llnl · johnbowen42 · Dec 12, 2025 · Dec 12, 2025
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -30,7 +30,7 @@ jobs:
         with:
           build-dir: build
           options:
-            CMAKE_CXX_STANDARD=17
+            CMAKE_CXX_STANDARD=20
             ENABLE_OPENMP=Off
             CMAKE_BUILD_TYPE=Release
           run-build: true

diff --git a/.travis.yml b/.travis.yml
@@ -34,7 +34,7 @@ matrix:
     env:
     - COMPILER=/opt/intel/bin/icpc
     - IMG=icc18
-    - CMAKE_EXTRA_FLAGS="-DRAJA_ENABLE_FORCEINLINE_RECURSIVE=Off -DRAJA_ENABLE_TBB=On -DBLT_CXX_STD=c++17"
+    - CMAKE_EXTRA_FLAGS="-DRAJA_ENABLE_FORCEINLINE_RECURSIVE=Off -DRAJA_ENABLE_TBB=On -DBLT_CXX_STD=c++20"
   - compiler: nvcc10.2
     env:
     - COMPILER=g++

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -54,14 +54,11 @@ if(NOT DEFINED BLT_CXX_STD)
   if("cxx_std_20" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
     set(BLT_CXX_STD c++20 CACHE STRING "Version of C++ standard")
     message("Using C++ standard: ${BLT_CXX_STD}")
-  elseif("cxx_std_17" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
-    set(BLT_CXX_STD c++17 CACHE STRING "Version of C++ standard")
-    message("Using C++ standard: ${BLT_CXX_STD}")
   elseif("${CMAKE_CXX_COMPILER_ID}" IN_LIST COMPILERS_KNOWN_TO_CMAKE33)
-    set(BLT_CXX_STD c++17 CACHE STRING "Version of C++ standard")
+    set(BLT_CXX_STD c++20 CACHE STRING "Version of C++ standard")
     message("Using C++ standard: ${BLT_CXX_STD}")
   else() #cmake has no idea what to do, do it ourselves...
-    set(flag_var "c++17")
+    set(flag_var "c++20")
     CHECK_CXX_COMPILER_FLAG("-std=${flag_var}" COMPILER_SUPPORTS_${flag_var})
     if(COMPILER_SUPPORTS_${flag_var})
       set(BLT_CXX_STD ${flag_var} CACHE STRING "Version of C++ standard")
@@ -72,8 +69,9 @@ if(NOT DEFINED BLT_CXX_STD)
 else() #check BLT_CXX_STD is high enough by disallowing the only invalid option
   if(("${BLT_CXX_STD}" STREQUAL "c++98") OR
      ("${BLT_CXX_STD}" STREQUAL "c++11") OR
-     ("${BLT_CXX_STD}" STREQUAL "c++14"))
-    message(FATAL_ERROR "RAJA requires minimum C++ standard of c++17")
+     ("${BLT_CXX_STD}" STREQUAL "c++14") OR 
+     ("${BLT_CXX_STD}" STREQUAL "c++17"))
+    message(FATAL_ERROR "RAJA requires minimum C++ standard of c++20")
   endif()
 endif(NOT DEFINED BLT_CXX_STD)
 

diff --git a/Dockerfile b/Dockerfile
@@ -15,7 +15,7 @@ FROM ghcr.io/llnl/radiuss:gcc-12-ubuntu-24.04 AS gcc12
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -24,7 +24,7 @@ FROM ghcr.io/llnl/radiuss:gcc-12-ubuntu-24.04 AS gcc12_debug
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Debug -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Debug -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -33,7 +33,7 @@ FROM ghcr.io/llnl/radiuss:gcc-13-ubuntu-24.04 AS gcc13
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -42,7 +42,7 @@ FROM ghcr.io/llnl/radiuss:gcc-13-ubuntu-24.04 AS gcc13_desul
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -51,7 +51,7 @@ FROM ghcr.io/llnl/radiuss:clang-14-ubuntu-22.04 AS clang14_debug
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Debug  -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Debug  -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -69,7 +69,7 @@ FROM ghcr.io/llnl/radiuss:clang-14-ubuntu-22.04 AS clang14_desul
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure && \
     make clean
@@ -80,7 +80,7 @@ ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
 RUN /bin/bash -c "source /opt/intel/oneapi/setvars.sh 2>&1 > /dev/null && \
-    cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+    cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     make clean"
 
