */
    #include <stddef.h>
    #include <signal.h>
!   #include <stdio.h>
!   #include <time.h>
!   #include <wchar.h>
  ]])
  
  dnl gl_STDINT_TYPE_PROPERTIES
--- 361,371 ----
       included before <wchar.h>.  */
    #include <stddef.h>
    #include <signal.h>
!   #if HAVE_WCHAR_H
!   # include <stdio.h>
!   # include <time.h>
!   # include <wchar.h>
!   #endif
  ]])
  
  dnl gl_STDINT_TYPE_PROPERTIES
*** m4/wchar.m4 13 Jan 2007 05:23:37 -0000      1.1
--- m4/wchar.m4 7 Jun 2007 13:25:51 -0000
***************
*** 7,13 ****
  
  dnl Written by Eric Blake.
  
! # wchar.m4 serial 1
  
  AC_DEFUN([gl_WCHAR_H],
  [
--- 7,13 ----
  
  dnl Written by Eric Blake.
  
! # wchar.m4 serial 2
  
  AC_DEFUN([gl_WCHAR_H],
  [
***************
*** 20,25 ****
--- 20,34 ----
    if test $gl_cv_header_wchar_h_standalone = yes; then
      WCHAR_H=
    else
+     dnl Check for <wchar.h> (missing in Linux uClibc when built without wide
+     dnl character support).
+     AC_CHECK_HEADERS_ONCE([wchar.h])
+     if test $ac_cv_header_wchar_h = yes; then
+       HAVE_WCHAR_H=1
+     else
+       HAVE_WCHAR_H=0
+     fi
+     AC_SUBST([HAVE_WCHAR_H])
      gl_ABSOLUTE_HEADER([wchar.h])
      ABSOLUTE_WCHAR_H=\"$gl_cv_absolute_wchar_h\"
      WCHAR_H=wchar.h
*** modules/mbfile      26 Sep 2005 13:58:51 -0000      1.2
--- modules/mbfile      7 Jun 2007 13:25:51 -0000
***************
*** 8,13 ****
--- 8,14 ----
  
  Depends-on:
  mbchar
+ wchar
  stdbool
  
  configure.ac:
*** modules/mbiter      26 Sep 2005 13:58:51 -0000      1.2
--- modules/mbiter      7 Jun 2007 13:25:51 -0000
***************
*** 8,13 ****
--- 8,14 ----
  
  Depends-on:
  mbchar
+ wchar
  stdbool
  
  configure.ac:
*** modules/mbuiter     26 Sep 2005 13:58:51 -0000      1.2
--- modules/mbuiter     7 Jun 2007 13:25:51 -0000
***************
*** 8,13 ****
--- 8,14 ----
  
  Depends-on:
  mbchar
+ wchar
  stdbool
  strnlen1
  
*** modules/wchar       17 May 2007 06:14:30 -0000      1.2
--- modules/wchar       7 Jun 2007 13:25:51 -0000
***************
*** 21,26 ****
--- 21,27 ----
        { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
          sed -e 's|@''ABSOLUTE_WCHAR_H''@|$(ABSOLUTE_WCHAR_H)|g' \
              -e 's/@''HAVE_INCLUDE_NEXT''@/$(HAVE_INCLUDE_NEXT)/g' \
+             -e 's/@''HAVE_WCHAR_H''@/$(HAVE_WCHAR_H)/g' \
            < $(srcdir)/wchar_.h; \
        } > address@hidden
        mv address@hidden $@
*** doc/headers/wchar.texi      27 Apr 2007 21:04:08 -0000      1.2
--- doc/headers/wchar.texi      7 Jun 2007 13:31:29 -0000
***************
*** 8,13 ****
--- 8,16 ----
  Portability problems fixed by Gnulib:
  @itemize
  @item
+ This header file cannot be included on some platforms:
+ Linux uClibc built without wide character support.
+ @item
  This header file is not self-contained on some platforms:
  OSF/1 with Desktop Toolkit C, BSD/OS 4.0.1.
  @end itemize