Replace mpark.variant with std::variant

.gitmodules

@@ -4,9 +4,6 @@
 [submodule "externalpackages/git-archive-all.sh"]
 	path = externalpackages/git-archive-all.sh
 	url = https://github.com/meitar/git-archive-all.sh/
-[submodule "mpark.variant"]
-	path = externalpackages/mpark.variant
-	url = https://github.com/mpark/variant.git
 [submodule "externalpackages/fmt"]
 	path = externalpackages/fmt
 	url = https://github.com/fmtlib/fmt.git

CMakeLists.txt

@@ -814,10 +814,7 @@ string(REPLACE
   "${CMAKE_BINARY_DIR}/lib" "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}"
   CONFIG_LDFLAGS "${CONFIG_LDFLAGS}")
 set(BOUT_LIB_PATH "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
-# Update mpark.variant and fmt include paths if we're building them
-if (NOT BOUT_USE_SYSTEM_MPARK_VARIANT)
-  set(MPARK_VARIANT_INCLUDE_PATH "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_INCLUDEDIR}")
-endif()
+# Update fmt include paths if we're building it
 if (NOT BOUT_USE_SYSTEM_FMT)
   set(FMT_INCLUDE_PATH "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_INCLUDEDIR}")
 endif()

bin/bout-config.in

@@ -12,7 +12,6 @@
 
 BOUT_LIB_PATH=@BOUT_LIB_PATH@
 BOUT_INCLUDE_PATH=@BOUT_INCLUDE_PATH@
-MPARK_VARIANT_INCLUDE_PATH=@MPARK_VARIANT_INCLUDE_PATH@
 FMT_INCLUDE_PATH=@FMT_INCLUDE_PATH@
 BOUT_CONFIG_FILE=@PREFIX@/make.config
 

bout++Config.cmake.in

@@ -37,9 +37,6 @@ if(NOT "@ISINSTALLED@")
   if(EXISTS "@CMAKE_BINARY_DIR@/externalpackages/fmt")
     list(APPEND CMAKE_PREFIX_PATH "@CMAKE_BINARY_DIR@/externalpackages/fmt")
   endif()
-  if(EXISTS "@CMAKE_BINARY_DIR@/externalpackages/mpark.variant")
-    list(APPEND CMAKE_PREFIX_PATH "@CMAKE_BINARY_DIR@/externalpackages/mpark.variant")
-  endif()
   if(EXISTS "@CMAKE_BINARY_DIR@/externalpackages/PVODE")
     list(APPEND CMAKE_PREFIX_PATH "@CMAKE_BINARY_DIR@/externalpackages/PVODE")
   endif()
@@ -104,13 +101,6 @@ if(EXISTS "@Libuuid_ROOT@")
   set(Libuuid_ROOT "@Libuuid_ROOT@")
 endif()
 
-if(@BOUT_USE_SYSTEM_MPARK_VARIANT@)
-  set(mpark_variant_ROOT "@mpark_variant_ROOT@")
-else()
-  # mpark.variant doesn't use GNUInstallDirs, always installs to lib
-  set(mpark_variant_ROOT "${CMAKE_CURRENT_LIST_DIR}/../../../lib/cmake/mpark_variant")
-endif()
-
 if(@BOUT_USE_SYSTEM_FMT@)
   set(fmt_ROOT "@fmt_ROOT@")
 endif()
@@ -147,7 +137,6 @@ if (BOUT_HAS_GETTEXT)
   find_dependency(Gettext @Gettext_VERSION@)
   find_dependency(Intl @Intl_VERSION@)
 endif()
-find_dependency(mpark_variant @mpark_variant_VERSION@)
 find_dependency(fmt @fmt_VERSION@)
 if (BOUT_HAS_SLEPC)
   find_dependency(SLEPc @SLEPC_VERSION@)

cmake/SetupBOUTThirdParty.cmake

@@ -90,26 +90,6 @@ endif()
 message(STATUS "PETSc support: ${BOUT_USE_PETSC}")
 set(BOUT_HAS_PETSC ${BOUT_USE_PETSC})
 
