diff --git a/bindings/CXX11/adios2/cxx11/fstream/ADIOS2fstream.tcc b/bindings/CXX11/adios2/cxx11/fstream/ADIOS2fstream.tcc
index e9e258455e..c253c2a824 100644
--- a/bindings/CXX11/adios2/cxx11/fstream/ADIOS2fstream.tcc
+++ b/bindings/CXX11/adios2/cxx11/fstream/ADIOS2fstream.tcc
@@ -15,6 +15,17 @@
 
 #include "adios2/core/Stream.h"
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wstrict-aliasing"
+#endif
+
 namespace adios2
 {
 
@@ -182,4 +193,12 @@ std::vector<T> fstream::read_attribute(const std::string &name,
 
 } // end namespace adios2
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+
 #endif /* ADIOS2_BINDINGS_CXX11_CXX11_FSTREAM_ADIOS2FSTREAM_TCC_ */
diff --git a/bindings/Python/py11File.cpp b/bindings/Python/py11File.cpp
index 096241a3f9..13dc12ae21 100644
--- a/bindings/Python/py11File.cpp
+++ b/bindings/Python/py11File.cpp
@@ -216,7 +216,7 @@ pybind11::array File::Read(const std::string &name, const Dims &start,
             m_Stream->Read<std::string>(name, blockID).front();
         pybind11::array_t<char> pyArray(Dims{value.size()});
         std::copy(value.begin(), value.end(), pyArray.mutable_data());
-        return pyArray;
+        return std::move(pyArray);
     }
 
     return Read(name, start, count, 0, 0, blockID);
@@ -270,7 +270,7 @@ pybind11::array File::ReadAttribute(const std::string &name,
         pybind11::array_t<T> pyArray(attribute->m_Elements);                   \
         m_Stream->ReadAttribute<T>(name, pyArray.mutable_data(), variableName, \
                                    separator);                                 \
-        return pyArray;                                                        \
+        return std::move(pyArray);                                             \
     }
     ADIOS2_FOREACH_NUMPY_ATTRIBUTE_TYPE_1ARG(declare_type)
 #undef declare_type
diff --git a/bindings/Python/py11File.tcc b/bindings/Python/py11File.tcc
index d8fa1b5da8..e102c1bfdf 100644
--- a/bindings/Python/py11File.tcc
+++ b/bindings/Python/py11File.tcc
@@ -91,7 +91,7 @@ pybind11::array File::DoRead(const std::string &name, const Dims &_start,
     }
     m_Stream->m_Engine->Get(variable, pyArray.mutable_data(), Mode::Sync);
 
-    return pyArray;
+    return std::move(pyArray);
 }
 
 } // end namespace py11
diff --git a/cmake/FindPythonModule.cmake b/cmake/FindPythonModule.cmake
index 4f9cf29f57..7a71efb78c 100644
--- a/cmake/FindPythonModule.cmake
+++ b/cmake/FindPythonModule.cmake
@@ -141,7 +141,7 @@ if(PythonModule_${module_NAME}_FOUND AND
   add_library(${module_NAME} INTERFACE)
   add_library(Python::${module_NAME} ALIAS ${module_NAME})
   foreach(inc_var IN LISTS include_vars)
-    target_include_directories(${module_NAME} INTERFACE ${${inc_var}})
+    target_include_directories(${module_NAME} SYSTEM INTERFACE ${${inc_var}})
   endforeach()
   foreach(lib_var IN LISTS library_vars)
     target_link_libraries(${module_NAME} INTERFACE ${${lib_var}})
diff --git a/examples/basics/values/values_write.cpp b/examples/basics/values/values_write.cpp
index 668cffa62c..99f27bb226 100644
--- a/examples/basics/values/values_write.cpp
+++ b/examples/basics/values/values_write.cpp
@@ -71,6 +71,8 @@ int main(int argc, char *argv[])
          */
         // 1. Global constant, same value across processes, constant over time
         adios2::Variable<int> varNproc = io.DefineVariable<int>("Nproc");
+        (void)varNproc; // For the sake of the example we create an unused
+                        // variable
 
         // 2. Global value, same value across processes, varying value over time
         adios2::Variable<int> varStep = io.DefineVariable<int>("Step");
diff --git a/examples/hello/bpReader/helloBPReader_nompi.cpp b/examples/hello/bpReader/helloBPReader_nompi.cpp
index 776543d8a5..f8161897d0 100644
--- a/examples/hello/bpReader/helloBPReader_nompi.cpp
+++ b/examples/hello/bpReader/helloBPReader_nompi.cpp
@@ -36,7 +36,7 @@ int main(int argc, char *argv[])
             bpIO.AvailableVariables(true);
 
         std::cout << "List of variables:";
-        for (const auto variablePair : variables)
+        for (const auto &variablePair : variables)
         {
             std::cout << "  " << variablePair.first;
         }
diff --git a/examples/hello/bpWriter/helloBPSZ.cpp b/examples/hello/bpWriter/helloBPSZ.cpp
index 3b24095e1e..a9943557ed 100644
--- a/examples/hello/bpWriter/helloBPSZ.cpp
+++ b/examples/hello/bpWriter/helloBPSZ.cpp
@@ -89,6 +89,9 @@ int main(int argc, char *argv[])
         adios2::Attribute<double> attribute =
             bpIO.DefineAttribute<double>("SZ_accuracy", accuracy);
 
+        // To avoid compiling warnings
+        (void)attribute;
+
         /** Engine derived class, spawned to start IO operations */
         adios2::Engine bpFileWriter =
             bpIO.Open("SZexample.bp", adios2::Mode::Write);
diff --git a/examples/hello/bpWriter/helloBPSubStreams.cpp b/examples/hello/bpWriter/helloBPSubStreams.cpp
index 73e9412775..59ed618eef 100644
--- a/examples/hello/bpWriter/helloBPSubStreams.cpp
+++ b/examples/hello/bpWriter/helloBPSubStreams.cpp
@@ -67,6 +67,8 @@ int main(int argc, char *argv[])
 
         adios2::Attribute<int> attribute =
             bpIO.DefineAttribute<int>("attrINT", -1);
+        (void)attribute; // For the sake of the example we create an unused
+                         // variable
 
         /** Engine derived class, spawned to start IO operations */
         adios2::Engine bpFileWriter =
diff --git a/examples/hello/bpWriter/helloBPWriter.cpp b/examples/hello/bpWriter/helloBPWriter.cpp
index e67c82ba92..6c5714b8e7 100644
--- a/examples/hello/bpWriter/helloBPWriter.cpp
+++ b/examples/hello/bpWriter/helloBPWriter.cpp
@@ -63,6 +63,8 @@ int main(int argc, char *argv[])
 
         adios2::Variable<std::string> bpString =
             bpIO.DefineVariable<std::string>("bpString");
+        (void)bpString; // For the sake of the example we create an unused
+                        // variable
 
         std::string filename = "myVector_cpp.bp";
         /** Engine derived class, spawned to start IO operations */
diff --git a/examples/hello/hdf5Reader/helloHDF5Reader_nompi.cpp b/examples/hello/hdf5Reader/helloHDF5Reader_nompi.cpp
index a6f64151ad..9aab7f8b5f 100644
--- a/examples/hello/hdf5Reader/helloHDF5Reader_nompi.cpp
+++ b/examples/hello/hdf5Reader/helloHDF5Reader_nompi.cpp
@@ -93,7 +93,7 @@ int main(int argc, char *argv[])
         const std::map<std::string, adios2::Params> variables =
             h5IO.AvailableVariables();
 
-        for (const auto variablePair : variables)
+        for (const auto &variablePair : variables)
         {
             std::cout << "Name: " << variablePair.first;
             std::cout << std::endl;
diff --git a/scripts/ci/cmake/ci-ascent-gcc.cmake b/scripts/ci/cmake/ci-ascent-gcc.cmake
index 9e67411f6e..5d627975c3 100644
--- a/scripts/ci/cmake/ci-ascent-gcc.cmake
+++ b/scripts/ci/cmake/ci-ascent-gcc.cmake
@@ -14,9 +14,6 @@ env_module(load zeromq)
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS}   "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{CXXFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{FFLAGS}   "-Werror -Wno-error=builtin-declaration-mismatch")
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:BOOL=OFF
@@ -30,6 +27,10 @@ ADIOS2_USE_SST:BOOL=ON
 ADIOS2_USE_SZ:BOOL=OFF
 ADIOS2_USE_ZeroMQ:STRING=ON
 ADIOS2_USE_ZFP:BOOL=OFF
+
+CMAKE_C_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
+CMAKE_CXX_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
+CMAKE_Fortran_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
 ")
 
 set(NCPUS 4)
diff --git a/scripts/ci/cmake/ci-debian-sid-openmpi.cmake b/scripts/ci/cmake/ci-debian-sid-openmpi.cmake
index 889a7ed5a0..ad1623109b 100644
--- a/scripts/ci/cmake/ci-debian-sid-openmpi.cmake
+++ b/scripts/ci/cmake/ci-debian-sid-openmpi.cmake
@@ -12,6 +12,7 @@ set(ENV{CXXFLAGS} "-Wno-deprecated -Wno-deprecated-declarations")
 set(dashboard_cache "
 ADIOS2_USE_EXTERNAL_DEPENDENCIES:BOOL=ON
 ADIOS2_USE_EXTERNAL_EVPATH:BOOL=OFF
+ADIOS2_USE_EXTERNAL_NLOHMANN_JSON:BOOL=OFF
 ADIOS2_USE_BZip2:BOOL=ON
 ADIOS2_USE_Blosc:BOOL=ON
 ADIOS2_USE_Fortran:BOOL=ON
diff --git a/scripts/ci/cmake/ci-debian-sid.cmake b/scripts/ci/cmake/ci-debian-sid.cmake
index a94eb99b92..b576832c0f 100644
--- a/scripts/ci/cmake/ci-debian-sid.cmake
+++ b/scripts/ci/cmake/ci-debian-sid.cmake
@@ -12,6 +12,7 @@ set(ENV{CXXFLAGS} "-Wno-deprecated -Wno-deprecated-declarations")
 set(dashboard_cache "
 ADIOS2_USE_EXTERNAL_DEPENDENCIES:BOOL=ON
 ADIOS2_USE_EXTERNAL_EVPATH:BOOL=OFF
+ADIOS2_USE_EXTERNAL_NLOHMANN_JSON:BOOL=OFF
 ADIOS2_USE_BZip2:BOOL=ON
 ADIOS2_USE_Blosc:BOOL=ON
 ADIOS2_USE_Fortran:BOOL=ON
diff --git a/scripts/ci/cmake/ci-el7-gnu8-ohpc.cmake b/scripts/ci/cmake/ci-el7-gnu8-ohpc.cmake
index 6bbc905f82..242bd3f2f1 100644
--- a/scripts/ci/cmake/ci-el7-gnu8-ohpc.cmake
+++ b/scripts/ci/cmake/ci-el7-gnu8-ohpc.cmake
@@ -10,9 +10,6 @@ env_module(load hdf5)
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{CXXFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{FFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:BOOL=ON
@@ -25,6 +22,10 @@ ADIOS2_USE_Python:BOOL=ON
 ADIOS2_USE_SZ:BOOL=ON
 ADIOS2_USE_ZeroMQ:STRING=ON
 ADIOS2_USE_ZFP:BOOL=ON
+
+CMAKE_C_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_CXX_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_Fortran_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
 ")
 
 set(CTEST_CMAKE_GENERATOR "Unix Makefiles")
diff --git a/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc-static.cmake b/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc-static.cmake
index 581be161aa..90dc63a0e1 100644
--- a/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc-static.cmake
+++ b/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc-static.cmake
@@ -16,9 +16,6 @@ env_module(load py3-mpi4py)
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{CXXFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{FFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
 
 set(dashboard_cache "
 BUILD_SHARED_LIBS:BOOL=OFF
@@ -36,6 +33,10 @@ ADIOS2_USE_SZ:BOOL=OFF
 ADIOS2_USE_ZeroMQ:STRING=OFF
 ADIOS2_USE_ZFP:BOOL=OFF
 
