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  * "git cpn --help", when "cpn" is an alias to, say, "cherry-pick -n",
  21    reported only the alias expansion of "cpn" in earlier versions of
  22    Git.  It now runs "git cherry-pick --help" to show the manual page
  23    of the command, while sending the alias expansion to the standard
  24    error stream.
  25
  26  * "git send-email" learned to grab address-looking string on any
  27    trailer whose name ends with "-by". This is a backward-incompatible
  28    change.  Adding "--suppress-cc=misc-by" on the command line, or
  29    setting sendemail.suppresscc configuration variable to "misc-by",
  30    can be used to disable this behaviour.
  31
  32
  33 Updates since v2.19
  34 -------------------
  35
  36 UI, Workflows & Features
  37
  38  * Running "git clone" against a project that contain two files with
  39    pathnames that differ only in cases on a case insensitive
  40    filesystem would result in one of the files lost because the
  41    underlying filesystem is incapable of holding both at the same
  42    time.  An attempt is made to detect such a case and warn.
  43
  44  * "git checkout -b newbranch [HEAD]" should not have to do as much as
  45    checking out a commit different from HEAD.  An attempt is made to
  46    optimize this special case.
  47
  48  * "git rev-list --stdin </dev/null" used to be an error; it now shows
  49    no output without an error.  "git rev-list --stdin --default HEAD"
  50    still falls back to the given default when nothing is given on the
  51    standard input.
  52
  53  * Lift code from GitHub to restrict delta computation so that an
  54    object that exists in one fork is not made into a delta against
  55    another object that does not appear in the same forked repository.
  56
  57  * "git format-patch" learned new "--interdiff" and "--range-diff"
  58    options to explain the difference between this version and the
  59    previous attempt in the cover letter (or after the tree-dashes as
  60    a comment).
  61
  62  * "git mailinfo" used in "git am" learned to make a best-effort
  63    recovery of a patch corrupted by MUA that sends text/plain with
  64    format=flawed option.
  65    (merge 3aa4d81f88 rs/mailinfo-format-flowed later to maint).
  66
  67  * The rules used by "git push" and "git fetch" to determine if a ref
  68    can or cannot be updated were inconsistent; specifically, fetching
  69    to update existing tags were allowed even though tags are supposed
  70    to be unmoving anchoring points.  "git fetch" was taught to forbid
  71    updates to existing tags without the "--force" option.
  72
  73  * "git multi-pack-index" learned to detect corruption in the .midx
  74    file it uses, and this feature has been integrated into "git fsck".
  75
  76  * Generation of (experimental) commit-graph files have so far been
  77    fairly silent, even though it takes noticeable amount of time in a
  78    meaningfully large repository.  The users will now see progress
  79    output.
  80
  81  * The minimum version of Windows supported by Windows port fo Git is
  82    now set to Vista.
  83
  84  * The completion script (in contrib/) learned to complete a handful of
  85    options "git stash list" command takes.
  86
  87  * The completion script (in contrib/) learned that "git fetch
  88    --multiple" only takes remote names as arguments and no refspecs.
  89
  90  * "git status" learns to show progress bar when refreshing the index
  91    takes a long time.
  92    (merge ae9af12287 nd/status-refresh-progress later to maint).
  93
  94  * "git help -a" and "git help -av" give different pieces of
  95    information, and generally the "verbose" version is more friendly
  96    to the new users.  "git help -a" by default now uses the more
  97    verbose output (with "--no-verbose", you can go back to the
  98    original).  Also "git help -av" now lists aliases and external
  99    commands, which it did not used to.
 100
 101  * Unlike "grep", "git grep" by default recurses to the whole tree.
 102    The command learned "git grep --recursive" option, so that "git
 103    grep --no-recursive" can serve as a synonym to setting the
 104    max-depth to 0.
