Get rid of more base tags

src/ControlSystem/Tags/FunctionsOfTimeInitialize.hpp

@@ -46,10 +46,8 @@ void check_expiration_time_consistency(
 /// \ingroup ControlSystemGroup
 /// The FunctionsOfTime initialized from a DomainCreator, initial time, and
 /// control system OptionHolders.
-struct FunctionsOfTimeInitialize : domain::Tags::FunctionsOfTime,
-                                   db::SimpleTag {
-  using type = std::unordered_map<
-      std::string, std::unique_ptr<domain::FunctionsOfTime::FunctionOfTime>>;
+struct FunctionsOfTimeInitialize : domain::Tags::FunctionsOfTime {
+  using base = domain::Tags::FunctionsOfTime;
 
   static constexpr bool pass_metavariables = true;
 

src/ControlSystem/Tags/SystemTags.hpp

@@ -62,19 +62,7 @@ struct WriteDataToDisk : db::SimpleTag {
   static type create_from_options(const type& option) { return option; }
 };
 
-/// \ingroup DataBoxTagsGroup
-/// \ingroup ControlSystemGroup
-/// DataBox tag for writing the centers of the horizons to disk.
-///
-/// This is controlled by the `control_system::OptionTags::WriteDataToDisk`
-/// option in the input file.
-struct ObserveCenters : ::ah::Tags::ObserveCentersBase, db::SimpleTag {
-  using type = bool;
-  using option_tags = tmpl::list<OptionTags::WriteDataToDisk>;
-
-  static constexpr bool pass_metavariables = false;
-  static type create_from_options(const type& option) { return option; }
-};
+using ObserveCenters = ah::Tags::ObserveCenters;
 
 /// \ingroup DataBoxTagsGroup
 /// \ingroup ControlSystemGroup

src/DataStructures/DataBox/DataBox.hpp

@@ -870,8 +870,9 @@ auto DataBox<tmpl::list<Tags...>>::compute_tag_graphs() -> TagGraphs {
       });
 
   // Set mutation function
-  tmpl::for_each<mutable_item_tags>([&result](auto tag_v) {
-    using tag = tmpl::type_from<decltype(tag_v)>;
+  tmpl::for_each<mutable_item_tags>([&result]<typename Tag>(
+                                        tmpl::type_<Tag> /*meta*/) {
+    using tag = detail::get_base<Tag>;
     const std::string tag_name = pretty_type::get_name<tag>();
     if (result.tag_mutate_functions.find(tag_name) ==
         result.tag_mutate_functions.end()) {
@@ -988,7 +989,8 @@ void DataBox<tmpl::list<Tags...>>::reset_compute_items(
 template <typename... Tags>
 template <typename MutatedTag>
 void DataBox<tmpl::list<Tags...>>::reset_compute_items_after_mutate() {
-  static const std::string mutated_tag = pretty_type::get_name<MutatedTag>();
+  using tag = detail::get_base<MutatedTag>;
+  static const std::string mutated_tag = pretty_type::get_name<tag>();
   if (tag_graphs_.tags_and_dependents.find(mutated_tag) !=
       tag_graphs_.tags_and_dependents.end()) {
     reset_compute_items(mutated_tag);
@@ -1069,7 +1071,9 @@ template <typename... Tags>
 template <typename Tag>
 void* DataBox<tmpl::list<Tags...>>::get_item_as_void_pointer_for_mutate() {
   // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
-  return reinterpret_cast<void*>(&this->template get_item<Tag>());
+  return reinterpret_cast<void*>(
+      &this->template get_item<
+          detail::first_matching_tag<tmpl::list<Tags...>, Tag>>());
 }
 
 template <typename... Tags>

src/Domain/Creators/Tags/FunctionsOfTime.hpp

@@ -21,9 +21,8 @@ struct FunctionOfTime;
 
