Also fetch proper module name for system modules

Author: DavidGoldman

lib/Index/IndexRecord.cpp

@@ -426,16 +426,16 @@ static void addModuleDependencies(ArrayRef<ImportedModule> imports,
           bool withoutUnitName = true;
           if (FU->getKind() == FileUnitKind::ClangModule) {
             auto clangModUnit = cast<ClangModuleUnit>(LFU);
-            if ((!clangModUnit->isSystemModule() || indexSystemModules)) {
-              withoutUnitName = !indexClangModules;
-              if (auto clangMod = clangModUnit->getUnderlyingClangModule()) {
-                moduleName = clangMod->getTopLevelModuleName();
-                // FIXME: clang's -Rremarks do not seem to go through Swift's
-                // diagnostic emitter.
-                if (indexClangModules)
-                  clang::index::emitIndexDataForModuleFile(clangMod,
-                                                           clangCI, unitWriter);
-              }
+            bool shouldIndexModule = indexClangModules &&
+                (!clangModUnit->isSystemModule() || indexSystemModules);
+            withoutUnitName = !shouldIndexModule;
+            if (auto clangMod = clangModUnit->getUnderlyingClangModule()) {
+              moduleName = clangMod->getTopLevelModuleName();
+              // FIXME: clang's -Rremarks do not seem to go through Swift's
+              // diagnostic emitter.
+              if (shouldIndexModule)
+                clang::index::emitIndexDataForModuleFile(clangMod,
+                                                         clangCI, unitWriter);
             }
           } else {
             // Serialized AST file.