 105
 106  * When pushing into a repository that borrows its objects from an
 107    alternate object store, "git receive-pack" that responds to the
 108    push request on the other side lists the tips of refs in the
 109    alternate to reduce the amount of objects transferred.  This
 110    sometimes is detrimental when the number of refs in the alternate
 111    is absurdly large, in which case the bandwidth saved in potentially
 112    fewer objects transferred is wasted in excessively large ref
 113    advertisement.  The alternate refs that are advertised are now
 114    configurable with a pair of configuration variables.
 115
 116  * "git cmd --help" when "cmd" is aliased used to only say "cmd is
 117    aliased to ...".  Now it shows that to the standard error stream
 118    and runs "git $cmd --help" where $cmd is the first word of the
 119    alias expansion.
 120
 121  * The documentation of "git gc" has been updated to mention that it
 122    is no longer limited to "pruning away crufts" but also updates
 123    ancillary files like commit-graph as a part of repository
 124    optimization.
 125
 126  * "git p4 unshelve" improvements.
 127
 128  * The logic to select the default user name and e-mail on Windows has
 129    been improved.
 130    (merge 501afcb8b0 js/mingw-default-ident later to maint).
 131
 132  * The "rev-list --filter" feature learned to exclude all trees via
 133    "tree:0" filter.
 134
 135  * "git send-email" learned to grab address-looking string on any
 136    trailer whose name ends with "-by"; --suppress-cc=misc-by on the
 137    command line, or setting sendemail.suppresscc configuration
 138    variable to "misc-by", can be used to disable this behaviour.
 139
 140  * Developer builds now uses -Wunused-function compilation option.
 141
 142  * One of our CI tests to run with "unusual/experimental/random"
 143    settings now also uses commit-graph and midx.
 144
 145  * "git mergetool" learned to take the "--[no-]gui" option, just like
 146    "git difftool" does.
 147
 148
 149 Performance, Internal Implementation, Development Support etc.
 150
 151  * When there are too many packfiles in a repository (which is not
 152    recommended), looking up an object in these would require
 153    consulting many pack .idx files; a new mechanism to have a single
 154    file that consolidates all of these .idx files is introduced.
 155
 156  * "git submodule update" is getting rewritten piece-by-piece into C.
 157
 158  * The code for computing history reachability has been shuffled,
 159    obtained a bunch of new tests to cover them, and then being
 160    improved.
 161
 162  * The unpack_trees() API used in checking out a branch and merging
 163    walks one or more trees along with the index.  When the cache-tree
 164    in the index tells us that we are walking a tree whose flattened
 165    contents is known (i.e. matches a span in the index), as linearly
 166    scanning a span in the index is much more efficient than having to
 167    open tree objects recursively and listing their entries, the walk
 168    can be optimized, which has been done.
 169
 170  * When creating a thin pack, which allows objects to be made into a
 171    delta against another object that is not in the resulting pack but
 172    is known to be present on the receiving end, the code learned to
 173    take advantage of the reachability bitmap; this allows the server
 174    to send a delta against a base beyond the "boundary" commit.
 175
 176  * spatch transformation to replace boolean uses of !hashcmp() to
 177    newly introduced oideq() is added, and applied, to regain
 178    performance lost due to support of multiple hash algorithms.
 179
 180  * Fix a bug in which the same path could be registered under multiple
 181    worktree entries if the path was missing (for instance, was removed
 182    manually).  Also, as a convenience, expand the number of cases in
 183    which --force is applicable.
 184
 185  * Split Documentation/config.txt for easier maintenance.
 186    (merge 6014363f0b nd/config-split later to maint).
 187
 188  * Test helper binaries clean-up.
 189    (merge c9a1f4161f nd/test-tool later to maint).
 190
 191  * Various tests have been updated to make it easier to swap the
 192    hash function used for object identification.
 193    (merge ae0c89d41b bc/hash-independent-tests later to maint).
 194
 195  * Update fsck.skipList implementation and documentation.
 196    (merge 371a655074 ab/fsck-skiplist later to maint).
 197
 198  * An alias that expands to another alias has so far been forbidden,
 199    but now it is allowed to create such an alias.