 namespace domain::Tags {
 /// \brief The FunctionsOfTime initialized from a DomainCreator
-struct FunctionsOfTimeInitialize : FunctionsOfTime, db::SimpleTag {
-  using type = std::unordered_map<
-      std::string, std::unique_ptr<domain::FunctionsOfTime::FunctionOfTime>>;
+struct FunctionsOfTimeInitialize : FunctionsOfTime {
+  using base = FunctionsOfTime;
 
   static constexpr bool pass_metavariables = true;
 

src/Domain/FunctionsOfTime/Tags.hpp

@@ -3,9 +3,22 @@
 
 #pragma once
 
+#include <memory>
+#include <string>
+#include <unordered_map>
+
 #include "DataStructures/DataBox/Tag.hpp"
 
+/// \cond
+namespace domain::FunctionsOfTime {
+struct FunctionOfTime;
+}  // namespace domain::FunctionsOfTime
+/// \endcond
+
 namespace domain::Tags {
 /// Tag to retrieve the FunctionsOfTime from the GlobalCache.
-struct FunctionsOfTime : db::BaseTag {};
+struct FunctionsOfTime : db::SimpleTag {
+  using type = std::unordered_map<
+      std::string, std::unique_ptr<domain::FunctionsOfTime::FunctionOfTime>>;
+};
 }  // namespace domain::Tags

src/Evolution/Systems/Cce/Actions/InitializeCharacteristicEvolutionScri.hpp

@@ -82,7 +82,7 @@ struct InitializeCharacteristicEvolutionScri {
         db::get<InitializationTags::ScriInterpolationOrder>(*box);
     const size_t vector_size =
         Spectral::Swsh::number_of_swsh_collocation_points(
-            db::get<Spectral::Swsh::Tags::LMaxBase>(*box));
+            db::get<Spectral::Swsh::Tags::LMax>(*box));
     // silence compiler warnings when pack is empty
     (void)vector_size;
     if constexpr (sizeof...(TagPack) > 0) {

src/Evolution/Systems/Cce/Actions/InitializeCharacteristicEvolutionVariables.hpp

@@ -132,9 +132,9 @@ struct InitializeCharacteristicEvolutionVariables {
 
   template <typename TagList>
   static void initialize_impl(const gsl::not_null<db::DataBox<TagList>*> box) {
-    const size_t l_max = db::get<Spectral::Swsh::Tags::LMaxBase>(*box);
+    const size_t l_max = db::get<Spectral::Swsh::Tags::LMax>(*box);
     const size_t number_of_radial_points =
-        db::get<Spectral::Swsh::Tags::NumberOfRadialPointsBase>(*box);
+        db::get<Spectral::Swsh::Tags::NumberOfRadialPoints>(*box);
     const size_t boundary_size =
         Spectral::Swsh::number_of_swsh_collocation_points(l_max);
     const size_t volume_size = boundary_size * number_of_radial_points;

src/Evolution/Systems/Cce/Actions/InitializeKleinGordonVariables.hpp

@@ -70,9 +70,9 @@ struct InitializeKleinGordonVariables {
       const Parallel::GlobalCache<Metavariables>& /*cache*/,
       const ArrayIndex& /*array_index*/, const ActionList /*meta*/,
       const ParallelComponent* const /*meta*/) {
-    const size_t l_max = db::get<Spectral::Swsh::Tags::LMaxBase>(box);
+    const size_t l_max = db::get<Spectral::Swsh::Tags::LMax>(box);
     const size_t number_of_radial_points =
-        db::get<Spectral::Swsh::Tags::NumberOfRadialPointsBase>(box);
+        db::get<Spectral::Swsh::Tags::NumberOfRadialPoints>(box);
     const size_t boundary_size =
         Spectral::Swsh::number_of_swsh_collocation_points(l_max);
     const size_t volume_size = boundary_size * number_of_radial_points;

src/Evolution/Systems/Cce/GaugeTransformBoundaryData.hpp

@@ -21,13 +21,6 @@
 #include "Utilities/TMPL.hpp"
 
