New module 'dup'. * lib/unistd.in.h (dup): Declare only if the 'dup' module is in use. Allow replacement. * lib/dup.c: New file. * lib/fchdir.c (rpl_dup): Remove function. * m4/dup.m4: New file. * m4/fchdir.m4 (gl_FUNC_FCHDIR): Don't set REPLACE_DUP here. * m4/unistd_h.m4 (gl_UNISTD_H): Test whether 'dup' is declared. (gl_UNISTD_H_DEFAULTS): Initialize GNULIB_DUP. * modules/unistd (Makefile.am): Substitute GNULIB_DUP. * modules/dup: New file. * tests/test-unistd-c++.cc: Check the signature of 'dup' only if the 'dup' module is in use. * modules/fdopendir (Depends-on): Add dup. * modules/fdutimensat-tests (Depends-on): Likewise. * modules/fts (Depends-on): Likewise. * modules/futimens-tests (Depends-on): Likewise. * modules/posix_spawnp-tests (Depends-on): Likewise. * modules/unistd-safer-tests (Depends-on): Likewise. * modules/utimens-tests (Depends-on): Likewise. * doc/posix-functions/dup.texi: Mention the new module and the problem on MSVC.

Files:
tests/nap.h
tests/test-futimens.h
tests/test-lutimens.h
tests/test-utimens.h
tests/test-utimens-common.h
tests/test-fdutimensat.c
tests/macros.h

Depends-on:
ignore-value
timespec
dup
usleep
utimecmp

configure.ac:

Makefile.am:
TESTS += test-fdutimensat
check_PROGRAMS += test-fdutimensat
test_fdutimensat_LDADD = $(LDADD) $(LIB_CLOCK_GETTIME) @LIBINTL@