Use forward decls for nlohmann/json types.

builtins/nlohmann/CMakeLists.txt

@@ -17,18 +17,10 @@ add_custom_command(
      COMMENT "Copying nlohmann/json.hpp header to ${CMAKE_BINARY_DIR}/include"
      DEPENDS ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json.hpp)
 
-add_custom_command(
-     OUTPUT ${CMAKE_BINARY_DIR}/include/nlohmann/json_fwd.hpp
-     COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json_fwd.hpp ${CMAKE_BINARY_DIR}/include/nlohmann/json_fwd.hpp
-     COMMENT "Copying nlohmann/json_fwd.hpp header to ${CMAKE_BINARY_DIR}/include"
-     DEPENDS ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json_fwd.hpp)
-
-add_custom_target(builtin_nlohmann_json_incl
-     DEPENDS ${CMAKE_BINARY_DIR}/include/nlohmann/json.hpp ${CMAKE_BINARY_DIR}/include/nlohmann/json_fwd.hpp)
+add_custom_target(builtin_nlohmann_json_incl DEPENDS ${CMAKE_BINARY_DIR}/include/nlohmann/json.hpp)
 
 set_property(GLOBAL APPEND PROPERTY ROOT_HEADER_TARGETS builtin_nlohmann_json_incl)
 
-install(FILES ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json.hpp ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json_fwd.hpp
-        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/nlohmann/)
+install(FILES ${CMAKE_SOURCE_DIR}/builtins/nlohmann/json.hpp DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/nlohmann/)
 
 

cmake/modules/SearchInstalledSoftware.cmake

@@ -74,8 +74,8 @@ if(NOT builtin_nlohmannjson)
   else()
     find_package(nlohmann_json QUIET)
     if(nlohmann_json_FOUND)
-      get_target_property(_nlohmann_json_inlc nlohmann_json::nlohmann_json INTERFACE_INCLUDE_DIRECTORIES)
-      message(STATUS "Found nlohmann/json.hpp in ${_nlohmann_json_inlc} (found version ${nlohmann_json_VERSION})")
+      get_target_property(_nlohmann_json_incl nlohmann_json::nlohmann_json INTERFACE_INCLUDE_DIRECTORIES)
+      message(STATUS "Found nlohmann/json.hpp in ${_nlohmann_json_incl} (found version ${nlohmann_json_VERSION})")
     else()
       message(STATUS "nlohmann/json.hpp not found. Switching on builtin_nlohmannjson option")
       set(builtin_nlohmannjson ON CACHE BOOL "Enabled because nlohmann/json.hpp not found" FORCE)
@@ -965,7 +965,7 @@ if(xrootd AND NOT builtin_xrootd)
   if(NOT XROOTD_FOUND)
     if(fail-on-missing)
       message(FATAL_ERROR "XROOTD not found. Set environment variable XRDSYS to point to your XROOTD installation, "
-                          "or inlcude the installation of XROOTD in the CMAKE_PREFIX_PATH. "
+                          "or include the installation of XROOTD in the CMAKE_PREFIX_PATH. "
                           "Alternatively, you can also enable the option 'builtin_xrootd' to build XROOTD internally")
     else()
       message(STATUS "XROOTD not found, enabling 'builtin_xrootd' option")

core/clingutils/CMakeLists.txt

@@ -107,9 +107,7 @@ set(clinginclude ${CMAKE_SOURCE_DIR}/interpreter/cling/include)
 
 set(custom_modulemaps)
 if (runtime_cxxmodules)
-  set(custom_modulemaps boost.modulemap tinyxml2.modulemap cuda.modulemap
-                        module.modulemap.build
-                        json.modulemap)
+  set(custom_modulemaps boost.modulemap tinyxml2.modulemap cuda.modulemap module.modulemap.build)
   # FIXME: We should install vc.modulemap only when Vc is found (Vc_FOUND) but
   # some systems install it under /usr/include/Vc/Vc which allows rootcling to
   # discover it and assert that the modulemap is not found.