 namespace Cce {
-
-namespace Tags {
-/// \cond
-struct LMax;
-/// \endcond
-}  // namespace Tags
-
 /// The set of tags that should be calculated before the initial data is
 /// computed on the first hypersurface.
 using gauge_adjustments_setup_tags =

src/Evolution/Systems/Cce/Initialize/InitializeJ.hpp

@@ -27,13 +27,6 @@ class ComplexDataVector;
 /// \endcond
 
 namespace Cce {
-namespace Tags {
-/// \cond
-struct LMax;
-struct NumberOfRadialPoints;
-/// \endcond
-}  // namespace Tags
-
 /// Contains utilities and \ref DataBoxGroup mutators for generating data for
 /// \f$J\f$ on the initial CCE hypersurface.
 namespace InitializeJ {

src/Evolution/Systems/Cce/LinearOperators.hpp

@@ -29,10 +29,6 @@ void logical_partial_directional_derivative_of_complex(
     const Mesh<3>& mesh, size_t dimension_to_differentiate);
 
 namespace Tags {
-/// \cond
-struct LMax;
-/// \endcond
-
 /*!
  * \brief Compute tag for a manually-handled partial y derivative in the volume.
  *

src/Evolution/Systems/Cce/NewmanPenrose.hpp

@@ -20,9 +20,6 @@ class ComplexDataVector;
 namespace Cce {
 
 /// \cond
-namespace Tags {
-struct LMax;
-}  // namespace Tags
 template <typename Tag>
 struct VolumeWeyl;
 /// \endcond

src/Evolution/Systems/Cce/OptionTags.hpp

@@ -66,13 +66,6 @@ struct BondiSachsOutputFilePrefix {
   using group = Cce;
 };
 
-struct LMax {
-  using type = size_t;
-  static constexpr Options::String help{
-      "Maximum l value for spin-weighted spherical harmonics"};
-  using group = Cce;
-};
-
 struct FilterLMax {
   using type = size_t;
   static constexpr Options::String help{"l mode cutoff for angular filtering"};
@@ -99,13 +92,6 @@ struct ObservationLMax {
   using group = Cce;
 };
 
-struct NumberOfRadialPoints {
-  using type = size_t;
-  static constexpr Options::String help{
-      "Number of radial grid points in the spherical domain"};
-  using group = Cce;
-};
-
 struct ExtractionRadius {
   using type = double;
   static constexpr Options::String help{"Extraction radius of the CCE system."};
@@ -233,11 +219,12 @@ struct ScriOutputDensity : db::SimpleTag {
 }  // namespace InitializationTags
 
 namespace Tags {
-struct ExtractionRadius : db::BaseTag {};
-
-struct ExtractionRadiusSimple : ExtractionRadius, db::SimpleTag {
-  static std::string name() { return "ExtractionRadius"; }
+struct ExtractionRadius : db::SimpleTag {
   using type = double;
+};
+
+struct ExtractionRadiusSimple : ExtractionRadius {
+  using base = ExtractionRadius;
   using option_tags = tmpl::list<OptionTags::ExtractionRadius>;
 
   static constexpr bool pass_metavariables = false;
@@ -246,9 +233,8 @@ struct ExtractionRadiusSimple : ExtractionRadius, db::SimpleTag {
   }
 };
 
-struct ExtractionRadiusFromH5 : ExtractionRadius, db::SimpleTag {
-  static std::string name() { return "ExtractionRadius"; }
-  using type = double;
+struct ExtractionRadiusFromH5 : ExtractionRadius {
+  using base = ExtractionRadius;
   using option_tags = tmpl::list<OptionTags::BoundaryDataFilename,
                                  OptionTags::StandaloneExtractionRadius>;
 
