Documentation/RelNotes/2.20.0.txt

   1 Git Release Notes
   2 =================
   3
   4 Backward Compatibility Notes
   5 ----------------------------
   6
   7  * "git branch -l <foo>" used to be a way to ask a reflog to be
   8    created while creating a new branch, but that is no longer the
   9    case.  It is a short-hand for "git branch --list <foo>" now.
  10
  11  * "git push" into refs/tags/* hierarchy is rejected without getting
  12    forced, but "git fetch" (misguidedly) used the "fast forwarding"
  13    rule used for the refs/heads/* hierarchy; this has been corrected,
  14    which means some fetches of tags that did not fail with older
  15    version of Git will fail without "--force" with this version.
  16
  17  * "git help -a" now gives verbose output (same as "git help -av").
  18    Those who want the old output may say "git help --no-verbose -a"..
  19
  20
  21 Updates since v2.19
  22 -------------------
  23
  24 UI, Workflows & Features
  25
  26  * Running "git clone" against a project that contain two files with
  27    pathnames that differ only in cases on a case insensitive
  28    filesystem would result in one of the files lost because the
  29    underlying filesystem is incapable of holding both at the same
  30    time.  An attempt is made to detect such a case and warn.
  31
  32  * "git checkout -b newbranch [HEAD]" should not have to do as much as
  33    checking out a commit different from HEAD.  An attempt is made to
  34    optimize this special case.
  35
  36  * "git rev-list --stdin </dev/null" used to be an error; it now shows
  37    no output without an error.  "git rev-list --stdin --default HEAD"
  38    still falls back to the given default when nothing is given on the
  39    standard input.
  40
  41  * Lift code from GitHub to restrict delta computation so that an
  42    object that exists in one fork is not made into a delta against
  43    another object that does not appear in the same forked repository.
  44
  45  * "git format-patch" learned new "--interdiff" and "--range-diff"
  46    options to explain the difference between this version and the
  47    previous attempt in the cover letter (or after the tree-dashes as
  48    a comment).
  49
  50  * "git mailinfo" used in "git am" learned to make a best-effort
  51    recovery of a patch corrupted by MUA that sends text/plain with
  52    format=flawed option.
  53    (merge 3aa4d81f88 rs/mailinfo-format-flowed later to maint).
  54
  55  * The rules used by "git push" and "git fetch" to determine if a ref
  56    can or cannot be updated were inconsistent; specifically, fetching
  57    to update existing tags were allowed even though tags are supposed
  58    to be unmoving anchoring points.  "git fetch" was taught to forbid
  59    updates to existing tags without the "--force" option.
  60
  61  * "git multi-pack-index" learned to detect corruption in the .midx
  62    file it uses, and this feature has been integrated into "git fsck".
  63
  64  * Generation of (experimental) commit-graph files have so far been
  65    fairly silent, even though it takes noticeable amount of time in a
  66    meaningfully large repository.  The users will now see progress
  67    output.
  68
  69  * The minimum version of Windows supported by Windows port fo Git is
  70    now set to Vista.
  71
  72  * The completion script (in contrib/) learned to complete a handful of
  73    options "git stash list" command takes.
  74
  75  * The completion script (in contrib/) learned that "git fetch
  76    --multiple" only takes remote names as arguments and no refspecs.
  77
  78  * "git status" learns to show progress bar when refreshing the index
  79    takes a long time.
  80    (merge ae9af12287 nd/status-refresh-progress later to maint).
  81
  82  * "git help -a" and "git help -av" give different pieces of
  83    information, and generally the "verbose" version is more friendly
  84    to the new users.  "git help -a" by default now uses the more
  85    verbose output (with "--no-verbose", you can go back to the
  86    original).  Also "git help -av" now lists aliases and external
  87    commands, which it did not used to.
  88
  89  * Unlike "grep", "git grep" by default recurses to the whole tree.
  90    The command learned "git grep --recursive" option, so that "git
  91    grep --no-recursive" can serve as a synonym to setting the
  92    max-depth to 0.
  93
  94  * When pushing into a repository that borrows its objects from an
  95    alternate object store, "git receive-pack" that responds to the
  96    push request on the other side lists the tips of refs in the
  97    alternate to reduce the amount of objects transferred.  This
  98    sometimes is detrimental when the number of refs in the alternate
  99    is absurdly large, in which case the bandwidth saved in potentially
 100    fewer objects transferred is wasted in excessively large ref
 101    advertisement.  The alternate refs that are advertised are now
 102    configurable with a pair of configuration variables.
 103
 104
 105 Performance, Internal Implementation, Development Support etc.
 106
 107  * When there are too many packfiles in a repository (which is not
 108    recommended), looking up an object in these would require
 109    consulting many pack .idx files; a new mechanism to have a single
 110    file that consolidates all of these .idx files is introduced.
 111
 112  * "git submodule update" is getting rewritten piece-by-piece into C.
 113
 114  * The code for computing history reachability has been shuffled,
 115    obtained a bunch of new tests to cover them, and then being
 116    improved.
