hi,

trying to backport samba 4.2.0 to ubuntu 14.04 (amd64) i'm facing the following error : 

ubuntu-14-04-build:~/samba-4.2.0_bpo/samba-4.2.0/bin$ gcc -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -fPIC -D_REENTRANT -D_POSIX_PTHREAD_SEMANTICS -DCTDB_HELPER_BINDIR="/usr/bin" -DLOGDIR="/var/log" -DSOCKPATH="/var/run/ctdb/ctdbd.socket" -DCTDB_ETCDIR="/etc/ctdb" -DCTDB_VARDIR="/var/lib/ctdb" -DCTDB_RUNDIR="/var/run/ctdb" -DSTATIC_CREDENTIALS_KRB5_MODULES=NULL -DSTATIC_CREDENTIALS_KRB5_MODULES_PROTO='extern void __CREDENTIALS_KRB5_dummy_module_proto(void)' -MD -pthread -Idefault/auth/credentials -I../auth/credentials -Idefault/include/public -I../include/public -Idefault/source4 -I../source4 -Idefault/lib -I../lib -Idefault/source4/lib -I../source4/lib -Idefault/source4/include -I../source4/include -Idefault/include -I../include -Idefault/lib/replace -I../lib/replace -Idefault/ctdb/include -I../ctdb/include -Idefault -I.. -Idefault/lib/ldb/include -I../lib/ldb/include -Idefault/lib/ldb -I../lib/ldb -Idefault/source4/lib/tls -I../source4/lib/tls -Idefault/lib/param -I../lib/param -Idefault/librpc -I../librpc -Idefault/libcli/util -I../libcli/util -Idefault/libds/common -I../libds/common -Idefault/libcli/ldap -I../libcli/ldap -Idefault/libcli/auth -I../libcli/auth -Idefault/lib/ldb-samba -I../lib/ldb-samba -Idefault/source4/auth/kerberos -I../source4/auth/kerberos -Idefault/libcli/security -I../libcli/security -Idefault/auth -I../auth -Idefault/lib/dbwrap -I../lib/dbwrap -Idefault/source3 -I../source3 -Idefault/source3/include -I../source3/include -Idefault/source3/lib -I../source3/lib -Idefault/lib/tdb_compat -I../lib/tdb_compat -Idefault/lib/tdb/include -I../lib/tdb/include -Idefault/lib/tevent -I../lib/tevent -Idefault/source3/librpc -I../source3/librpc -Idefault/libcli/nbt -I../libcli/nbt -Idefault/source4/param -I../source4/param -Idefault/auth/kerberos -I../auth/kerberos -Idefault/source4/lib/stream -I../source4/lib/stream -Idefault/source4/heimdal_build -I../source4/heimdal_build -Idefault/source4/dsdb -I../source4/dsdb -Idefault/lib/crypto -I../lib/crypto -Idefault/lib/krb5_wrap -I../lib/krb5_wrap -Idefault/source4/lib/socket -I../source4/lib/socket -Idefault/lib/compression -I../lib/compression -Idefault/lib/util/charset -I../lib/util/charset -Idefault/libcli/lsarpc -I../libcli/lsarpc -Idefault/source4/lib/events -I../source4/lib/events -Idefault/source4/libcli -I../source4/libcli -Idefault/lib/tdb -I../lib/tdb -Idefault/dynconfig -I../dynconfig -Idefault/lib/tsocket -I../lib/tsocket -I/usr/local/include -I/usr/include/heimdal -I/usr/include/et -I/usr/include/p11-kit-1 -D_FORTIFY_SOURCE=2 -D_SAMBA_BUILD_=4 -DHAVE_CONFIG_H=1 -D_GNU_SOURCE=1 -D_XOPEN_SOURCE_EXTENDED=1 ../auth/credentials/credentials_krb5.c -c -o default/auth/credentials/credentials_krb5_7.o
In file included from /usr/include/heimdal/krb5.h:941:0,
                 from ../lib/replace/system/kerberos.h:33,
                 from ../auth/credentials/credentials_krb5.c:25:
/usr/include/heimdal/krb5-protos.h:3892:1: error: unknown type name ‘HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE’
 HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 ^
/usr/include/heimdal/krb5-protos.h:3893:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘krb5_generate_random’
 krb5_generate_random (
 ^

HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE seems to be defined in /usr/include/heimdal/krb5-types.h

$ dpkg -S /usr/include/heimdal/krb5-protos.h
heimdal-multidev: /usr/include/heimdal/krb5-protos.h
$ dpkg -l | grep heimdal-multidev
ii  heimdal-multidev                    1.6~git20131207+dfsg-1ubuntu1    amd64        Heimdal Kerberos - Multi-implementation Development

build option derivated from ubuntu packages (4.1.6) and debian unstable (4.1.17), both building fine on the same host :
                --prefix=/usr \
                --enable-fhs \
                --sysconfdir=/etc \
                --localstatedir=/var \
                --with-privatedir=/var/lib/samba/private \
                --with-smbpasswd-file=/etc/samba/smbpasswd \
                --with-piddir=/var/run/samba \
                --with-pammodulesdir=/lib/$(DEB_HOST_MULTIARCH)/security \
                --with-pam \
                --with-syslog \
                --with-utmp \
                --with-pam_smbpass \
                --with-winbind \
                --with-shared-modules=idmap_rid,idmap_ad,idmap_adex,idmap_hash,idmap_ldap,idmap_tdb2,vfs_dfs_samba4,auth_samba4 \
                --with-automount \
                --with-ldap \
                --with-ads \
                --with-dnsupdate \
                --libdir=/usr/lib/$(DEB_HOST_MULTIARCH) \
                --with-modulesdir=/usr/lib/$(DEB_HOST_MULTIARCH)/samba \
                --datadir=/usr/share \
                --with-lockdir=/var/run/samba \
                --with-statedir=/var/lib/samba \
                --with-cachedir=/var/cache/samba \
                --disable-avahi \
                --with-cluster-support \
                --disable-rpath \
                --disable-rpath-install \
                --bundled-libraries=NONE,pytevent,iniparser,tdb,ldb,pyldb-util,nss_wrapper,socket_wrapper,uid_wrapper,tevent \
                --builtin-libraries=replace,ccan \
                --minimum-library-version="$(shell ./debian/autodeps.py --minimum-library-version)"

error is the same using gcc or ccache

feel free to ask any further information

regards,