diff --git a/cmake/modules/RootConfiguration.cmake b/cmake/modules/RootConfiguration.cmake
index 7ad4a463f0fae..1c566078384ec 100644
--- a/cmake/modules/RootConfiguration.cmake
+++ b/cmake/modules/RootConfiguration.cmake
@@ -536,7 +536,7 @@ else()
 endif()
 
 CHECK_CXX_SOURCE_COMPILES("#include <tuple>
-int main() { std::tuple<int> tup;std::apply(tup, [](int){}); return 0;}" found_stdapply)
+int main() { std::apply([](int, int){}, std::make_tuple(1,2)); return 0;}" found_stdapply)
 if(found_stdapply)
   set(hasstdapply define)
 else()
diff --git a/core/base/v7/inc/ROOT/impl_tuple_apply.hxx b/core/base/v7/inc/ROOT/impl_tuple_apply.hxx
index ee0f63118eda1..d9d37161fc361 100644
--- a/core/base/v7/inc/ROOT/impl_tuple_apply.hxx
+++ b/core/base/v7/inc/ROOT/impl_tuple_apply.hxx
@@ -65,6 +65,7 @@ decltype(auto) invoke(F&& f, ArgTypes&&... args) {
 }
 #endif // ndef R__HAS_STD_INVOKE
 
+#ifndef R__HAS_STD_APPLY
 // From http://en.cppreference.com/w/cpp/experimental/apply
 namespace detail {
 template<class F, class Tuple, std::size_t... I>
@@ -82,6 +83,7 @@ constexpr decltype(auto) apply(F &&f, Tuple &&t) {
                             std::make_index_sequence < std::tuple_size <
                             std::decay_t < Tuple >> {} > {});
 }
+#endif // ndef R__HAS_STD_APPLY
 } // namespace __ROOT
 } // namespace std
 
diff --git a/hist/hist/v7/inc/ROOT/THistImpl.hxx b/hist/hist/v7/inc/ROOT/THistImpl.hxx
index d179c6c9b2f91..a0c29bc71971d 100644
--- a/hist/hist/v7/inc/ROOT/THistImpl.hxx
+++ b/hist/hist/v7/inc/ROOT/THistImpl.hxx
@@ -16,6 +16,7 @@
 #define ROOT7_THistImpl
 
 #include <cctype>
+#include <functional>
 #include "ROOT/RArrayView.hxx"
 #include "ROOT/RTupleApply.hxx"
 
diff --git a/interpreter/llvm/src/tools/clang/lib/Frontend/InitPreprocessor.cpp b/interpreter/llvm/src/tools/clang/lib/Frontend/InitPreprocessor.cpp
index 6b93c697d9b1e..bd9672bf413de 100644
--- a/interpreter/llvm/src/tools/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/interpreter/llvm/src/tools/clang/lib/Frontend/InitPreprocessor.cpp
@@ -377,9 +377,11 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
     else if (!LangOpts.GNUMode && LangOpts.Digraphs)
       Builder.defineMacro("__STDC_VERSION__", "199409L");
   } else {
-    // FIXME: Use correct value for C++17.
+    // C++17 [cpp.predefined]p1:
+    //   The name __cplusplus is defined to the value 201703L when compiling a
+    //   C++ translation unit.
     if (LangOpts.CPlusPlus1z)
-      Builder.defineMacro("__cplusplus", "201406L");
+      Builder.defineMacro("__cplusplus", "201703L");
     // C++1y [cpp.predefined]p1:
     //   The name __cplusplus is defined to the value 201402L when compiling a
     //   C++ translation unit.
diff --git a/io/io/v7/inc/ROOT/TFile.hxx b/io/io/v7/inc/ROOT/TFile.hxx
index dd62024076e2f..020ea837896ba 100644
--- a/io/io/v7/inc/ROOT/TFile.hxx
+++ b/io/io/v7/inc/ROOT/TFile.hxx
@@ -160,7 +160,7 @@ public:
 
   /// Write an object that is already lifetime managed by this TFileImplBase.
   void Write(std::string_view name) {
-    auto dep = Find(name.to_string());
+    auto dep = Find(std::string(name.data(), name.size()));
     WriteMemoryWithType(name, dep.GetPointer().get(), dep.GetType());
   }
 
diff --git a/io/io/v7/src/TFile.cxx b/io/io/v7/src/TFile.cxx
index 4d75333c46d1b..dfb875c037a5f 100644
--- a/io/io/v7/src/TFile.cxx
+++ b/io/io/v7/src/TFile.cxx
@@ -97,7 +97,7 @@ class TV6Storage: public ROOT::Experimental::Internal::TFileStorageInterface {
   }
 
   void WriteMemoryWithType(std::string_view name, const void* address, TClass* cl) final {
-    fOldFile->WriteObjectAny(address, cl, name.to_string().c_str());
+     fOldFile->WriteObjectAny(address, cl, std::string(name.data(), name.size()).c_str());
   }
 };
 }
@@ -144,7 +144,7 @@ OpenV6TFile(std::string_view name, const char* mode,
     }
   } setCacheDirRAII(opts.fCachedRead);
 
-  auto v6storage = std::make_unique<TV6Storage>(name.to_string(), GetV6TFileOpts(mode, opts));
+  auto v6storage = std::make_unique<TV6Storage>(std::string(name.data(), name.size()), GetV6TFileOpts(mode, opts));
 
   using namespace ROOT::Experimental::Internal;
   return std::unique_ptr<TFileStorageInterface>{std::move(v6storage)};
@@ -191,7 +191,7 @@ std::string ROOT::Experimental::TFile::SetCacheDir(std::string_view path) {
   std::lock_guard<std::mutex> lock(GetCacheDirMutex());
 
   std::string ret = ::TFile::GetCacheFileDir();
-  ::TFile::SetCacheFileDir(path.to_string().c_str());
+  ::TFile::SetCacheFileDir(std::string(path.data(), path.size()).c_str());
   return ret;
 }