#2885: test for std::filesystem availability in Silo output likely broken

Reporter: Roland Haas Status: new Milestone: Version: Type: bug Priority: minor Component:

The test

``` #if defined __cpp_lib_filesystem && __cpp_lib_filesystem < 201703L #include <experimental/filesystem> namespace fs = std::experimental::filesystem; #else #include <filesystem> namespace fs = std::filesystem; #endif ```

(or so) in the Silo output routines is quite likely not performing as intended.

Namely

1. `__cpp_lib_filesystem` is defined either in `<version>` (C++20) or in `<filesystem>` (which is what we want to test for) 2. if defined (at least in g++12) it is set to the constant `201703L` anyway

References: * [https://en.cppreference.com/w/cpp/feature%5C_test.html%5D(https://en.cpprefe...) (though g++ does provide a version file even in version of gcc that do not support C++20 and also when C++20 is not the language version used) * [https://stackoverflow.com/a/53365539%5D(https://stackoverflow.com/a/53365539) which is somewhat more complex than we’d want, and also would require access to `<version>`.

The current workaround exists b/c of old gcc versions (7 apparently) and also for some clusters where the (AMD / clang / hip) compiler is old.

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-- Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2885/test-for-std-files...