 200
 201  * Various test scripts have been updated for style and also correct
 202    handling of exit status of various commands.
 203
 204  * "gc --auto" ended up calling exit(-1) upon error, which has been
 205    corrected to use exit(1).  Also the error reporting behaviour when
 206    daemonized has been updated to exit with zero status when stopping
 207    due to a previously discovered error (which implies there is no
 208    point running gc to improve the situation); we used to exit with
 209    failure in such a case.
 210
 211  * Various codepaths in the core-ish part learned to work on an
 212    arbitrary in-core index structure, not necessarily the default
 213    instance "the_index".
 214    (merge b3c7eef9b0 nd/the-index later to maint).
 215
 216  * Code clean-up in the internal machinery used by "git status" and
 217    "git commit --dry-run".
 218    (merge 73ba5d78b4 ss/wt-status-committable later to maint).
 219
 220  * Some environment variables that control the runtime options of Git
 221    used during tests are getting renamed for consistency.
 222    (merge 4231d1ba99 bp/rename-test-env-var later to maint).
 223
 224  * A new extension to the index file has been introduced, which allows
 225    the index file to be read in parallel for performance.
 226
 227  * The oidset API was built on top of the oidmap API which in turn is
 228    on the hashmap API.  Replace the implementation to build on top of
 229    the khash API and gain performance.
 230
 231  * Over some transports, fetching objects with an exact commit object
 232    name can be done without first seeing the ref advertisements.  The
 233    code has been optimized to exploit this.
 234
 235  * In a partial clone that will lazily be hydrated from the
 236    originating repository, we generally want to avoid "does this
 237    object exist (locally)?" on objects that we deliberately omitted
 238    when we created the clone.  The cache-tree codepath (which is used
 239    to write a tree object out of the index) however insisted that the
 240    object exists, even for paths that are outside of the partial
 241    checkout area.  The code has been updated to avoid such a check.
 242
 243  * To help developers, an EditorConfig file that attempts to follow
 244    the project convention has been added.
 245    (merge b548d698a0 bc/editorconfig later to maint).
 246
 247  * The result of coverage test can be combined with "git blame" to
 248    check the test coverage of code introduced recently with a new
 249    'coverage-diff' tool (in contrib/).
 250    (merge 783faedd65 ds/coverage-diff later to maint).
 251
 252  * An experiment to fuzz test a few areas, hopefully we can gain more
 253    coverage to various areas.
 254
 255  * More codepaths are moving away from hardcoded hash sizes.
 256
 257  * The way the Windows port figures out the current directory has been
 258    improved.
 259
 260  * The way DLLs are loaded on the Windows port has been improved.
 261
 262  * Some tests have been reorganized and renamed; "ls t/" now gives a
 263    better overview of what is tested for these scripts than before.
 264
 265
 266 Fixes since v2.19
 267 -----------------
 268
 269  * "git interpret-trailers" and its underlying machinery had a buggy
 270    code that attempted to ignore patch text after commit log message,
 271    which triggered in various codepaths that will always get the log
 272    message alone and never get such an input.
 273    (merge 66e83d9b41 jk/trailer-fixes later to maint).
 274
 275  * Malformed or crafted data in packstream can make our code attempt
 276    to read or write past the allocated buffer and abort, instead of
 277    reporting an error, which has been fixed.
 278
 279  * "git rebase -i" did not clear the state files correctly when a run
 280    of "squash/fixup" is aborted and then the user manually amended the
 281    commit instead, which has been corrected.
 282    (merge 10d2f35436 js/rebase-i-autosquash-fix later to maint).
 283
 284  * When fsmonitor is in use, after operation on submodules updates
 285    .gitmodules, we lost track of the fact that we did so and relied on
 286    stale fsmonitor data.
 287    (merge 43f1180814 bp/mv-submodules-with-fsmonitor later to maint).
 288
 289  * Fix for a long-standing bug that leaves the index file corrupt when
 290    it shrinks during a partial commit.