@@ -90,7 +90,7 @@ ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
 RUN /bin/bash -c "source /opt/intel/oneapi/setvars.sh 2>&1 > /dev/null && \
-    cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=Debug -DENABLE_OPENMP=On -DBLT_CXX_STD=c++17 .. && \
+    cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=Debug -DENABLE_OPENMP=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     make clean"
 
@@ -99,7 +99,7 @@ ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
 RUN /bin/bash -c "source /opt/intel/oneapi/setvars.sh 2>&1 > /dev/null && \
-    cmake -DCMAKE_CXX_COMPILER=dpcpp -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=Off -DRAJA_ENABLE_SYCL=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++17 .. && \
+    cmake -DCMAKE_CXX_COMPILER=dpcpp -DCMAKE_BUILD_TYPE=Release -DENABLE_OPENMP=Off -DRAJA_ENABLE_SYCL=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     make clean"
 
@@ -108,6 +108,6 @@ ENV GTEST_COLOR=1
 ENV HCC_AMDGPU_TARGET=gfx900
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=/opt/rocm-6.4.3/bin/amdclang++ -DROCM_PATH=/opt/rocm-6.4.3 -DCMAKE_BUILD_TYPE=Release -DENABLE_HIP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=Off -DBLT_CXX_STD=c++17 .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=/opt/rocm-6.4.3/bin/amdclang++ -DROCM_PATH=/opt/rocm-6.4.3 -DCMAKE_BUILD_TYPE=Release -DENABLE_HIP=On -DRAJA_ENABLE_DESUL_ATOMICS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=Off -DBLT_CXX_STD=c++20 .. && \
     make -j 16 &&\
     make clean 
diff --git a/README.md b/README.md
@@ -24,7 +24,7 @@ and programming model portability for HPC applications. RAJA has two main goals:
 
 RAJA offers portable, parallel loop execution by providing building blocks 
 that extend the generally-accepted parallel for idiom. RAJA relies on standard 
-C++17 features.
+C++20 features.
 
 RAJA's design is rooted in decades of experience working on 
 production mesh-based multiphysics applications. Based on the diversity of
@@ -55,7 +55,7 @@ To clone the repo, use the command:
     git clone --recursive https://github.com/llnl/raja.git
 
 Then, you can build RAJA like any other CMake project, provided you have a C++
-compiler that supports the C++17 standard. The simplest way to build the code,
+compiler that supports the C++20 standard. The simplest way to build the code,
 using your system default compiler, is to run the following sequence of 
 commands in the top-level RAJA directory (in-source builds are not allowed!):
 

diff --git a/cmake/SetupCompilers.cmake b/cmake/SetupCompilers.cmake
@@ -59,7 +59,7 @@ endif()
 # end RAJA_ENABLE_CUDA section
 
 if (RAJA_ENABLE_HIP)
-  set(RAJA_HIPCC_STD_FLAG -std=c++17)
+  set(RAJA_HIPCC_STD_FLAG -std=c++20)
   if (NOT RAJA_HOST_CONFIG_LOADED)
     #list(APPEND RAJA_EXTRA_HIPCC_FLAGS)
 

diff --git a/docs/index.rst b/docs/index.rst
@@ -47,7 +47,7 @@ reductions, scans, atomic operations, sorts, data layouts, views, and loop
 iteration spaces, as well as compile-time loop transformations. Features
 are continually growing as new use cases arise due to expanding user adoption.
 
-RAJA uses standard C++17 -- C++ is the programming language model of choice
+RAJA uses standard C++20 -- C++ is the programming language model of choice
 for many HPC applications. RAJA requirements and design are rooted in a 
 decades of developer experience working on production mesh-based 
 multiphysics applications. An important RAJA requirement is that

diff --git a/docs/sphinx/user_guide/feature/policies.rst b/docs/sphinx/user_guide/feature/policies.rst
@@ -1156,7 +1156,7 @@ RAJA Kernel Execution Policies
 
 RAJA kernel execution policy constructs form a simple domain specific language
 for composing and transforming complex loops that relies
-**solely on standard C++17 template support**.
+**solely on standard C++20 template support**.
 RAJA kernel policies are constructed using a combination of *Statements* and
 *Statement Lists*. A RAJA Statement is an action, such as execute a loop,
 invoke a lambda, set a thread barrier, etc. A StatementList is an ordered list

diff --git a/docs/sphinx/user_guide/getting_started.rst b/docs/sphinx/user_guide/getting_started.rst
@@ -19,15 +19,15 @@ This section should help get you up and running with RAJA quickly.
 Requirements
 ============
 
-The primary requirement for using RAJA is a C++17 standard compliant compiler.
+The primary requirement for using RAJA is a C++20 standard compliant compiler.
 Certain features, such as programming model back-ends like CUDA or HIP,
 must be supported by the compiler you chose to use them. Available RAJA
 configuration options and how to enable or disable features are described 
 in :ref:`configopt-label`. 
 
