External dependency `nlohmann/json.hpp` fails to build under Intel compiler icpc with warnings as error

[mlxd]

• Expected behavior: The external library nlohmann/json.hpp should compile and link without any modifications required.

• Actual behavior: Compiling with the classic intel compiler (icpc) causes several errors to be reported (see below).

• Reproduces how often: Only when building with icpc (2021.2.0 20210228) on Niagara.

• System information: Niagara HPC system, using the Jet benchmark for the TBCC.

Source code and backtraces

Please include any additional code snippets and backtraces related to the issue here.

Additional information

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[ 50%] Building CXX object CMakeFiles/tbcc.dir/tbcc_benchmark.cpp.o
/cvmfs/restricted.computecanada.ca/easybuild/software/2020/Core/intel/2021.2.0/compiler/2021.2.0/linux/bin/intel64/icpc   -I/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include -I/cvmfs/soft.computecanada.ca/easybuild/software/2020/Core/imkl/2021.2.0/mkl/2021.2.0/include -I/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/taskflow-src  -O3 -DNDEBUG   -Wall -Wextra -Werror -march=native -DENABLE_MKL -qopenmp -std=gnu++17 -o CMakeFiles/tbcc.dir/tbcc_benchmark.cpp.o -c /home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/tbcc_benchmark.cpp
/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/external/nlohmann/json.hpp(4697): error #1011: missing return statement at end of non-void function "nlohmann::detail::hash(const BasicJsonType &)"
  }
  ^

/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/external/nlohmann/json.hpp(16141): error #186: pointless comparison of unsigned integer with zero
          const bool is_negative = std::is_same<NumberType, number_integer_t>::value && !(x >= 0); // see issue #755
                                                                                            ^
          detected during:
            instantiation of "void nlohmann::detail::serializer<BasicJsonType>::dump_integer(NumberType) [with BasicJsonType=nlohmann::basic_json<std::map, std::vector, std::string, bool, int64_t={__int64_t={signed long}}, uint64_t={__uint64_t={unsigned long}}, double, std::allocator, nlohmann::adl_serializer, std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>>, NumberType=uint8_t={__uint8_t={unsigned char}}, <unnamed>=0]" at line 15703
            instantiation of "void nlohmann::detail::serializer<BasicJsonType>::dump(const BasicJsonType &, bool, bool, unsigned int, unsigned int) [with BasicJsonType=nlohmann::basic_json<std::map, std::vector, std::string, bool, int64_t={__int64_t={signed long}}, uint64_t={__uint64_t={unsigned long}}, double, std::allocator, nlohmann::adl_serializer, std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>>]" at line 18769
            instantiation of "nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::string_t nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::dump(int, char, bool, nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType,
                      NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::error_handler_t={nlohmann::detail::error_handler_t}) const [with ObjectType=std::map, ArrayType=std::vector, StringType=std::string, BooleanType=bool, NumberIntegerType=int64_t={__int64_t={signed long}}, NumberUnsignedType=uint64_t={__uint64_t={unsigned long}}, NumberFloatType=double, AllocatorType=std::allocator, JSONSerializer=nlohmann::adl_serializer,
                      BinaryType=std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>]" at line 254 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/TensorNetworkIO.hpp"
            instantiation of "std::vector<S, std::allocator<S>> Jet::TensorNetworkSerializer<Tensor>::TensorDataFromJSON_<S>(const Jet::json &, size_t={unsigned long}) [with Tensor=Jet::Tensor<std::complex<float>>, S=std::complex<float>]" at line 153 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/TensorNetworkIO.hpp"
            instantiation of "Jet::TensorNetworkFile<Tensor> Jet::TensorNetworkSerializer<Tensor>::operator()(std::string) [with Tensor=Jet::Tensor<std::complex<float>>]" at line 34 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/tbcc_benchmark.cpp"