+CMAKE_C_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_CXX_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_Fortran_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
+
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
diff --git a/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc.cmake b/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc.cmake
index 16f5ccf725..6e652110c2 100644
--- a/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc.cmake
+++ b/scripts/ci/cmake/ci-el7-gnu8-openmpi-ohpc.cmake
@@ -16,9 +16,6 @@ env_module(load py3-mpi4py)
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{CXXFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{FFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:BOOL=ON
@@ -32,6 +29,10 @@ ADIOS2_USE_SZ:BOOL=ON
 ADIOS2_USE_ZeroMQ:STRING=ON
 ADIOS2_USE_ZFP:BOOL=ON
 
+CMAKE_C_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_CXX_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_Fortran_FLAGS:STRING=-Werror -Wno-error=builtin-declaration-mismatch
+
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
diff --git a/scripts/ci/cmake/ci-el7-intel-ohpc.cmake b/scripts/ci/cmake/ci-el7-intel-ohpc.cmake
index 6aec07e815..2124b4afbd 100644
--- a/scripts/ci/cmake/ci-el7-intel-ohpc.cmake
+++ b/scripts/ci/cmake/ci-el7-intel-ohpc.cmake
@@ -10,11 +10,10 @@ env_module(load hdf5)
 set(ENV{CC}  icc)
 set(ENV{CXX} icpc)
 set(ENV{FC}  ifort)
-set(ENV{CFLAGS} -Werror)
-set(ENV{CXXFLAGS} -Werror)
-set(ENV{FFLAGS} "-warn errors")
 
 set(dashboard_cache "
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
 ADIOS2_USE_BZip2:BOOL=ON
 ADIOS2_USE_Blosc:BOOL=ON
 ADIOS2_USE_DataMan:BOOL=ON
diff --git a/scripts/ci/cmake/ci-el7-intel-openmpi-ohpc.cmake b/scripts/ci/cmake/ci-el7-intel-openmpi-ohpc.cmake
index 696ca55aad..e95dfd9fae 100644
--- a/scripts/ci/cmake/ci-el7-intel-openmpi-ohpc.cmake
+++ b/scripts/ci/cmake/ci-el7-intel-openmpi-ohpc.cmake
@@ -16,9 +16,6 @@ env_module(load py3-mpi4py)
 set(ENV{CC}  icc)
 set(ENV{CXX} icpc)
 set(ENV{FC}  ifort)
-set(ENV{CFLAGS} -Werror)
-set(ENV{CXXFLAGS} -Werror)
-set(ENV{FFLAGS} "-warn errors")
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:BOOL=ON
@@ -32,6 +29,10 @@ ADIOS2_USE_SZ:BOOL=ON
 ADIOS2_USE_ZeroMQ:STRING=ON
 ADIOS2_USE_ZFP:STRING=ON
 
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
+CMAKE_Fortran_FLAGS:STRING=-warn errors
+
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
diff --git a/scripts/ci/cmake/ci-el7-spack.cmake b/scripts/ci/cmake/ci-el7-spack.cmake
index 6fcd590243..e69c6882a8 100644
--- a/scripts/ci/cmake/ci-el7-spack.cmake
+++ b/scripts/ci/cmake/ci-el7-spack.cmake
@@ -26,6 +26,9 @@ ADIOS2_USE_EXTERNAL_DEPENDENCIES:BOOL=ON
 ADIOS2_USE_EXTERNAL_GTEST:BOOL=OFF
 ADIOS2_USE_EXTERNAL_PUGIXML:BOOL=OFF
 
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
+
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
diff --git a/scripts/ci/cmake/ci-el7.cmake b/scripts/ci/cmake/ci-el7.cmake
index 4ee0370760..b76f843cb9 100644
--- a/scripts/ci/cmake/ci-el7.cmake
+++ b/scripts/ci/cmake/ci-el7.cmake
@@ -3,9 +3,6 @@
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS} -Werror)
-set(ENV{CXXFLAGS} -Werror)
-set(ENV{FFLAGS} -Werror)
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:STRING=ON
@@ -16,6 +13,9 @@ ADIOS2_USE_MPI:STRING=OFF
 ADIOS2_USE_Python:STRING=ON
 ADIOS2_USE_ZeroMQ:STRING=ON
 ADIOS2_USE_ZFP:STRING=ON
+
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
 ")
 
 set(CTEST_CMAKE_GENERATOR "Unix Makefiles")
diff --git a/scripts/ci/cmake/ci-macos1014-xcode103-ninja.cmake b/scripts/ci/cmake/ci-macos1014-xcode103-ninja.cmake
index b9f1eba04e..9b1a72c968 100644
--- a/scripts/ci/cmake/ci-macos1014-xcode103-ninja.cmake
+++ b/scripts/ci/cmake/ci-macos1014-xcode103-ninja.cmake
@@ -7,6 +7,9 @@ set(dashboard_cache "
 ADIOS2_USE_Fortran:BOOL=ON
 ADIOS2_USE_MPI:BOOL=OFF
 ADIOS2_USE_Python:BOOL=ON
+
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
 ")
 
 set(ENV{MACOSX_DEPLOYMENT_TARGET} "10.14")
diff --git a/scripts/ci/cmake/ci-macos1014-xcode103-openmpi-make.cmake b/scripts/ci/cmake/ci-macos1014-xcode103-openmpi-make.cmake
index 51ba0bfc31..6632850247 100644
--- a/scripts/ci/cmake/ci-macos1014-xcode103-openmpi-make.cmake
+++ b/scripts/ci/cmake/ci-macos1014-xcode103-openmpi-make.cmake
@@ -11,6 +11,9 @@ set(dashboard_cache "
 ADIOS2_USE_Fortran:BOOL=ON
 ADIOS2_USE_MPI:STRING=ON
 
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
+
 MPIEXEC_EXTRA_FLAGS:STRING=--oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=4
 ")
diff --git a/scripts/ci/cmake/ci-macos1015-xcode111-make.cmake b/scripts/ci/cmake/ci-macos1015-xcode111-make.cmake
index c422af45a0..48f12fd6d2 100644
--- a/scripts/ci/cmake/ci-macos1015-xcode111-make.cmake
+++ b/scripts/ci/cmake/ci-macos1015-xcode111-make.cmake
@@ -7,6 +7,9 @@ set(dashboard_cache "
 ADIOS2_USE_Fortran:BOOL=ON
 ADIOS2_USE_MPI:BOOL=OFF
 ADISO2_USE_Python:BOOL=ON
+
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
 ")
 
 set(ENV{MACOSX_DEPLOYMENT_TARGET} "10.15")
diff --git a/scripts/ci/cmake/ci-macos1015-xcode111-openmpi-ninja.cmake b/scripts/ci/cmake/ci-macos1015-xcode111-openmpi-ninja.cmake
index af2ffa94c8..561996515e 100644
--- a/scripts/ci/cmake/ci-macos1015-xcode111-openmpi-ninja.cmake
+++ b/scripts/ci/cmake/ci-macos1015-xcode111-openmpi-ninja.cmake
@@ -11,6 +11,9 @@ set(dashboard_cache "
 ADIOS2_USE_Fortran:BOOL=ON
 ADIOS2_USE_MPI:STRING=ON
 
+CMAKE_C_FLAGS:STRING=-Wall -Werror
+CMAKE_CXX_FLAGS:STRING=-Wall -Werror
+
 MPIEXEC_EXTRA_FLAGS:STRING=--oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=4
 ")
diff --git a/scripts/ci/cmake/ci-ubuntu1804-spack.cmake b/scripts/ci/cmake/ci-ubuntu1804-spack.cmake
index 2b833980d4..326a30c6f6 100644
--- a/scripts/ci/cmake/ci-ubuntu1804-spack.cmake
+++ b/scripts/ci/cmake/ci-ubuntu1804-spack.cmake
@@ -7,9 +7,6 @@ math(EXPR N2CPUS "${NCPUS}*2")
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
-set(ENV{CFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{CXXFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
-set(ENV{FFLAGS} "-Werror -Wno-error=builtin-declaration-mismatch")
 
 set(dashboard_cache "
 ADIOS2_USE_BZip2:BOOL=ON
@@ -29,6 +26,9 @@ ADIOS2_USE_EXTERNAL_DEPENDENCIES:BOOL=ON
 ADIOS2_USE_EXTERNAL_GTEST:BOOL=OFF
 ADIOS2_USE_EXTERNAL_PUGIXML:BOOL=OFF
 