@@ -296,8 +282,9 @@ struct H5WorldtubeBoundaryDataManager : db::SimpleTag {
   using type = std::unique_ptr<WorldtubeDataManager<
       Tags::characteristic_worldtube_boundary_tags<Tags::BoundaryValue>>>;
   using option_tags =
-      tmpl::list<OptionTags::LMax, OptionTags::BoundaryDataFilename,
-                 OptionTags::H5LookaheadTimes, OptionTags::H5Interpolator,
+      tmpl::list<Spectral::Swsh::OptionTags::LMax,
+                 OptionTags::BoundaryDataFilename, OptionTags::H5LookaheadTimes,
+                 OptionTags::H5Interpolator,
                  OptionTags::StandaloneExtractionRadius>;
 
   static constexpr bool pass_metavariables = false;
@@ -335,7 +322,8 @@ struct KleinGordonH5WorldtubeBoundaryDataManager : db::SimpleTag {
   using type = std::unique_ptr<
       WorldtubeDataManager<Tags::klein_gordon_worldtube_boundary_tags>>;
   using option_tags =
-      tmpl::list<OptionTags::LMax, OptionTags::KleinGordonBoundaryDataFilename,
+      tmpl::list<Spectral::Swsh::OptionTags::LMax,
+                 OptionTags::KleinGordonBoundaryDataFilename,
                  OptionTags::H5LookaheadTimes, OptionTags::H5Interpolator,
                  OptionTags::StandaloneExtractionRadius>;
 
@@ -352,25 +340,6 @@ struct KleinGordonH5WorldtubeBoundaryDataManager : db::SimpleTag {
   }
 };
 
-struct LMax : db::SimpleTag, Spectral::Swsh::Tags::LMaxBase {
-  using type = size_t;
-  using option_tags = tmpl::list<OptionTags::LMax>;
-
-  static constexpr bool pass_metavariables = false;
-  static size_t create_from_options(const size_t l_max) { return l_max; }
-};
-
-struct NumberOfRadialPoints : db::SimpleTag,
-                              Spectral::Swsh::Tags::NumberOfRadialPointsBase {
-  using type = size_t;
-  using option_tags = tmpl::list<OptionTags::NumberOfRadialPoints>;
-
-  static constexpr bool pass_metavariables = false;
-  static size_t create_from_options(const size_t number_of_radial_points) {
-    return number_of_radial_points;
-  }
-};
-
 struct ObservationLMax : db::SimpleTag {
   using type = size_t;
   using option_tags = tmpl::list<OptionTags::ObservationLMax>;
@@ -418,8 +387,8 @@ struct RadialFilterHalfPower : db::SimpleTag {
 /// `OptionTags::StartTime` is set to "Auto"), this will find the start time
 /// from the provided H5 file. If `OptionTags::StartTime` takes any other value,
 /// it will be used directly as the start time for the CCE evolution instead.
-struct StartTimeFromFile : Tags::StartTime, db::SimpleTag {
-  using type = double;
+struct StartTimeFromFile : Tags::StartTime {
+  using base = Tags::StartTime;
   using option_tags =
       tmpl::list<OptionTags::StartTime, OptionTags::BoundaryDataFilename,
                  OptionTags::StandaloneExtractionRadius>;
@@ -441,8 +410,8 @@ struct StartTimeFromFile : Tags::StartTime, db::SimpleTag {
 
 /// \brief Represents the start time of a bounded CCE evolution that must be
 /// supplied in the input file (for e.g. analytic tests).
-struct SpecifiedStartTime : Tags::StartTime, db::SimpleTag {
-  using type = double;
+struct SpecifiedStartTime : Tags::StartTime {
+  using base = Tags::StartTime;
   using option_tags = tmpl::list<OptionTags::StartTime>;
 
   static constexpr bool pass_metavariables = false;
@@ -463,8 +432,8 @@ struct SpecifiedStartTime : Tags::StartTime, db::SimpleTag {
 /// `OptionTags::EndTime` is set to "Auto"), this will find the end time
 /// from the provided H5 file. If `OptionTags::EndTime` takes any other value,
 /// it will be used directly as the final time for the CCE evolution instead.
-struct EndTimeFromFile : Tags::EndTime, db::SimpleTag {
-  using type = double;
+struct EndTimeFromFile : Tags::EndTime {
+  using base = Tags::EndTime;
   using option_tags =
       tmpl::list<OptionTags::EndTime, OptionTags::BoundaryDataFilename,
                  OptionTags::StandaloneExtractionRadius>;
@@ -485,8 +454,8 @@ struct EndTimeFromFile : Tags::EndTime, db::SimpleTag {
 
