linux build failing

[rhelmer]

libprio is failing to build for Linux, although it works for macOS (which is a very similar environment which makes the failure kinda confusing to me)

• multiple definitions of main https://treeherder.mozilla.org/logviewer.html#?job_id=192678977&repo=try&lineNumber=38219 - I think this one is just that we're building files that are including other .c. files that we don't need to, I can probably fix this in the Firefox side (moz.build)
• lots of NSS "undefined references" in https://treeherder.mozilla.org/logviewer.html#?job_id=192717640&repo=try&lineNumber=38958

[henrycg]

The moz.build file should not include the pclient/main.c file in the SOURCES array (line 34):
https://hg.mozilla.org/try/file/f25a14180c85b64334e028fea81f94ed71917454/third_party/prio/moz.build#l34
The pclient directory just contains a test/example program.

This is probably responsible for the multiple definitions of main problem. There may be other build problems too.

[rhelmer]

Thanks, pushed a new tryserver build:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=4b019f9365e07c8544bc37d5cbcfb5038d9bda25

Will check it in a bit and post if there are still any problems.

[rhelmer]

This gets us further (thanks!) but seeing a ton of "undefined references" in https://treeherder.mozilla.org/logviewer.html#?job_id=192717640&repo=try&lineNumber=38958

[henrycg]

Hmm... I wonder why it's not linking properly against NSS.

Is there an easy way to get a diff between this version of the source and one that works? I wonder if one of the moz.build files got messed up along the way.

[franziskuskiefer]

I don't see any changes that could've caused this (the error is coming from security/apps that you didn't touch as far as I can see), but the error message is pretty clear in that it''s not linking to NSS.
Firefox offers ways to get NSS initialised etc. that could be used. But not sure if that makes sense, considering that it should work standalone as well.

[henrycg]

When building locally, I get many errors of the form:
25:38.08 /usr/bin/ld.gold: error: /gecko-dev/obj-x86_64-pc-linux-gnu/toolkit/library/../../third_party/prio/prg.o: requires dynamic R_X86_64_PC32 reloc against 'PK11_GetInternalSlot' which may overflow at runtime; recompile with -fPIC
before the other linker errors. It looks sort of similar to what happened here:
https://bugzilla.mozilla.org/show_bug.cgi?id=1194520

[rhelmer]

Hm. Well it's clear one of my patches is causing it, I'll bisect to see which.

[rhelmer]

Actually, bisection isn't going to be very useful here, as we need all the patches except the DOM one (vendoring both libprio and msgpack plus moz.build for each), I'll start digging around in the build config and asking build folks.

[rhelmer]

Build folks suspect this has something to do with MOZ_FOLD_LIBS being set only on macOS (aka darwin) not Linux... I don't really understand what this setting does yet.

[rhelmer]

Poking around in bugzilla for code outside of NSS that uses these symbols, noticed https://bugzilla.mozilla.org/show_bug.cgi?id=903135 - trying something similar with USE_LIBS in https://treeherder.mozilla.org/#/jobs?repo=try&revision=90efd6352eb7ea5cab81da764676c4993e850fdc (may need to #ifdef this for different platforms if it works...)

[rhelmer]

Oops, the way shared libraries are named has changed since that old bug - cribbing from a modern example (sqlite) instead https://searchfox.org/mozilla-central/source/config/external/sqlite/moz.build#16

https://treeherder.mozilla.org/#/jobs?repo=try&revision=d689fe49cb946b8af242ad1b1b938412506a4523

[rhelmer]

Hm. None of this is helping so far, going to focus on Windows for a bit and ask around for help.

[henrycg]

If I add NoVisibilityFlags() to the top of third_party/prio/moz.build, the NSS linker errors disappear. There are still some msgpack errors though.

I have no idea what NoVisibilityFlags() does though... it doesn't seem to be documented anywhere.

[henrycg]

If I use the following file for third_party/prio/moz.build, I can build the browser on Linux. The only changes are that I included the NoVisibilityFlags() line and included the msgpack source files here directly. (I couldn't figure out how to get libprio to link against msgpack otherwise.)

Edit: I also included the MPI file mpcpucache.c in SOURCES.

# vim: set filetype=python:
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#

DEFINES['PRIO_BUILD_LIBRARY'] = True

LOCAL_INCLUDES += [
    '/third_party/msgpack/include',
    'include',
]

EXPORTS += [
    'include/mprio.h',
]

# We allow warnings for third-party code that can be updated from upstream.
AllowCompilerWarnings()

# Does something that we don't understand.
NoVisibilityFlags()

SOURCES += [
    '../../security/nss/lib/freebl/mpi/montmulf.c',
    '../../security/nss/lib/freebl/mpi/mp_comba.c',
    '../../security/nss/lib/freebl/mpi/mp_gf2m.c',
    '../../security/nss/lib/freebl/mpi/mpcpucache.c',
    '../../security/nss/lib/freebl/mpi/mpi.c',
    '../../security/nss/lib/freebl/mpi/mplogic.c',
    '../../security/nss/lib/freebl/mpi/mpmontg.c',
    '../../security/nss/lib/freebl/mpi/mpprime.c',
    '../../security/nss/lib/freebl/mpi/mulsqr.c',
]

SOURCES += [
    '../msgpack/src/objectc.c',
    '../msgpack/src/unpack.c',
    '../msgpack/src/version.c',
    '../msgpack/src/vrefbuffer.c',
    '../msgpack/src/zone.c',

    'prio/client.c',
    'prio/config.c',
    'prio/encrypt.c',
    'prio/mparray.c',
    'prio/poly.c',
    'prio/prg.c',
    'prio/rand.c',
    'prio/serial.c',
    'prio/server.c',
    'prio/share.c',
]

FINAL_LIBRARY = 'xul'

[rhelmer]

Thanks! About to give that a shot.

[rhelmer]

Latest try run https://treeherder.mozilla.org/#/jobs?repo=try&revision=d5ec03bec0b44f383ea55f21f5254150dad13dca

[rhelmer]

Better but the multiple definition of main crept back in... I can handle that though.

[rhelmer]

Hrm well the tryserver is shut down for a bit, will update here when I can :)

[rhelmer]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=5a61c6839dcef4e40219a497e42584676a786708

[rhelmer]

After following this through the build system, I think NoVisibilityFlags() suppresses the -fvisibility=hidden flag: https://gcc.gnu.org/wiki/Visibility

I'll ask for build peer review in the bug though.

[rhelmer]

In any case, we're getting good Linux builds now! https://treeherder.mozilla.org/#/jobs?repo=try&revision=5a61c6839dcef4e40219a497e42584676a786708

[henrycg]

Sweet! Adding the msgpack files to the SOURCES array in third_party/prio/moz.build seems like a bit of a hack, though I couldn't find any documentation that explained a better way... maybe whoever reviews the patch will know what the right way to do this is.

[rhelmer]

This is working \o/ https://treeherder.mozilla.org/#/jobs?repo=try&revision=5da61e100e5d5e021b0893ba44452624f3c6ef98

All related PRs are merged and patches have been rebased into my Firefox+libprio integration patch as necessary, so I think we're done here.

Thanks all!