+CMAKE_C_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+CMAKE_CXX_FLAGS:STRING=-Werror -Wall -Wno-error=builtin-declaration-mismatch
+
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe
 MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
diff --git a/source/adios2/engine/bp5/BP5Reader.cpp b/source/adios2/engine/bp5/BP5Reader.cpp
index b4e78c8f49..96c49197ba 100644
--- a/source/adios2/engine/bp5/BP5Reader.cpp
+++ b/source/adios2/engine/bp5/BP5Reader.cpp
@@ -24,8 +24,8 @@ namespace engine
 BP5Reader::BP5Reader(IO &io, const std::string &name, const Mode mode,
                      helper::Comm comm)
 : Engine("BP5Reader", io, name, mode, std::move(comm)), m_MDFileManager(m_Comm),
-  m_FileMetaMetadataManager(m_Comm), m_DataFileManager(m_Comm),
-  m_MDIndexFileManager(m_Comm), m_ActiveFlagFileManager(m_Comm)
+  m_DataFileManager(m_Comm), m_MDIndexFileManager(m_Comm),
+  m_FileMetaMetadataManager(m_Comm), m_ActiveFlagFileManager(m_Comm)
 {
     PERFSTUBS_SCOPED_TIMER("BP5Reader::Open");
     Init();
@@ -606,8 +606,8 @@ void BP5Reader::ParseMetadataIndex(format::BufferSTL &bufferSTL,
         for (uint64_t i = 0; i < m_WriterCount; i++)
         {
             size_t DataPosPos = ptrs[2] + sizeof(uint64_t) * i;
-            const uint64_t DataPos = helper::ReadValue<uint64_t>(
-                buffer, DataPosPos, m_Minifooter.IsLittleEndian);
+            helper::ReadValue<uint64_t>(buffer, DataPosPos,
+                                        m_Minifooter.IsLittleEndian);
         }
 
         position += sizeof(uint64_t) * m_WriterCount;
diff --git a/source/adios2/engine/bp5/BP5Writer.cpp b/source/adios2/engine/bp5/BP5Writer.cpp
index 594d4a47a0..38963f280b 100644
--- a/source/adios2/engine/bp5/BP5Writer.cpp
+++ b/source/adios2/engine/bp5/BP5Writer.cpp
@@ -32,7 +32,7 @@ BP5Writer::BP5Writer(IO &io, const std::string &name, const Mode mode,
                      helper::Comm comm)
 : Engine("BP5Writer", io, name, mode, std::move(comm)), m_BP5Serializer(),
   m_FileDataManager(m_Comm), m_FileMetadataManager(m_Comm),
-  m_FileMetaMetadataManager(m_Comm), m_FileMetadataIndexManager(m_Comm)
+  m_FileMetadataIndexManager(m_Comm), m_FileMetaMetadataManager(m_Comm)
 {
     PERFSTUBS_SCOPED_TIMER("BP5Writer::Open");
     m_IO.m_ReadStreaming = false;
@@ -459,7 +459,6 @@ void BP5Writer::InitTransports()
         m_FileMetadataManager.OpenFiles(m_MetadataFileNames, m_OpenMode,
                                         m_IO.m_TransportsParameters, false);
 
-        uint64_t WriterCount = m_Comm.Size();
         m_FileMetadataIndexManager.OpenFiles(
             m_MetadataIndexFileNames, m_OpenMode, m_IO.m_TransportsParameters,
             false);
@@ -640,6 +639,7 @@ void BP5Writer::InitBPBuffer()
         MakeHeader(bi, "Index Table", true);
         m_FileMetadataIndexManager.WriteFiles(bi.m_Buffer.data(),
                                               bi.m_Position);
+
         // where each rank's data will end up
         m_FileMetadataIndexManager.WriteFiles((char *)Assignment.data(),
                                               sizeof(Assignment[0]) *
diff --git a/source/adios2/engine/dataman/DataManMonitor.cpp b/source/adios2/engine/dataman/DataManMonitor.cpp
index 7be79c4717..cbcc178bd8 100644
--- a/source/adios2/engine/dataman/DataManMonitor.cpp
+++ b/source/adios2/engine/dataman/DataManMonitor.cpp
@@ -12,7 +12,7 @@
 #include <fstream>
 #include <iostream>
 #include <math.h>
-#include <nlohmann/json.hpp>
+#include <nlohmann_json.hpp>
 
 namespace adios2
 {
diff --git a/source/adios2/engine/dataman/DataManMonitor.h b/source/adios2/engine/dataman/DataManMonitor.h
index e8d732e8a6..9a95cf496d 100644
--- a/source/adios2/engine/dataman/DataManMonitor.h
+++ b/source/adios2/engine/dataman/DataManMonitor.h
@@ -76,7 +76,6 @@ class DataManMonitor
     bool m_WriterThreading = false;
 
     bool m_Verbose = true;
-    bool m_JsonOutput = true;
 };
 
 } // end namespace engine
diff --git a/source/adios2/engine/hdf5/HDF5ReaderP.cpp b/source/adios2/engine/hdf5/HDF5ReaderP.cpp
index 25bafada34..6e007ff9be 100644
--- a/source/adios2/engine/hdf5/HDF5ReaderP.cpp
+++ b/source/adios2/engine/hdf5/HDF5ReaderP.cpp
@@ -202,8 +202,8 @@ size_t HDF5ReaderP::ReadDataset(hid_t dataSetId, hid_t h5Type,
             size_t typesize = H5Tget_size(h5Type);
 
             char *val = (char *)(calloc(typesize, sizeof(char)));
-            hid_t ret2 = H5Dread(dataSetId, h5Type, memDataSpace, fileSpace,
-                                 H5P_DEFAULT, val);
+            H5Dread(dataSetId, h5Type, memDataSpace, fileSpace, H5P_DEFAULT,
+                    val);
 
             ((std::string *)values)->assign(val, typesize);
             free(val);
diff --git a/source/adios2/engine/ssc/SscHelper.cpp b/source/adios2/engine/ssc/SscHelper.cpp
index b5cf30a550..d734862c97 100644
--- a/source/adios2/engine/ssc/SscHelper.cpp
+++ b/source/adios2/engine/ssc/SscHelper.cpp
@@ -421,7 +421,7 @@ void AggregateMetadata(const Buffer &localBuffer, Buffer &globalBuffer,
     globalBuffer.resize(globalSize + 10);
 
     std::vector<int> displs(mpiSize);
-    for (size_t i = 1; i < mpiSize; ++i)
+    for (size_t i = 1; i < static_cast<size_t>(mpiSize); ++i)
     {
         displs[i] = displs[i - 1] + localSizes[i - 1];
     }
@@ -438,7 +438,7 @@ void BroadcastMetadata(Buffer &globalBuffer, const int root, MPI_Comm comm)
 {
     int globalBufferSize = static_cast<int>(globalBuffer.size());
     MPI_Bcast(&globalBufferSize, 1, MPI_INT, root, comm);
-    if (globalBuffer.size() < globalBufferSize)
+    if (globalBuffer.size() < static_cast<size_t>(globalBufferSize))
     {
         globalBuffer.resize(globalBufferSize);
     }
diff --git a/source/adios2/engine/ssc/SscReader.cpp b/source/adios2/engine/ssc/SscReader.cpp
index 7701d2d21b..f82fb325e9 100644
--- a/source/adios2/engine/ssc/SscReader.cpp
+++ b/source/adios2/engine/ssc/SscReader.cpp
@@ -140,9 +140,12 @@ StepStatus SscReader::BeginStep(const StepMode stepMode,
         auto variable = m_IO.InquireVariable<T>(v.name);                       \
         if (variable)                                                          \
         {                                                                      \
-            std::memcpy(&variable->m_Min, value.data(), value.size());         \
-            std::memcpy(&variable->m_Max, value.data(), value.size());         \
-            std::memcpy(&variable->m_Value, value.data(), value.size());       \
+            std::memcpy(reinterpret_cast<char *>(&variable->m_Min),            \
+                        value.data(), value.size());                           \
+            std::memcpy(reinterpret_cast<char *>(&variable->m_Max),            \
+                        value.data(), value.size());                           \
+            std::memcpy(reinterpret_cast<char *>(&variable->m_Value),          \
+                        value.data(), value.size());                           \
         }                                                                      \
     }
                 ADIOS2_FOREACH_STDTYPE_1ARG(declare_type)
diff --git a/source/adios2/engine/ssc/SscReader.tcc b/source/adios2/engine/ssc/SscReader.tcc
index d787a4d763..8799b275c5 100644
--- a/source/adios2/engine/ssc/SscReader.tcc
+++ b/source/adios2/engine/ssc/SscReader.tcc
@@ -197,11 +197,13 @@ SscReader::BlocksInfoCommon(const Variable<T> &variable,
                         m_WriterDefinitionsLocked == false ||
                         m_ReaderSelectionsLocked == false)
                     {
-                        std::memcpy(&b.Value, v.value.data(), v.value.size());
+                        std::memcpy(reinterpret_cast<char *>(&b.Value),
+                                    v.value.data(), v.value.size());
                     }
                     else
                     {
-                        std::memcpy(&b.Value, m_Buffer.data() + v.bufferStart,
+                        std::memcpy(reinterpret_cast<char *>(&b.Value),
+                                    m_Buffer.data() + v.bufferStart,
                                     v.bufferCount);
                     }
                 }
diff --git a/source/adios2/engine/sst/SstReader.cpp b/source/adios2/engine/sst/SstReader.cpp
index a5aae390e6..f911edc778 100644
--- a/source/adios2/engine/sst/SstReader.cpp
+++ b/source/adios2/engine/sst/SstReader.cpp
@@ -486,7 +486,7 @@ void SstReader::Init()
             size_t *Start = NULL;                                              \
             size_t *Count = NULL;                                              \
             size_t DimCount = 0;                                               \
-            int NeedSync;                                                      \
+            int NeedSync = 0;                                                  \
                                                                                \
             if (variable.m_SelectionType ==                                    \
                 adios2::SelectionType::BoundingBox)                            \
@@ -586,7 +586,7 @@ void SstReader::Init()
         }                                                                      \
         if (m_WriterMarshalMethod == SstMarshalBP5)                            \
         {                                                                      \
-            bool need_sync = m_BP5Deserializer->QueueGet(variable, data);      \
+            m_BP5Deserializer->QueueGet(variable, data);                       \
         }                                                                      \
     }
 ADIOS2_FOREACH_STDTYPE_1ARG(declare_gets)
diff --git a/source/adios2/helper/adiosJSONcomplex.h b/source/adios2/helper/adiosJSONcomplex.h
index e3a9e3ae92..496336ffb5 100644
--- a/source/adios2/helper/adiosJSONcomplex.h
+++ b/source/adios2/helper/adiosJSONcomplex.h
@@ -11,8 +11,8 @@
 #ifndef ADIOS2_HELPER_ADIOSJSONCOMPLEX_H_
 #define ADIOS2_HELPER_ADIOSJSONCOMPLEX_H_
 
-#include "nlohmann/json.hpp"
 #include <complex>
+#include <nlohmann_json.hpp>
 
 // JSON std::complex handling
 namespace std
diff --git a/source/adios2/helper/adiosMemory.inl b/source/adios2/helper/adiosMemory.inl
index 95a2889be1..41217f5af0 100644
--- a/source/adios2/helper/adiosMemory.inl
+++ b/source/adios2/helper/adiosMemory.inl
@@ -623,7 +623,7 @@ void Resize(std::vector<T> &vec, const size_t dataSize, const std::string hint,
 // functions) and copies to the output buffer in blocks. the memory address
 // calculation complexity for copying each block is minimized to O(1), which is
 // independent of the number of dimensions.
-static void NdCopyRecurDFSeqPadding(size_t curDim, const char *&inOvlpBase,
+static inline void NdCopyRecurDFSeqPadding(size_t curDim, const char *&inOvlpBase,
                                     char *&outOvlpBase, Dims &inOvlpGapSize,
                                     Dims &outOvlpGapSize, Dims &ovlpCount,
                                     size_t &minContDim, size_t &blockSize)
@@ -666,7 +666,7 @@ static void NdCopyRecurDFSeqPadding(size_t curDim, const char *&inOvlpBase,
 // each element is minimized to average O(1), which is independent of
 // the number of dimensions.
 
