Merge lp:~afrantzis/mir/fix-1577357-pthread-link into lp:mir

[Alexandros Frantzis]

examples: Work around pthread linking issues when using LTO

examples: Work around pthread linking issues when using LTO

Our previous workaround, which was enough for the gold/libstdc++ bug, isn't sufficient for the LTO/pthread issue. The new workaround creates a dummy std::thread which forces pthread linkage in all cases.

[Mir CI Bot (mir-ci-bot)]

FAILED: Continuous integration, rev:3565
https://mir-jenkins.ubuntu.com/job/mir-ci/1211/
Executed test runs:
    FAILURE: https://mir-jenkins.ubuntu.com/job/build-mir/1389/console
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/1440
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/1431
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial/1431
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1403
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1403/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1403
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1403/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1403
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1403/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1403
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1403/artifact/output/*zip*/output.zip
    FAILURE: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial/1403/console

Click here to trigger a rebuild:
https://mir-jenkins.ubuntu.com/job/mir-ci/1211/rebuild

review: Needs Fixing (continuous-integration)

[Alexandros Frantzis (afrantzis)]

CI failure is: https://bugs.launchpad.net/mir/+bug/1576760 . Retrying.

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:3565
https://mir-jenkins.ubuntu.com/job/mir-ci/1212/
Executed test runs:
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-mir/1390
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/1441
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/1432
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial/1432
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1404
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1404/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1404
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1404/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1404
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1404/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1404
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1404/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial/1404
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial/1404/artifact/output/*zip*/output.zip

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Kevin DuBois (kdub)]

lgtm

review: Approve

[Cemil Azizoglu (cemil-azizoglu)]

lgtm

review: Approve

[Mir CI Bot (mir-ci-bot)]

FAILED: Autolanding.
More details in the following jenkins job:
https://mir-jenkins.ubuntu.com/job/mir-autolanding/360/
Executed test runs:
    FAILURE: https://mir-jenkins.ubuntu.com/job/build-mir/1392/console
    None: https://mir-jenkins.ubuntu.com/job/generic-land-mp/387/console
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/1443
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/1434
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial/1434
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1406
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=vivid+overlay/1406/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1406
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial/1406/artifact/output/*zip*/output.zip
    FAILURE: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1406/console
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/1406/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1406
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/1406/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial/1406
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial/1406/artifact/output/*zip*/output.zip

review: Needs Fixing (continuous-integration)

[Alexandros Frantzis (afrantzis)]

"Slave went offline during the build". Reapproving.

[Mir CI Bot (mir-ci-bot)]

review: Approve (continuous-integration)

=== modified file 'examples/mir_demo_server_loader.cpp'
--- examples/mir_demo_server_loader.cpp	2016-05-03 06:55:25 +0000
+++ examples/mir_demo_server_loader.cpp	2016-06-29 11:19:49 +0000
@@ -19,7 +19,7 @@
 #include <dlfcn.h>
 #include <stdexcept>
 #include <iostream>
-#include <pthread.h>
+#include <thread>
 
 namespace
 {
@@ -28,14 +28,14 @@
 
 // Work around gold (or gcc/libstdc++-4.9 bug, it's not yet clear) bug
 // https://sourceware.org/bugzilla/show_bug.cgi?id=16417 by ensuring the
-// executable links with libpthread.
+// executable links with libpthread. A similar problem, where the pthread
+// link dependency mysteriously disappears, also exists when using LTO
+// with ld.bfd.
 struct GoldBug16417Workaround
 {
     GoldBug16417Workaround()
     {
-        pthread_attr_t attr;
-        pthread_attr_init(&attr);
-        pthread_attr_destroy(&attr);
+        std::thread{[]{}}.join();
     }
 } gold_bug_16417_workaround;
 }