uninitialized variable

[PhilipDeegan]

since upgrading to fedora 44 I now see as werror

include/highfive/bits/H5Object_misc.hpp:72:13: error: ‘((const HighFive::Object*)this)[2305843009213693951].HighFive::Object::_hid’ is used uninitialized [-Werror=uninitialized]
   72 |     return (_hid > 0) && (detail::nothrow::h5i_is_valid(_hid) > 0);

[1uc]

Thank you for reporting this. I'd like to look into it. Do you have a reproducer, or the full output from the compiler (just paste the whole wall of gibberish). Please also include the output of ${COMPILER} --version since it will very likely matter.

[PhilipDeegan]

you should be able to reproduce it in docker with fedora gcc on 44 - I will validate the steps tomorrow

[PhilipDeegan]

the entire message is just

In file included from /root/highfive/include/highfive/H5Object.hpp:139,
                 from /root/highfive/include/highfive/H5File.hpp:14,
                 from /root/highfive/include/highfive/H5Easy.hpp:58,
                 from /root/highfive/src/examples/easy_attribute.cpp:31:
In member function ‘bool HighFive::Object::isValid() const’,
    inlined from ‘HighFive::PathTraits<Derivate>::PathTraits() [with Derivate = HighFive::Attribute]’ at /root/highfive/include/highfive/bits/H5Path_traits_misc.hpp:24:20:
/root/highfive/include/highfive/bits/H5Object_misc.hpp:72:13: error: ‘((const HighFive::Object*)this)[2305843009213693951].HighFive::Object::_hid’ is used uninitialized [-Werror=uninitialized]
   72 |     return (_hid > 0) && (detail::nothrow::h5i_is_valid(_hid) > 0);
      |             ^~~~
In member function ‘bool HighFive::Object::isValid() const’,
    inlined from ‘HighFive::PathTraits<Derivate>::PathTraits() [with Derivate = HighFive::DataSet]’ at /root/highfive/include/highfive/bits/H5Path_traits_misc.hpp:24:20:
/root/highfive/include/highfive/bits/H5Object_misc.hpp:72:13: error: ‘((const HighFive::Object*)this)[2305843009213693951].HighFive::Object::_hid’ is used uninitialized [-Werror=uninitialized]
   72 |     return (_hid > 0) && (detail::nothrow::h5i_is_valid(_hid) > 0);

g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/16/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,m2,cobol,algol68,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugzilla.redhat.com/ --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --enable-libstdcxx-backtrace --with-libstdcxx-zoneinfo=/usr/share/zoneinfo --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl=/builddir/build/BUILD/gcc-16.1.1-build/gcc-16.1.1-20260515/obj-x86_64-redhat-linux/isl-install --enable-offload-targets=nvptx-none,amdgcn-amdhsa --enable-offload-defaulted --without-cuda-driver --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-tls=gnu2 --with-arch_32=i686 --build=x86_64-redhat-linux --with-build-config=bootstrap-lto --enable-link-serialization=1 --disable-libssp
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.1.1 20260515 (Red Hat 16.1.1-2) (GCC) 

docker docker run --rm -it fedora:44

dnf install -y git make cmake openmpi openmpi-devel hdf5 m4 hdf5-openmpi-devel  g++ ninja-build hdf5-devel
cd root; git clone https://github.com/highfive-devs/highfive --recursive
cd highfive/
mkdir build
cd build/
cmake .. -DCMAKE_CXX_FLAGS="-Werror -Wextra -pedantic -Wall -march=native -mtune=native" -DCMAKE_BUILD_TYPE="Release"
make 

log

[root@a1d15b5f96ba build]# cmake .. -DCMAKE_CXX_FLAGS="-Werror -Wextra -pedantic -Wall -march=native -mtune=native" -DCMAKE_BUILD_TYPE="Release"
-- The C compiler identification is GNU 16.1.1
-- The CXX compiler identification is GNU 16.1.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/sbin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/sbin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found HDF5: /usr/lib64/libhdf5.so (found version "1.14.6")
-- Performing Test HAVE_FLAG__ffile_prefix_map__root_highfive_deps_catch2__
-- Performing Test HAVE_FLAG__ffile_prefix_map__root_highfive_deps_catch2__ - Success
-- Could NOT find Doxygen (missing: DOXYGEN_EXECUTABLE) 
--   Documentation (doc) cannot be built since Doxygen is not available.
-- Configuring done (0.4s)
-- Generating done (0.0s)
-- Build files have been written to: /root/highfive/build