 117
 118  * The unpack_trees() API used in checking out a branch and merging
 119    walks one or more trees along with the index.  When the cache-tree
 120    in the index tells us that we are walking a tree whose flattened
 121    contents is known (i.e. matches a span in the index), as linearly
 122    scanning a span in the index is much more efficient than having to
 123    open tree objects recursively and listing their entries, the walk
 124    can be optimized, which has been done.
 125
 126  * When creating a thin pack, which allows objects to be made into a
 127    delta against another object that is not in the resulting pack but
 128    is known to be present on the receiving end, the code learned to
 129    take advantage of the reachability bitmap; this allows the server
 130    to send a delta against a base beyond the "boundary" commit.
 131
 132  * spatch transformation to replace boolean uses of !hashcmp() to
 133    newly introduced oideq() is added, and applied, to regain
 134    performance lost due to support of multiple hash algorithms.
 135
 136  * Fix a bug in which the same path could be registered under multiple
 137    worktree entries if the path was missing (for instance, was removed
 138    manually).  Also, as a convenience, expand the number of cases in
 139    which --force is applicable.
 140
 141  * Split Documentation/config.txt for easier maintenance.
 142    (merge 6014363f0b nd/config-split later to maint).
 143
 144  * Test helper binaries clean-up.
 145    (merge c9a1f4161f nd/test-tool later to maint).
 146
 147  * Various tests have been updated to make it easier to swap the
 148    hash function used for object identification.
 149    (merge ae0c89d41b bc/hash-independent-tests later to maint).
 150
 151  * Update fsck.skipList implementation and documentation.
 152    (merge 371a655074 ab/fsck-skiplist later to maint).
 153
 154  * An alias that expands to another alias has so far been forbidden,
 155    but now it is allowed to create such an alias.
 156
 157  * Various test scripts have been updated for style and also correct
 158    handling of exit status of various commands.
 159
 160  * "gc --auto" ended up calling exit(-1) upon error, which has been
 161    corrected to use exit(1).  Also the error reporting behaviour when
 162    daemonized has been updated to exit with zero status when stopping
 163    due to a previously discovered error (which implies there is no
 164    point running gc to improve the situation); we used to exit with
 165    failure in such a case.
 166
 167  * Various codepaths in the core-ish part learned to work on an
 168    arbitrary in-core index structure, not necessarily the default
 169    instance "the_index".
 170    (merge b3c7eef9b0 nd/the-index later to maint).
 171
 172  * Code clean-up in the internal machinery used by "git status" and
 173    "git commit --dry-run".
 174    (merge 73ba5d78b4 ss/wt-status-committable later to maint).
 175
 176  * Some environment variables that control the runtime options of Git
 177    used during tests are getting renamed for consistency.
 178    (merge 4231d1ba99 bp/rename-test-env-var later to maint).
 179
 180  * A new extension to the index file has been introduced, which allows
 181    the index file to be read in parallel for performance.
 182
 183  * The oidset API was built on top of the oidmap API which in turn is
 184    on the hashmap API.  Replace the implementation to build on top of
 185    the khash API and gain performance.
 186
 187  * Over some transports, fetching objects with an exact commit object
 188    name can be done without first seeing the ref advertisements.  The
 189    code has been optimized to exploit this.
 190
 191  * In a partial clone that will lazily be hydrated from the
 192    originating repository, we generally want to avoid "does this
 193    object exist (locally)?" on objects that we deliberately omitted
 194    when we created the clone.  The cache-tree codepath (which is used
 195    to write a tree object out of the index) however insisted that the
 196    object exists, even for paths that are outside of the partial
 197    checkout area.  The code has been updated to avoid such a check.
 198
 199
 200 Fixes since v2.19
 201 -----------------
 202
 203  * "git interpret-trailers" and its underlying machinery had a buggy
 204    code that attempted to ignore patch text after commit log message,
 205    which triggered in various codepaths that will always get the log
 206    message alone and never get such an input.
 207    (merge 66e83d9b41 jk/trailer-fixes later to maint).
 208
 209  * Malformed or crafted data in packstream can make our code attempt
 210    to read or write past the allocated buffer and abort, instead of
 211    reporting an error, which has been fixed.
 212
 213  * "git rebase -i" did not clear the state files correctly when a run
 214    of "squash/fixup" is aborted and then the user manually amended the
 215    commit instead, which has been corrected.
 216    (merge 10d2f35436 js/rebase-i-autosquash-fix later to maint).
 217
 218  * When fsmonitor is in use, after operation on submodules updates
 219    .gitmodules, we lost track of the fact that we did so and relied on
 220    stale fsmonitor data.
 221    (merge 43f1180814 bp/mv-submodules-with-fsmonitor later to maint).
 222
 223  * Fix for a long-standing bug that leaves the index file corrupt when
 224    it shrinks during a partial commit.
 225    (merge 6c003d6ffb jk/reopen-tempfile-truncate later to maint).
 226
 227  * Further fix for O_APPEND emulation on Windows
 228    (merge eeaf7ddac7 js/mingw-o-append later to maint).
