C++17 support for LBANN and HIP (#25406)

* Added logic to explicitly pass the c++17 language flags to the
HIP/ROCm software stack to ensure that HIP complies with the C++17
requirements.

var/spack/repos/builtin/packages/aluminum/package.py

@@ -60,12 +60,15 @@ class Aluminum(CMakePackage, CudaPackage, ROCmPackage):
     def cmake_args(self):
         spec = self.spec
         args = [
-            '-DCMAKE_CXX_STANDARD=14',
+            '-DCMAKE_CXX_STANDARD:STRING=17',
             '-DALUMINUM_ENABLE_CUDA:BOOL=%s' % ('+cuda' in spec),
             '-DALUMINUM_ENABLE_NCCL:BOOL=%s' % ('+nccl' in spec or '+rccl' in spec),
             '-DALUMINUM_ENABLE_ROCM:BOOL=%s' % ('+rocm' in spec)]
 
         if '+cuda' in spec:
+            if spec.satisfies('^cuda@11.0:'):
+                args.append('-DCMAKE_CUDA_STANDARD=17')
+            else:
                 args.append('-DCMAKE_CUDA_STANDARD=14')
             archs = spec.variants['cuda_arch'].value
             if archs != 'none':
@@ -98,13 +101,14 @@ def cmake_args(self):
         if '+rocm' in spec:
             args.extend([
                 '-DHIP_ROOT_DIR={0}'.format(spec['hip'].prefix),
-                '-DHIP_CXX_COMPILER={0}'.format(self.spec['hip'].hipcc)])
+                '-DHIP_CXX_COMPILER={0}'.format(self.spec['hip'].hipcc),
+                '-DCMAKE_CXX_FLAGS=-std=c++17'])
             archs = self.spec.variants['amdgpu_target'].value
             if archs != 'none':
                 arch_str = ",".join(archs)
                 args.append(
                     '-DHIP_HIPCC_FLAGS=--amdgpu-target={0}'
-                    ' -g -fsized-deallocation -fPIC'.format(arch_str)
+                    ' -g -fsized-deallocation -fPIC -std=c++17'.format(arch_str)
                 )
 
         return args

var/spack/repos/builtin/packages/dihydrogen/package.py

@@ -187,6 +187,7 @@ def cmake_args(self):
 
         if '+rocm' in spec:
             args.extend([
+                '-DCMAKE_CXX_FLAGS=-std=c++17',
                 '-DHIP_ROOT_DIR={0}'.format(spec['hip'].prefix),
                 '-DHIP_CXX_COMPILER={0}'.format(self.spec['hip'].hipcc)])
             archs = self.spec.variants['amdgpu_target'].value
@@ -194,7 +195,7 @@ def cmake_args(self):
                 arch_str = ",".join(archs)
                 args.append(
                     '-DHIP_HIPCC_FLAGS=--amdgpu-target={0}'
-                    ' -g -fsized-deallocation -fPIC'.format(arch_str)
+                    ' -g -fsized-deallocation -fPIC -std=c++17'.format(arch_str)
                 )
 
         return args

var/spack/repos/builtin/packages/hydrogen/package.py

@@ -172,6 +172,7 @@ def cmake_args(self):
 
         if '+rocm' in spec:
             args.extend([
+                '-DCMAKE_CXX_FLAGS=-std=c++17',
                 '-DHIP_ROOT_DIR={0}'.format(spec['hip'].prefix),
                 '-DHIP_CXX_COMPILER={0}'.format(self.spec['hip'].hipcc)])
             archs = self.spec.variants['amdgpu_target'].value
@@ -180,7 +181,8 @@ def cmake_args(self):
                 cxxflags_str = " ".join(self.spec.compiler_flags['cxxflags'])
                 args.append(
                     '-DHIP_HIPCC_FLAGS=--amdgpu-target={0}'
-                    ' -g -fsized-deallocation -fPIC {1}'.format(arch_str, cxxflags_str)
+                    ' -g -fsized-deallocation -fPIC {1}'
+                    ' -std=c++17'.format(arch_str, cxxflags_str)
                 )
 
         # Add support for OS X to find OpenMP (LLVM installed via brew)

var/spack/repos/builtin/packages/lbann/package.py

@@ -249,6 +249,7 @@ def common_config_args(self):
         # Environment variables
         cppflags = []
         cppflags.append('-DLBANN_SET_EL_RNG')
+        cppflags.append('-std=c++17')
         args = []
         args.extend([
             '-DCMAKE_CXX_FLAGS=%s' % ' '.join(cppflags),