-static void
+static inline void
 NdCopyRecurDFSeqPaddingRevEndian(size_t curDim, const char *&inOvlpBase,
                                  char *&outOvlpBase, Dims &inOvlpGapSize,
                                  Dims &outOvlpGapSize, Dims &ovlpCount,
@@ -707,7 +707,7 @@ NdCopyRecurDFSeqPaddingRevEndian(size_t curDim, const char *&inOvlpBase,
 // used for buffer of Column major
 // the memory address calculation complexity for copying each element is
 // minimized to average O(1), which is independent of the number of dimensions.
-static void NdCopyRecurDFNonSeqDynamic(size_t curDim, const char *inBase,
+static inline void NdCopyRecurDFNonSeqDynamic(size_t curDim, const char *inBase,
                                        char *outBase, Dims &inRltvOvlpSPos,
                                        Dims &outRltvOvlpSPos, Dims &inStride,
                                        Dims &outStride, Dims &ovlpCount,
@@ -737,7 +737,7 @@ static void NdCopyRecurDFNonSeqDynamic(size_t curDim, const char *inBase,
 // The memory address calculation complexity for copying each element is
 // minimized to average O(1), which is independent of the number of dimensions.
 
-static void NdCopyRecurDFNonSeqDynamicRevEndian(
+static inline void NdCopyRecurDFNonSeqDynamicRevEndian(
     size_t curDim, const char *inBase, char *outBase, Dims &inRltvOvlpSPos,
     Dims &outRltvOvlpSPos, Dims &inStride, Dims &outStride, Dims &ovlpCount,
     size_t elmSize)
@@ -763,7 +763,7 @@ static void NdCopyRecurDFNonSeqDynamicRevEndian(
     }
 }
 
-static void NdCopyIterDFSeqPadding(const char *&inOvlpBase, char *&outOvlpBase,
+static inline void NdCopyIterDFSeqPadding(const char *&inOvlpBase, char *&outOvlpBase,
                                    Dims &inOvlpGapSize, Dims &outOvlpGapSize,
                                    Dims &ovlpCount, size_t minContDim,
                                    size_t blockSize)
@@ -794,7 +794,7 @@ static void NdCopyIterDFSeqPadding(const char *&inOvlpBase, char *&outOvlpBase,
     }
 }
 
-static void NdCopyIterDFSeqPaddingRevEndian(
+static inline void NdCopyIterDFSeqPaddingRevEndian(
     const char *&inOvlpBase, char *&outOvlpBase, Dims &inOvlpGapSize,
     Dims &outOvlpGapSize, Dims &ovlpCount, size_t minContDim, size_t blockSize,
     size_t elmSize, size_t numElmsPerBlock)
@@ -830,7 +830,7 @@ static void NdCopyIterDFSeqPaddingRevEndian(
         } while (pos[curDim] == ovlpCount[curDim]);
     }
 }
-static void NdCopyIterDFDynamic(const char *inBase, char *outBase,
+static inline void NdCopyIterDFDynamic(const char *inBase, char *outBase,
                                 Dims &inRltvOvlpSPos, Dims &outRltvOvlpSPos,
                                 Dims &inStride, Dims &outStride,
                                 Dims &ovlpCount, size_t elmSize)
@@ -867,7 +867,7 @@ static void NdCopyIterDFDynamic(const char *inBase, char *outBase,
     }
 }
 
-static void NdCopyIterDFDynamicRevEndian(const char *inBase, char *outBase,
+static inline void NdCopyIterDFDynamicRevEndian(const char *inBase, char *outBase,
                                          Dims &inRltvOvlpSPos,
                                          Dims &outRltvOvlpSPos, Dims &inStride,
                                          Dims &outStride, Dims &ovlpCount,
diff --git a/source/adios2/helper/adiosNetwork.cpp b/source/adios2/helper/adiosNetwork.cpp
index d966a10e6f..b35a19c0ed 100644
--- a/source/adios2/helper/adiosNetwork.cpp
+++ b/source/adios2/helper/adiosNetwork.cpp
@@ -25,7 +25,7 @@
 #include <sys/ioctl.h>  //AvailableIpAddresses() ioctl
 #include <unistd.h>     //AvailableIpAddresses() close
 
-#include <nlohmann/json.hpp>
+#include <nlohmann_json.hpp>
 
 namespace adios2
 {
diff --git a/source/adios2/helper/adiosType.inl b/source/adios2/helper/adiosType.inl
index 23eb7d02f8..a5ea08612e 100644
--- a/source/adios2/helper/adiosType.inl
+++ b/source/adios2/helper/adiosType.inl
@@ -179,7 +179,7 @@ inline std::string VectorToCSV(const std::vector<std::string> &input) noexcept
     }
 
     std::ostringstream valueSS;
-    for (const auto value : input)
+    for (const auto& value : input)
     {
         valueSS << "\"" << value << "\", ";
     }
@@ -200,7 +200,7 @@ inline std::string VectorToCSV(const std::vector<std::string> &input) noexcept
         }                                                                      \
                                                                                \
         std::ostringstream valueSS;                                            \
-        for (const auto value : input)                                         \
+        for (const auto& value : input)                                         \
         {                                                                      \
             const int valueInt = static_cast<int>(value);                      \
             valueSS << valueInt << ", ";                                       \
@@ -223,7 +223,7 @@ inline std::string VectorToCSV(const std::vector<T> &input) noexcept
     }
 
     std::ostringstream valueSS;
-    for (const auto value : input)
+    for (const auto& value : input)
     {
         valueSS << value << ", ";
     }
diff --git a/source/adios2/helper/adiosXMLUtil.cpp b/source/adios2/helper/adiosXMLUtil.cpp
index 74e0a9b990..61f49600e0 100644
--- a/source/adios2/helper/adiosXMLUtil.cpp
+++ b/source/adios2/helper/adiosXMLUtil.cpp
@@ -125,7 +125,7 @@ adios2::Params XMLGetParameters(const pugi::xml_node &node,
                                    ", " + hint);
     Params parameters;
 
-    for (const pugi::xml_node paramNode : node.children("parameter"))
+    for (const pugi::xml_node &paramNode : node.children("parameter"))
     {
         const std::unique_ptr<pugi::xml_attribute> key =
             XMLAttribute("key", paramNode, errorMessage);
diff --git a/source/adios2/toolkit/format/bp/BPBase.cpp b/source/adios2/toolkit/format/bp/BPBase.cpp
index 0ec23a9a02..382b4a7ce4 100644
--- a/source/adios2/toolkit/format/bp/BPBase.cpp
+++ b/source/adios2/toolkit/format/bp/BPBase.cpp
@@ -393,7 +393,7 @@ BPBase::GetTransportIDs(const std::vector<std::string> &transportsTypes) const
     std::vector<uint8_t> transportsIDs;
     transportsIDs.reserve(transportsTypes.size());
 
-    for (const std::string transportType : transportsTypes)
+    for (const std::string &transportType : transportsTypes)
     {
         transportsIDs.push_back(lf_GetTransportID(transportType));
     }
diff --git a/source/adios2/toolkit/format/bp/BPSerializer.tcc b/source/adios2/toolkit/format/bp/BPSerializer.tcc
index ff89ad2abf..d8309088d1 100644
--- a/source/adios2/toolkit/format/bp/BPSerializer.tcc
+++ b/source/adios2/toolkit/format/bp/BPSerializer.tcc
@@ -98,8 +98,8 @@ void BPSerializer::UpdateIndexOffsetsCharacteristics(size_t &currentPosition,
                                                      std::vector<char> &buffer)
 {
     const bool isLittleEndian = helper::IsLittleEndian();
-    const uint8_t characteristicsCount =
-        helper::ReadValue<uint8_t>(buffer, currentPosition, isLittleEndian);
+
+    helper::ReadValue<uint8_t>(buffer, currentPosition, isLittleEndian);
 
     const uint32_t characteristicsLength =
         helper::ReadValue<uint32_t>(buffer, currentPosition, isLittleEndian);
diff --git a/source/adios2/toolkit/format/bp/bp3/BP3Deserializer.cpp b/source/adios2/toolkit/format/bp/bp3/BP3Deserializer.cpp
index af9cec95fe..f7034a02d7 100644
--- a/source/adios2/toolkit/format/bp/bp3/BP3Deserializer.cpp
+++ b/source/adios2/toolkit/format/bp/bp3/BP3Deserializer.cpp
@@ -29,7 +29,7 @@ namespace format
 std::mutex BP3Deserializer::m_Mutex;
 
 BP3Deserializer::BP3Deserializer(helper::Comm const &comm)
-: BP3Base(comm), BPBase(comm), m_Minifooter(3)
+: BPBase(comm), BP3Base(comm), m_Minifooter(3)
 {
 }
 
@@ -139,8 +139,7 @@ void BP3Deserializer::ParsePGIndex(const BufferSTL &bufferSTL,
 
     m_MetadataSet.DataPGCount = helper::ReadValue<uint64_t>(
         buffer, position, m_Minifooter.IsLittleEndian);
-    const size_t length = helper::ReadValue<uint64_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint64_t>(buffer, position, m_Minifooter.IsLittleEndian);
 
     size_t localPosition = 0;
 
@@ -210,10 +209,8 @@ void BP3Deserializer::ParseVariablesIndex(const BufferSTL &bufferSTL,
         m_Minifooter.VarsIndexStart, m_Minifooter.PGIndexStart,
         " BP3 variable index start < pg index start, in call to Open");
 
-    const uint32_t count = helper::ReadValue<uint32_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
-    const uint64_t length = helper::ReadValue<uint64_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint32_t>(buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint64_t>(buffer, position, m_Minifooter.IsLittleEndian);
 
     const size_t startPosition = position;
     size_t localPosition = 0;
@@ -319,10 +316,8 @@ void BP3Deserializer::ParseAttributesIndex(const BufferSTL &bufferSTL,
         m_Minifooter.AttributesIndexStart, m_Minifooter.PGIndexStart,
         " BP3 attributes index start < pg index start, in call to Open");
 
-    const uint32_t count = helper::ReadValue<uint32_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
-    const uint64_t length = helper::ReadValue<uint64_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint32_t>(buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint64_t>(buffer, position, m_Minifooter.IsLittleEndian);
 
     const size_t startPosition = position;
     size_t localPosition = 0;
diff --git a/source/adios2/toolkit/format/bp/bp4/BP4Deserializer.cpp b/source/adios2/toolkit/format/bp/bp4/BP4Deserializer.cpp
index 05728c9a41..d6a7ac8408 100644
--- a/source/adios2/toolkit/format/bp/bp4/BP4Deserializer.cpp
+++ b/source/adios2/toolkit/format/bp/bp4/BP4Deserializer.cpp
@@ -33,7 +33,7 @@ namespace format
 std::mutex BP4Deserializer::m_Mutex;
 
