Use std filesystem instead of Boost.Filesystem if available.

.travis.yml

@@ -102,6 +102,23 @@ matrix:
       compiler: clang++
       env: TOOLSET=clang CXXSTD=03,11,14,1z
 
+    - os: linux
+      compiler: g++
+      env: CMAKE=1
+      addons:
+        apt:
+          packages:
+            - libboost-filesystem-dev
+            - g++-8
+          sources:
+            - ubuntu-toolchain-r-test
+      install: true
+      script:
+        - export CC=gcc-8 && export CXX=g++-8
+        - mkdir __build__ && cd __build__
+        - cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=~ ..
+        - cmake --build . --target install
+
     - os: linux
       compiler: g++
       env: CMAKE=1

CMakeLists.txt

@@ -7,9 +7,28 @@ cmake_minimum_required( VERSION 3.1 )
 
 project( boostdep LANGUAGES CXX )
 
+option( BOOSTDEP_USE_STD_FS "Use std::filesystem instead of boost::filesystem" OFF )
+
 add_executable( boostdep src/boostdep.cpp )
 
-find_package( Boost COMPONENTS filesystem REQUIRED )
-target_link_libraries( boostdep Boost::filesystem )
+if( BOOSTDEP_USE_STD_FS )
+
+    message(STATUS "Using std::filesystem as filesystem library")
+
+    target_compile_definitions( boostdep PUBLIC BOOSTDEP_USE_STD_FS )
+    target_compile_features( boostdep PUBLIC cxx_std_17 )
+
+    # NOTE: Some compilers (e.g. g++-8) will require additional linker flags
+    #        in order to use std::filesystem (e.g. -lstdc++fs).
+    #        We are NOT handling those special cases
+
+else()
+
+    message(STATUS "Using Boost::filesystem as filesystem library")
+
+    find_package( Boost COMPONENTS filesystem REQUIRED )
+    target_link_libraries( boostdep PUBLIC Boost::filesystem )
+
+endif()
 
 install( TARGETS boostdep RUNTIME DESTINATION bin )

src/boostdep.cpp

@@ -9,8 +9,6 @@
 
 #define _CRT_SECURE_NO_WARNINGS
 
-#include <boost/filesystem.hpp>
-#include <boost/filesystem/fstream.hpp>
 #include <string>
 #include <iostream>
 #include <fstream>
@@ -23,7 +21,18 @@
 #include <streambuf>
 #include <sstream>
 
-namespace fs = boost::filesystem;
+#ifdef BOOSTDEP_USE_STD_FS
+    #include <filesystem>
+    namespace fs = std::filesystem;
+    typedef std::ifstream ifstream_t;
+#else
+    #include <boost/filesystem.hpp>
+    #include <boost/filesystem/fstream.hpp>
+    namespace fs = boost::filesystem;
+    typedef fs::ifstream ifstream_t;
+#endif
+
+
 
 // header -> module
 static std::map< std::string, std::string > s_header_map;
@@ -50,7 +59,7 @@ static void scan_module_headers( fs::path const & path )
 
         for( ; it != last; ++it )
         {
-            if( it->status().type() == fs::directory_file )
+            if( fs::is_directory( it->status() ) )
             {
                 continue;
             }
@@ -76,7 +85,7 @@ static void scan_submodules( fs::path const & path )
     {
         fs::directory_entry const & e = *it;
 
-        if( e.status().type() != fs::directory_file )
+        if( !fs::is_directory( it->status() ) )
         {
             continue;
         }
@@ -211,7 +220,7 @@ static void scan_module_path( fs::path const & dir, bool remove_prefix, std::map
 
         for( ; it != last; ++it )
         {
-            if( it->status().type() == fs::directory_file )
+            if( fs::is_directory( it->status() ) )
             {
                 continue;
             }
@@ -223,7 +232,7 @@ static void scan_module_path( fs::path const & dir, bool remove_prefix, std::map
                 header = header.substr( n+1 );
             }
 
-            fs::ifstream is( it->path() );
+            ifstream_t is( it->path() );
 
             scan_header_dependencies( header, is, deps, from );
         }
@@ -1669,7 +1678,7 @@ static void add_module_headers( fs::path const & dir, std::set<std::string> & he
 
         for( ; it != last; ++it )
         {
-            if( it->status().type() == fs::directory_file )
+            if( fs::is_directory( it->status() ) )
             {
                 continue;
             }