 229
 230  * A corner case bugfix in "git rerere" code.
 231    (merge ad2bf0d9b4 en/rerere-multi-stage-1-fix later to maint).
 232
 233  * "git add ':(attr:foo)'" is not supported and is supposed to be
 234    rejected while the command line arguments are parsed, but we fail
 235    to reject such a command line upfront.
 236    (merge 84d938b732 nd/attr-pathspec-fix later to maint).
 237
 238  * Recent update broke the reachability algorithm when refs (e.g.
 239    tags) that point at objects that are not commit were involved,
 240    which has been fixed.
 241
 242  * "git rebase" etc. in Git 2.19 fails to abort when given an empty
 243    commit log message as result of editing, which has been corrected.
 244    (merge a3ec9eaf38 en/sequencer-empty-edit-result-aborts later to maint).
 245
 246  * The code to backfill objects in lazily cloned repository did not
 247    work correctly, which has been corrected.
 248    (merge e68302011c jt/lazy-object-fetch-fix later to maint).
 249
 250  * Update error messages given by "git remote" and make them consistent.
 251    (merge 5025425dff ms/remote-error-message-update later to maint).
 252
 253  * "git update-ref" learned to make both "--no-deref" and "--stdin"
 254    work at the same time.
 255    (merge d345e9fbe7 en/update-ref-no-deref-stdin later to maint).
 256
 257  * Recently added "range-diff" had a corner-case bug to cause it
 258    segfault, which has been corrected.
 259    (merge e467a90c7a tg/range-diff-corner-case-fix later to maint).
 260
 261  * The recently introduced commit-graph auxiliary data is incompatible
 262    with mechanisms such as replace & grafts that "breaks" immutable
 263    nature of the object reference relationship.  Disable optimizations
 264    based on its use (and updating existing commit-graph) when these
 265    incompatible features are in use in the repository.
 266    (merge 829a321569 ds/commit-graph-with-grafts later to maint).
 267
 268  * The mailmap file update.
 269    (merge 255eb03edf jn/mailmap-update later to maint).
 270
 271  * The code in "git status" sometimes hit an assertion failure.  This
 272    was caused by a structure that was reused without cleaning the data
 273    used for the first run, which has been corrected.
 274    (merge 3e73cc62c0 en/status-multiple-renames-to-the-same-target-fix later to maint).
 275
 276  * "git fetch $repo $object" in a partial clone did not correctly
 277    fetch the asked-for object that is referenced by an object in
 278    promisor packfile, which has been fixed.
 279
 280  * A corner-case bugfix.
 281    (merge c5cbb27cb5 sm/show-superproject-while-conflicted later to maint).
 282
 283  * Various fixes to "diff --color-moved-ws".
 284
 285  * A partial clone that is configured to lazily fetch missing objects
 286    will on-demand issue a "git fetch" request to the originating
 287    repository to fill not-yet-obtained objects.  The request has been
 288    optimized for requesting a tree object (and not the leaf blob
 289    objects contained in it) by telling the originating repository that
 290    no blobs are needed.
 291    (merge 4c7f9567ea jt/non-blob-lazy-fetch later to maint).
 292
 293  * Code cleanup, docfix, build fix, etc.
 294    (merge 96a7501aad ts/doc-build-manpage-xsl-quietly later to maint).
 295    (merge b9b07efdb2 tg/conflict-marker-size later to maint).
 296    (merge fa0aeea770 sg/doc-trace-appends later to maint).
 297    (merge d64324cb60 tb/void-check-attr later to maint).
 298    (merge c3b9bc94b9 en/double-semicolon-fix later to maint).
 299    (merge 79336116f5 sg/t3701-tighten-trace later to maint).
 300    (merge 801fa63a90 jk/dev-build-format-security later to maint).
 301    (merge 0597dd62ba sb/string-list-remove-unused later to maint).
 302    (merge db2d36fad8 bw/protocol-v2 later to maint).
 303    (merge 456d7cd3a9 sg/split-index-test later to maint).
 304    (merge 7b6057c852 tq/refs-internal-comment-fix later to maint).
 305    (merge 29e8dc50ad tg/t5551-with-curl-7.61.1 later to maint).
 306    (merge 55f6bce2c9 fe/doc-updates later to maint).
 307    (merge 7987d2232d jk/check-everything-connected-is-long-gone later to maint).
 308    (merge 4ba3c9be47 dz/credential-doc-url-matching-rules later to maint).
 309    (merge 4c399442f7 ma/commit-graph-docs later to maint).
 310    (merge fc0503b04e ma/t1400-undebug-test later to maint).
 311    (merge e56b53553a nd/packobjectshook-doc-fix later to maint).
 312    (merge c56170a0c4 ma/mailing-list-address-in-git-help later to maint).
 313    (merge 6e8fc70fce rs/sequencer-oidset-insert-avoids-dups later to maint).
 314    (merge ad0b8f9575 mw/doc-typofixes later to maint).
 315    (merge d9f079ad1a jc/how-to-document-api later to maint).