-
-cmake_dependent_option(BOUT_USE_SYSTEM_MPARK_VARIANT "Use external installation of mpark.variant" OFF
-  "BOUT_UPDATE_GIT_SUBMODULE OR EXISTS ${PROJECT_SOURCE_DIR}/externalpackages/mpark.variant/CMakeLists.txt" ON)
-
-if(BOUT_USE_SYSTEM_MPARK_VARIANT)
-  message(STATUS "Using external mpark.variant")
-  find_package(mpark_variant REQUIRED)
-  get_target_property(MPARK_VARIANT_INCLUDE_PATH mpark_variant INTERFACE_INCLUDE_DIRECTORIES)
-else()
-  message(STATUS "Using mpark.variant submodule")
-  bout_update_submodules()
-  add_subdirectory(externalpackages/mpark.variant)
-  if(NOT TARGET mpark_variant)
-    message(FATAL_ERROR "mpark_variant not found! Have you disabled the git submodules (BOUT_UPDATE_GIT_SUBMODULE)?")
-  endif()
-  set(MPARK_VARIANT_INCLUDE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/externalpackages/mpark.variant/include")
-  set(CONFIG_CFLAGS "${CONFIG_CFLAGS} -I\${MPARK_VARIANT_INCLUDE_PATH}")
-endif()
-target_link_libraries(bout++ PUBLIC mpark_variant)
-
 cmake_dependent_option(BOUT_USE_SYSTEM_FMT "Use external installation of fmt" OFF
   "BOUT_UPDATE_GIT_SUBMODULE OR EXISTS ${PROJECT_SOURCE_DIR}/externalpackages/fmt/CMakeLists.txt" ON)
 

include/bout/sys/variant.hxx

@@ -18,10 +18,7 @@
 #ifndef __VARIANT_HXX__
 #define __VARIANT_HXX__
 
-// std::variant added in C++17
-//#include <variant>
-
-#include "mpark/variant.hpp"
+#include <variant>
 
 #include "bout/utils.hxx"
 
@@ -30,16 +27,10 @@ namespace utils {
 
 /// Import variant, visit into bout::utils namespace
 
-// From C++17
-// using std::variant;
-// using std::visit;
-// using std::holds_alternative;
-// using std::get;
-
-using mpark::get;
-using mpark::holds_alternative;
-using mpark::variant;
-using mpark::visit;
+using std::get;
+using std::holds_alternative;
+using std::variant;
+using std::visit;
 
 ////////////////////////////////////////////////////////////
 // Variant comparison
@@ -73,15 +64,6 @@ struct IsEqual {
   }
 };
 
-/// Backport of std::disjunction
-template <class...>
-struct disjunction : std::false_type {};
-template <class B1>
-struct disjunction<B1> : B1 {};
-template <class B1, class... Bn>
-struct disjunction<B1, Bn...>
-    : std::conditional_t<bool(B1::value), B1, disjunction<Bn...>> {};
-
 } // namespace details
 
 template <typename T, typename VARIANT_T>
@@ -90,7 +72,7 @@ struct isVariantMember;
 /// Is type `T` a member of variant `variant<ALL_T>`?
 template <typename T, typename... ALL_T>
 struct isVariantMember<T, variant<ALL_T...>>
-    : public details::disjunction<std::is_same<T, ALL_T>...> {};
+    : public std::disjunction<std::is_same<T, ALL_T>...> {};
 
 /// Return true only if the given variant \p v
 /// has the same type and value as \p t

manual/sphinx/conf.py

@@ -76,9 +76,6 @@ def __getattr__(cls, name):
     pydir = "/".join(python.split("/")[:-2])
     os.system("which clang-format")
     os.system("which clang-format-6.0")
-    os.system(
-        "git submodule update --init --recursive ../../externalpackages/mpark.variant"
-    )
     pwd = "/".join(os.getcwd().split("/")[:-2])
     os.system("git submodule update --init --recursive ../../externalpackages/fmt")
     cmake = (
@@ -89,7 +86,6 @@ def __getattr__(cls, name):
         + " -DBOUT_TESTS=OFF"
         + " -DBOUT_ALLOW_INSOURCE_BUILD=ON"
         + f" -DPython_ROOT_DIR={pydir}"
-        + f" -Dmpark_variant_DIR={pwd}/externalpackages/mpark.variant/"
         + f" -Dfmt_DIR={pwd}/externalpackages/fmt/"
     )
     # os.system("mkdir ../../build")

manual/sphinx/user_docs/advanced_install.rst

@@ -698,26 +698,6 @@ to
 
     typedef long CVODEINT;
 
