dirstate-v2: adjust the meaning of directory flags Tracking directory "explicitly" give use the opportunity to distinct between entry that are untracked because they are part of the directory structure and entry that are ignored/unknown files on the files system. The help is adjusted to the new semantic and the code now comply to it for both read and write. Differential Revision: https://phab.mercurial-scm.org/D11694

dirstate-v2: actually use sub-second mtime precision Instead of zero, set the nanoseconds field to its correct value whenever possible and preserve it across serialization+parsing. Differential Revision: https://phab.mercurial-scm.org/D11702

dirstate: ignore sub-second component when either is zero in mtime When comparing mtimes for equality. Some APIs simply return zero when more precision is not available. When comparing values from different sources, if only one is truncated in that way, doing a simple comparison would cause many false negatives. Differential Revision: https://phab.mercurial-scm.org/D11701

dirstate-v2: add a new MTIME_SECOND_AMBIGUOUS flags This flag will let us use more `mtime` value in the future. For now we have a minimal handling of the flag at read time, but we will never put ourself in a situation where we will needs to writes it. See the flag documentation for details. Differential Revision: https://phab.mercurial-scm.org/D11700

dirstate: store mtimes with nanosecond precision in memory Keep integer seconds since the Unix epoch, together with integer nanoseconds in the `0 <= n < 1e9` range. For now, nanoseconds are still always zero. This commit is about data structure changes. Differential Revision: https://phab.mercurial-scm.org/D11684

rust: remove now-unused DirstateEntry::clear_ambiguous_mtime method Differential Revision: https://phab.mercurial-scm.org/D11696

dirstate: align Rust function name to `need_delay` The rest of the code use this name. It is not a great name, but it is better to stay consistent. Differential Revision: https://phab.mercurial-scm.org/D11699

dirstate: rename a `very_likely_equal` method to `likely_equal` No need to oversell it. Differential Revision: https://phab.mercurial-scm.org/D11691

backout: backed out changeset 2f2107c01dee After discussion on the original phab patch, we've decided to wait until Python 2 support is dropped to do this since the behavior differs for relatively obscure reasons. Differential Revision: https://phab.mercurial-scm.org/D11692

backout: backed out changeset 6edc8800dbc3 Same as the previous changeset. Differential Revision: https://phab.mercurial-scm.org/D11693

dirstate-v2: preserve the fallback values on disk When the fallback values are set, they are now read and written to disk. See format documentation for details. Differential Revision: https://phab.mercurial-scm.org/D11688

dirstate: make DirstateItem constructor accept fallback value This could arguably goes in the previous changeset, but I wanted to keep that previous changeset small to focus more on the user code and the documentation. Differential Revision: https://phab.mercurial-scm.org/D11687

dirstate: add a concept of "fallback" flags to dirstate item The concept is defined and "used" by the flag code, but it is neither persisted nor set anywhere yet. We currently focus on defining the semantic of the attribute. More to come in the next changesets Check the inline documentation for details. Differential Revision: https://phab.mercurial-scm.org/D11686

dirstate-v2: adds two flag to track the presence of some unrecorded files Right now, we don't record ignored or unknown files in the dirstate. However the structure would allow it. So we introduce two flags that can be used to clarify whether all unknown/ignored children are recorded or not. This will allow for more information to be stored in the future if this end up being relevant. Differential Revision: https://phab.mercurial-scm.org/D11682