Add infrastructure for working with concepts

This commit adds the `TRACCC_CONSTRAINT` macro which acts as a concept
in C++20 builds, and simply acts as the `typename` keyword in builds
with older standards. It also adds the `TRACCC_ENFORCE_CONCEPTS` CMake
flag which will throw an error if concepts are not available.

Author: stephenswat

.github/ci_setup.sh

@@ -10,8 +10,22 @@
 # Usage: source .github/ci_setup.sh <platform name>
 #
 
+# Function to compare version numbers. Returns a true-like value if the first
+# argument is a smaller or equal version to the second. Taken from:
+# https://stackoverflow.com/a/25731924
+verleq() {
+   printf "%s\n%s" $1 $2 | sort -Ct '.' -k 1,1 -k 2,2 -k 3,3 -k 4,4 -g
+}
+
+# Regex to match NVCC versions
+NVCC_VERSION_REGEX="Cuda compilation tools, release ([0-9]+\.[0-9]+)"
+
+# Regex to match CMake versions
+CMAKE_VERSION_REGEX="cmake version ([0-9]+\.[0-9]+\.[0-9]+)"
+
 # The platform name.
 PLATFORM_NAME=$1
+CXX_STANDARD=$2
 
 # Make sure that the build and CTest would use all available cores.
 export CMAKE_BUILD_PARALLEL_LEVEL=`nproc`
@@ -23,4 +37,22 @@ if [ "${PLATFORM_NAME}" = "SYCL" ]; then
    if [ -f "/opt/intel/oneapi/setvars.sh" ]; then
       source /opt/intel/oneapi/setvars.sh --include-intel-llvm
    fi
+elif [ "${PLATFORM_NAME}" = "CUDA" ]; then
+   if verleq 20 $CXX_STANDARD; then
+      if [[ $(nvcc --version) =~ $NVCC_VERSION_REGEX ]]; then
+         nvcc_version="${BASH_REMATCH[1]}"
+
+         if [[ $(cmake --version) =~ $CMAKE_VERSION_REGEX ]]; then
+            cmake_version="${BASH_REMATCH[1]}"
+
+            if verleq 12.0 $nvcc_version && verleq $cmake_version 3.25.2; then
+               export CUDAFLAGS="-std=c++20 $CUDAFLAGS"
+            fi
+         else
+            echo "Warning: CMake version didn't match regex '$CMAKE_VERSION_REGEX'"
+         fi
+      else
+         echo "Warning: NVCC version didn't match regex '$NVCC_VERSION_REGEX'"
+      fi
+   fi
 fi

.github/workflows/builds.yml

@@ -35,7 +35,7 @@ jobs:
           - name: CPU
             container: ghcr.io/acts-project/ubuntu2404:48
             cxx_standard: "20"
-            options: -DTRACCC_USE_ROOT=FALSE
+            options: -DTRACCC_USE_ROOT=FALSE -DTRACCC_ENFORCE_CONCEPTS=TRUE
           - name: HIP
             container: ghcr.io/acts-project/ubuntu2004_rocm:47
             cxx_standard: "17"
@@ -47,7 +47,7 @@ jobs:
           - name: CUDA
             container: ghcr.io/acts-project/ubuntu2204_cuda:48
             cxx_standard: "20"
-            options: -DTRACCC_BUILD_CUDA=TRUE -DTRACCC_USE_ROOT=FALSE
+            options: -DTRACCC_BUILD_CUDA=TRUE -DTRACCC_USE_ROOT=FALSE -DTRACCC_ENFORCE_CONCEPTS=TRUE
           - name: SYCL
             container: ghcr.io/acts-project/ubuntu2004_oneapi:47
             cxx_standard: "17"
@@ -84,7 +84,7 @@ jobs:
       - uses: actions/checkout@v3
       - name: Configure
         run: |
-          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }}
+          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }} ${{ matrix.platform.cxx_standard }}
           cmake \
             -DCMAKE_BUILD_TYPE=${{ matrix.build }} \
             -DCMAKE_CXX_STANDARD=${{ matrix.platform.cxx_standard }} \
@@ -97,7 +97,7 @@ jobs:
             -B build
       - name: Build
         run: |
-          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }}
+          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }} ${{ matrix.platform.cxx_standard }}
           cmake --build build
       - name: Download data files
         if: "matrix.platform.name == 'CPU'"
@@ -106,7 +106,7 @@ jobs:
         if: "matrix.platform.name == 'CPU'"
         run: |
           cd build
-          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }}
+          source ${GITHUB_WORKSPACE}/.github/ci_setup.sh ${{ matrix.platform.name }} ${{ matrix.platform.cxx_standard }}
           ctest --output-on-failure
       - name: FP64 Compliance
         if: "matrix.platform.name == 'CUDA' && matrix.build == 'Debug'"