-Compiling with IBM xlC compiler fails
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-When using the ``xlC`` compiler, an error may occur::
-
-  variant.hpp(1568) parameter pack "Ts" was referenced but not expanded
-
-
-The workaround is to change line 428 of  ``externalpackages/mpark.variant/include/mpark/lib.hpp`` from::
-
-  #ifdef MPARK_TYPE_PACK_ELEMENT
-
-to::
-
-  #ifdef CAUSES_ERROR // MPARK_TYPE_PACK_ELEMENT
-
-This will force an alternate implementation of type_pack_element to be defined.
-See also https://software.intel.com/en-us/forums/intel-c-compiler/topic/501502
-
-
 Compiling fails after changing branch
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

manual/sphinx/user_docs/installing.rst

@@ -380,16 +380,14 @@ to read and write this high-performance parallel file format.
 Bundled Dependencies
 ~~~~~~~~~~~~~~~~~~~~
 
-BOUT++ bundles some dependencies, currently `mpark.variant
-<https://github.com/mpark/variant>`_, `fmt <https://fmt.dev>`_ and
-`googletest <https://github.com/google/googletest>`_. If you wish to
-use an existing installation of ``mpark.variant``, you can set
-``-DBOUT_USE_SYSTEM_MPARK_VARIANT=ON``, and supply the installation
-path using ``mpark_variant_ROOT`` via the command line or environment
-variable if it is installed in a non standard loction. Similarly for
-``fmt``, using ``-DBOUT_USE_SYSTEM_FMT=ON`` and ``fmt_ROOT``
-respectively. To turn off both, you can set
-``-DBOUT_USE_GIT_SUBMODULE=OFF``.
+BOUT++ bundles some dependencies, currently `fmt <https://fmt.dev>`_
+and `googletest <https://github.com/google/googletest>`_. If you wish
+to use an existing installation of ``fmt``, you can set
+``-DBOUT_USE_SYSTEM_FMT=ON``, and supply the installation path using
+``fmt_ROOT`` via the command line or environment variable if it is
+installed in a non standard location. It's also possible to turn off
+all bundled dependencies with ``-DBOUT_USE_GIT_SUBMODULE=OFF``
+(currently this just affects ``fmt``).
 
 The recommended way to use ``googletest`` is to compile it at the same
 time as your project, therefore there is no option to use an external

tests/MMS/diffusion2/runtest

@@ -27,7 +27,7 @@ build_and_log("MMS diffusion test")
 inputs = [
     ("X", ["mesh:nx"]),
     ("Y", ["mesh:ny"]),
-    ("Z", ["MZ"])  # ,
+    ("Z", ["MZ"]),  # ,
     # ("XYZ", ["mesh:nx", "mesh:ny", "MZ"])
 ]
 

tools/pylib/_boutpp_build/backend.py

@@ -174,7 +174,9 @@ def build_sdist(sdist_directory, config_settings=None):
     print(config_settings, sdist_directory)
     enable_gz = True
     enable_xz = False
-    external = {"fmt", "mpark.variant"}
+    external = {
+        "fmt",
+    }
     if config_settings is not None:
         global useLocalVersion, pkgname
         for k, v in config_settings.items():

tools/pylib/boutconfig/__init__.py.cin

@@ -38,9 +38,6 @@ for k, v in config.items():
         v.replace(
             "${BOUT_INCLUDE_PATH}", "@BOUT_INCLUDE_PATH@"
         )
-        .replace(
-            "${MPARK_VARIANT_INCLUDE_PATH}", "@MPARK_VARIANT_INCLUDE_PATH@"
-        )
         .replace(
             "${FMT_INCLUDE_PATH}", "@FMT_INCLUDE_PATH@"
         )

tools/pylib/boutconfig/__init__.py.in

@@ -7,7 +7,6 @@ _yesno = {'"yes"': True, '"no"': False, "yes": True, "no": False}
 _vars = dict(
     BOUT_LIB_PATH="@BOUT_LIB_PATH@",
     BOUT_INCLUDE_PATH="@BOUT_INCLUDE_PATH@",
-    MPARK_VARIANT_INCLUDE_PATH="@MPARK_VARIANT_INCLUDE_PATH@",
     FMT_INCLUDE_PATH="@FMT_INCLUDE_PATH@",
     BOUT_CONFIG_FILE="@PREFIX@/make.config",
 )

tools/tokamak_grids/all/grid2bout.py

@@ -3,6 +3,7 @@
 
 
 """
+
 from __future__ import print_function
 
 from numpy import max