Segmentation fault

[jzakrzewski]

In #325 (commit f9baaea from your fork) you've fixed #330.
Unfortunately, in commit 399e040 of the same PR a use case below started to SIGSEGV:

TEST_F(TApp, EnumCheckedDefaultTransformCallback) {
    enum class existing : int16_t { abort, overwrite, remove };
    auto cmd = std::make_shared<CLI::App>("deploys the repository somewhere", "deploy");
    cmd->add_option("--existing", "What to do if file already exists in the destination")
        ->transform(
            CLI::CheckedTransformer(std::unordered_map<std::string, existing>{{"abort", existing::abort},
                                                                              {"overwrite", existing ::overwrite},
                                                                              {"delete", existing::remove},
                                                                              {"remove", existing::remove}}))
        ->default_val("abort");

    cmd->callback([cmd]() {
        EXPECT_EQ(cmd->get_option("--existing")->as<existing>(), existing::abort);
    });
    app.add_subcommand( cmd );

    args = {"deploy"};
    run();
}

stack trace:

$ gdb ./tests/TransformTest 
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Function(s) boost::.* will be skipped when stepping.
File(s) include/bits/*.h will be skipped when stepping.
Function(s) std::.* will be skipped when stepping.
Reading symbols from ./tests/TransformTest...(no debugging symbols found)...done.
(gdb) r
Starting program: /tmp/cli11/build/tests/TransformTest 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Running main() from /tmp/cli11/CLI11/extern/googletest/googletest/src/gtest_main.cc
[==========] Running 34 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 34 tests from TApp
[ RUN      ] TApp.SimpleTransform
[       OK ] TApp.SimpleTransform (0 ms)
[ RUN      ] TApp.SimpleTransformInitList
[       OK ] TApp.SimpleTransformInitList (0 ms)
[ RUN      ] TApp.SimpleNumericalTransform
[       OK ] TApp.SimpleNumericalTransform (0 ms)
[ RUN      ] TApp.EnumTransform
[       OK ] TApp.EnumTransform (0 ms)
[ RUN      ] TApp.EnumCheckedTransform
[       OK ] TApp.EnumCheckedTransform (1 ms)
[ RUN      ] TApp.EnumCheckedDefaultTransformCallback

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7b32ec0 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::empty() const () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
(gdb) bt
#0  0x00007ffff7b32ec0 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::empty() const () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#1  0x0000000000441223 in bool CLI::detail::lexical_assign<TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing, TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing, (CLI::detail::enabler)0>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing&) ()
#2  0x0000000000439afa in bool CLI::detail::lexical_conversion<TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing, TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing, (CLI::detail::enabler)0>(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing&) ()
#3  0x00000000004334dc in void CLI::Option::results<TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing, (CLI::detail::enabler)0>(TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing&) const ()
#4  0x000000000042ea22 in TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing CLI::Option::as<TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::existing>() const ()
#5  0x000000000040bf8e in TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::{lambda()#1}::operator()() const ()
#6  0x000000000043389a in std::_Function_handler<void (), TApp_EnumCheckedDefaultTransformCallback_Test::TestBody()::{lambda()#1}>::_M_invoke(std::_Any_data const&) ()
#7  0x000000000047c166 in std::function<void ()>::operator()() const ()
#8  0x0000000000469173 in CLI::App::run_callback(bool) ()
#9  0x0000000000469015 in CLI::App::run_callback(bool) ()
#10 0x0000000000466a61 in CLI::App::parse(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&) ()
#11 0x00000000004740f1 in TApp::run() ()
#12 0x000000000040caaa in TApp_EnumCheckedDefaultTransformCallback_Test::TestBody() ()
#13 0x00000000004f8435 in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ()
#14 0x00000000004f2fe5 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ()
#15 0x00000000004d2ae8 in testing::Test::Run() ()
#16 0x00000000004d3429 in testing::TestInfo::Run() ()
#17 0x00000000004d3a93 in testing::TestCase::Run() ()
#18 0x00000000004dea92 in testing::internal::UnitTestImpl::RunAllTests() ()
#19 0x00000000004f936b in bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) ()
#20 0x00000000004f3de1 in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) ()
#21 0x00000000004dd51a in testing::UnitTest::Run() ()
#22 0x000000000050569b in RUN_ALL_TESTS() ()
#23 0x0000000000505635 in main ()