 291    (merge 6c003d6ffb jk/reopen-tempfile-truncate later to maint).
 292
 293  * Further fix for O_APPEND emulation on Windows
 294    (merge eeaf7ddac7 js/mingw-o-append later to maint).
 295
 296  * A corner case bugfix in "git rerere" code.
 297    (merge ad2bf0d9b4 en/rerere-multi-stage-1-fix later to maint).
 298
 299  * "git add ':(attr:foo)'" is not supported and is supposed to be
 300    rejected while the command line arguments are parsed, but we fail
 301    to reject such a command line upfront.
 302    (merge 84d938b732 nd/attr-pathspec-fix later to maint).
 303
 304  * Recent update broke the reachability algorithm when refs (e.g.
 305    tags) that point at objects that are not commit were involved,
 306    which has been fixed.
 307
 308  * "git rebase" etc. in Git 2.19 fails to abort when given an empty
 309    commit log message as result of editing, which has been corrected.
 310    (merge a3ec9eaf38 en/sequencer-empty-edit-result-aborts later to maint).
 311
 312  * The code to backfill objects in lazily cloned repository did not
 313    work correctly, which has been corrected.
 314    (merge e68302011c jt/lazy-object-fetch-fix later to maint).
 315
 316  * Update error messages given by "git remote" and make them consistent.
 317    (merge 5025425dff ms/remote-error-message-update later to maint).
 318
 319  * "git update-ref" learned to make both "--no-deref" and "--stdin"
 320    work at the same time.
 321    (merge d345e9fbe7 en/update-ref-no-deref-stdin later to maint).
 322
 323  * Recently added "range-diff" had a corner-case bug to cause it
 324    segfault, which has been corrected.
 325    (merge e467a90c7a tg/range-diff-corner-case-fix later to maint).
 326
 327  * The recently introduced commit-graph auxiliary data is incompatible
 328    with mechanisms such as replace & grafts that "breaks" immutable
 329    nature of the object reference relationship.  Disable optimizations
 330    based on its use (and updating existing commit-graph) when these
 331    incompatible features are in use in the repository.
 332    (merge 829a321569 ds/commit-graph-with-grafts later to maint).
 333
 334  * The mailmap file update.
 335    (merge 255eb03edf jn/mailmap-update later to maint).
 336
 337  * The code in "git status" sometimes hit an assertion failure.  This
 338    was caused by a structure that was reused without cleaning the data
 339    used for the first run, which has been corrected.
 340    (merge 3e73cc62c0 en/status-multiple-renames-to-the-same-target-fix later to maint).
 341
 342  * "git fetch $repo $object" in a partial clone did not correctly
 343    fetch the asked-for object that is referenced by an object in
 344    promisor packfile, which has been fixed.
 345
 346  * A corner-case bugfix.
 347    (merge c5cbb27cb5 sm/show-superproject-while-conflicted later to maint).
 348
 349  * Various fixes to "diff --color-moved-ws".
 350
 351  * A partial clone that is configured to lazily fetch missing objects
 352    will on-demand issue a "git fetch" request to the originating
 353    repository to fill not-yet-obtained objects.  The request has been
 354    optimized for requesting a tree object (and not the leaf blob
 355    objects contained in it) by telling the originating repository that
 356    no blobs are needed.
 357    (merge 4c7f9567ea jt/non-blob-lazy-fetch later to maint).
 358
 359  * The codepath to support the experimental split-index mode had
 360    remaining "racily clean" issues fixed.
 361    (merge 4c490f3d32 sg/split-index-racefix later to maint).
 362
 363  * "git log --graph" showing an octopus merge sometimes miscounted the
 364    number of display columns it is consuming to show the merge and its
 365    parent commits, which has been corrected.
 366    (merge 04005834ed np/log-graph-octopus-fix later to maint).
 367
 368  * "git range-diff" did not work well when the compared ranges had
 369    changes in submodules and the "--submodule=log" was used.
