Build fails on RHEL 7.5: filesystem: No such file or directory

[bmyates]

rhel-log.txt

[kbenzie]

[2023-04-10T18:58:36.193Z] In file included from _deps/unified-runtime-src/source/common/logger/ur_logger_details.hpp:8:0,

[2023-04-10T18:58:36.193Z]                  from _deps/unified-runtime-src/source/common/logger/ur_logger.hpp:10,

[2023-04-10T18:58:36.193Z]                  from _deps/unified-runtime-src/source/loader/ur_adapter_registry.hpp:13,

[2023-04-10T18:58:36.193Z]                  from _deps/unified-runtime-src/source/loader/ur_loader.hpp:12,

[2023-04-10T18:58:36.193Z]                  from _deps/unified-runtime-src/source/loader/ur_loader.cpp:8:

[2023-04-10T18:58:36.193Z] _deps/unified-runtime-src/source/common/logger/ur_sinks.hpp:7:10: fatal error: filesystem: No such file or directory

[2023-04-10T18:58:36.193Z]  #include <filesystem>

This points to RHEL 7.5 not fully supporting C++17.

Currently our CI does not test on RHEL 7.5, only the Ubuntu latest on the Linux side.

[bmyates]

This bug was discovered when integrating UR into SYCL. SYCL has pre-merge CI checks for RHEL7 that are failing due to this.

I think the build is using gcc version 7.5 with RHEL 7.x.

gcc 7.5 does not have support for filesystem.

[kbenzie]

Perhaps we could use <experimental/filesystem> when we detect a GCC version less that 8.1

[kbenzie]

I think this could work

#if defined(__GNUG__) && __GNUC__ < 8
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;
#else
#include <filesystem>
namespace fs = std::filesystem;
#endif

[pbalcer]

I'm not sure if rhel 7.5 is a useful target to test against. RHEL 7 is now at .9 release, maybe they've fixed it since then?