 BP4Deserializer::BP4Deserializer(helper::Comm const &comm)
-: BP4Base(comm), BPBase(comm), m_Minifooter(4)
+: BPBase(comm), BP4Base(comm), m_Minifooter(4)
 {
 }
 
@@ -335,8 +335,7 @@ void BP4Deserializer::ParseVariablesIndexPerStep(const BufferSTL &bufferSTL,
     const auto &buffer = bufferSTL.m_Buffer;
     size_t position = m_MetadataIndexTable[submetadatafileId][step][1];
 
-    const uint32_t count = helper::ReadValue<uint32_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint32_t>(buffer, position, m_Minifooter.IsLittleEndian);
     const uint64_t length = helper::ReadValue<uint64_t>(
         buffer, position, m_Minifooter.IsLittleEndian);
 
@@ -528,8 +527,7 @@ void BP4Deserializer::ParseAttributesIndexPerStep(const BufferSTL &bufferSTL,
     const auto &buffer = bufferSTL.m_Buffer;
     size_t position = m_MetadataIndexTable[submetadatafileId][step][2];
 
-    const uint32_t count = helper::ReadValue<uint32_t>(
-        buffer, position, m_Minifooter.IsLittleEndian);
+    helper::ReadValue<uint32_t>(buffer, position, m_Minifooter.IsLittleEndian);
     const uint64_t length = helper::ReadValue<uint64_t>(
         buffer, position, m_Minifooter.IsLittleEndian);
 
diff --git a/source/adios2/toolkit/format/bp/bp4/BP4Serializer.tcc b/source/adios2/toolkit/format/bp/bp4/BP4Serializer.tcc
index d86a63e684..99a8371327 100644
--- a/source/adios2/toolkit/format/bp/bp4/BP4Serializer.tcc
+++ b/source/adios2/toolkit/format/bp/bp4/BP4Serializer.tcc
@@ -624,14 +624,12 @@ void BP4Serializer::PutBoundsRecord(const bool singleValue,
                     static_cast<uint64_t>(stats.SubBlockInfo.SubBlockSize);
                 helper::InsertToBuffer(buffer, &subBlockSize);
 
-                const uint16_t N =
-                    static_cast<uint16_t>(stats.SubBlockInfo.Div.size());
                 for (auto const d : stats.SubBlockInfo.Div)
                 {
                     helper::InsertToBuffer(buffer, &d);
                 }
                 // insert min+max (alternating) elements (2*M values)
-                for (auto const m : stats.MinMaxs)
+                for (auto const &m : stats.MinMaxs)
                 {
                     helper::InsertToBuffer(buffer, &m);
                 }
@@ -678,14 +676,12 @@ void BP4Serializer::PutBoundsRecord(const bool singleValue,
                     static_cast<uint64_t>(stats.SubBlockInfo.SubBlockSize);
                 helper::CopyToBuffer(buffer, position, &subBlockSize);
 
-                const uint16_t N =
-                    static_cast<uint16_t>(stats.SubBlockInfo.Div.size());
                 for (auto const d : stats.SubBlockInfo.Div)
                 {
                     helper::CopyToBuffer(buffer, position, &d);
                 }
                 // insert min+max (alternating) elements (2*M values)
-                for (auto const m : stats.MinMaxs)
+                for (auto const &m : stats.MinMaxs)
                 {
                     helper::CopyToBuffer(buffer, position, &m);
                 }
diff --git a/source/adios2/toolkit/format/bp5/BP5Base.cpp b/source/adios2/toolkit/format/bp5/BP5Base.cpp
index 8a7b974e9a..9ec26e4cf7 100644
--- a/source/adios2/toolkit/format/bp5/BP5Base.cpp
+++ b/source/adios2/toolkit/format/bp5/BP5Base.cpp
@@ -25,7 +25,7 @@ namespace format
 
 void BP5Base::FFSBitfieldSet(struct FFSMetadataInfoStruct *MBase, int Bit)
 {
-    int Element = Bit / (sizeof(size_t) * 8);
+    size_t Element = Bit / (sizeof(size_t) * 8);
     int ElementBit = Bit % (sizeof(size_t) * 8);
     if (Element >= MBase->BitFieldCount)
     {
@@ -40,7 +40,7 @@ void BP5Base::FFSBitfieldSet(struct FFSMetadataInfoStruct *MBase, int Bit)
 
 int BP5Base::FFSBitfieldTest(struct FFSMetadataInfoStruct *MBase, int Bit)
 {
-    int Element = Bit / (sizeof(size_t) * 8);
+    size_t Element = Bit / (sizeof(size_t) * 8);
     int ElementBit = Bit % (sizeof(size_t) * 8);
     if (Element >= MBase->BitFieldCount)
     {
diff --git a/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp b/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp
index 291388f8ca..c9a73335ce 100644
--- a/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp
+++ b/source/adios2/toolkit/format/bp5/BP5Deserializer.cpp
@@ -13,6 +13,8 @@
 #include "BP5Deserializer.h"
 #include "BP5Deserializer.tcc"
 
+#include <limits.h>
+#include <math.h>
 #include <string.h>
 
 #ifdef _WIN32
@@ -428,7 +430,7 @@ void BP5Deserializer::InstallMetaData(void *MetadataBlock, size_t BlockLen,
             {
                 VarRec->PerWriterBlockStart[WriterRank] = 0;
             }
-            if (WriterRank < m_WriterCohortSize - 1)
+            if (WriterRank < static_cast<size_t>(m_WriterCohortSize - 1))
             {
                 VarRec->PerWriterBlockStart[WriterRank + 1] =
                     VarRec->PerWriterBlockStart[WriterRank] +
@@ -599,7 +601,7 @@ bool BP5Deserializer::NeedWriter(BP5ArrayRequest Req, int i)
         return (NodeFirst <= Req.BlockID) && (NodeLast >= Req.BlockID);
     }
     // else Global case
-    for (int j = 0; j < Req.VarRec->DimCount; j++)
+    for (size_t j = 0; j < Req.VarRec->DimCount; j++)
     {
         size_t SelOffset = Req.Start[j];
         size_t SelSize = Req.Count[j];
@@ -686,7 +688,7 @@ void BP5Deserializer::FinalizeGets(std::vector<ReadRequest> Requests)
                 const size_t *SelOffset = NULL;
                 const size_t *SelSize = Req.Count.data();
                 int ReqIndex = 0;
-                while (Requests[ReqIndex].WriterRank != i)
+                while (Requests[ReqIndex].WriterRank != static_cast<size_t>(i))
                     ReqIndex++;
                 char *IncomingData =
                     (char *)Requests[ReqIndex].DestinationAddr +
@@ -752,7 +754,7 @@ void BP5Deserializer::MapGlobalToLocalIndex(size_t Dims,
                                             const size_t *LocalOffsets,
                                             size_t *LocalIndex)
 {
-    for (int i = 0; i < Dims; i++)
+    for (size_t i = 0; i < Dims; i++)
     {
         LocalIndex[i] = GlobalIndex[i] - LocalOffsets[i];
     }
@@ -762,7 +764,7 @@ int BP5Deserializer::FindOffset(size_t Dims, const size_t *Size,
                                 const size_t *Index)
 {
     int Offset = 0;
-    for (int i = 0; i < Dims; i++)
+    for (size_t i = 0; i < Dims; i++)
     {
         Offset = Index[i] + (Size[i] * Offset);
     }
@@ -771,12 +773,13 @@ int BP5Deserializer::FindOffset(size_t Dims, const size_t *Size,
 
 static int FindOffsetCM(size_t Dims, const size_t *Size, const size_t *Index)
 {
-    int Offset = 0;
-    for (int i = Dims - 1; i >= 0; i--)
+    size_t Offset = 0;
+    for (int i = static_cast<int>(Dims - 1); i >= 0; i--)
     {
         Offset = Index[i] + (Size[i] * Offset);
     }
-    return Offset;
+
+    return std::min(static_cast<size_t>(INT_MAX), Offset);
 }
 
 #define MAX(x, y) (((x) > (y)) ? (x) : (y))
@@ -830,8 +833,8 @@ void BP5Deserializer::ExtractSelectionFromPartialRM(
 
     BlockSize = 1;
     OperantDims = Dims;
-    OperantElementSize = ElementSize;
-    for (int Dim = Dims - 1; Dim >= 0; Dim--)
+    OperantElementSize = static_cast<size_t>(ElementSize);
+    for (int Dim = static_cast<int>(Dims - 1); Dim >= 0; Dim--)
     {
         if ((GlobalDims[Dim] == PartialCounts[Dim]) &&
             (SelectionCounts[Dim] == PartialCounts[Dim]))
@@ -859,7 +862,7 @@ void BP5Deserializer::ExtractSelectionFromPartialRM(
     /* calculate first selected element and count */
     BlockCount = 1;
     size_t *FirstIndex = (size_t *)malloc(Dims * sizeof(FirstIndex[0]));
-    for (int Dim = 0; Dim < Dims; Dim++)
+    for (size_t Dim = 0; Dim < Dims; Dim++)
     {
         size_t Left = MAX(PartialOffsets[Dim], SelectionOffsets[Dim]);
         size_t Right = MIN(PartialOffsets[Dim] + PartialCounts[Dim],
@@ -911,7 +914,7 @@ void BP5Deserializer::ExtractSelectionFromPartialCM(
 
     BlockSize = 1;
     OperantElementSize = ElementSize;
-    for (int Dim = 0; Dim < Dims; Dim++)
+    for (size_t Dim = 0; Dim < Dims; Dim++)
     {
         if ((GlobalDims[Dim] == PartialCounts[Dim]) &&
             (SelectionCounts[Dim] == PartialCounts[Dim]))
@@ -947,7 +950,7 @@ void BP5Deserializer::ExtractSelectionFromPartialCM(
     /* calculate first selected element and count */
     BlockCount = 1;
     size_t *FirstIndex = (size_t *)malloc(Dims * sizeof(FirstIndex[0]));
-    for (int Dim = 0; Dim < Dims; Dim++)
+    for (size_t Dim = 0; Dim < Dims; Dim++)
     {
         int Left = MAX(PartialOffsets[Dim], SelectionOffsets[Dim]);
         int Right = MIN(PartialOffsets[Dim] + PartialCounts[Dim],
@@ -984,8 +987,8 @@ void BP5Deserializer::ExtractSelectionFromPartialCM(
 
