rust: Fix "panic message is not a string literal" warnings These deprecation warnings would not become errors until we actively port crates to the (not yet released) Rust 2021 edition, but fixing them anyway reduces console output noise. Differential Revision: https://phab.mercurial-scm.org/D10743

rust: Add type annotation to fix inference on Rust Nightly When compiling with Rust Nightly, the im-rs crate silently makes use of the experimental language feature for trait impl specialization. This apperently changes public its APIs in subtle ways such that type inference of some user code can fail where it succeeds when specialization is disabled. This made Mercurial’s Rust unit tests have compilation errors on Nightly. I have not managed to find the exactl root cause, but I wrote down my findings so far at https://github.com/bodil/im-rs/issues/188 This adds type annotation to make unit tests rely less on type inference and work around the issue. Differential Revision: https://phab.mercurial-scm.org/D10742

recover: only apply last journal record per file (issue6423) This got broken in 2019 when the size check was introduced. It is most noticable when dealing with transactions that involve an inline to non-inline revlog storage transaction. It wasn't seen as much at the time because the in-memory journal actually de-duplicated the entry implicity, but since 63edc384d3b7 the on-disk journal is used for rollback as well as recover. Differential Revision: https://phab.mercurial-scm.org/D10726

revlog: update data file record before index rename When migrating from inline to non-inline data storage, the data file is recorded initially as zero sized so that it is removed on failure. But the record has to be updated before the index is renamed, otherwise data is lost on rollback. Differential Revision: https://phab.mercurial-scm.org/D10725

revlog: fix index computation during inline->non-inline transition The computation in 63edc384d3b7 failed to factor in the index entries themselve as revlog.start() doesn't count them. Found by Valtenin Gatienbaron with a more precise test case from me. Differential Revision: https://phab.mercurial-scm.org/D10724

dirstate-v2: Change the on-disk format to be tree-shaped Nodes are stored not only for tracked files but also for their ancestor directories. A node has "pointers" (byte count from the start of the file) to its direct child nodes. Everything can be accessed with zero copy. Differential Revision: https://phab.mercurial-scm.org/D10722