--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2010-03-07  Bruno Haible  <bruno@clisp.org>
 
+	langinfo: Avoid #define replacements in C++ mode.
+	* lib/langinfo.in.h: Include c++defs.h.
+	(nl_langinfo): In C++, define a namespaced alias symbol.
+	* modules/langinfo (Depends-on): Add c++defs.
+	(Makefile.am): Update langinfo.h rule.
+
 	iconv-h: Avoid #define replacements in C++ mode.
 	* lib/iconv.in.h: Include c++defs.h, warn-on-use.h.
 	(iconv_open, iconv, iconv_close): In C++, define a namespaced alias

--- a/lib/langinfo.in.h
+++ b/lib/langinfo.in.h
@@ -123,14 +123,12 @@
 
 #endif
 
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
 /* The definition of _GL_WARN_ON_USE is copied here.  */
 
 /* Declare overridden functions.  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 
 /* Return a piece of locale dependent information.
    Note: The difference between nl_langinfo (CODESET) and locale_charset ()
@@ -138,12 +136,19 @@
 
 #if @GNULIB_NL_LANGINFO@
 # if @REPLACE_NL_LANGINFO@
-#  undef nl_langinfo
-#  define nl_langinfo rpl_nl_langinfo
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef nl_langinfo
+#   define nl_langinfo rpl_nl_langinfo
+#  endif
+_GL_FUNCDECL_RPL (nl_langinfo, char *, (nl_item item));
+_GL_CXXALIAS_RPL (nl_langinfo, char *, (nl_item item));
+# else
+#  if !@HAVE_NL_LANGINFO@
+_GL_FUNCDECL_SYS (nl_langinfo, char *, (nl_item item));
+#  endif
+_GL_CXXALIAS_SYS (nl_langinfo, char *, (nl_item item));
 # endif
-# if !@HAVE_NL_LANGINFO@ || @REPLACE_NL_LANGINFO@
-extern char *nl_langinfo (nl_item item);
-# endif
+_GL_CXXALIASWARN (nl_langinfo);
 #elif defined GNULIB_POSIXCHECK
 # undef nl_langinfo
 # if HAVE_RAW_DECL_NL_LANGINFO
@@ -153,10 +158,5 @@
 #endif
 
 
-#ifdef __cplusplus
-}
-#endif
-
-
 #endif /* _GL_LANGINFO_H */
 #endif /* _GL_LANGINFO_H */

--- a/modules/langinfo
+++ b/modules/langinfo
@@ -8,6 +8,7 @@
 Depends-on:
 extensions
 include_next
+c++defs
 warn-on-use
 
 configure.ac:
@@ -18,7 +19,7 @@
 
 # We need the following in order to create an empty placeholder for
 # <langinfo.h> when the system doesn't have one.
-langinfo.h: langinfo.in.h $(WARN_ON_USE_H)
+langinfo.h: langinfo.in.h $(CXXDEFS_H) $(WARN_ON_USE_H)
 	$(AM_V_GEN)rm -f $@-t $@ && \
 	{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
 	  sed -e 's|@''HAVE_LANGINFO_H''@|$(HAVE_LANGINFO_H)|g' \
@@ -30,6 +31,7 @@
 	      -e 's|@''HAVE_LANGINFO_ERA''@|$(HAVE_LANGINFO_ERA)|g' \
 	      -e 's|@''HAVE_NL_LANGINFO''@|$(HAVE_NL_LANGINFO)|g' \
 	      -e 's|@''REPLACE_NL_LANGINFO''@|$(REPLACE_NL_LANGINFO)|g' \
+	      -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
 	      -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
 	      < $(srcdir)/langinfo.in.h; \
 	} > $@-t && \