make compile on linux gcc 7.2

CMakeLists.txt

@@ -22,6 +22,10 @@ else()
   message(ERROR "The compiler ${CMAKE_CXX_COMPILER} has no C++11 or C++17 support. Please use a different C++ compiler.")
 endif()
 
+# attempting to fix linux gcc 7.2 which COMPILER_SUPPORTS_CXX17 but doesn't have filesystem.h
+include(CheckIncludeFileCXX)
+CHECK_INCLUDE_FILE_CXX(filesystem.h HAVE_STD_FS)
+
 set(THREAD_LIB "-pthread")
 
 if(STATIC_LINK)
@@ -313,18 +317,18 @@ else()
 
   if(WITH_STATIC)
     add_library(${STATIC_LIB} STATIC ${LIB_SRC})
-    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
       add_library(backport-static STATIC ${CPP_BACKPORT_SRC})
-    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
     add_library(llarpplatform-static STATIC ${LIB_PLATFORM_SRC})
     target_link_libraries(llarpplatform-static ${THREAD_LIB})
-    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
       target_link_libraries(${STATIC_LIB} ${LIBS} backport-static llarpplatform-static)
     else()
       target_link_libraries(${STATIC_LIB} ${LIBS} llarpplatform-static)
-    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
     if(NOT WITH_SHARED)
-      if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+      if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
         target_link_libraries(${EXE} ${STATIC_LINK_LIBS} ${STATIC_LIB} backport-static llarpplatform-static)
         target_link_libraries(${CLIENT_EXE} ${STATIC_LINK_LIBS} ${STATIC_LIB} backport-static llarpplatform-static)
         target_link_libraries(rcutil ${STATIC_LINK_LIBS} ${STATIC_LIB} backport-static llarpplatform-static)
@@ -350,7 +354,7 @@ else()
           target_link_libraries(${CLIENT_EXE} ${STATIC_LINK_LIBS} ${STATIC_LIB} llarpplatform-static ws2_32)
           target_link_libraries(rcutil ${STATIC_LINK_LIBS} ${STATIC_LIB} llarpplatform-static ws2_32)
         endif(MINGW)
-      endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+      endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
       if (MINGW)
         target_link_libraries(dns ${STATIC_LIB} llarpplatform-static pthread ws2_32 stdc++fs)
       elseif(WIN32)
@@ -362,11 +366,11 @@ else()
 
   if(WITH_SHARED)
     add_library(${SHARED_LIB} SHARED ${LIB_SRC})
-    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
       add_library(backport SHARED ${CPP_BACKPORT_SRC})
-    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
     add_library(llarpplatform SHARED ${LIB_PLATFORM_SRC})
-    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
       target_link_libraries(${SHARED_LIB} ${LIBS} backport llarpplatform)
       if (MINGW)
         target_link_libraries(${SHARED_LIB} ${LIBS} backport llarpplatform ws2_32 stdc++fs)
@@ -380,9 +384,9 @@ else()
       elseif(WIN32)
         target_link_libraries(${SHARED_LIB} ${LIBS} llarpplatform ws2_32)
       endif(MINGW)
-    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
     if(NOT WITH_STATIC)
-      if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+      if(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
         target_link_libraries(${EXE} ${SHARED_LIB} backport llarpplatform)
         target_link_libraries(${CLIENT_EXE} ${SHARED_LIB} backport llarpplatform)
         target_link_libraries(rcutil ${SHARED_LIB} backport llarpplatform)
@@ -390,7 +394,7 @@ else()
         target_link_libraries(${EXE} ${SHARED_LIB} llarpplatform)
         target_link_libraries(${CLIENT_EXE} ${SHARED_LIB} llarpplatform)
         target_link_libraries(rcutil ${SHARED_LIB} llarpplatform)
-      endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+      endif(COMPILER_SUPPORTS_CXX11 AND NOT COMPILER_SUPPORTS_CXX17 OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD" OR NOT HAVE_STD_FS)
     target_link_libraries(dns ${SHARED_LIB} llarpplatform pthread)
     endif(NOT WITH_STATIC)
   endif(WITH_SHARED)

llarp/fs.hpp

@@ -8,14 +8,15 @@
 #endif
 
 #include "filesystem.h"
-#if !defined(CPP17) || defined(__OpenBSD__)
-namespace fs = cpp17::filesystem;
-#else
-#ifndef __MINGW32__
-namespace fs = std::filesystem;
-#else
+
+// mingw32 in the only one that doesn't use cpp17::filesystem
+#if defined(__MINGW32__)
 namespace fs = std::experimental::filesystem;
-#endif
-#endif
+#else
+// not CPP17 needs this
+// openbsd needs this
+// linux gcc 7.2 needs this
+namespace fs = cpp17::filesystem;
+#endif // end mingw32
 
-#endif
+#endif // end LLARP_FS_HPP

llarp/nodedb.cpp

@@ -182,7 +182,7 @@ struct llarp_nodedb
   {
     ssize_t sz = 0;
     fs::directory_iterator i(dir);
-#if defined(CPP17) && !defined(__OpenBSD__)
+#if __has_include(<filesystem>) && !defined(__OpenBSD__)
     auto itr = fs::begin(i);
     while(itr != fs::end(i))
 #else

vendor/cppbackport-master/lib/filesystem.h

@@ -32,13 +32,19 @@
 
 #include "version.h"
 
-#if defined(CPP17) && !defined(__OpenBSD__)
+// linux gcc 7.2 has CPP17 but doesn't have filesystem.h
+#if defined(CPP17) && !defined(__OpenBSD__) && __has_include(<filesystem>)
+
 #if defined(__MINGW32__)
+// mingw32 needs experimental
 #include <experimental/filesystem>
 #else
 #include <filesystem>
 #endif
+
 #else
+// OpenBSD needs this
+// MacOS llvm 3.8 needs this
 #include "fs/absolute.h"
 #include "fs/basename.h"
 #include "fs/cleanpath.h"
@@ -55,6 +61,6 @@
 #include "fs/remove.h"
 #include "fs/rename.h"
 #include "fs/tempdir.h"
-#endif
+#endif // if not cpp17 and not openbsd
 
 #endif  // PBL_CPP_FILESYSTEM_H