Comment lines have always been ignored but this is not documented.
The primary motivation here is to be reasonably complete in the
documentation of how trailers are parsed; this is after all the only
documentation page that documents this format. However, and going beyond
that point, we could imagine that someone would want to use this format
outside a commit (or tag) message context, like say in Git notes.
On the other hand, it seems far-fetched that someone would be caught
off guard by this considering that comment characters/strings are not
likely to be alphanumeric,[1] which would mean that these comment lines
would be treated as non-trailer lines if they were *not* detected and
removed as comment lines.
† 1: A notable exception is that Jujutsu VCS uses `JJ:` as
the comment string
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Two commits ago we moved new-trailers paragraph next to each other.
But there is something curious about two of them:
By default the new trailer will appear at the end of the trailer
block. [...]
Then a source block and a paragraph later:
By default, a `<key>=<value>` or `<key>:<value>` argument given
using `--trailer` will be appended after the existing trailers only
if [...]
Why are there two paragraphs that talk about how “By default” a trailer
will be appended?
We can make these paragraphs flow better, and with a more distinct
character each, by dividing the flow like this:
1. Declare that we are about to talk about `--trailer` appending
2. Explain the default behavior
3. Explain how this affects the trailer block
4. Then discuss what each trailer line will look like
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We chose to introduce the term “trailer block” into the documentation a
few commits ago.[1] It is used in the code though, so it is not a newly
invented term.
That term was useful to explain where the trailers are found (they
*trail* the message). But it is also useful here, where we explain
how trailers are added to existing messages, how trailer blocks are
found (beyond the simple case in the introduction), and how the end
of the message is found.
Also note that we simplify the “blank line” point. The text says:
A blank line will be added before the new trailer if there isn't one
already.
But this isn’t quite coherent. The previous sentence says “If there is
no existing trailer”, so we are in one of these modes:
1. discussing trailer blocks in general; or
2. discussing creating a new trailer block in particular.
If (1), then we shouldn’t add a blank line before the new trailer if
there exists a trailer block already. And if (2), then the “if there
isn’t one already” is redundant.[2] So just talking about the higher-
level “trailer block” simplifies the text, since we don’t have to worry
about the different contexts that *trailers* can find themselves in.
† 1: in commit “explain the format after the intro”
† 2: Note that non-trailer lines don’t matter here; if you have a
trailer block consisting of `(cherry picked from commit <commit>)`,
then you still shouldn’t insert a blank line before the new trailer
since that would create a new trailer block
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are three paragraphs that talk about how a new trailer is added.
But the first one is separated from the other two by two paragraphs
about how `key-alias` can make using `--trailer` more convenient. This
short how-to does not follow thematically from the previous paragraph,
and can wait until we have fully described how a new trailer is
added. So let’s move the three paragraphs about the new-trailer topic
together and move the how-to paragraphs after that.
***
Let’s now review the history of the document. Even if the document
is not quite correct in its current state, just doing the apparently
obvious edit without considering the history does not respect the
effort that went into changing the document in the past.
These three paragraphs were originally next to each other, in the first
version of the doc.[1] But extra sentences about this how-to topic was
added to the first paragraph nine years later:[2]
[...]
`': '` (one colon followed by one space). For convenience, the
<token> can be a shortened string key (e.g., "sign") instead of the
full string which should [...]
And then it was split into it’s own paragraph a little later.[3]
This evolution shows, in my opinion, that this how-to never followed
thematically from the existing topic. Which means that there is nothing
that was potentially lost to time that we need to restore or respect.
† 1: dfd66ddf (Documentation: add documentation for 'git
interpret-trailers', 2014-10-13)
† 2: eda2c44c (doc: trailer: mention 'key' in DESCRIPTION, 2023-06-15)
† 3: 6ccbc667 (trailer doc: <token> is a <key> or <keyAlias>, not both,
2023-09-07)
Suggested-by: D. Ben Knoble <ben.knoble+github@gmail.com>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
All of the examples speak of the Happy Path where everything works
as intended. But failure examples can also be instructive. Especially
for explaining again, by example, the key format (see previous commit).
This also allows us to demonstrate trailer block detection with a
concrete example.
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A trailer key must consist of ASCII alphanumeric characters and
hyphens *only*. Let’s document it explicitly instead of relying on
readers being conservative and only basing their trailer keys on the
documentation examples.[1]
The previous commit provided us with an appropriate paragraph to
describe the key format.
† 1: Technically they would then miss out on using digits in them since
all of the example keys just use letters and hyphens
Reported-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
You need to read the entire “Description” section in order to understand
the full trailer format. But there are many nuances, so that’s fine.
As a starter though we have an introductory example.[1] That turns out
to be crucial; the rest of this section talks about the mechanics of the
command and only incidentally the format itself.
Now, although the example might arguably be self-explanatory, we can
add a little preamble which defines the format in its simplest form as
well as define the most important terms.