/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/external/nlohmann/json.hpp(16141): error #186: pointless comparison of unsigned integer with zero
          const bool is_negative = std::is_same<NumberType, number_integer_t>::value && !(x >= 0); // see issue #755
                                                                                            ^
          detected during:
            instantiation of "void nlohmann::detail::serializer<BasicJsonType>::dump_integer(NumberType) [with BasicJsonType=nlohmann::basic_json<std::map, std::vector, std::string, bool, int64_t={__int64_t={signed long}}, uint64_t={__uint64_t={unsigned long}}, double, std::allocator, nlohmann::adl_serializer, std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>>, NumberType=uint64_t={__uint64_t={unsigned long}}, <unnamed>=0]" at line 15775
            instantiation of "void nlohmann::detail::serializer<BasicJsonType>::dump(const BasicJsonType &, bool, bool, unsigned int, unsigned int) [with BasicJsonType=nlohmann::basic_json<std::map, std::vector, std::string, bool, int64_t={__int64_t={signed long}}, uint64_t={__uint64_t={unsigned long}}, double, std::allocator, nlohmann::adl_serializer, std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>>]" at line 18769
            instantiation of "nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::string_t nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::dump(int, char, bool, nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType,
                      NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType>::error_handler_t={nlohmann::detail::error_handler_t}) const [with ObjectType=std::map, ArrayType=std::vector, StringType=std::string, BooleanType=bool, NumberIntegerType=int64_t={__int64_t={signed long}}, NumberUnsignedType=uint64_t={__uint64_t={unsigned long}}, NumberFloatType=double, AllocatorType=std::allocator, JSONSerializer=nlohmann::adl_serializer,
                      BinaryType=std::vector<uint8_t={__uint8_t={unsigned char}}, std::allocator<uint8_t={__uint8_t={unsigned char}}>>]" at line 254 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/TensorNetworkIO.hpp"
            instantiation of "std::vector<S, std::allocator<S>> Jet::TensorNetworkSerializer<Tensor>::TensorDataFromJSON_<S>(const Jet::json &, size_t={unsigned long}) [with Tensor=Jet::Tensor<std::complex<float>>, S=std::complex<float>]" at line 153 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/_deps/jet-src/include/jet/TensorNetworkIO.hpp"
            instantiation of "Jet::TensorNetworkFile<Tensor> Jet::TensorNetworkSerializer<Tensor>::operator()(std::string) [with Tensor=Jet::Tensor<std::complex<float>>]" at line 34 of "/home/s/sipejohn/mlxd/TMP/jet_benchmarks/benchmarks/Jet_TBCC/tbcc_benchmark.cpp"

The Jet benchmark Jet_TBCC was built and failed with the commands:

cmake . -DCMAKE_CXX_COMPILER=icpc -DENABLE_NATIVE=1 -DENABLE_OPENMP=1
make VERBOSE=1

and succeeded with

cmake . -DCMAKE_CXX_COMPILER=icpc -DENABLE_NATIVE=1 -DENABLE_OPENMP=1 -DENABLE_WARNINGS=0
make VERBOSE=1

[Mandrenkov]

Nice catch! Given that the library is under an MIT license, I think we are allowed to fix these errors in our copy of the header.

[trevor-vincent]

Weird I haven't had any problem running the serializer on niagara with the intel compiler, but I usually compile with a one-liner command. I will take more of a look.

[mlxd]

Weird I haven't had any problem running the serializer on niagara with the intel compiler, but I usually compile with a one-liner command. I will take more of a look.

Does your build enable warnings as errors? This could also be tied to the version of the Intel compiler I am using, as I did not test it with others available on the system.

[mlxd]

Nice catch! Given that the library is under an MIT license, I think we are allowed to fix these errors in our copy of the header.

This may be a good idea. Any thoughts on whether we just fix it locally, or consider creating a PR against the repo?

[Mandrenkov]

Any thoughts on whether we just fix it locally, or consider creating a PR against the repo?

Ideally, we should do both; however, our first priority is fixing the copy in the Jet repository.

[mlxd]

Just a note on this, Intel is phasing out the icc compiler in favour of the newer LLVM-backed compiler (icx), and requests all users to port to the newer suite. This issue can likely be ignored when the classica compiler is no longer supported.