Try using c++20 throughout catalyst

mlir/CMakeLists.txt

@@ -4,7 +4,7 @@ project(catalyst LANGUAGES CXX C)
 set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")
+set(CMAKE_CXX_STANDARD 20)
 
 find_package(MLIR REQUIRED CONFIG)
 find_package(MHLO REQUIRED CONFIG)

mlir/lib/Catalyst/Transforms/CMakeLists.txt

@@ -42,7 +42,7 @@ set(DEPENDS
 )
 
 add_mlir_library(${LIBRARY_NAME} STATIC ${SRC} LINK_LIBS PRIVATE ${LIBS} DEPENDS ${DEPENDS})
-target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_17)
+target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_20)
 target_include_directories(${LIBRARY_NAME} PUBLIC
                            .
                            ${PROJECT_SOURCE_DIR}/include

mlir/lib/Gradient/Transforms/CMakeLists.txt

@@ -32,7 +32,7 @@ set(DEPENDS
 )
 
 add_mlir_library(${LIBRARY_NAME} STATIC ${SRC} LINK_LIBS PRIVATE ${LIBS} DEPENDS ${DEPENDS})
-target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_17)
+target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_20)
 target_include_directories(${LIBRARY_NAME} PUBLIC
                            .
                            ${PROJECT_SOURCE_DIR}/include

mlir/lib/Mitigation/Transforms/CMakeLists.txt

@@ -19,7 +19,7 @@ set(DEPENDS
 )
 
 add_mlir_library(${LIBRARY_NAME} STATIC ${SRC} LINK_LIBS PRIVATE ${LIBS} DEPENDS ${DEPENDS})
-target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_17)
+target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_20)
 target_include_directories(${LIBRARY_NAME} PUBLIC
                            .
                            ${PROJECT_SOURCE_DIR}/include

mlir/lib/Quantum/Transforms/CMakeLists.txt

@@ -30,7 +30,7 @@ set(DEPENDS
 )
 
 add_mlir_library(${LIBRARY_NAME} STATIC ${SRC} LINK_LIBS PRIVATE ${LIBS} DEPENDS ${DEPENDS})
-target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_17)
+target_compile_features(${LIBRARY_NAME} PUBLIC cxx_std_20)
 target_include_directories(${LIBRARY_NAME} PUBLIC
                            .
                            ${PROJECT_SOURCE_DIR}/include

mlir/lib/Quantum/Transforms/remove_chained_self_inverse.cpp

@@ -15,6 +15,7 @@
 #define DEBUG_TYPE "remove-chained-self-inverse"
 
 #include <memory>
+#include <numbers>
 #include <vector>
 
 #include "llvm/Support/Debug.h"
@@ -52,6 +53,8 @@ struct RemoveChainedSelfInversePass
         LLVM_DEBUG(dbgs() << "remove chained self inverse pass"
                           << "\n");
 
+        llvm::errs() << std::numbers::pi << "\n";
+
         // Run cse pass before running remove-chained-self-inverse,
         // to aid identifying equivalent SSA values when verifying
         // the gates have the same params

setup.py

@@ -181,7 +181,7 @@ def run(self):
             "frontend/catalyst/utils/jax_cpu_lapack_kernels/lapack_kernels.cpp",
             "frontend/catalyst/utils/jax_cpu_lapack_kernels/lapack_kernels_using_lapack.cpp",
         ],
-        extra_compile_args=["-std=c++17"],
+        extra_compile_args=["-std=c++20"],
     )
     cmdclass = {"build_ext": CustomBuildExtLinux}
 
@@ -198,7 +198,7 @@ def run(self):
             "frontend/catalyst/utils/jax_cpu_lapack_kernels/lapack_kernels.cpp",
             "frontend/catalyst/utils/jax_cpu_lapack_kernels/lapack_kernels_using_lapack.cpp",
         ],
-        extra_compile_args=["-std=c++17"],
+        extra_compile_args=["-std=c++20"],
     )
     cmdclass = {"build_ext": CustomBuildExtMacos}
 
@@ -211,7 +211,7 @@ def run(self):
     ext._add_ldflags(["-L", lib_path_npymath])  # pylint: disable=protected-access
     ext._add_ldflags(["-lnpymath"])  # pylint: disable=protected-access
     ext._add_cflags(["-I", np.get_include()])  # pylint: disable=protected-access
-    ext._add_cflags(["-std=c++17"])  # pylint: disable=protected-access
+    ext._add_cflags(["-std=c++20"])  # pylint: disable=protected-access
 ext_modules.extend(intree_extension_list)
 # For any compiler packages seeking to be registered in PennyLane, it is imperative that they
 # expose the entry_points metadata under the designated group name `pennylane.compilers`, with