graf3d/eve7/CMakeLists.txt

@@ -123,8 +123,6 @@ ROOT_STANDARD_LIBRARY_PACKAGE(ROOTEve
     src/REveViewer.cxx
     src/REveVSD.cxx
     src/REveVSDStructs.cxx
-  DICTIONARY_OPTIONS
-    -mByproduct Json
   DEPENDENCIES
     Core
     Geom
@@ -138,23 +136,8 @@ ROOT_STANDARD_LIBRARY_PACKAGE(ROOTEve
 
 if(builtin_nlohmannjson)
    target_include_directories(ROOTEve PRIVATE ${CMAKE_SOURCE_DIR}/builtins)
-   target_compile_definitions(ROOTEve INTERFACE NLOHMANN_JSON_PROVIDES_FWD_HPP)
 else()
    target_link_libraries(ROOTEve PUBLIC nlohmann_json::nlohmann_json)
-
-   get_target_property(inc_dirs nlohmann_json::nlohmann_json INTERFACE_INCLUDE_DIRECTORIES)
-   foreach(dir ${inc_dirs})
-      if(EXISTS "${dir}/nlohmann/json_fwd.hpp")
-         set(found_fwd true)
-      endif()
-   endforeach()
-
-   if(found_fwd)
-      target_compile_definitions(ROOTEve INTERFACE NLOHMANN_JSON_PROVIDES_FWD_HPP)
-   else()
-      message("-- missing nlohmann/json_fwd.hpp required by eve7")
-   endif()
-
 endif()
 
 # this is required for glew

graf3d/eve7/inc/ROOT/REveElement.hxx

@@ -16,16 +16,26 @@
 #include <ROOT/REveVector.hxx>
 #include <ROOT/REveProjectionBases.hxx>
 
+#include <map>
 #include <memory>
 
-#ifdef NLOHMANN_JSON_PROVIDES_FWD_HPP
-#include <nlohmann/json_fwd.hpp>
-#else
-#include <nlohmann/json.hpp>
-#endif
-
 class TGeoMatrix;
 
+namespace nlohmann {
+template<typename T, typename SFINAE>
+struct adl_serializer;
+
+template <template <typename U, typename V, typename... Args> class ObjectType,
+          template <typename U, typename... Args> class ArrayType, class StringType, class BooleanType,
+          class NumberIntegerType, class NumberUnsignedType, class NumberFloatType,
+          template <typename U> class AllocatorType, template <typename T, typename SFINAE = void> class JSONSerializer,
+          class BinaryType>
+class basic_json;
+
+using json = basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, double, std::allocator,
+                        adl_serializer, std::vector<std::uint8_t>>;
+} // namespace nlohmann
+
 namespace ROOT {
 namespace Experimental {
 

graf3d/eve7/src/REveViewer.cxx

@@ -17,6 +17,8 @@
 #include <ROOT/REveManager.hxx>
 #include <ROOT/REveSelection.hxx>
 
+#include <nlohmann/json.hpp>
+
 using namespace ROOT::Experimental;
 namespace REX = ROOT::Experimental;
 

interpreter/cling/lib/Interpreter/CIFactory.cpp

@@ -580,7 +580,6 @@ namespace {
     llvm::SmallString<256> tinyxml2IncLoc(getIncludePathForHeader(HS, "tinyxml2.h"));
     llvm::SmallString<256> cudaIncLoc(getIncludePathForHeader(HS, "cuda.h"));
     llvm::SmallString<256> vcVcIncLoc(getIncludePathForHeader(HS, "Vc/Vc"));
-    llvm::SmallString<256> jsonIncLoc(getIncludePathForHeader(HS, "nlohmann/json.hpp"));
     llvm::SmallString<256> clingIncLoc(getIncludePathForHeader(HS,
                                         "cling/Interpreter/RuntimeUniverse.h"));
 
@@ -706,11 +705,6 @@ namespace {
                               clingIncLoc.str(), MOverlay,
                               /*RegisterModuleMap=*/ true,
                               /*AllowModulemapOverride=*/ false);
-    if (!jsonIncLoc.empty())
-      maybeAppendOverlayEntry(jsonIncLoc.str(), "json.modulemap",
-                              clingIncLoc.str(), MOverlay,
-                              /*RegisterModuleMap=*/ true,
-                              /*AllowModulemapOverride=*/ false);
     if (!boostIncLoc.empty()) {
       // Add the modulemap in the include/boost folder not in include.
       llvm::sys::path::append(boostIncLoc, "boost");