 To build RAJA and use its most basic features, you will need:
 
-- C++ compiler with C++17 support
+- C++ compiler with C++20 support
 - `CMake <https://cmake.org/>`_ version 3.23 or greater.
 
 

diff --git a/host-configs/alcf-builds/cooley_nvcc_clang4_0.cmake b/host-configs/alcf-builds/cooley_nvcc_clang4_0.cmake
@@ -14,8 +14,8 @@ set(CMAKE_CXX_FLAGS_RELEASE "-O3" CACHE STRING "")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3" CACHE STRING "")
 set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g" CACHE STRING "")
 
-set(CUDA_COMMON_OPT_FLAGS -restrict; -arch sm_35; -std c++17; --expt-extended-lambda)
-set(CUDA_COMMON_DEBUG_FLAGS -restrict; -arch compute_30; -std c++17; --expt-extended-lambda)
+set(CUDA_COMMON_OPT_FLAGS -restrict; -arch sm_35; -std c++20; --expt-extended-lambda)
+set(CUDA_COMMON_DEBUG_FLAGS -restrict; -arch compute_30; -std c++20; --expt-extended-lambda)
 
 set(HOST_OPT_FLAGS -Xcompiler -O3 -Xcompiler -fopenmp)
 

diff --git a/host-configs/alcf-builds/sycl.cmake b/host-configs/alcf-builds/sycl.cmake
@@ -14,16 +14,11 @@
 
 set(RAJA_COMPILER "RAJA_COMPILER_CLANG" CACHE STRING "")
 
-#set(CMAKE_CXX_COMPILER "clang++" CACHE PATH "")
-#set(CMAKE_CXX_COMPILER "g++" CACHE PATH "")
 set(CMAKE_CXX_COMPILER "dpcpp" CACHE PATH "")
 
-#set(CMAKE_CXX_FLAGS_RELEASE "-O3 -fsycl -fsycl-unnamed-lambda -fsycl-targets=spir64_gen-unknown-unknown-sycldevice -Xsycl-target-backend '-device skl' " CACHE STRING "")
-#set(CMAKE_CXX_FLAGS_RELWITHDEBINFO " -O3 -g  -fsycl -fsycl-unnamed-lambda -fsycl-targets=spir64_gen-unknown-unknown-sycldevice -Xsycl-target-backend '-device skl'" CACHE STRING "")
-#set(CMAKE_CXX_FLAGS_DEBUG " -O0 -g -fsycl -fsycl-unnamed-lambda -fsycl-targets=spir64_gen-unknown-unknown-sycldevice -Xsycl-target-backend '-device skl'" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_RELEASE "-O3 -std=c++17 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_RELWITHDEBINFO " -O3 -g -std=c++17 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_DEBUG " -O0 -g -std=c++17 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELEASE "-O3 -std=c++20 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO " -O3 -g -std=c++20 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_DEBUG " -O0 -g -std=c++20 -fsycl -fsycl-unnamed-lambda" CACHE STRING "")
 set(CMAKE_CXX_LINK_FLAGS "-fsycl -Wl,-rpath,/usr/tce/packages/oneapi/oneapi-2021.2/compiler/2021.2.0/linux/compiler/lib/intel64_lin/"  CACHE STRING "")
 
 set(RAJA_RANGE_ALIGN 4 CACHE INT "")

diff --git a/host-configs/lc-builds/toss4/corona_sycl.cmake b/host-configs/lc-builds/toss4/corona_sycl.cmake
@@ -10,12 +10,8 @@ set(RAJA_COMPILER "RAJA_COMPILER_CLANG" CACHE STRING "")
 set(CMAKE_CXX_COMPILER "clang++" CACHE PATH "")
 #set(CMAKE_CXX_COMPILER "dpcpp" CACHE PATH "")
 
