More context: basically it fills up (+ add the right library to link against) the ` filesystem.h.in` header template with the right #include and namespace based on what is found on the platform. The idea was to use <filesystem> or <experimental/filesystem> where available, and fallback to https://github.com/gulrak/filesystem where not available.
On Wed, Jul 6, 2022 at 10:24 PM Ruben Di Battista <rubendibatti...@gmail.com> wrote: > A partial solution I implemented using `cmake` for a project of mine: > > 1. > https://gitlab.com/rdbisme/mercurve/-/blob/master/cmake/ConfigureFilesystemHeader.cmake > 2. https://gitlab.com/rdbisme/mercurve/-/blob/master/src/filesystem.h.in > 3. > https://gitlab.com/rdbisme/mercurve/-/blob/master/src/apps/CMakeLists.txt#L20 > > > > That can be improved for the use case here mentioned? The check for macOS > is commented in the ConfigureFilesystemHeader, but maybe it can be > completed to make it work. > > > On Sun, Jul 3, 2022 at 8:38 PM Ken Cunningham < > ken.cunningham.web...@gmail.com> wrote: > >> This is an issue that will need solving, otherwise as filesystem is used >> more (and it seems popular) all the systems prior to 10.15 will be left >> behind. >> >> Filesystem uses features in libc++.dylib that are only present in 10.15 >> and newer. You are blocked from trying to use them on 10.14 and below by a >> blocker in the clang "__config" header, that is easy to override, but when >> you try to use filesystem, it will not find the libc++.dylib features and >> will fail. >> >> You can (sometimes) use macports-libcxx to get past this. This however >> introduces two versions of libc++.dylib into the softare mixture, and this >> sometimes causes errors due to incompatibilities between libc++ versions >> (ODR errors). If you are taking this route, linking in the newer libc++.a >> statically has a higher chance of working properly (that is what Chrome >> does on older MacOS systems). >> >> You can use gcc/libgcc, and newer versions of that have filesystem >> support, but that causes it's own issues. >> >> There was an early version of filesystem available as >> <experimental/filesystem> with a linking static library on older versions >> of clang. I forget when that disappeared, but maybe clang-8.0. It is >> possible that this might be brought forward to newer clangs and made >> available to older systems with modest effort. This is likely the most >> robust approach going forward, as it is the same code (although older). >> >> There are a few versions of filesystem available from other places, some >> header-only, that might or might not work in a general sense. These have >> the disadvantage of having nothing to do with clang/llvm, therefore I >> presume the chances of unfavourable interactions would be somewhat higher. >> >> Hope this is helpful, >> >> Ken >> >> On Sun, Jul 3, 2022 at 4:12 AM Mojca Miklavec <mo...@macports.org> wrote: >> >>> Hi, >>> >>> I'm trying to build some sources that require <filesystem> on 10.13 >>> using clang 13 (I can try with clang 14, but I doubt that it helps). >>> >>> What's the correct way to compile the following minimal example? Do I >>> need to link against a newer libc++ somehow? >>> >>> If it's not feasible to do that, I'll target a newer OS, I was just >>> silently hoping to have some success ;) >>> >>> Thank you, >>> Mojca >>> >>> #include <cstdlib> >>> #include <filesystem> >>> >>> int main() { >>> auto cwd = std::filesystem::current_path(); >>> printf("%s", cwd.c_str()); >>> return EXIT_SUCCESS; >>> } >>> >>> > clang++-mp-13 test.cpp -o test >>> test.cpp:5:16: error: no member named 'filesystem' in namespace 'std'; >>> did you mean 'std::__fs::filesystem'? >>> auto cwd = std::filesystem::current_path(); >>> ^~~~~~~~~~~~~~~ >>> std::__fs::filesystem >>> /opt/local/libexec/llvm-13/bin/../include/c++/v1/filesystem:268:1: >>> note: 'std::__fs::filesystem' declared here >>> _LIBCPP_BEGIN_NAMESPACE_FILESYSTEM >>> ^ >>> /opt/local/libexec/llvm-13/bin/../include/c++/v1/__config:816:58: >>> note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM' >>> _LIBCPP_BEGIN_NAMESPACE_STD namespace __fs { namespace filesystem { >>> ^ >>> 1 error generated. >>> >>> > clang++-mp-13 -std=c++17 test.cpp -o test >>> Undefined symbols for architecture x86_64: >>> "std::__1::__fs::filesystem::__current_path(std::__1::error_code*)", >>> referenced from: >>> std::__1::__fs::filesystem::current_path() in test-1b2bbf.o >>> ld: symbol(s) not found for architecture x86_64 >>> clang: error: linker command failed with exit code 1 (use -v to see >>> invocation) >>> >> > > -- > .. > /**\ > /****\ > /\****/\ > / \**/ \ > / \/ \ > / /\ /\ > / \ / \ / \ > / \ / \/ \ > \ /\ /\ / > \ / \ / \ / > \/ \/ \/ > /\ > / +\ > \+ / > \/ > rdb.is > Book a meeting with me: > https://calendly.com/rdbisme > > > -- .. /**\ /****\ /\****/\ / \**/ \ / \/ \ / /\ /\ / \ / \ / \ / \ / \/ \ \ /\ /\ / \ / \ / \ / \/ \/ \/ /\ / +\ \+ / \/ rdb.is Book a meeting with me: https://calendly.com/rdbisme
