move to c++20

scripts/spack_packages/packages/camp/package.py

@@ -0,0 +1,18 @@
+from spack.package import *
+from spack_repo.builtin.packages.camp.package import Camp as BuiltinCamp
+
+
+class Camp(BuiltinCamp):
+    version(
+        "2026.05.18",
+        commit="47a3682c3d5ff43b542ad7e29569eb5e157f918e",
+        submodules=False,
+    )
+
+    def cmake_args(self):
+        args = super().cmake_args()
+        args.append(self.define("BLT_CXX_STD", "c++20"))
+        args.append(self.define("CMAKE_CXX_STANDARD", 20))
+        args.append(self.define("CMAKE_CUDA_STANDARD", 20))
+        args.append(self.define("CMAKE_HIP_STANDARD", 20))
+        return args

scripts/spack_packages/packages/chai/package.py

@@ -4,6 +4,19 @@
 from spack_repo.builtin.packages.chai.package import Chai as BuiltinChai
 
 class Chai(BuiltinChai):
+    version(
+        "2026.04.13",
+        commit="c4de793a61596a6787afb07ed0dd1dfee349f34f",
+        submodules=False,
+    )
+
     # Bypass llnl_link_helpers failure
     depends_on("fortran")
 
+    def cmake_args(self):
+        args = super().cmake_args()
+        args.append(self.define("BLT_CXX_STD", "c++20"))
+        args.append(self.define("CMAKE_CXX_STANDARD", 20))
+        args.append(self.define("CMAKE_CUDA_STANDARD", 20))
+        args.append(self.define("CMAKE_HIP_STANDARD", 20))
+        return args

scripts/spack_packages/packages/geosx/package.py

@@ -77,7 +77,8 @@ class Geosx(CMakePackage, CudaPackage, ROCmPackage):
             multi=False)
     variant('grpc', default=False, description='Enable gRPC.')
     variant('pygeosx', default=True, description='Enable pygeosx.')
-    variant('cxxstd', default='17', description='CXX standard.')
+    variant('cxxstd', default='20', values=('20',), multi=False,
+            description='CXX standard.')
 
     # SPHINX_END_VARIANTS
 
@@ -93,6 +94,8 @@ class Geosx(CMakePackage, CudaPackage, ROCmPackage):
     variant('cuda_stack_size', default="0", description="Defines the adjusted cuda stack \
         size limit if required. Zero or negative keep default behavior")
 
+    requires('cxxstd=20', msg='GEOS.AI TPL snapshots require C++20.')
+
     # SPHINX_BEGIN_DEPENDS
     depends_on("c", type="build")
     depends_on("cxx", type="build")
@@ -112,11 +115,14 @@ class Geosx(CMakePackage, CudaPackage, ROCmPackage):
     #
     # Performance portability
     #
-    raja_suite_version="2025.12.0"
-    depends_on(f"raja @{raja_suite_version} ~examples~exercises~shared")
-    depends_on(f"chai @{raja_suite_version} +raja~examples~shared")
-    depends_on(f"camp @{raja_suite_version}")
-    depends_on(f"umpire @{raja_suite_version} +c~examples+fortran~device_alloc~shared")
+    raja_version = "2026.05.19"
+    chai_version = "2026.04.13"
+    camp_version = "2026.05.18"
+    umpire_version = "2026.03.31"
+    depends_on(f"chai @{chai_version} +raja~examples~shared")
+    depends_on(f"raja @{raja_version} ~examples~exercises~shared")
+    depends_on(f"camp @{camp_version}")
+    depends_on(f"umpire @{umpire_version} +c~examples+fortran~device_alloc~shared")
     with when('+openmp'):
         for pkg in ('raja', 'chai', 'umpire'):
             depends_on(f"{pkg}+openmp", when="+openmp")
@@ -152,9 +158,7 @@ class Geosx(CMakePackage, CudaPackage, ROCmPackage):
 
     depends_on('pugixml@1.13 ~shared')
 
-    depends_on('fmt@11')
-    for _fmt_cxxstd in ('14', '17', '20'):
-        depends_on(f'fmt@11 cxxstd={_fmt_cxxstd}', when=f'cxxstd={_fmt_cxxstd}')
+    depends_on('fmt@12.1.0 cxxstd=20')
     depends_on('vtk@9.4.2', when='+vtk')
 
     #

scripts/spack_packages/packages/raja/package.py

@@ -0,0 +1,18 @@
+from spack.package import *
+from spack_repo.builtin.packages.raja.package import Raja as BuiltinRaja
+
+
+class Raja(BuiltinRaja):
+    version(
+        "2026.05.19",
+        commit="d9a03fd56f7fb81540aeacbf082eb35dbb840b9c",
+        submodules=False,
+    )
+
+    def cmake_args(self):
+        args = super().cmake_args()
+        args.append(self.define("BLT_CXX_STD", "c++20"))
+        args.append(self.define("CMAKE_CXX_STANDARD", 20))
+        args.append(self.define("CMAKE_CUDA_STANDARD", 20))
+        args.append(self.define("CMAKE_HIP_STANDARD", 20))
+        return args

scripts/spack_packages/packages/umpire/package.py

@@ -0,0 +1,20 @@
+from spack.package import *
+from spack_repo.builtin.packages.umpire.package import Umpire as BuiltinUmpire
+
+
+class Umpire(BuiltinUmpire):
+    version(
+        "2026.03.31",
+        commit="5ff0d696d84f1048faf72085743630fcf33c0928",
+        submodules=False,
+    )
+
+    depends_on("fmt@12.1.0", when="@2026.03.31")
+
+    def cmake_args(self):
+        args = super().cmake_args()
+        args.append(self.define("BLT_CXX_STD", "c++20"))
+        args.append(self.define("CMAKE_CXX_STANDARD", 20))
+        args.append(self.define("CMAKE_CUDA_STANDARD", 20))
+        args.append(self.define("CMAKE_HIP_STANDARD", 20))
+        return args