iswblank: ensure declaration

[Bruno Haible]

On glibc systems, I'm seeing this warning (similarly when it was still under
the 'wctype-h' module):

test-iswblank.c: In function ‘main’:
test-iswblank.c:30: warning: implicit declaration of function ‘iswblank’

This fixes it:


2011-02-06  Bruno Haible  <address@hidden>

        iswblank: Ensure declaration on glibc systems.
        * m4/iswblank.m4 (gl_FUNC_ISWBLANK): Require gl_USE_SYSTEM_EXTENSIONS.
        * modules/iswblank (Dependencies): Add 'extensions'.
        * doc/posix-functions/iswblank.texi: Document the glibc problem.

--- doc/posix-functions/iswblank.texi.orig      Sun Feb  6 22:11:21 2011
+++ doc/posix-functions/iswblank.texi   Sun Feb  6 22:08:40 2011
@@ -15,6 +15,9 @@
 This function is declared but not defined on some platforms:
 IRIX 6.5.30.
 @item
+This function is not declared (without @code{-D_GNU_SOURCE}) on some platforms:
+glibc 2.8.
address@hidden
 This function returns 0 for all possible arguments on some platforms:
 Linux libc5.
 @end itemize
--- m4/iswblank.m4.orig Sun Feb  6 22:11:21 2011
+++ m4/iswblank.m4      Sun Feb  6 22:09:24 2011
@@ -1,4 +1,4 @@
-# iswblank.m4 serial 1
+# iswblank.m4 serial 2
 dnl Copyright (C) 2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,6 +8,8 @@
 [
   AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
   AC_REQUIRE([gl_WCTYPE_H])
+  dnl Persuade glibc <wctype.h> to declare iswblank().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   AC_CHECK_FUNCS_ONCE([iswblank])
   AC_CHECK_DECLS_ONCE([iswblank])
   if test $ac_cv_func_iswblank = no; then
--- modules/iswblank.orig       Sun Feb  6 22:11:21 2011
+++ modules/iswblank    Sun Feb  6 22:10:02 2011
@@ -7,6 +7,7 @@
 
 Depends-on:
 wctype-h
+extensions
 
 configure.ac:
 gl_FUNC_ISWBLANK

-- 
In memoriam Chris Gueffroy <http://en.wikipedia.org/wiki/Chris_Gueffroy>