 BP5Deserializer::BP5Deserializer(int WriterCount, bool WriterIsRowMajor,
                                  bool ReaderIsRowMajor)
-: m_WriterCohortSize{WriterCount}, m_WriterIsRowMajor{WriterIsRowMajor},
-  m_ReaderIsRowMajor{ReaderIsRowMajor}
+: m_WriterIsRowMajor{WriterIsRowMajor}, m_ReaderIsRowMajor{ReaderIsRowMajor},
+  m_WriterCohortSize{WriterCount}
 {
     FMContext Tmp = create_local_FMcontext();
     ReaderFFSContext = create_FFSContext_FM(Tmp);
diff --git a/source/adios2/toolkit/format/bp5/BP5Deserializer.h b/source/adios2/toolkit/format/bp5/BP5Deserializer.h
index 0503bea936..aaf8b75f61 100644
--- a/source/adios2/toolkit/format/bp5/BP5Deserializer.h
+++ b/source/adios2/toolkit/format/bp5/BP5Deserializer.h
@@ -130,7 +130,6 @@ class BP5Deserializer : virtual public BP5Base
     int m_WriterCohortSize;
     std::unordered_map<std::string, BP5VarRec *> VarByName;
     std::unordered_map<void *, BP5VarRec *> VarByKey;
-    FMContext LocalFMContext;
     //    Ffsarrayrequest PendingVarRequests;
 
     std::vector<void *> MetadataBaseAddrs;
diff --git a/source/adios2/toolkit/format/bp5/BP5Deserializer.tcc b/source/adios2/toolkit/format/bp5/BP5Deserializer.tcc
index d52e6f0d9f..0e4e6a7e42 100644
--- a/source/adios2/toolkit/format/bp5/BP5Deserializer.tcc
+++ b/source/adios2/toolkit/format/bp5/BP5Deserializer.tcc
@@ -43,7 +43,7 @@ BP5Deserializer::BlocksInfo(const core::Variable<T> &variable,
         int FieldOffset = ControlArray[i].FieldOffset;
         void *field_data = (char *)BaseData + FieldOffset;
         MetaArrayRec *meta_base = (MetaArrayRec *)field_data;
-        for (int i = 0; i < VarRec->PerWriterBlockCount[WriterRank]; i++)
+        for (size_t i = 0; i < VarRec->PerWriterBlockCount[WriterRank]; i++)
         {
             size_t *Offsets = NULL;
             if (meta_base->Offsets)
@@ -58,7 +58,7 @@ BP5Deserializer::BlocksInfo(const core::Variable<T> &variable,
             size_t *Count = meta_base->Count;
             if (Shape)
             {
-                for (int i = 0; i < DimCount; i++)
+                for (size_t i = 0; i < DimCount; i++)
                 {
                     VecShape.push_back(Shape[i]);
                     VecStart.push_back(Start[i]);
@@ -69,7 +69,7 @@ BP5Deserializer::BlocksInfo(const core::Variable<T> &variable,
             {
                 VecShape = {};
                 VecStart = {};
-                for (int i = 0; i < DimCount; i++)
+                for (size_t i = 0; i < DimCount; i++)
                 {
                     VecCount.push_back(Count[i]);
                 }
diff --git a/source/adios2/toolkit/format/bp5/BP5Serializer.cpp b/source/adios2/toolkit/format/bp5/BP5Serializer.cpp
index 4d5bb01100..12d5510f7a 100644
--- a/source/adios2/toolkit/format/bp5/BP5Serializer.cpp
+++ b/source/adios2/toolkit/format/bp5/BP5Serializer.cpp
@@ -49,7 +49,8 @@ BP5Serializer::~BP5Serializer()
 
 void BP5Serializer::Init()
 {
-    memset(&Info, 0, sizeof(Info));
+    // Re-init Info to zero
+    Info = FFSWriterMarshalBase();
     Info.RecCount = 0;
     Info.RecList = (BP5Serializer::BP5WriterRec)malloc(sizeof(Info.RecList[0]));
     Info.MetaFieldCount = 0;
diff --git a/source/adios2/toolkit/format/bp5/BP5Serializer.h b/source/adios2/toolkit/format/bp5/BP5Serializer.h
index 23e79b8d53..c9ec971eeb 100644
--- a/source/adios2/toolkit/format/bp5/BP5Serializer.h
+++ b/source/adios2/toolkit/format/bp5/BP5Serializer.h
@@ -100,7 +100,7 @@ class BP5Serializer : virtual public BP5Base
     {
         int RecCount = 0;
         BP5WriterRec RecList = NULL;
-        FMContext LocalFMContext;
+        FMContext LocalFMContext = {0};
         int MetaFieldCount = 0;
         FMFieldList MetaFields = NULL;
         FMFormat MetaFormat;
diff --git a/source/adios2/toolkit/format/dataman/DataManSerializer.h b/source/adios2/toolkit/format/dataman/DataManSerializer.h
index 64179b43c4..5699604b14 100644
--- a/source/adios2/toolkit/format/dataman/DataManSerializer.h
+++ b/source/adios2/toolkit/format/dataman/DataManSerializer.h
@@ -19,7 +19,7 @@
 #include <mutex>
 #include <unordered_map>
 
-#include <nlohmann/json.hpp>
+#include <nlohmann_json.hpp>
 
 // A - Address
 // C - Count
diff --git a/source/adios2/toolkit/format/dataman/DataManSerializer.tcc b/source/adios2/toolkit/format/dataman/DataManSerializer.tcc
index da2db22e13..eda90e798d 100644
--- a/source/adios2/toolkit/format/dataman/DataManSerializer.tcc
+++ b/source/adios2/toolkit/format/dataman/DataManSerializer.tcc
@@ -460,7 +460,8 @@ int DataManSerializer::GetData(T *outputData, const std::string &varName,
             }
             if (j.shape.empty() or (j.shape.size() == 1 and j.shape[0] == 1))
             {
-                std::memcpy(outputData, input_data, sizeof(T));
+                std::memcpy(reinterpret_cast<char *>(outputData), input_data,
+                            sizeof(T));
             }
         }
     }
diff --git a/source/adios2/toolkit/query/JsonWorker.cpp b/source/adios2/toolkit/query/JsonWorker.cpp
index 10c4d0caec..c538d69fb7 100644
--- a/source/adios2/toolkit/query/JsonWorker.cpp
+++ b/source/adios2/toolkit/query/JsonWorker.cpp
@@ -1,5 +1,6 @@
 #include "Worker.h"
-#include <nlohmann/json.hpp>
+
+#include <nlohmann_json.hpp>
 
 namespace adios2
 {
diff --git a/source/adios2/toolkit/query/XmlWorker.cpp b/source/adios2/toolkit/query/XmlWorker.cpp
index dbecccabcf..e270d95cab 100644
--- a/source/adios2/toolkit/query/XmlWorker.cpp
+++ b/source/adios2/toolkit/query/XmlWorker.cpp
@@ -169,7 +169,7 @@ void XmlWorker::ConstructTree(RangeTree &host, const pugi::xml_node &node)
     std::string relationStr =
         adios2::helper::XMLAttribute("value", node, "in query")->value();
     host.SetRelation(adios2::query::strToRelation(relationStr));
-    for (const pugi::xml_node rangeNode : node.children("range"))
+    for (const pugi::xml_node &rangeNode : node.children("range"))
     {
         std::string valStr =
             adios2::helper::XMLAttribute("value", rangeNode, "in query")
@@ -181,7 +181,7 @@ void XmlWorker::ConstructTree(RangeTree &host, const pugi::xml_node &node)
         host.AddLeaf(adios2::query::strToQueryOp(opStr), valStr);
     }
 
-    for (const pugi::xml_node opNode : node.children("op"))
+    for (const pugi::xml_node &opNode : node.children("op"))
     {
         adios2::query::RangeTree subNode;
         ConstructTree(subNode, opNode);
diff --git a/source/adios2/toolkit/sst/dp/rdma_dp.c b/source/adios2/toolkit/sst/dp/rdma_dp.c
index a6060b38bf..d54480b7cd 100644
--- a/source/adios2/toolkit/sst/dp/rdma_dp.c
+++ b/source/adios2/toolkit/sst/dp/rdma_dp.c
@@ -1139,7 +1139,7 @@ static void *RdmaReadRemoteMemory(CP_Services Svcs, DP_RS_Stream Stream_v,
                                   size_t Length, void *Buffer,
                                   void *DP_TimestepInfo)
 {
-    RdmaCompletionHandle ret;
+    RdmaCompletionHandle ret = {0};
     Rdma_RS_Stream RS_Stream = (Rdma_RS_Stream)Stream_v;
     RdmaBufferHandle Info = (RdmaBufferHandle)DP_TimestepInfo;
     RdmaStepLogEntry StepLog;
@@ -1539,9 +1539,10 @@ static void RdmaDestroyReader(CP_Services Svcs, DP_RS_Stream RS_Stream_v)
 static void RdmaDestroyWriterPerReader(CP_Services Svcs,
                                        DP_WSR_Stream WSR_Stream_v)
 {
-    Rdma_WSR_Stream WSR_Stream = (Rdma_WSR_Stream)WSR_Stream_v;
+    Rdma_WSR_Stream WSR_Stream = {0};
+    memcpy(&WSR_Stream, &WSR_Stream_v, sizeof(Rdma_WSR_Stream));
     Rdma_WS_Stream WS_Stream = WSR_Stream->WS_Stream;
-    RdmaWriterContactInfo WriterContactInfo;
+    RdmaWriterContactInfo WriterContactInfo = {0};
 
     pthread_mutex_lock(&wsr_mutex);
     for (int i = 0; i < WS_Stream->ReaderCount; i++)
@@ -2067,7 +2068,7 @@ static void PullSelection(CP_Services Svcs, Rdma_WSR_Stream Stream)
     Rdma_WS_Stream WS_Stream = Stream->WS_Stream;
     FabricState Fabric = WS_Stream->Fabric;
     RdmaBuffer ReaderRoll = (RdmaBuffer)Stream->ReaderRoll->Handle.Block;
-    struct _RdmaBuffer ReqBuffer = {0};
+    struct _RdmaBuffer ReqBuffer = {{0}};
     struct fi_cq_data_entry CQEntry = {0};
     struct fid_mr *rrmr = NULL;
     void *rrdesc = NULL;
diff --git a/source/adios2/toolkit/zmq/zmqreqrep/ZmqReqRep.h b/source/adios2/toolkit/zmq/zmqreqrep/ZmqReqRep.h
index 6afa8d266f..56cae2b2aa 100644
--- a/source/adios2/toolkit/zmq/zmqreqrep/ZmqReqRep.h
+++ b/source/adios2/toolkit/zmq/zmqreqrep/ZmqReqRep.h
@@ -45,7 +45,6 @@ class ZmqReqRep
     void SendReply(const void *reply, const size_t size);
 
 private:
-    int m_Verbosity = 0;
     int m_Timeout;
 