 /// \brief Represents the final time of a CCE evolution that should just proceed
 /// until it receives no more boundary data and becomes quiescent.
-struct NoEndTime : Tags::EndTime, db::SimpleTag {
-  using type = double;
+struct NoEndTime : Tags::EndTime {
+  using base = Tags::EndTime;
   using option_tags = tmpl::list<>;
 
   static constexpr bool pass_metavariables = false;
@@ -497,8 +466,8 @@ struct NoEndTime : Tags::EndTime, db::SimpleTag {
 
 /// \brief Represents the final time of a bounded CCE evolution that must be
 /// supplied in the input file (for e.g. analytic tests).
-struct SpecifiedEndTime : Tags::EndTime, db::SimpleTag {
-  using type = double;
+struct SpecifiedEndTime : Tags::EndTime {
+  using base = Tags::EndTime;
   using option_tags = tmpl::list<OptionTags::EndTime>;
 
   static constexpr bool pass_metavariables = false;
@@ -560,8 +529,9 @@ struct AnalyticInitializeJ : db::SimpleTag, InitializeJBase {
 /// A tag that constructs a `AnalyticBoundaryDataManager` from options
 struct AnalyticBoundaryDataManager : db::SimpleTag {
   using type = ::Cce::AnalyticBoundaryDataManager;
-  using option_tags = tmpl::list<OptionTags::ExtractionRadius, OptionTags::LMax,
-                                 OptionTags::AnalyticSolution>;
+  using option_tags =
+      tmpl::list<OptionTags::ExtractionRadius, Spectral::Swsh::OptionTags::LMax,
+                 OptionTags::AnalyticSolution>;
 
   static constexpr bool pass_metavariables = false;
   static Cce::AnalyticBoundaryDataManager create_from_options(

src/Evolution/Systems/Cce/Tags.hpp

@@ -370,9 +370,16 @@ struct BondiR : db::SimpleTag {
   static std::string name() { return "R"; }
 };
 
-struct EndTime : db::BaseTag {};
+struct EndTime : db::SimpleTag {
+  using type = double;
+};
+
+struct StartTime : db::SimpleTag {
+  using type = double;
+};
 
-struct StartTime : db::BaseTag {};
+using LMax = Spectral::Swsh::Tags::LMax;
+using NumberOfRadialPoints = Spectral::Swsh::Tags::NumberOfRadialPoints;
 
 /// The (adapted) Newman-Penrose spin coefficient $\alpha^{SW}$. See
 /// documentation of `newman_penrose_alpha()` for definition.

src/NumericalAlgorithms/SpinWeightedSphericalHarmonics/SwshDerivatives.hpp

@@ -187,9 +187,8 @@ struct AngularDerivativesImpl<tmpl::list<DerivativeTags...>,
   using return_tags =
       tmpl::list<DerivativeTags..., Tags::SwshTransform<DerivativeTags>...,
                  Tags::SwshTransform<UniqueDifferentiatedFromTags>...>;
-  using argument_tags =
-      tmpl::list<UniqueDifferentiatedFromTags..., Tags::LMaxBase,
-                 Tags::NumberOfRadialPointsBase>;
+  using argument_tags = tmpl::list<UniqueDifferentiatedFromTags..., Tags::LMax,
+                                   Tags::NumberOfRadialPoints>;
 
   static void apply(
       const gsl::not_null<typename DerivativeTags::type*>... derivative_scalars,