Re: strnlen on OSX & C++

[Jarno Rajahalme]

Bruno,

I have those patches applied (and a up-to-date gnulib, as git diff shows 
nothing), but now get a different compilation error:

In file included from main.cc:4:
../lib/string.h:684: error: 'strnlen' was not declared in this scope
../lib/string.h:684: error: invalid type in declaration before ';' token

This is the same issue as with fchownat before, and this patch makes the 
compile and run successful:

$ git diff
diff --git a/lib/string.in.h b/lib/string.in.h
index de446b4..e01dbd8 100644
--- a/lib/string.in.h
+++ b/lib/string.in.h
@@ -389,7 +389,9 @@ _GL_FUNCDECL_SYS (strnlen, size_t, (char const *__string, si
 #  endif
 _GL_CXXALIAS_SYS (strnlen, size_t, (char const *__string, size_t __maxlen));
 # endif
+# if @HAVE_DECL_STRNLEN@
 _GL_CXXALIASWARN (strnlen);
+# endif
 #elif defined GNULIB_POSIXCHECK
 # undef strnlen
 # if HAVE_RAW_DECL_STRNLEN

  Jarno

On Apr 10, 2010, at 2:29 AM, ext Bruno Haible wrote:

> Jarno Rajahalme wrote:
>> main.cc:9: warning: call to 'rpl_strnlen' declared with attribute warning: 
>> The symbol ::rpl_strnlen refers to the system function. Use 
>> gnulib::rpl_strnlen instead.
> 
> The problem here is that gnulib's handling of strnlen is using an ancient
> idiom. In string.in.h it uses _GL_CXXALIAS_SYS. _GL_CXXALIAS_RPL has a
> workaround against a strange behaviour of g++, but _GL_CXXALIAS_SYS doesn't.
> 
> This should fix it.
> 
> 
> 2010-04-10  Bruno Haible  <address@hidden>
> 
>       strnlen: Fix warning in C++ mode on MacOS X.
>       * lib/string.in.h (strnlen): Use the modern idiom.
>       * m4/strnlen.m4 (gl_FUNC_STRNLEN): Set REPLACE_STRNLEN to 1, instead of
>       defining strnlen as a macro already in <config.h>.
>       * m4/string_h.m4 (gl_HEADER_STRING_H_DEFAULTS): Initialize
>       REPLACE_STRNLEN.
>       * modules/string (Makefile.am): Substitute REPLACE_STRNLEN.
>       Reported by Jarno Rajahalme <address@hidden>.
> 
> --- lib/string.in.h.orig      Sat Apr 10 11:25:04 2010
> +++ lib/string.in.h   Sat Apr 10 11:22:32 2010
> @@ -372,12 +372,23 @@
>    MAXLEN bytes.  If no '\0' terminator is found in that many bytes,
>    return MAXLEN.  */
> #if @GNULIB_STRNLEN@
> -# if ! @HAVE_DECL_STRNLEN@
> +# if @REPLACE_STRNLEN@
> +#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
> +#   undef strnlen
> +#   define strnlen rpl_strnlen
> +#  endif
> +_GL_FUNCDECL_RPL (strnlen, size_t, (char const *__string, size_t __maxlen)
> +                                   __attribute__ ((__pure__))
> +                                   _GL_ARG_NONNULL ((1)));
> +_GL_CXXALIAS_RPL (strnlen, size_t, (char const *__string, size_t __maxlen));
> +# else
> +#  if ! @HAVE_DECL_STRNLEN@
> _GL_FUNCDECL_SYS (strnlen, size_t, (char const *__string, size_t __maxlen)
>                                    __attribute__ ((__pure__))
>                                    _GL_ARG_NONNULL ((1)));
> -# endif
> +#  endif
> _GL_CXXALIAS_SYS (strnlen, size_t, (char const *__string, size_t __maxlen));
> +# endif
> _GL_CXXALIASWARN (strnlen);
> #elif defined GNULIB_POSIXCHECK
> # undef strnlen
> --- m4/string_h.m4.orig       Sat Apr 10 11:25:04 2010
> +++ m4/string_h.m4    Sat Apr 10 11:23:01 2010
> @@ -5,7 +5,7 @@
> # gives unlimited permission to copy and/or distribute it,
> # with or without modifications, as long as this notice is preserved.
> 
> -# serial 16
> +# serial 17
> 
> # Written by Paul Eggert.
> 
> @@ -105,6 +105,7 @@
>   REPLACE_STRERROR=0;           AC_SUBST([REPLACE_STRERROR])
>   REPLACE_STRNCAT=0;            AC_SUBST([REPLACE_STRNCAT])
>   REPLACE_STRNDUP=0;            AC_SUBST([REPLACE_STRNDUP])
> +  REPLACE_STRNLEN=0;            AC_SUBST([REPLACE_STRNLEN])
>   REPLACE_STRSIGNAL=0;          AC_SUBST([REPLACE_STRSIGNAL])
>   REPLACE_STRTOK_R=0;           AC_SUBST([REPLACE_STRTOK_R])
>   UNDEFINE_STRTOK_R=0;          AC_SUBST([UNDEFINE_STRTOK_R])
> --- m4/strnlen.m4.orig        Sat Apr 10 11:25:04 2010
> +++ m4/strnlen.m4     Sat Apr 10 11:24:45 2010
> @@ -1,4 +1,4 @@
> -# strnlen.m4 serial 10
> +# strnlen.m4 serial 11
> dnl Copyright (C) 2002-2003, 2005-2007, 2009-2010 Free Software Foundation,
> dnl Inc.
> dnl This file is free software; the Free Software Foundation
> @@ -7,10 +7,11 @@
> 
> AC_DEFUN([gl_FUNC_STRNLEN],
> [
> +  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
> +
>   dnl Persuade glibc <string.h> to declare strnlen().
>   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
> 
> -  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
>   AC_CHECK_DECLS_ONCE([strnlen])
>   if test $ac_cv_have_decl_strnlen = no; then
>     HAVE_DECL_STRNLEN=0
> @@ -18,12 +19,11 @@
> 
>   AC_FUNC_STRNLEN
>   if test $ac_cv_func_strnlen_working = no; then
> +    REPLACE_STRNLEN=1
>     # This is necessary because automake-1.6.1 doesn't understand
>     # that the above use of AC_FUNC_STRNLEN means we may have to use
>     # lib/strnlen.c.
>     #AC_LIBOBJ([strnlen])
> -    AC_DEFINE([strnlen], [rpl_strnlen],
> -      [Define to rpl_strnlen if the replacement function should be used.])
>     gl_PREREQ_STRNLEN
>   fi
> ])
> --- modules/string.orig       Sat Apr 10 11:25:04 2010
> +++ modules/string    Sat Apr 10 11:23:17 2010
> @@ -89,6 +89,7 @@
>             -e 's|@''REPLACE_STRERROR''@|$(REPLACE_STRERROR)|g' \
>             -e 's|@''REPLACE_STRNCAT''@|$(REPLACE_STRNCAT)|g' \
>             -e 's|@''REPLACE_STRNDUP''@|$(REPLACE_STRNDUP)|g' \
> +           -e 's|@''REPLACE_STRNLEN''@|$(REPLACE_STRNLEN)|g' \
>             -e 's|@''REPLACE_STRSIGNAL''@|$(REPLACE_STRSIGNAL)|g' \
>             -e 's|@''REPLACE_STRTOK_R''@|$(REPLACE_STRTOK_R)|g' \
>             -e 's|@''UNDEFINE_STRTOK_R''@|$(UNDEFINE_STRTOK_R)|g' \