     std::vector<char> m_ReceiverBuffer;
diff --git a/source/h5vol/H5VolError.h b/source/h5vol/H5VolError.h
index 1437bac82a..824a45f5ad 100644
--- a/source/h5vol/H5VolError.h
+++ b/source/h5vol/H5VolError.h
@@ -11,7 +11,12 @@ void *safe_malloc(size_t n, unsigned long line);
 #define SAFE_MALLOC(n) safe_malloc(n, __LINE__)
 
 void safe_free(void *p);
-#define SAFE_FREE(ptr) safe_free(ptr)
+
+#ifdef __cplusplus
+#define SAFE_FREE(ptr) safe_free(reinterpret_cast<void *>(ptr))
+#else
+#define SAFE_FREE(ptr) safe_free((void *)(ptr))
+#endif
 
 void *safe_ralloc(void *ptr, size_t newsize, unsigned long line);
 #define SAFE_REALLOC(ptr, newsize) safe_ralloc(ptr, newsize, __LINE__)
diff --git a/source/utils/bpls/bpls.cpp b/source/utils/bpls/bpls.cpp
index 74d0b8e8af..ac28a48bfc 100644
--- a/source/utils/bpls/bpls.cpp
+++ b/source/utils/bpls/bpls.cpp
@@ -2416,7 +2416,8 @@ bool matchesAMask(const char *name)
             if (excode == 0 && // matches
                 (pmatch[0].rm_so == 0 ||
                  pmatch[0].rm_so == startpos) && // from the beginning
-                pmatch[0].rm_eo == strlen(name)  // to the very end of the name
+                static_cast<size_t>(pmatch[0].rm_eo) ==
+                    strlen(name) // to the very end of the name
             )
 #else
             bool matches = std::regex_match(name, varregex[i]);
diff --git a/testing/adios2/engine/bp/TestBPInquireVariableException.cpp b/testing/adios2/engine/bp/TestBPInquireVariableException.cpp
index f47f7647c7..3dca82bbb0 100644
--- a/testing/adios2/engine/bp/TestBPInquireVariableException.cpp
+++ b/testing/adios2/engine/bp/TestBPInquireVariableException.cpp
@@ -47,9 +47,9 @@ TEST_F(ADIOSInquireVariableException, Read)
         auto var1 =
             io_w.DefineVariable<int32_t>("variable1", shape, start, count);
 
-        for (int32_t step = 0; step < NSteps; ++step)
+        for (size_t step = 0; step < NSteps; ++step)
         {
-            std::vector<int32_t> Ints(10, step);
+            std::vector<int32_t> Ints(10, static_cast<int32_t>(step));
             writer.BeginStep();
             writer.Put(var1, Ints.data());
             writer.EndStep();
@@ -61,7 +61,7 @@ TEST_F(ADIOSInquireVariableException, Read)
         auto reader = io_r.Open(filename, adios2::Mode::Read);
         auto var = io_r.InquireVariable<int32_t>("variable1");
 
-        for (int32_t step = 0; step < NSteps; step++)
+        for (size_t step = 0; step < NSteps; step++)
         {
             reader.BeginStep();
             std::vector<int32_t> myInts;
diff --git a/testing/adios2/engine/bp/TestBPWriteAppendReadADIOS2.cpp b/testing/adios2/engine/bp/TestBPWriteAppendReadADIOS2.cpp
index ef7288f05a..122a72743f 100644
--- a/testing/adios2/engine/bp/TestBPWriteAppendReadADIOS2.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteAppendReadADIOS2.cpp
@@ -15,6 +15,20 @@
 
 #include "../SmallTestData.h"
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wstrict-aliasing"
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 std::string engineName; // comes from command line
 
 class BPWriteAppendReadTestADIOS2 : public ::testing::Test
@@ -733,3 +747,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/bp/TestBPWriteProfilingJSON.cpp b/testing/adios2/engine/bp/TestBPWriteProfilingJSON.cpp
index c50f2f1df9..389fb1d06a 100644
--- a/testing/adios2/engine/bp/TestBPWriteProfilingJSON.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteProfilingJSON.cpp
@@ -19,7 +19,7 @@
 #include <adios2.h>
 
 #include <gtest/gtest.h>
-#include <nlohmann/json.hpp>
+#include <nlohmann_json.hpp>
 
 #include "../SmallTestData.h"
 
diff --git a/testing/adios2/engine/bp/TestBPWriteReadAsStreamADIOS2.cpp b/testing/adios2/engine/bp/TestBPWriteReadAsStreamADIOS2.cpp
index a0b868afcf..c887d317ca 100644
--- a/testing/adios2/engine/bp/TestBPWriteReadAsStreamADIOS2.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteReadAsStreamADIOS2.cpp
@@ -14,6 +14,18 @@
 
 #include "../SmallTestData.h"
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 std::string engineName; // comes from command line
 
 class BPWriteReadAsStreamTestADIOS2 : public ::testing::Test
@@ -1070,3 +1082,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/bp/TestBPWriteReadAttributesMultirank.cpp b/testing/adios2/engine/bp/TestBPWriteReadAttributesMultirank.cpp
index baddebc521..564fe34733 100644
--- a/testing/adios2/engine/bp/TestBPWriteReadAttributesMultirank.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteReadAttributesMultirank.cpp
@@ -17,6 +17,18 @@
 
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 std::string engineName; // comes from command line
 
 class BPWriteReadAttributeTestMultirank : public ::testing::Test
@@ -137,3 +149,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/bp/TestBPWriteReadLocalVariables.cpp b/testing/adios2/engine/bp/TestBPWriteReadLocalVariables.cpp
index 1feaeb246e..9dee0ba78b 100644
--- a/testing/adios2/engine/bp/TestBPWriteReadLocalVariables.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteReadLocalVariables.cpp
@@ -15,6 +15,18 @@
 
 #include "../SmallTestData.h"
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 std::string engineName; // comes from command line
 
 class BPWriteReadLocalVariables : public ::testing::Test
@@ -1948,3 +1960,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/bp/TestBPWriteReadVariableSpan.cpp b/testing/adios2/engine/bp/TestBPWriteReadVariableSpan.cpp
index f59d273186..14ca78080c 100644
--- a/testing/adios2/engine/bp/TestBPWriteReadVariableSpan.cpp
+++ b/testing/adios2/engine/bp/TestBPWriteReadVariableSpan.cpp
@@ -14,6 +14,18 @@
 
 #include "../SmallTestData.h"
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 std::string engineName; // comes from command line
 
 class BPWriteReadSpan : public ::testing::Test
@@ -1535,3 +1547,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/bp/operations/TestBPWriteReadSzComplex.cpp b/testing/adios2/engine/bp/operations/TestBPWriteReadSzComplex.cpp
index 6ef77aeaa3..49944ff309 100644
--- a/testing/adios2/engine/bp/operations/TestBPWriteReadSzComplex.cpp
+++ b/testing/adios2/engine/bp/operations/TestBPWriteReadSzComplex.cpp
@@ -179,7 +179,7 @@ void Writer(const Dims &shape, const Dims &start, const Dims &count,
     bpDComplexes.AddOperation(compressor, {{"accuracy", accuracy}});
     io.DefineAttribute<int>("AttInt", 110);
     adios2::Engine writerEngine = io.Open(fileName, adios2::Mode::Write);
-    for (int i = 0; i < steps; ++i)
+    for (int i = 0; i < static_cast<int>(steps); ++i)
     {
         writerEngine.BeginStep();
         GenData(myChars, i, start, count, shape);
diff --git a/testing/adios2/engine/bp/operations/TestBPWriteReadZfpComplex.cpp b/testing/adios2/engine/bp/operations/TestBPWriteReadZfpComplex.cpp
index 930a6a3e81..ffb1aad7c7 100644
--- a/testing/adios2/engine/bp/operations/TestBPWriteReadZfpComplex.cpp
+++ b/testing/adios2/engine/bp/operations/TestBPWriteReadZfpComplex.cpp
@@ -179,7 +179,7 @@ void Writer(const Dims &shape, const Dims &start, const Dims &count,
     bpDComplexes.AddOperation(zfpOp, {{"accuracy", accuracy}});
     io.DefineAttribute<int>("AttInt", 110);
     adios2::Engine writerEngine = io.Open(fileName, adios2::Mode::Write);
-    for (int i = 0; i < steps; ++i)
+    for (int i = 0; i < static_cast<int>(steps); ++i)
     {
         writerEngine.BeginStep();
         GenData(myChars, i, start, count, shape);
diff --git a/testing/adios2/engine/bp/operations/TestBPWriteReadZfpConfig.cpp b/testing/adios2/engine/bp/operations/TestBPWriteReadZfpConfig.cpp
index 5adcc94a25..ab7751e3af 100644
--- a/testing/adios2/engine/bp/operations/TestBPWriteReadZfpConfig.cpp
+++ b/testing/adios2/engine/bp/operations/TestBPWriteReadZfpConfig.cpp
@@ -13,6 +13,18 @@
 
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 #define str_helper(X) #X
 #define mystr(X) str_helper(X)
 
@@ -900,3 +912,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/engine/dataman/TestDataMan2DSz.cpp b/testing/adios2/engine/dataman/TestDataMan2DSz.cpp
index 07cb00d16d..65f576a198 100644
--- a/testing/adios2/engine/dataman/TestDataMan2DSz.cpp
+++ b/testing/adios2/engine/dataman/TestDataMan2DSz.cpp
@@ -142,7 +142,7 @@ void DataManWriterP2PMemSelect(const Dims &shape, const Dims &start,
     dataManIO.DefineAttribute<int>("AttInt", 110);
     adios2::Engine dataManWriter =
         dataManIO.Open("stream", adios2::Mode::Write);
-    for (int i = 0; i < steps; ++i)
+    for (size_t i = 0; i < steps; ++i)
     {
         dataManWriter.BeginStep();
         GenData(myChars, i, start, count, shape);
diff --git a/testing/adios2/engine/dataman/TestDataMan2DZfp.cpp b/testing/adios2/engine/dataman/TestDataMan2DZfp.cpp
index 0ee1b26c48..a38c8d4566 100644
--- a/testing/adios2/engine/dataman/TestDataMan2DZfp.cpp
+++ b/testing/adios2/engine/dataman/TestDataMan2DZfp.cpp
@@ -146,7 +146,7 @@ void DataManWriterP2PMemSelect(const Dims &shape, const Dims &start,
     dataManIO.DefineAttribute<int>("AttInt", 110);
     adios2::Engine dataManWriter =
         dataManIO.Open("stream", adios2::Mode::Write);
-    for (int i = 0; i < steps; ++i)
+    for (size_t i = 0; i < steps; ++i)
     {
         dataManWriter.BeginStep();
         GenData(myChars, i, start, count, shape);
diff --git a/testing/adios2/engine/skeleton/TestSkeletonReader.cpp b/testing/adios2/engine/skeleton/TestSkeletonReader.cpp
index cdf30bac5a..05136746a9 100644
--- a/testing/adios2/engine/skeleton/TestSkeletonReader.cpp
+++ b/testing/adios2/engine/skeleton/TestSkeletonReader.cpp
@@ -113,9 +113,11 @@ int main(int argc, char *argv[])
                 adios2::Variable<float> varArray = io.DefineVariable<float>(
                     "myArray", {gndx}, {gndx / (size_t)nproc},
                     {gndx / (size_t)nproc});
+                (void)varArray;
 
                 adios2::Variable<std::string> varSyncString =
                     io.DefineVariable<std::string>("mySyncString");
+                (void)varSyncString;
             }
             else
             {
diff --git a/testing/adios2/engine/staging-common/ParseArgs.h b/testing/adios2/engine/staging-common/ParseArgs.h
index d4fb4aa80a..30671f8f9d 100644
--- a/testing/adios2/engine/staging-common/ParseArgs.h
+++ b/testing/adios2/engine/staging-common/ParseArgs.h
@@ -77,7 +77,7 @@ static adios2::Params ParseEngineParams(std::string Input)
     return Ret;
 }
 
