Fails to compile flatbuffers tests: memest clearing an object of non-trivial type ‘struct MyGame::Example::Vec3'

[maxgerhardt]

When compiling this project as shown in the README, it gives

[ 17%] Completed 'capnproto'
[ 17%] Built target capnproto
Scanning dependencies of target flatbuffers
[ 18%] Creating directories for 'flatbuffers'
[ 19%] Performing download step (download, verify and extract) for 'flatbuffers'
-- Downloading...
   dst='/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/v1.10.0.tar.gz'
   timeout='none'
-- Using src='https://github.com/google/flatbuffers/archive/v1.10.0.tar.gz'
-- [download 100% complete]
-- verifying file...
       file='/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/v1.10.0.tar.gz'
-- Downloading... done
-- extracting...
     src='/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/v1.10.0.tar.gz'
     dst='/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers'
-- extracting... [tar xfz]
-- extracting... [analysis]
-- extracting... [rename]
-- extracting... [clean up]
-- extracting... done
[ 20%] No patch step for 'flatbuffers'
[ 21%] No update step for 'flatbuffers'
[ 22%] Performing configure step for 'flatbuffers'
-- flatbuffers configure command succeeded.  See also /home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers-stamp/flatbuffers-configure-*.log
[ 23%] Performing build step for 'flatbuffers'
CMake Error at /home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers-stamp/flatbuffers-build-Release.cmake:49 (message):
  Command failed: 2

   '/usr/bin/make'

  See also

    /home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers-stamp/flatbuffers-build-*.log


make[2]: *** [CMakeFiles/flatbuffers.dir/build.make:115: external/flatbuffers/src/flatbuffers-stamp/flatbuffers-build] Error 1
make[1]: *** [CMakeFiles/Makefile2:240: CMakeFiles/flatbuffers.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

with the further inner log being

$ cat /home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers-stamp/flatbuffers-build-*.log
In file included from /home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers/tests/test.cpp:32:
/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers/tests/monster_test_generated.h: In constructor ‘MyGame::Example::Vec3::Vec3()’:
/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers/tests/monster_test_generated.h:315:33: error: ‘void* memset(void*, int, size_t)’ clearing an object of non-trivial type ‘struct MyGame::Example::Vec3’; use assignment or value-initialization instead [-Werror=class-memaccess]
  315 |     memset(this, 0, sizeof(Vec3));
      |                                 ^
/home/max/md_compile_test/cpp-serializers/build/external/flatbuffers/src/flatbuffers/tests/monster_test_generated.h:301:41: note: ‘struct MyGame::Example::Vec3’ declared here
  301 | FLATBUFFERS_MANUALLY_ALIGNED_STRUCT(16) Vec3 FLATBUFFERS_FINAL_CLASS {
      |                                         ^~~~
cc1plus: all warnings being treated as errors
make[5]: *** [CMakeFiles/flattests.dir/build.make:145: CMakeFiles/flattests.dir/tests/test.cpp.o] Error 1
make[4]: *** [CMakeFiles/Makefile2:113: CMakeFiles/flattests.dir/all] Error 2
make[3]: *** [Makefile:141: all] Error 2

Machine is running Ubuntu Budgie 20.04, x64.

[Shark-Lucas]

try to update the CMakeLists: ExternalProject_Add(
flatbuffers
......
URL "https://github.com/google/flatbuffers/archive/v1.10.0.tar.gz"
to
URL "https://github.com/google/flatbuffers/archive/v1.11.0.tar.gz"

&&

URL_MD5 to "02c64880acb89dbd57eebacfd67200d8"