-set(CMAKE_CXX_FLAGS_RELEASE "-O3 -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3 -g -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
-set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
-#set(CMAKE_CXX_FLAGS_RELEASE "-O3 -std=c++17 -fsycl -fsycl-unnamed-lambda --gcc-toolchain=/usr/tce/packages/gcc/gcc-7.1.0" CACHE STRING "")
-#set(CMAKE_CXX_FLAGS_RELWITHDEBINFO " -O3 -g  -std=c++17 -fsycl -fsycl-unnamed-lambda --gcc-toolchain=/usr/tce/packages/gcc/gcc-7.1.0" CACHE STRING "")
-#set(CMAKE_CXX_FLAGS_DEBUG " -O0 -g -std=c++17 -fsycl -fsycl-unnamed-lambda --gcc-toolchain=/usr/tce/packages/gcc/gcc-7.1.0" CACHE STRING "")
-#set(CMAKE_CXX_LINK_FLAGS "-fsycl -Wl,-rpath,/usr/tce/packages/oneapi/oneapi-2021.2/compiler/2021.2.0/linux/compiler/lib/intel64_lin/"  CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELEASE "-O3 -std=c++20 -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3 -std=c++20 -g -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_DEBUG "-O0 -std=c++20 -g -L${SYCL_LIB_PATH} -fsycl -fsycl-unnamed-lambda -fsycl-targets=amdgcn-amd-amdhsa -Xsycl-target-backend --offload-arch=gfx906" CACHE STRING "")
 
 set(RAJA_HOST_CONFIG_LOADED On CACHE BOOL "")
diff --git a/scripts/alcf-builds/sycl.sh b/scripts/alcf-builds/sycl.sh
@@ -35,7 +35,7 @@ cmake \
   -DRAJA_ENABLE_SYCL=On \
   -DCMAKE_LINKER=clang++ \
   -DCMAKE_CXX_STANDARD=17 \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_TESTS=On \
   -DENABLE_EXAMPLES=On \
   "$@" \

diff --git a/scripts/lc-builds/corona_sycl.sh b/scripts/lc-builds/corona_sycl.sh
@@ -54,7 +54,7 @@ cmake \
   -DCMAKE_C_COMPILER=clang \
   -DCMAKE_CXX_COMPILER=clang++ \
   -DCMAKE_LINKER=clang++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_TESTS=On \
   -DENABLE_EXAMPLES=On \
   "$@" \

diff --git a/scripts/lc-builds/toss4_amdclang.sh b/scripts/lc-builds/toss4_amdclang.sh
@@ -70,7 +70,7 @@ cmake \
   -DCMAKE_HIP_ARCHITECTURES="${COMP_ARCH}" \
   -DGPU_TARGETS="${COMP_ARCH}" \
   -DAMDGPU_TARGETS="${COMP_ARCH}" \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C "../host-configs/lc-builds/toss4/${HOSTCONFIG}.cmake" \
   -DENABLE_HIP=ON \
   -DENABLE_OPENMP=ON \

diff --git a/scripts/lc-builds/toss4_amdclang_asan.sh b/scripts/lc-builds/toss4_amdclang_asan.sh
@@ -80,7 +80,7 @@ cmake \
   -DCMAKE_CXX_FLAGS="-fsanitize=address -shared-libsan" \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/opt/rocm-5.2.3/llvm/bin/clang-format \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C "../host-configs/lc-builds/toss4/${HOSTCONFIG}.cmake" \
   -DENABLE_HIP=ON \
   -DENABLE_OPENMP=ON \

diff --git a/scripts/lc-builds/toss4_cce_hip.sh b/scripts/lc-builds/toss4_cce_hip.sh
@@ -52,7 +52,7 @@ cmake \
   -DCMAKE_HIP_ARCHITECTURES=${HIP_ARCH} \
   -DGPU_TARGETS=${HIP_ARCH} \
   -DAMDGPU_TARGETS=${HIP_ARCH} \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/opt/rocm-5.2.3/llvm/bin/clang-format \
   -C "../host-configs/lc-builds/toss4/${HOSTCONFIG}.cmake" \

diff --git a/scripts/lc-builds/toss4_cce_omptarget.sh b/scripts/lc-builds/toss4_cce_omptarget.sh
@@ -44,7 +44,7 @@ cmake \
   -DHIP_ARCH=${HIP_ARCH} \
   -DCMAKE_C_COMPILER="/usr/tce/packages/cce/cce-${COMP_VER}/bin/craycc" \
   -DCMAKE_CXX_COMPILER="/usr/tce/packages/cce/cce-${COMP_VER}/bin/crayCC" \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=Off \
   -C "../host-configs/lc-builds/toss4/${HOSTCONFIG}.cmake" \
   -DENABLE_HIP=OFF \

