Revert "Revert "[cxxmodules] Don't generate rootmap files with cxxmod…

core/base/src/TSystem.cxx

@@ -3499,13 +3499,22 @@ int TSystem::CompileMacro(const char *filename, Option_t *opt,
    }
    mapfileStream.close();
 
+   bool useCxxModules = false;
+#ifdef R__USE_CXXMODULES
+   useCxxModules = true;
+#endif
+
    // ======= Generate the rootcling command line
    TString rcling = "rootcling";
    PrependPathName(TROOT::GetBinDir(), rcling);
    rcling += " -v0 \"--lib-list-prefix=";
    rcling += mapfile;
    rcling += "\" -f \"";
    rcling.Append(dict).Append("\" ");
+
+   if (useCxxModules)
+      rcling += " -cxxmodule ";
+
    if (produceRootmap) {
       rcling += " -rml " + libname + " -rmf \"" + libmapfilename + "\" ";
    }

core/dictgen/res/Scanner.h

@@ -70,7 +70,7 @@ class RScanner: public clang::RecursiveASTVisitor<RScanner>
    typedef std::vector<const clang::FunctionDecl*> FunctionColl_t;
    typedef std::vector<const clang::VarDecl*> VariableColl_t;
    typedef std::vector<const clang::EnumDecl*> EnumColl_t;
-   typedef void (*DeclCallback)(const char *type);
+   typedef void (*DeclCallback)(const clang::RecordDecl*);
    typedef std::map<const clang::Decl*,const BaseSelectionRule*> DeclsSelRulesMap_t;
 
    enum class EScanType : char {kNormal, kTwoPasses, kOnePCM};

core/dictgen/src/Scanner.cxx

@@ -653,9 +653,7 @@ bool RScanner::TreatRecordDeclOrTypedefNameDecl(clang::TypeDecl* typeDecl)
       // them either directly or indirectly.   Any false positive can be
       // resolved by removing the spurrious dependency in the (user) header
       // files.
-      std::string qual_name;
-      GetDeclQualName(recordDecl,qual_name);
-      fRecordDeclCallback(qual_name.c_str());
+      fRecordDeclCallback(recordDecl);
    }
 
    // in case it is implicit or a forward declaration, we are not interested.

core/dictgen/src/rootcling_impl.cxx

@@ -772,9 +772,17 @@ string gLibsNeeded;
 
 ////////////////////////////////////////////////////////////////////////////////
 
-void RecordDeclCallback(const char *c)
+void RecordDeclCallback(const clang::RecordDecl* recordDecl)
 {
-   string need(gAutoloads[c]);
+   std::string need;
+   if (recordDecl->hasOwningModule()) {
+      clang::Module *M = recordDecl->getOwningModule()->getTopLevelModule();
+      need = "lib" + M->Name + ".so";
+   } else {
+      auto N = clang::dyn_cast<const clang::NamedDecl> (recordDecl);
+      need = gAutoloads[N->getName()];
+   }
+
    if (need.length() && gLibsNeeded.find(need) == string::npos) {
       gLibsNeeded += " " + need;
    }
@@ -4159,6 +4167,7 @@ int RootClingMain(int argc,
    bool selSyntaxOnly = false;
    bool noIncludePaths = false;
    bool cxxmodule = getenv("ROOT_MODULES") != nullptr;
+   bool isAclic = false;
 
    // Collect the diagnostic pragmas linked to the usage of -W
    // Workaround for ROOT-5656
@@ -4298,6 +4307,8 @@ int RootClingMain(int argc,
       }
       ic++;
    }
+   if (liblistPrefix.length())
+      isAclic = true;
 
    // Check if we have a multi dict request but no target library
    if (multiDict && sharedLibraryPathName.empty()) {
@@ -5054,7 +5065,7 @@ int RootClingMain(int argc,
          // Write the module/PCH depending on what mode we are on
          if (modGen.IsPCH()) {
             if (!GenerateAllDict(modGen, CI, currentDirectory)) return 1;
-         } else if (cxxmodule) {
+         } else if (cxxmodule && !isAclic) {
             if (!CheckModuleValid(modGen, resourceDir, interp, linkdefFilename, moduleName.str()))
                return 1;
          }
@@ -5096,7 +5107,7 @@ int RootClingMain(int argc,
       else return a + " " + b;
    });
 
-   bool rootMapNeeded = !rootmapFileName.empty() || !rootmapLibName.empty();
+   bool rootMapNeeded = (!rootmapFileName.empty() || !rootmapLibName.empty()) && !(cxxmodule && !isAclic);
 
    std::list<std::string> classesNames;
    std::list<std::string> classesNamesForRootmap;
@@ -5169,6 +5180,7 @@ int RootClingMain(int argc,
    // Manually call end of translation unit because we never call the
    // appropriate deconstructors in the interpreter. This writes out the C++
    // module file that we currently generate.
+   if (!isAclic)
    {
       cling::Interpreter::PushTransactionRAII RAII(&interp);
       CI->getSema().getASTConsumer().HandleTranslationUnit(CI->getSema().getASTContext());

core/metacling/src/TCling.cxx

@@ -1311,10 +1311,6 @@ TCling::TCling(const char *name, const char *title, const char* const argv[])
       // This should be vector in order to be able to pass it to LoadModules
       std::vector<std::string> CoreModules = {"ROOT_Foundation_C","ROOT_Config",
          "ROOT_Foundation_Stage1_NoRTTI", "Core", "RIO"};
-      // These modules contain global variables which conflict with users' code such as "PI".
-      // FIXME: Reducing those will let us be less dependent on rootmap files
-      static constexpr std::array<const char*, 4> ExcludeModules =
-         { { "Rtools", "RSQLite", "RInterface", "RMVA"} };
 
       LoadModules(CoreModules, *fInterpreter);
 
@@ -1332,8 +1328,7 @@ TCling::TCling(const char *name, const char *title, const char* const argv[])
 
             std::string ModuleName = GetModuleNameAsString(M, PP);
             if (!ModuleName.empty() &&
-                  std::find(CoreModules.begin(), CoreModules.end(), ModuleName) == CoreModules.end()
-                  && std::find(ExcludeModules.begin(), ExcludeModules.end(), ModuleName) == ExcludeModules.end()) {
+                  std::find(CoreModules.begin(), CoreModules.end(), ModuleName) == CoreModules.end()) {
                if (M->IsSystem && !M->IsMissingRequirement)
                   LoadModule(ModuleName, *fInterpreter);
                else if (!M->IsSystem && !M->IsMissingRequirement)