Error in test "30.10.15.15 hard_link_count"

[phprus]

Describe the bug
hard_link_count test logic is wrong on BTRFS.
The links counter is always equal to 1 (https://unix.stackexchange.com/a/618726).

Error:

40: /home/.../3rdparty/ghc-filesystem/src/test/filesystem_test.cpp:2037: FAILED:
40:   CHECK( fs::hard_link_count(t.path()) == 2 )
40: with expansion:
40:   1 == 2
40:
40: /home/.../3rdparty/ghc-filesystem/src/test/filesystem_test.cpp:2039: FAILED:
40:   CHECK( fs::hard_link_count(t.path()) == 3 )
40: with expansion:
40:   1 == 3

To Reproduce
Run test on BTRFS.

[phprus]

Btrfs is are default file system on SUSE 12+ and Fedora 33+.

Possible workaround:
Replace CHECK(fs::hard_link_count(t.path()) == 2) to CHECK(fs::hard_link_count(t.path()) == 2 || fs::hard_link_count(t.path()) == 1);
and
CHECK(fs::hard_link_count(t.path()) == 3) to CHECK(fs::hard_link_count(t.path()) == 3 || fs::hard_link_count(t.path()) == 1);

[gulrak]

Nice find. Ich think I prefer to use an lstat helper in filesystem_test for Linux to compare to its result, to keep the test from accepting 1 when the fs is not BTRFS. I'll look into it later today after work.

[gulrak]

This is now part of release v1.5.2