Tests fail on Fedora with gcc 6.1.1

[daveisfera]

I just started working on packaging fmt library for Fedora and the test 9 fails on Rawhide with gcc 6.1.1. Here's the output:

      Start  9: posix-mock-test
 9/10 Test  #9: posix-mock-test ..................***Exception: SegFault  0.22 sec

What can I do to help diagnose the source of this issue?

[nabijaczleweli]

Use GDB

[daveisfera]

I know 0 about the tests and how they're run. So I need some info like:

• Can a parameter be given to make test so it will run the tests in GDB?
• How do I run an individual test?

[daveisfera]

I played around a bit and figured out how to run the failing test in GDB. Here's what I ran:

/usr/bin/ctest
gdb /usr/bin/ctest
set follow-fork-mode child
run --rerun-failed

And here's the stacktrace:

#0  testing::internal::FunctionMockerBase<void (__locale_struct*)>::InvokeWith(std::tuple<__locale_struct*> const&) (args=std::tuple containing = {...}, this=0x7fffffffe100)
    at /builddir/build/BUILD/fmt-3.0.0/test/gmock/gmock.h:10094
#1  testing::internal::FunctionMocker<void (__locale_struct*)>::Invoke(__locale_struct*) (a1=0x2a, this=0x7fffffffe100)
        at /builddir/build/BUILD/fmt-3.0.0/test/gmock/gmock.h:10408
#2  LocaleMock::freelocale (gmock_a1=0x2a, this=0x7fffffffe068) at /builddir/build/BUILD/fmt-3.0.0/test/posix-mock-test.cc:483
#3  freelocale (locale=locale@entry=0x2a) at /builddir/build/BUILD/fmt-3.0.0/test/posix-mock-test.cc:518
#4  0x000055555558e7b6 in fmt::Locale::~Locale (this=<synthetic pointer>, __in_chrg=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/fmt/posix.h:379
#5  LocaleTest_Locale_Test::TestBody (this=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/test/posix-mock-test.cc:542
#6  0x00005555555d3ea4 in testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void> (location=0x5555555da5ab "the test body", method=<optimized out>,
            object=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3562
#7  testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void> (object=object@entry=0x555555807530, method=<optimized out>,
                location=location@entry=0x5555555da5ab "the test body") at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3598
#8  0x00005555555c9d7a in testing::Test::Run (this=this@entry=0x555555807530) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3635
#9  0x00005555555c9f6d in testing::Test::Run (this=0x555555807530) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3626
#10 testing::TestInfo::Run (this=0x555555808d50) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3810
#11 0x00005555555ca0f5 in testing::TestInfo::Run (this=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3785
#12 testing::TestCase::Run (this=0x555555808be0) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3928
#13 0x00005555555ca5ad in testing::TestCase::Run (this=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:5837
#14 testing::internal::UnitTestImpl::RunAllTests (this=0x555555806d30) at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:5799
#15 0x00005555555d4354 in testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> (
                    location=0x5555555d9920 "auxiliary test code (environments or event listeners)", method=<optimized out>, object=<optimized out>)
    at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3562
#16 testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> (object=0x555555806d30, method=<optimized out>,
        location=location@entry=0x5555555d9920 "auxiliary test code (environments or event listeners)") at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:3598
#17 0x00005555555ca889 in testing::UnitTest::Run (this=0x5555557f4b60 <testing::UnitTest::GetInstance()::instance>)
            at /builddir/build/BUILD/fmt-3.0.0/test/gmock-gtest-all.cc:5410
#18 0x000055555558882f in RUN_ALL_TESTS () at /builddir/build/BUILD/fmt-3.0.0/test/./gtest/gtest.h:20058
#19 main (argc=<optimized out>, argv=<optimized out>) at /builddir/build/BUILD/fmt-3.0.0/test/test-main.cc:57

[vitaut]

Thanks for the bug report. I was able to reproduce it and will look into it. As an interesting detail, this seems to only occur in the release version.

[vitaut]

The problem is caused by "delete this" in GMock when this is a null pointer. It is related to google/googletest#705. Should be fixed in d00b43c

I should probably submit the fix to GMock to fix this once and for all.

[daveisfera]

Ok, I applied the patch from d00b43c and the tests pass. Thanks.

[vitaut]

This might have been fixed in Google Test too, at least InvokeWith no longer calls GetValueAndDelete:

  Result InvokeWith(const ArgumentTuple& args)
        GTEST_LOCK_EXCLUDED_(g_gmock_mutex) {
    scoped_ptr<ResultHolder> holder(
        DownCast_<ResultHolder*>(this->UntypedInvokeWith(&args)));
    return holder->Unwrap();
}