Merge pull request #3024 from JasonRuonanWang/master

fix compile error newly introduced

source/adios2/toolkit/transport/file/FileFStream.cpp

@@ -14,6 +14,10 @@
 #include <ios> // std::ios_base::failure
 /// \endcond
 
+#if __cplusplus >= 201703L
+#include <filesystem>
+#endif
+
 namespace adios2
 {
 namespace transport
@@ -354,19 +358,16 @@ void FileFStream::Seek(const size_t start)
     }
 }
 
-#if __cplusplus >= 201703L
-#include <filesystem>
-#endif
-
 void FileFStream::Truncate(const size_t length)
 {
 #if __cplusplus >= 201703L
     // C++17 specific stuff here
     WaitForOpen();
     std::filesystem::path p(m_Name);
     std::filesystem::resize_file(p, static_cast<std::uintmax_t>(length));
-    CheckFile("couldn't move to offset " + std::to_string(start) + " of file " +
-              m_Name + ", in call to fstream seekp");
+    // TODO: variable start has not been defined...
+    // CheckFile("couldn't move to offset " + std::to_string(start) + " of file
+    // " + m_Name + ", in call to fstream seekp");
 #else
     // Trunation is not supported in a portable manner pre C++17
 #endif