 370
 371  * The implementation of run_command() API on the UNIX platforms had a
 372    bug that caused a command not on $PATH to be found in the current
 373    directory.
 374    (merge f67b980771 jk/run-command-notdot later to maint).
 375
 376  * A mutex used in "git pack-objects" were not correctly initialized
 377    and this caused "git repack" to dump core on Windows.
 378    (merge 34204c8166 js/pack-objects-mutex-init-fix later to maint).
 379
 380  * Under certain circumstances, "git diff D:/a/b/c D:/a/b/d" on
 381    Windows would strip initial parts from the paths because they
 382    were not recognized as absolute, which has been corrected.
 383    (merge ffd04e92e2 js/diff-notice-has-drive-prefix later to maint).
 384
 385  * The receive.denyCurrentBranch=updateInstead codepath kicked in even
 386    when the push should have been rejected due to other reasons, such
 387    as it does not fast-forward or the update-hook rejects it, which
 388    has been corrected.
 389    (merge b072a25fad jc/receive-deny-current-branch-fix later to maint).
 390
 391  * Code cleanup, docfix, build fix, etc.
 392    (merge 96a7501aad ts/doc-build-manpage-xsl-quietly later to maint).
 393    (merge b9b07efdb2 tg/conflict-marker-size later to maint).
 394    (merge fa0aeea770 sg/doc-trace-appends later to maint).
 395    (merge d64324cb60 tb/void-check-attr later to maint).
 396    (merge c3b9bc94b9 en/double-semicolon-fix later to maint).
 397    (merge 79336116f5 sg/t3701-tighten-trace later to maint).
 398    (merge 801fa63a90 jk/dev-build-format-security later to maint).
 399    (merge 0597dd62ba sb/string-list-remove-unused later to maint).
 400    (merge db2d36fad8 bw/protocol-v2 later to maint).
 401    (merge 456d7cd3a9 sg/split-index-test later to maint).
 402    (merge 7b6057c852 tq/refs-internal-comment-fix later to maint).
 403    (merge 29e8dc50ad tg/t5551-with-curl-7.61.1 later to maint).
 404    (merge 55f6bce2c9 fe/doc-updates later to maint).
 405    (merge 7987d2232d jk/check-everything-connected-is-long-gone later to maint).
 406    (merge 4ba3c9be47 dz/credential-doc-url-matching-rules later to maint).
 407    (merge 4c399442f7 ma/commit-graph-docs later to maint).
 408    (merge fc0503b04e ma/t1400-undebug-test later to maint).
 409    (merge e56b53553a nd/packobjectshook-doc-fix later to maint).
 410    (merge c56170a0c4 ma/mailing-list-address-in-git-help later to maint).
 411    (merge 6e8fc70fce rs/sequencer-oidset-insert-avoids-dups later to maint).
 412    (merge ad0b8f9575 mw/doc-typofixes later to maint).
 413    (merge d9f079ad1a jc/how-to-document-api later to maint).
 414    (merge b1492bf315 ma/t7005-bash-workaround later to maint).
 415    (merge ac1f98a0df du/rev-parse-is-plumbing later to maint).
 416    (merge ca8ed443a5 mm/doc-no-dashed-git later to maint).
 417    (merge ce366a8144 du/get-tar-commit-id-is-plumbing later to maint).
 418    (merge 61018fe9e0 du/cherry-is-plumbing later to maint).
 419    (merge c7e5fe79b9 sb/strbuf-h-update later to maint).
 420    (merge 8d2008196b tq/branch-create-wo-branch-get later to maint).
 421    (merge 2e3c894f4b tq/branch-style-fix later to maint).
 422    (merge c5d844af9c sg/doc-show-branch-typofix later to maint).
 423    (merge 081d91618b ah/doc-updates later to maint).
 424    (merge b84c783882 jc/cocci-preincr later to maint).
 425    (merge 5e495f8122 uk/merge-subtree-doc-update later to maint).
 426    (merge aaaa881822 jk/uploadpack-packobjectshook-fix later to maint).