--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2010-03-07  Bruno Haible  <bruno@clisp.org>
 
+	fcntl-h: Avoid #define replacements in C++ mode.
+	* lib/fcntl.in.h: Include c++defs.h.
+	(fcntl, open, openat): In C++, define a namespaced alias symbol.
+	* modules/fcntl-h (Depends-on): Add c++defs.
+	(Makefile.am): Update fcntl.h rule.
+
 	dirent: Avoid #define replacements in C++ mode.
 	* lib/dirent.in.h: Include c++defs.h.
 	(closedir, fdopendir, opendir, scandir, alphasort): In C++, define a

--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -50,6 +50,8 @@
 #endif
 
 
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
 /* The definition of _GL_ARG_NONNULL is copied here.  */
 
 /* The definition of _GL_WARN_ON_USE is copied here.  */
@@ -57,18 +59,21 @@
 
 /* Declare overridden functions.  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #if @GNULIB_FCNTL@
 # if @REPLACE_FCNTL@
-#  undef fcntl
-#  define fcntl rpl_fcntl
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef fcntl
+#   define fcntl rpl_fcntl
+#  endif
+_GL_FUNCDECL_RPL (fcntl, int, (int fd, int action, ...));
+_GL_CXXALIAS_RPL (fcntl, int, (int fd, int action, ...));
+# else
+#  if !@HAVE_FCNTL@
+_GL_FUNCDECL_SYS (fcntl, int, (int fd, int action, ...));
+#  endif
+_GL_CXXALIAS_SYS (fcntl, int, (int fd, int action, ...));
 # endif
-# if !@HAVE_FCNTL@ || @REPLACE_FCNTL@
-extern int fcntl (int fd, int action, ...);
-# endif
+_GL_CXXALIASWARN (fcntl);
 #elif defined GNULIB_POSIXCHECK
 # undef fcntl
 # if HAVE_RAW_DECL_FCNTL
@@ -79,10 +84,17 @@
 
 #if @GNULIB_OPEN@
 # if @REPLACE_OPEN@
-#  undef open
-#  define open rpl_open
-extern int open (const char *filename, int flags, ...) _GL_ARG_NONNULL ((1));
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef open
+#   define open rpl_open
+#  endif
+_GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
+                             _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
+# else
+_GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
 # endif
+_GL_CXXALIASWARN (open);
 #elif defined GNULIB_POSIXCHECK
 # undef open
 /* Assume open is always declared.  */
@@ -92,13 +104,25 @@
 
 #if @GNULIB_OPENAT@
 # if @REPLACE_OPENAT@
-#  undef openat
-#  define openat rpl_openat
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef openat
+#   define openat rpl_openat
+#  endif
+_GL_FUNCDECL_RPL (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...)
+                  _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...));
+# else
+#  if !@HAVE_OPENAT@
+_GL_FUNCDECL_SYS (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...)
+                  _GL_ARG_NONNULL ((2)));
+#  endif
+_GL_CXXALIAS_SYS (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...));
 # endif
-# if !@HAVE_OPENAT@ || @REPLACE_OPENAT@
-extern int openat (int fd, char const *file, int flags, /* mode_t mode */ ...)
-     _GL_ARG_NONNULL ((2));
-# endif
+_GL_CXXALIASWARN (openat);
 #elif defined GNULIB_POSIXCHECK
 # undef openat
 # if HAVE_RAW_DECL_OPENAT
@@ -107,9 +131,6 @@
 # endif
 #endif
 
-#ifdef __cplusplus
-}
-#endif
 
 /* Fix up the FD_* macros, only known to be missing on mingw.  */
 

--- a/modules/fcntl-h
+++ b/modules/fcntl-h
@@ -8,6 +8,7 @@
 
 Depends-on:
 arg-nonnull
+c++defs
 extensions
 include_next
 unistd
@@ -21,7 +22,7 @@
 
 # We need the following in order to create <fcntl.h> when the system
 # doesn't have one that works with the given compiler.
-fcntl.h: fcntl.in.h $(WARN_ON_USE_H) $(ARG_NONNULL_H)
+fcntl.h: fcntl.in.h $(CXXDEFS_H) $(ARG_NONNULL_H) $(WARN_ON_USE_H)
 	$(AM_V_GEN)rm -f $@-t $@ && \
 	{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
 	  sed -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
@@ -35,6 +36,7 @@
 	      -e 's|@''REPLACE_FCNTL''@|$(REPLACE_FCNTL)|g' \
 	      -e 's|@''REPLACE_OPEN''@|$(REPLACE_OPEN)|g' \
 	      -e 's|@''REPLACE_OPENAT''@|$(REPLACE_OPENAT)|g' \
+	      -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
 	      -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
 	      -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
 	      < $(srcdir)/fcntl.in.h; \