.gitlab-ci.yml

@@ -14,7 +14,7 @@ stages:
   before_script:
     - git clone $CLONE_URL src
     - git -C src checkout $HEAD_SHA
-    - source ./src/.github/ci_setup.sh ${TRACCC_BUILD_TYPE}
+    - source ./src/.github/ci_setup.sh ${TRACCC_BUILD_TYPE} 17
 
 # Build job template.
 .build_template: &build_job

CMakeLists.txt

@@ -66,6 +66,9 @@ option( TRACCC_BUILD_EXAMPLES "Build the examples of traccc" TRUE )
 option( TRACCC_USE_SYSTEM_LIBS "Use system libraries be default" FALSE )
 option( TRACCC_USE_ROOT "Use ROOT in the build (if needed)" TRUE )
 
+# Flag enforcing concept usage.
+option( TRACCC_ENFORCE_CONCEPTS "Throw an error if concepts are not available" FALSE )
+
 # Clean up.
 unset( TRACCC_BUILD_CUDA_DEFAULT )
 

core/CMakeLists.txt

@@ -15,6 +15,8 @@ traccc_add_library( traccc_core core TYPE SHARED
   "include/traccc/definitions/primitives.hpp"
   "include/traccc/definitions/common.hpp"
   "include/traccc/definitions/qualifiers.hpp"
+  # Compiler checks.
+  "src/compiler_checks.cpp"
   # Event data model.
   "include/traccc/edm/details/container_base.hpp"
   "include/traccc/edm/details/container_element.hpp"
@@ -110,3 +112,11 @@ target_link_libraries( traccc_core
 # CUDA or HIP backend with SYCL.
 target_compile_definitions( traccc_core
   PUBLIC $<$<COMPILE_LANGUAGE:SYCL>:EIGEN_NO_CUDA EIGEN_NO_HIP> )
+
+if ( TRACCC_ENFORCE_CONCEPTS )
+  target_compile_definitions(
+    traccc_core
+    PUBLIC
+    TRACCC_ENFORCE_CONCEPTS
+  )
+endif ()

core/include/traccc/definitions/concepts.hpp

@@ -0,0 +1,18 @@
+/**
+ * traccc library, part of the ACTS project (R&D line)
+ *
+ * (c) 2024 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+#pragma once
+
+#if __cpp_concepts >= 201907L
+#define TRACCC_CONSTRAINT(...) __VA_ARGS__
+#elif defined(TRACCC_ENFORCE_CONCEPTS)
+#error \
+    "`TRACCC_ENFORCE_CONCEPTS` is set, but concepts are not available. This constitutes a fatal error."
+#else
+#define TRACCC_CONSTRAINT(...) __VA_ARGS__
+#endif

core/src/compiler_checks.cpp

@@ -0,0 +1,9 @@
+/**
+ * traccc library, part of the ACTS project (R&D line)
+ *
+ * (c) 2024 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+#include "traccc/definitions/concepts.hpp"

device/cuda/CMakeLists.txt

@@ -28,6 +28,8 @@ traccc_add_library( traccc_cuda cuda TYPE SHARED
   "src/utils/opaque_stream.cpp"
   "src/utils/utils.hpp"
   "src/utils/utils.cpp"
+  # Compiler checks.
+  "src/compiler_checks.cu"
   # Seed finding code.
   "include/traccc/cuda/seeding/track_params_estimation.hpp"
   "src/seeding/track_params_estimation.cu"

device/cuda/src/compiler_checks.cu

@@ -0,0 +1,9 @@
+/**
+ * traccc library, part of the ACTS project (R&D line)
+ *
+ * (c) 2024 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+#include "traccc/definitions/concepts.hpp"

device/sycl/CMakeLists.txt

@@ -25,6 +25,8 @@ traccc_add_library( traccc_sycl sycl TYPE SHARED
   "include/traccc/sycl/utils/queue_wrapper.hpp"
   "include/traccc/sycl/utils/calculate1DimNdRange.hpp"
   "include/traccc/sycl/utils/make_prefix_sum_buff.hpp"
+  # Compiler checks.
+  "src/compiler_checks.sycl"
   # implementation files
   "src/clusterization/clusterization_algorithm.sycl"
   "src/clusterization/spacepoint_formation_algorithm.sycl"

device/sycl/src/compiler_checks.sycl

@@ -0,0 +1,9 @@
+/**
+ * traccc library, part of the ACTS project (R&D line)
+ *
+ * (c) 2024 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+#include "traccc/definitions/concepts.hpp"