Note that we name the “blank line” rule since I want to use that term
every time it comes up. It gets very mildly obfuscated if you call it
a “blank line” in one place[2] and “empty (or whitespace-only) ...” in
another one.[3]
We will define the format of the *key* in the next commit.
† 1: from d57fa7fc (doc: trailer: add more examples in DESCRIPTION,
2023-06-15)
† 2: `Documentation/git-interpret-trailers.adoc:86` in
5361983c (The 22nd batch, 2026-03-27)
† 3: `Documentation/git-interpret-trailers.adoc:93` in
5361983c (The 22nd batch, 2026-03-27)
Suggested-by: D. Ben Knoble <ben.knoble+github@gmail.com>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This command doesn’t interface with commits directly. You can
interpret or modify any kind of text, even though commit messages
are the most relevant.
The git(1) suite also isn’t restricted to only direct commit support
since git-tag(1) learned `--trailer` in 066cef77 (builtin/tag: add
--trailer option, 2024-05-05)
Now, we already introduce the command in the “Name” section as dealing
with commit messages as well. That is fine since that intro line needs
to remain pretty short.
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We now since the previous commit introduce the format as “trailer
metadata”. We can replace “structured information” with “metadata”
in the “Name” section to be consistent.
While “structured information” does emphasize that the data is not
loosely structured, we also say that this command adds to or parses
this format. I don’t think that we need to emphasize that it is
structured since clearly there is some structure there.
Both “metadata” and “structured information” can convey the same
information. But “metadata” is shorter and easier to deploy since
it’s just one word.
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We removed the initial comparison to email headers in the previous
commit. Now the introduction paragraph just says “trailer lines”, and
the only hint that this is metadata/structured information is the
“otherwise free-form” phrase.
Let’s replace “lines” with “metadata” since that is their purpose.
This also makes the introduction more consistent with how I chose
to define trailers in the glossary:[1] “Key-value metadata”. (We will
introduce “key–value” in the upcoming commit “explain the format after
the intro”.)
† 1: 68e3c69e (Documentation/glossary: describe "trailer", 2024-11-17)
Let’s not emphasize “trailer” here since we are going to define the term
in the upcoming commit “explain the format after the intro”.
Let’s call it “trailer metadata” rather than “trailers metadata”.
At first it seemed better to use the latter:
1. We’re introducing the jargon, and the format is often discussed as
plural “trailers”, with its constituent parts being singular
“trailer”
2. What this replaces uses “trailer”, but it rescues the plural mood
with “lines”
3. This is very soon going to go into the constituent parts, including
each trailer, so we’re contrasting the concept name (trailers) with
its parts
But:
1. The former reads better (most important)
2. “Trailer *metadata*” suggests plurality, similar to “trailer *lines*”
Helped-by: Matt Hunter <m@lfurio.us>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This command handles the trailer metadata format. But the command
isn’t introduced as such; it is instead introduced by stating that
these trailer lines look similar to RFC 822 email headers.
This is overwrought; most people do not deal directly with email
headers, and certainly not email RFCs.
Trailers are just key–value pairs that, like email headers, use colon
as the separator. The format in its simplest form is easy to describe
directly without comparing it to anything else; we will do that in the
upcoming commit “explain the format after the intro”.
For now, let’s:
• remove the first mention of email headers;
• keep the second, innocuous comparison with email line folding in the
middle; and
• remove the now-unneeded disclaimer that trailers do not share many of
the features of RFC 822 email headers—there is no invitation to
speculate that trailers would follow any other email format rules
since we do not compare them directly any more.
***
Talking about trailers as an RFC 822/2822-like format seems to go back
to the `--fixes`/`Fixes:` trailer topic,[1] the thread that precipitated
this command and in turn the first trailer support in git(1) beyond
adding s-o-b lines.
† 1: https://lore.kernel.org/all/20131027071407.GA11683@leaf/
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The unsigned integer that is used as an bitset to specify the kind
of branches interpret_branch_name() function has been changed to
use a dedicated enum type.
* jw/object-name-bitset-to-enum:
object-name: turn INTERPRET_BRANCH_* constants into enum values
"git apply" now reports the name of the input file along with the
line number when it encounters a corrupt patch, and correctly
resets the line counter when processing multiple patch files.
* jw/apply-corrupt-location:
apply: report input location in binary and garbage patch errors
apply: report input location in header parsing errors
apply: report the location of corrupt patches
split-index.c has been updated to not use the global the_repository
and the_hash_algo variables.
* rs/split-index-the-repo-fix:
split-index: stop using the_repository and the_hash_algo
The cleanup of remaining bitmaps in "ahead_behind()" has been
simplified.
* rs/ahead-behind-cleanup-optimization:
commit-reach: simplify cleanup of remaining bitmaps in ahead_behind ()
Code clean-up overdue by 19 years.
* jc/rerere-modern-strbuf-handling:
cocci: strbuf.buf is never NULL
rerere: update to modern representation of empty strbufs
Doc updates.