[root@a1d15b5f96ba build]# make
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[ 14%] Linking CXX executable read_write_vector_dataset_bin
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[ 14%] Building CXX object src/examples/CMakeFiles/read_write_vector_dataset_references_bin.dir/read_write_vector_dataset_references.cpp.o
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[ 14%] Built target read_write_vector_dataset_references_bin
[ 15%] Building CXX object src/examples/CMakeFiles/renaming_objects_bin.dir/renaming_objects.cpp.o
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[ 16%] Building CXX object src/examples/CMakeFiles/select_by_id_dataset_cpp11_bin.dir/select_by_id_dataset_cpp11.cpp.o
[ 16%] Linking CXX executable select_by_id_dataset_cpp11_bin
[ 16%] Built target select_by_id_dataset_cpp11_bin
[ 17%] Building CXX object src/examples/CMakeFiles/select_partial_dataset_cpp11_bin.dir/select_partial_dataset_cpp11.cpp.o
[ 17%] Linking CXX executable select_partial_dataset_cpp11_bin
[ 17%] Built target select_partial_dataset_cpp11_bin
[ 18%] Building CXX object src/examples/CMakeFiles/select_partial_dataset_no_alloc_bin.dir/select_partial_dataset_no_alloc.cpp.o
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[ 18%] Building CXX object src/examples/CMakeFiles/easy_attribute_bin.dir/easy_attribute.cpp.o
In file included from /root/highfive/include/highfive/H5Object.hpp:139,
                 from /root/highfive/include/highfive/H5File.hpp:14,
                 from /root/highfive/include/highfive/H5Easy.hpp:58,
                 from /root/highfive/src/examples/easy_attribute.cpp:31:
In member function ‘bool HighFive::Object::isValid() const’,
    inlined from ‘HighFive::PathTraits<Derivate>::PathTraits() [with Derivate = HighFive::Attribute]’ at /root/highfive/include/highfive/bits/H5Path_traits_misc.hpp:24:20:
/root/highfive/include/highfive/bits/H5Object_misc.hpp:72:13: error: ‘((const HighFive::Object*)this)[2305843009213693951].HighFive::Object::_hid’ is used uninitialized [-Werror=uninitialized]
   72 |     return (_hid > 0) && (detail::nothrow::h5i_is_valid(_hid) > 0);
      |             ^~~~
In member function ‘bool HighFive::Object::isValid() const’,
    inlined from ‘HighFive::PathTraits<Derivate>::PathTraits() [with Derivate = HighFive::DataSet]’ at /root/highfive/include/highfive/bits/H5Path_traits_misc.hpp:24:20:
/root/highfive/include/highfive/bits/H5Object_misc.hpp:72:13: error: ‘((const HighFive::Object*)this)[2305843009213693951].HighFive::Object::_hid’ is used uninitialized [-Werror=uninitialized]
   72 |     return (_hid > 0) && (detail::nothrow::h5i_is_valid(_hid) > 0);
      |             ^~~~
cc1plus: all warnings being treated as errors
make[2]: *** [src/examples/CMakeFiles/easy_attribute_bin.dir/build.make:79: src/examples/CMakeFiles/easy_attribute_bin.dir/easy_attribute.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:980: src/examples/CMakeFiles/easy_attribute_bin.dir/all] Error 2
make: *** [Makefile:146: all] Error 2