Portage 2.2.0_alpha149 (default/linux/amd64/10.0, gcc-4.7.2-asneeded, glibc-2.17, 3.5.4-hardened-r1 x86_64) ================================================================= System uname: Linux-3.5.4-hardened-r1-x86_64-AMD_Opteron-TM-_Processor_6272-with-gentoo-2.2 Timestamp of tree: Sun, 30 Dec 2012 00:00:01 +0000 ld GNU ld (GNU Binutils) 2.23.1 app-shells/bash: 4.2_p39-r1 dev-java/java-config: 2.1.12-r1 dev-lang/python: 2.7.3-r3, 3.2.3-r2 dev-util/cmake: 2.8.10.2 dev-util/pkgconfig: 0.27.1 sys-apps/baselayout: 2.2 sys-apps/openrc: 0.11.8 sys-apps/sandbox: 2.6 sys-devel/autoconf: 2.13, 2.69 sys-devel/automake: 1.11.6, 1.12.6 sys-devel/binutils: 2.23.1 sys-devel/gcc: 4.7.2 sys-devel/gcc-config: 1.8 sys-devel/libtool: 2.4.2 sys-devel/make: 3.82-r4 sys-kernel/linux-headers: 3.7 (virtual/os-headers) sys-libs/glibc: 2.17 Repositories: gentoo tbamd64 ACCEPT_KEYWORDS="amd64 ~amd64" ACCEPT_LICENSE="*" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -pipe -ggdb -march=native -ftracer -frecord-gcc-switches" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="${EPREFIX}/etc/gconf /etc/ca-certificates.conf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-O2 -pipe -ggdb -march=native -ftracer -frecord-gcc-switches" DISTDIR="/var/cache/portage/distfiles" FCFLAGS="-O2 -pipe -ggdb -march=native -frecord-gcc-switches" FEATURES="assume-digests binpkg-logs config-protect-if-modified distlocks ebuild-locks fail-clean fixlafiles merge-sync news parallel-fetch protect-owned sandbox sfperms strict test test-fail-continue unknown-features-warn unmerge-orphans userfetch userpriv usersandbox" FFLAGS="-O2 -pipe -ggdb -march=native -frecord-gcc-switches" GENTOO_MIRRORS="http://ftp.ucsb.edu/pub/mirrors/linux/gentoo/ http://gentoo.mirrors.hoobly.com/ http://gentoo.llarian.net/" LANG="en_US.utf8" LC_ALL="C" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j24" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/tmp" PORTDIR="/var/cache/tinderbox/tree" PORTDIR_OVERLAY="/root/overlay" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="3dnow 3dnowex acl amd64 berkdb bzip2 cli cracklib crypt cups cxx doc dri emacs ffmpeg fortran gnutls gpm iconv icu intl introspection ipv6 mmx modules mudflap multilib ncurses nls nptl openmp pam pax_kernel pcre pdf plasma pppd qt3support readline semantic-desktop session snmp sse sse2 sse3 sse4 ssl ssse3 tcmalloc tcpd udev unicode vhosts zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow plan sheets stage tables krita karbon braindump" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ubx" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" PHP_TARGETS="php5-3" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_2" RUBY_TARGETS="ruby18 ruby19" USERLAND="GNU" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Of course it compiled with Java 6. With Java 7 I reproduce that it fails to compile as reported: ../src/kodkod/engine/satlab/Clause.java:152: error: reference to superFastHash is ambiguous, both method superFastHash(int...) in Ints and method superFastHash(Object...) in Ints match hash = Ints.superFastHash(iter.next().hashCode(), hash); In this method: public int hashCode() { int hash = size() + numberOfAntecedents(); for(IntIterator iter = literals(); iter.hasNext(); ) { hash = Ints.superFastHashIncremental(iter.next(), hash); } for(Iterator<Clause> iter = antecedents(); iter.hasNext(); ) { hash = Ints.superFastHash(iter.next().hashCode(), hash); // <-- fails on this line } return Ints.superFastHashAvalanche(hash); } The overloaded method signatures it needs to choose from: public static int superFastHash(int key) public static int superFastHash(int... key) public static int superFastHash(Object... key) Both parameters are ints, you would think it would be simple to figure out that it should call the second method. The release notes say that is too hard now, so we have an introduced "slight source incompatibility" (as in, code that used to compile fine with Java 6 now fails to compile with Java 7): http://www.oracle.com/technetwork/java/javase/compatibility-417013.html#jdk7 Area: Tools Synopsis: Changes in Most Specific Varargs Method Selection Description: The overload resolution algorithm in the javac compiler has been fixed in how it selects the most specific varargs method when more than one method is applicable to a given call-site (see the JLS, Java SE 7 Edition, section 15.12.2.5). Because of a bug, both JDK 5.0 and JDK 6 compilers reject the following legal code: class Test { void foo(int... i) {} void foo(double... d) {} void test() { foo(1,2,3); } } In the above example, both methods are applicable (because you can pass an int where a double is expected). Since both methods are applicable, the compiler must select the so-called most-specific method, that is, the best candidate among the two. This is done by looking at the signatures of both methods; in this case, since one method (foo(double...)) is accepting an argument that is more general than the other (foo(int...)), the answer is straightforward: the most specific method is foo(int...). While the javac compiler accepts more code than it did prior to JDK 7, this fix also results in a slight source incompatibility in the following case: class Test { void foo(int... i) {} void foo(Object... o) {} void test() { foo(1,2,3); } } This code compiles in JDK 6 (the most specific method is foo(int...)). This code does not compile under JDK 7. As per 15.12.2.5, it is not possible to choose between foo(int...) and foo(Object...) as neither int is a subtype of Object, nor Object is a subtype of int. This program should be disallowed (in fact, it should never have been allowed in the first place). Nature of Incompatibility: behavioral and source RFE: 6199075 It seems though that the Oracle devs came to their senses and realised that this is compiler bug that was triggered by code encountering a fundamental problem in Java's type system, that primitive arrays are not covariant: 6199075 : Unambiguous varargs method calls flagged as ambiguous http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6199075 So its a compiler bug, I need to check if there is already a compiler bug for this, or if not, raise a compiler bug. Then set that compiler bug as a blocker.
I think I was misled by the title of the bug "6199075 : Unambiguous varargs method calls flagged as ambiguous" and its status of "fixed". That was back in 2010, so I guess the "fix" was to make it ambiguous as noted in the release notes. So change of plan, I won't raise a compiler bug, instead I patched kodkod to remove the third overloaded method.
