Memory sanitizer complaint

[atn34]

Description

Thanks for the awesome project!
I'm noticing memory sanitizer complaining about a usage of std::set.

Steps to reproduce

$ cat test.cc
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

int factorial(int number) { return number <= 1 ? number : factorial(number - 1) * number; }

TEST_CASE("testing the factorial function") {
    CHECK(factorial(1) == 1);
    CHECK(factorial(2) == 2);
    CHECK(factorial(3) == 6);
    CHECK(factorial(10) == 3628800);
}

$ clang++ -fsanitize=memory test.cc -Idoctest && ./a.out
==24883==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x53a394 in std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_get_insert_unique_pos(std::pair<int, doctest::String> const&) (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x53a394)
    #1 0x539e1b in std::pair<std::_Rb_tree_iterator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, bool> std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_insert_unique<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >(std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>&&) (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x539e1b)
    #2 0x4f9cae in std::map<std::pair<int, doctest::String>, doctest::IReporter* (*)(doctest::ContextOptions const&), std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::insert(std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>&&) (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x4f9cae)
    #3 0x4c78ef in doctest::detail::registerReporterImpl(char const*, int, doctest::IReporter* (*)(doctest::ContextOptions const&)) (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x4c78ef)
    #4 0x4b1ac6 in int doctest::registerReporter<doctest::(anonymous namespace)::ConsoleReporter>(char const*, int) (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x4b1ac6)
    #5 0x41d789 in __cxx_global_var_init.65 (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x41d789)
    #6 0x41d9f7 in _GLOBAL__sub_I_test.cc (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x41d9f7)
    #7 0x53cc2c in __libc_csu_init (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x53cc2c)
    #8 0x7f638b665b27 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:266
    #9 0x41da29 in _start (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x41da29)

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/home/anoyes/workspace/doctest-repro/doctest/a.out+0x53a394) in std::_Rb_tree<std::pair<int, doctest::String>, std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)>, std::_Select1st<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> >, std::less<std::pair<int, doctest::String> >, std::allocator<std::pair<std::pair<int, doctest::String> const, doctest::IReporter* (*)(doctest::ContextOptions const&)> > >::_M_get_insert_unique_pos(std::pair<int, doctest::String> const&)
Exiting

Extra information

$ uname -a
Linux sasquatch 4.15.0-54-generic #58-Ubuntu SMP Mon Jun 24 10:55:24 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

$ git rev-parse HEAD
c250f8a698b070f5859c94739258a556a577bcd3

$ clang++ --version
clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

$ git bisect start HEAD 1.0.0
Bisecting: 421 revisions left to test after this (roughly 9 steps)
[ab8f7cfce7034ca3d9753cd338fb58e57c2a9d42] gcc 7 cannot work yet on travis...

$ git bisect run bash -c 'clang++ -fsanitize=memory test.cc -Idoctest || exit 125; ./a.out; exit $?'

...

8def6b040fd176f929e9ebc881810745e11e0a2d is the first bad commit
commit 8def6b040fd176f929e9ebc881810745e11e0a2d
Author: onqtam <[email protected]>
Date:   Fri Jun 10 21:28:08 2016 +0300

    removed custom implementations of vector and hashtable and now using std::vector and std::set

:040000 040000 3881a9649b386a8da9f9be7a669acc684ff66047 80f1546c91cdb31406a1f13bb37eba44ac82799f M      doctest
:040000 040000 ad0d1dd74ec472f7bcc62266ae2d1fb5223aaf31 ee2f54dc30e4a68c7fb8ffa48c2a47add90952b9 M      examples
:040000 040000 60beec22921f96ef5d674ed955afbbac261f3b14 18d53e1d99078e285f70568769473d2226660a6d M      scripts
bisect run success

[atn34]

https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo

It looks like my problem is that I need to instrument libc++ with msan