diff --git a/scripts/lc-builds/toss4_clang-format.sh b/scripts/lc-builds/toss4_clang-format.sh
@@ -36,7 +36,7 @@ module load cmake/3.23.1
 cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/clang/clang-${COMP_VER}/bin/clang++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/clang_X.cmake \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-${COMP_VER}/bin/clang-format \

diff --git a/scripts/lc-builds/toss4_clang.sh b/scripts/lc-builds/toss4_clang.sh
@@ -33,7 +33,7 @@ module load cmake/3.23.1
 cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/clang/clang-${COMP_VER}/bin/clang++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \
   -C ../host-configs/lc-builds/toss4/clang_X.cmake \

diff --git a/scripts/lc-builds/toss4_clang_san.sh b/scripts/lc-builds/toss4_clang_san.sh
@@ -42,7 +42,7 @@ module load cmake/3.23.1
 cmake \
   -DCMAKE_BUILD_TYPE=Debug \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/clang/clang-${COMP_VER}/bin/clang++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \
   -C ../host-configs/lc-builds/toss4/clang_X_${SAN_VER}.cmake \

diff --git a/scripts/lc-builds/toss4_gcc.sh b/scripts/lc-builds/toss4_gcc.sh
@@ -33,7 +33,7 @@ module load cmake/3.23.1
 cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/gcc/gcc-${COMP_VER}/bin/g++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \
   -C ../host-configs/lc-builds/toss4/gcc_X.cmake \

diff --git a/scripts/lc-builds/toss4_hipcc.sh b/scripts/lc-builds/toss4_hipcc.sh
@@ -69,7 +69,7 @@ cmake \
   -DCMAKE_HIP_ARCHITECTURES="${COMP_ARCH}" \
   -DGPU_TARGETS="${COMP_ARCH}" \
   -DAMDGPU_TARGETS="${COMP_ARCH}" \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/opt/rocm-5.2.3/llvm/bin/clang-format \
   -C "../host-configs/lc-builds/toss4/${HOSTCONFIG}.cmake" \

diff --git a/scripts/lc-builds/toss4_icpc-classic.sh b/scripts/lc-builds/toss4_icpc-classic.sh
@@ -41,7 +41,7 @@ cmake \
   -DCMAKE_C_COMPILER=/usr/tce/packages/intel-classic/intel-classic-${COMP_VER}/bin/icc \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/icpc-classic_X.cmake \
   -DRAJA_ENABLE_FORCEINLINE_RECURSIVE=Off \
   -DENABLE_OPENMP=On \

diff --git a/scripts/lc-builds/toss4_icpc.sh b/scripts/lc-builds/toss4_icpc.sh
@@ -41,7 +41,7 @@ cmake \
   -DCMAKE_C_COMPILER=/usr/tce/packages/intel/intel-${COMP_VER}/bin/icc \
   -DENABLE_CLANGFORMAT=On \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/icpc_X.cmake \
   -DRAJA_ENABLE_FORCEINLINE_RECURSIVE=Off \
   -DENABLE_OPENMP=On \

diff --git a/scripts/lc-builds/toss4_icpx.sh b/scripts/lc-builds/toss4_icpx.sh
@@ -46,7 +46,7 @@ cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=icpx \
   -DCMAKE_C_COMPILER=icx \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/icpx_X.cmake \
   -DRAJA_ENABLE_FORCEINLINE_RECURSIVE=Off \
   -DENABLE_CLANGFORMAT=On \

diff --git a/scripts/lc-builds/toss4_nvcc_clang.sh b/scripts/lc-builds/toss4_nvcc_clang.sh
@@ -43,7 +43,7 @@ module load cmake/3.25.2
 cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/clang/clang-${COMP_CLANG_VER}/bin/clang++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/nvcc_clang_X.cmake \
   -DENABLE_CLANGFORMAT=Off \
   -DCLANGFORMAT_EXECUTABLE=/usr/tce/packages/clang/clang-14.0.6/bin/clang-format \

diff --git a/scripts/lc-builds/toss4_nvcc_gcc.sh b/scripts/lc-builds/toss4_nvcc_gcc.sh
@@ -43,7 +43,7 @@ module load cmake/3.25.2
 cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_CXX_COMPILER=/usr/tce/packages/gcc/gcc-${COMP_GCC_VER}/bin/g++ \
-  -DBLT_CXX_STD=c++17 \
+  -DBLT_CXX_STD=c++20 \
   -C ../host-configs/lc-builds/toss4/nvcc_gcc_X.cmake \
   -DENABLE_CLANGFORMAT=Off \
   -DENABLE_OPENMP=On \