-static void ParseArgs(int argc, char **argv)
+void ParseArgs(int argc, char **argv)
 {
     int bare_arg = 0;
     while (argc > 1)
diff --git a/testing/adios2/engine/table/TestTableMultiRank.cpp b/testing/adios2/engine/table/TestTableMultiRank.cpp
index 0c07706766..0fd03462f5 100644
--- a/testing/adios2/engine/table/TestTableMultiRank.cpp
+++ b/testing/adios2/engine/table/TestTableMultiRank.cpp
@@ -103,7 +103,7 @@ void Reader(const Dims &shape, const Dims &start, const Dims &count,
     std::vector<std::complex<float>> myComplexes(datasize);
     std::vector<std::complex<double>> myDComplexes(datasize);
 
-    adios2::StepStatus status = readerEngine.BeginStep();
+    readerEngine.BeginStep();
     const auto &vars = io.AvailableVariables();
     std::cout << "All available variables : ";
     for (const auto &var : vars)
diff --git a/testing/adios2/engine/table/TestTableSingleRank.cpp b/testing/adios2/engine/table/TestTableSingleRank.cpp
index 3fc5b1108d..9edc64a6cd 100644
--- a/testing/adios2/engine/table/TestTableSingleRank.cpp
+++ b/testing/adios2/engine/table/TestTableSingleRank.cpp
@@ -106,7 +106,7 @@ void Reader(const Dims &shape, const Dims &start, const Dims &count,
     std::vector<std::complex<float>> myComplexes(datasize);
     std::vector<std::complex<double>> myDComplexes(datasize);
 
-    adios2::StepStatus status = readerEngine.BeginStep();
+    readerEngine.BeginStep();
     const auto &vars = io.AvailableVariables();
     std::cout << "All available variables : ";
     for (const auto &var : vars)
diff --git a/testing/adios2/interface/TestADIOSDefineAttribute.cpp b/testing/adios2/interface/TestADIOSDefineAttribute.cpp
index 4ae737af9a..eeb4f30f5f 100644
--- a/testing/adios2/interface/TestADIOSDefineAttribute.cpp
+++ b/testing/adios2/interface/TestADIOSDefineAttribute.cpp
@@ -749,7 +749,7 @@ TEST_F(ADIOSDefineAttributeTest, VariableException)
                          "myVar1", separator),
                      std::invalid_argument);
 
-        auto var = io.DefineVariable<int>("myVar1");
+        io.DefineVariable<int>("myVar1");
 
         EXPECT_NO_THROW(
             io.DefineAttribute<std::string>("Hello Value", "Value", "myVar1"));
diff --git a/testing/adios2/interface/TestADIOSInterface.cpp b/testing/adios2/interface/TestADIOSInterface.cpp
index d5192cc9a3..56e8e646de 100644
--- a/testing/adios2/interface/TestADIOSInterface.cpp
+++ b/testing/adios2/interface/TestADIOSInterface.cpp
@@ -28,9 +28,7 @@ TEST(ADIOSInterface, BADConfigFile)
     EXPECT_THROW(adios2::ADIOS adios("notthere.xml");
                  adios2::IO io = adios.DeclareIO("TestIO");
 
-                 adios2::Engine engine =
-                     io.Open("test.bp", adios2::Mode::Write);
-                 , std::logic_error);
+                 io.Open("test.bp", adios2::Mode::Write);, std::logic_error);
 }
 
 /** ADIOS2_CXX11_API
diff --git a/testing/adios2/interface/TestADIOSInterfaceWrite.cpp b/testing/adios2/interface/TestADIOSInterfaceWrite.cpp
index 631f592393..a0d91817a1 100644
--- a/testing/adios2/interface/TestADIOSInterfaceWrite.cpp
+++ b/testing/adios2/interface/TestADIOSInterfaceWrite.cpp
@@ -7,6 +7,17 @@
 
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 class ADIOSInterfaceWriteTest : public ::testing::Test
 {
 public:
@@ -634,3 +645,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/performance/manyvars/TestManyVars.cpp b/testing/adios2/performance/manyvars/TestManyVars.cpp
index cf8c1e22c3..93e0d4bdf2 100644
--- a/testing/adios2/performance/manyvars/TestManyVars.cpp
+++ b/testing/adios2/performance/manyvars/TestManyVars.cpp
@@ -187,7 +187,7 @@ class TestManyVars : public ::testing::TestWithParam<RunParams>
             digit++;
         }
 
-        char fmt[16];
+        char fmt[32];
         sprintf(fmt, "v%%%d.%dd", digit, digit);
         for (size_t i = 0; i < NVARS; i++)
         {
diff --git a/testing/adios2/xml/TestXMLConfig.cpp b/testing/adios2/xml/TestXMLConfig.cpp
index a6f5b70ed8..043a6be906 100644
--- a/testing/adios2/xml/TestXMLConfig.cpp
+++ b/testing/adios2/xml/TestXMLConfig.cpp
@@ -7,6 +7,17 @@
 
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 #define str_helper(X) #X
 #define str(X) str_helper(X)
 
@@ -143,3 +154,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/adios2/yaml/TestYAMLConfig.cpp b/testing/adios2/yaml/TestYAMLConfig.cpp
index 1473b33e87..17f668947c 100644
--- a/testing/adios2/yaml/TestYAMLConfig.cpp
+++ b/testing/adios2/yaml/TestYAMLConfig.cpp
@@ -7,6 +7,17 @@
 
 #include <gtest/gtest.h>
 
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+#endif
+
 #define str_helper(X) #X
 #define str(X) str_helper(X)
 
@@ -113,3 +124,11 @@ int main(int argc, char **argv)
 
     return result;
 }
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
diff --git a/testing/install/CMakeLists.txt b/testing/install/CMakeLists.txt
index e039080036..cd8481d942 100644
--- a/testing/install/CMakeLists.txt
+++ b/testing/install/CMakeLists.txt
@@ -82,6 +82,17 @@ set_tests_properties(Install.Setup PROPERTIES
   FIXTURES_SETUP Install
   )
 
+# Remove -Wall -Werror in this scope
+if(CMAKE_C_FLAGS)
+  string(REPLACE "-Wall"    " " CMAKE_C_FLAGS   ${CMAKE_C_FLAGS})
+  string(REPLACE "-Werror"  " " CMAKE_C_FLAGS   ${CMAKE_C_FLAGS})
+endif()
+
+if(CMAKE_CXX_FLAGS)
+  string(REPLACE "-Wall"    " " CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+  string(REPLACE "-Werror"  " " CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+endif()
+
 add_install_cmake_test(C)
 add_install_cmake_test(CXX11)
 if(ADIOS2_HAVE_Fortran)
diff --git a/thirdparty/nlohmann_json/nlohmann_json/CMakeLists.txt b/thirdparty/nlohmann_json/nlohmann_json/CMakeLists.txt
index b3ed049b42..1014e73978 100644
--- a/thirdparty/nlohmann_json/nlohmann_json/CMakeLists.txt
+++ b/thirdparty/nlohmann_json/nlohmann_json/CMakeLists.txt
@@ -1,7 +1,14 @@
 add_library(nlohmann_json INTERFACE)
 target_sources(nlohmann_json INTERFACE
-  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/single_include/nlohmann/json.hpp>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/single_include/upstream/nlohmann/json.hpp>
 )
+
+target_sources(nlohmann_json INTERFACE
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/single_include/nlohmann_json.hpp>
+)
+
+target_compile_options(nlohmann_json INTERFACE $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:Intel>>:-Wno-all -Wno-error>)
+
 target_include_directories(nlohmann_json INTERFACE
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/single_include>
 )
diff --git a/thirdparty/nlohmann_json/nlohmann_json/src/single_include/nlohmann_json.hpp b/thirdparty/nlohmann_json/nlohmann_json/src/single_include/nlohmann_json.hpp
new file mode 100644
index 0000000000..b136629b74
--- /dev/null
+++ b/thirdparty/nlohmann_json/nlohmann_json/src/single_include/nlohmann_json.hpp
@@ -0,0 +1,36 @@
+#ifndef __NLOHMANN_JSON_HPP__
+#define __NLOHMANN_JSON_HPP__
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+
+#elif defined(__INTEL_COMPILER) && !defined(__clang__)
+#pragma warning push
+#pragma warning disable 1011
+_Pragma("warning(disable:1011)")
+
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wall"
+
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wall"
+#endif
+
+#include <upstream/nlohmann/json.hpp>
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+
+#elif defined(__INTEL_COMPILER) && !defined(__clang__)
+#pragma warning pop
+
+#elif defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic pop
+
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+
+#endif
diff --git a/thirdparty/nlohmann_json/nlohmann_json/src/single_include/nlohmann/json.hpp b/thirdparty/nlohmann_json/nlohmann_json/src/single_include/upstream/nlohmann/json.hpp
similarity index 100%
rename from thirdparty/nlohmann_json/nlohmann_json/src/single_include/nlohmann/json.hpp
rename to thirdparty/nlohmann_json/nlohmann_json/src/single_include/upstream/nlohmann/json.hpp
diff --git a/thirdparty/nlohmann_json/update.sh b/thirdparty/nlohmann_json/update.sh
index dfd8eaf94d..dac32324da 100755
--- a/thirdparty/nlohmann_json/update.sh
+++ b/thirdparty/nlohmann_json/update.sh
@@ -6,7 +6,7 @@ shopt -s dotglob
 
 readonly name="nlohmann_json/single_include"
 readonly ownership="JSON For Modern C++ Upstream <robot@adios2>"
-readonly subtree="thirdparty/nlohmann_json/nlohmann_json/src/single_include"
+readonly subtree="thirdparty/nlohmann_json/nlohmann_json/src/single_include/upstream"
 readonly repo="https://github.com/nlohmann/json.git"
 readonly tag="master"
 readonly shortlog="true"