* kh/doc-interpret-trailers-1:
interpret-trailers: use placeholder instead of *
doc: config: convert trailers section to synopsis style
doc: interpret-trailers: normalize and fill out options
doc: interpret-trailers: convert to synopsis style
The reference-transaction hook was taught to be triggered before
taking locks on references in the "preparing" phase.
* ej/ref-transaction-hook-preparing:
refs: add 'preparing' phase to the reference-transaction hook
merge-file --object-id used to trigger a BUG when run in a linked
worktree, which has been fixed.
* mr/merge-file-object-id-worktree-fix:
merge-file: fix BUG when --object-id is used in a worktree
Uses of prio_queue as a LIFO stack of commits have been written
with commit_stack.
* rs/prio-queue-to-commit-stack:
use commit_stack instead of prio_queue in LIFO mode
The handling of the incomplete lines at the end by "git
diff-highlight" has been fixed.
* jk/diff-highlight-identical-pairs:
contrib/diff-highlight: do not highlight identical pairs
The logic to count objects has been cleaned up.
* ps/object-counting:
odb: introduce generic object counting
odb/source: introduce generic object counting
object-file: generalize counting objects
object-file: extract logic to approximate object count
packfile: extract logic to count number of objects
odb: stop including "odb/source.h"
Further work on incremental repacking using MIDX/bitmap
* tb/incremental-midx-part-3.2:
midx: enable reachability bitmaps during MIDX compaction
midx: implement MIDX compaction
t/helper/test-read-midx.c: plug memory leak when selecting layer
midx-write.c: factor fanout layering from `compute_sorted_entries()`
midx-write.c: enumerate `pack_int_id` values directly
midx-write.c: extract `fill_pack_from_midx()`
midx-write.c: introduce `midx_pack_perm()` helper
midx: do not require packs to be sorted in lexicographic order
midx-write.c: introduce `struct write_midx_opts`
midx-write.c: don't use `pack_perm` when assigning `bitmap_pos`
t/t5319-multi-pack-index.sh: fix copy-and-paste error in t5319.39
git-multi-pack-index(1): align SYNOPSIS with 'git multi-pack-index -h'
git-multi-pack-index(1): remove non-existent incompatibility
builtin/multi-pack-index.c: make '--progress' a common option
midx: introduce `midx_get_checksum_hex()`
midx: rename `get_midx_checksum()` to `midx_get_checksum_hash()`
midx: mark `get_midx_checksum()` arguments as const
Add a coccinelle rule to break the build when "struct strbuf" gets
passed by value.
* dd/cocci-do-not-pass-strbuf-by-value:
stash: do not pass strbuf by value
coccinelle: detect struct strbuf passed by value
"git diff -U<num>" was too lenient in its command line parsing and
took an empty string as a valid <num>.
* ty/doc-diff-u-wo-number:
diff: document -U without <n> as using default context
Reduce system overhead "git upload-pack" spends on relaying "git
pack-objects" output to the "git fetch" running on the other end of
the connection.
* ps/upload-pack-buffer-more-writes:
builtin/pack-objects: reduce lock contention when writing packfile data
csum-file: drop `hashfd_throughput()`
csum-file: introduce `hashfd_ext()`
sideband: use writev(3p) to send pktlines
wrapper: introduce writev(3p) wrappers
compat/posix: introduce writev(3p) wrapper
upload-pack: reduce lock contention when writing packfile data
upload-pack: prefer flushing data over sending keepalive
upload-pack: adapt keepalives based on buffering
upload-pack: fix debug statement when flushing packfile data
The final clean-up phase of the diff output could turn the result of
histogram diff algorithm suboptimal, which has been corrected.
* yc/histogram-hunk-shift-fix:
xdiff: re-diff shifted change groups when using histogram algorithm
"git history" learned the "split" subcommand.
* ps/history-split:
builtin/history: implement "split" subcommand
builtin/history: split out extended function to create commits
cache-tree: allow writing in-memory index as tree
add-patch: allow disabling editing of hunks
add-patch: add support for in-memory index patching
add-patch: remove dependency on "add-interactive" subsystem
add-patch: split out `struct interactive_options`
add-patch: split out header from "add-interactive.h"
"git fast-import" learned to optionally replace signature on
commits whose signatures get invalidated due to replaying by
signing afresh.
* jt/fast-import-sign-again:
fast-import: add mode to sign commits with invalid signatures
gpg-interface: allow sign_buffer() to use default signing key
commit: remove unused forward declaration
"imap-send" used to use functions whose use is going to be removed
with OpenSSL 4.0; rewrite them using public API that has been
available since OpenSSL 1.1 since 2016 or so.
* bb/imap-send-openssl-4.0-prep:
imap-send: move common code into function host_matches()
imap-send: use the OpenSSL API to access the subject common name
imap-send: use the OpenSSL API to access the subject alternative names
The code in "git help" that shows configuration items in sorted
order was awkwardly organized and prone to bugs.
* ac/help-sort-correctly:
help: cleanup the contruction of keys_uniq
Kristoffer Haugsbakk