2cc5fd7a9f1125e11f5bea3b3320ccb6a1820056
[git/git.git] / 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
18 Updates since v2.19
19 -------------------
20
21 UI, Workflows & Features
22
23 * Running "git clone" against a project that contain two files with
24 pathnames that differ only in cases on a case insensitive
25 filesystem would result in one of the files lost because the
26 underlying filesystem is incapable of holding both at the same
27 time. An attempt is made to detect such a case and warn.
28
29 * "git checkout -b newbranch [HEAD]" should not have to do as much as
30 checking out a commit different from HEAD. An attempt is made to
31 optimize this special case.
32
33 * "git rev-list --stdin </dev/null" used to be an error; it now shows
34 no output without an error. "git rev-list --stdin --default HEAD"
35 still falls back to the given default when nothing is given on the
36 standard input.
37
38 * Lift code from GitHub to restrict delta computation so that an
39 object that exists in one fork is not made into a delta against
40 another object that does not appear in the same forked repository.
41
42 * "git format-patch" learned new "--interdiff" and "--range-diff"
43 options to explain the difference between this version and the
44 previous attempt in the cover letter (or after the tree-dashes as
45 a comment).
46
47 * "git mailinfo" used in "git am" learned to make a best-effort
48 recovery of a patch corrupted by MUA that sends text/plain with
49 format=flawed option.
50 (merge 3aa4d81f88 rs/mailinfo-format-flowed later to maint).
51
52 * The rules used by "git push" and "git fetch" to determine if a ref
53 can or cannot be updated were inconsistent; specifically, fetching
54 to update existing tags were allowed even though tags are supposed
55 to be unmoving anchoring points. "git fetch" was taught to forbid
56 updates to existing tags without the "--force" option.
57
58 * "git multi-pack-index" learned to detect corruption in the .midx
59 file it uses, and this feature has been integrated into "git fsck".
60
61
62 Performance, Internal Implementation, Development Support etc.
63
64 * When there are too many packfiles in a repository (which is not
65 recommended), looking up an object in these would require
66 consulting many pack .idx files; a new mechanism to have a single
67 file that consolidates all of these .idx files is introduced.
68
69 * "git submodule update" is getting rewritten piece-by-piece into C.
70
71 * The code for computing history reachability has been shuffled,
72 obtained a bunch of new tests to cover them, and then being
73 improved.
74
75 * The unpack_trees() API used in checking out a branch and merging
76 walks one or more trees along with the index. When the cache-tree
77 in the index tells us that we are walking a tree whose flattened
78 contents is known (i.e. matches a span in the index), as linearly
79 scanning a span in the index is much more efficient than having to
80 open tree objects recursively and listing their entries, the walk
81 can be optimized, which has been done.
82
83 * When creating a thin pack, which allows objects to be made into a
84 delta against another object that is not in the resulting pack but
85 is known to be present on the receiving end, the code learned to
86 take advantage of the reachability bitmap; this allows the server
87 to send a delta against a base beyond the "boundary" commit.
88
89 * spatch transformation to replace boolean uses of !hashcmp() to
90 newly introduced oideq() is added, and applied, to regain
91 performance lost due to support of multiple hash algorithms.
92
93 * Fix a bug in which the same path could be registered under multiple
94 worktree entries if the path was missing (for instance, was removed
95 manually). Also, as a convenience, expand the number of cases in
96 which --force is applicable.
97
98 * Split Documentation/config.txt for easier maintenance.
99 (merge 6014363f0b nd/config-split later to maint).
100
101 * Test helper binaries clean-up.
102 (merge c9a1f4161f nd/test-tool later to maint).
103
104 * Various tests have been updated to make it easier to swap the
105 hash function used for object identification.
106 (merge ae0c89d41b bc/hash-independent-tests later to maint).
107
108 * Update fsck.skipList implementation and documentation.
109 (merge 371a655074 ab/fsck-skiplist later to maint).
110
111
112 Fixes since v2.19
113 -----------------
114
115 * "git interpret-trailers" and its underlying machinery had a buggy
116 code that attempted to ignore patch text after commit log message,
117 which triggered in various codepaths that will always get the log
118 message alone and never get such an input.
119 (merge 66e83d9b41 jk/trailer-fixes later to maint).
120
121 * Malformed or crafted data in packstream can make our code attempt
122 to read or write past the allocated buffer and abort, instead of
123 reporting an error, which has been fixed.
124
125 * "git rebase -i" did not clear the state files correctly when a run
126 of "squash/fixup" is aborted and then the user manually amended the
127 commit instead, which has been corrected.
128 (merge 10d2f35436 js/rebase-i-autosquash-fix later to maint).
129
130 * When fsmonitor is in use, after operation on submodules updates
131 .gitmodules, we lost track of the fact that we did so and relied on
132 stale fsmonitor data.
133 (merge 43f1180814 bp/mv-submodules-with-fsmonitor later to maint).
134
135 * Fix for a long-standing bug that leaves the index file corrupt when
136 it shrinks during a partial commit.
137 (merge 6c003d6ffb jk/reopen-tempfile-truncate later to maint).
138
139 * Further fix for O_APPEND emulation on Windows
140 (merge eeaf7ddac7 js/mingw-o-append later to maint).
141
142 * A corner case bugfix in "git rerere" code.
143 (merge ad2bf0d9b4 en/rerere-multi-stage-1-fix later to maint).
144
145 * "git add ':(attr:foo)'" is not supported and is supposed to be
146 rejected while the command line arguments are parsed, but we fail
147 to reject such a command line upfront.
148 (merge 84d938b732 nd/attr-pathspec-fix later to maint).
149
150 * Recent update broke the reachability algorithm when refs (e.g.
151 tags) that point at objects that are not commit were involved,
152 which has been fixed.
153
154 * "git rebase" etc. in Git 2.19 fails to abort when given an empty
155 commit log message as result of editing, which has been corrected.
156 (merge a3ec9eaf38 en/sequencer-empty-edit-result-aborts later to maint).
157
158 * The code to backfill objects in lazily cloned repository did not
159 work correctly, which has been corrected.
160 (merge e68302011c jt/lazy-object-fetch-fix later to maint).
161
162 * Update error messages given by "git remote" and make them consistent.
163 (merge 5025425dff ms/remote-error-message-update later to maint).
164
165 * "git update-ref" learned to make both "--no-deref" and "--stdin"
166 work at the same time.
167 (merge d345e9fbe7 en/update-ref-no-deref-stdin later to maint).
168
169 * Recently added "range-diff" had a corner-case bug to cause it
170 segfault, which has been corrected.
171 (merge e467a90c7a tg/range-diff-corner-case-fix later to maint).
172
173 * Code cleanup, docfix, build fix, etc.
174 (merge 96a7501aad ts/doc-build-manpage-xsl-quietly later to maint).
175 (merge b9b07efdb2 tg/conflict-marker-size later to maint).
176 (merge fa0aeea770 sg/doc-trace-appends later to maint).
177 (merge d64324cb60 tb/void-check-attr later to maint).
178 (merge c3b9bc94b9 en/double-semicolon-fix later to maint).
179 (merge 79336116f5 sg/t3701-tighten-trace later to maint).
180 (merge 801fa63a90 jk/dev-build-format-security later to maint).
181 (merge 0597dd62ba sb/string-list-remove-unused later to maint).
182 (merge db2d36fad8 bw/protocol-v2 later to maint).
183 (merge 456d7cd3a9 sg/split-index-test later to maint).