Merge branch 'tr/notes-display'

* tr/notes-display:
  git-notes(1): add a section about the meaning of history
  notes: track whether notes_trees were changed at all
  notes: add shorthand --ref to override GIT_NOTES_REF
  commit --amend: copy notes to the new commit
  rebase: support automatic notes copying
  notes: implement helpers needed for note copying during rewrite
  notes: implement 'git notes copy --stdin'
  rebase -i: invoke post-rewrite hook
  rebase: invoke post-rewrite hook
  commit --amend: invoke post-rewrite hook
  Documentation: document post-rewrite hook
  Support showing notes from more than one notes tree
  test-lib: unset GIT_NOTES_REF to stop it from influencing tests

Conflicts:
	git-am.sh
	refs.c

Documentation/config.txt

@@ -519,10 +519,12 @@ check that makes sure that existing object files will not get overwritten.
 core.notesRef::
 	When showing commit messages, also show notes which are stored in
 	the given ref.  This ref is expected to contain files named
-	after the full SHA-1 of the commit they annotate.
+	after the full SHA-1 of the commit they annotate.  The ref
+	must be fully qualified.
 +
 If such a file exists in the given ref, the referenced blob is read, and
-appended to the commit message, separated by a "Notes:" line.  If the
+appended to the commit message, separated by a "Notes (<refname>):"
+line (shortened to "Notes:" in the case of "refs/notes/commits").  If the
 given ref itself does not exist, it is not an error, but means that no
 notes should be printed.
 +
@@ -1334,6 +1336,53 @@ mergetool.keepTemporaries::
 mergetool.prompt::
 	Prompt before each invocation of the merge resolution program.
 
+notes.displayRef::
+	The (fully qualified) refname from which to show notes when
+	showing commit messages.  The value of this variable can be set
+	to a glob, in which case notes from all matching refs will be
+	shown.  You may also specify this configuration variable
+	several times.  A warning will be issued for refs that do not
+	exist, but a glob that does not match any refs is silently
+	ignored.
++
+This setting can be overridden with the `GIT_NOTES_DISPLAY_REF`
+environment variable, which must be a colon separated list of refs or
+globs.
++
+The effective value of "core.notesRef" (possibly overridden by
+GIT_NOTES_REF) is also implicitly added to the list of refs to be
+displayed.
+
+notes.rewrite.<command>::
+	When rewriting commits with <command> (currently `amend` or
+	`rebase`) and this variable is set to `true`, git
+	automatically copies your notes from the original to the
+	rewritten commit.  Defaults to `true`, but see
+	"notes.rewriteRef" below.
++
+This setting can be overridden with the `GIT_NOTES_REWRITE_REF`
+environment variable, which must be a colon separated list of refs or
+globs.
+
+notes.rewriteMode::
+	When copying notes during a rewrite (see the
+	"notes.rewrite.<command>" option), determines what to do if
+	the target commit already has a note.  Must be one of
+	`overwrite`, `concatenate`, or `ignore`.  Defaults to
+	`concatenate`.
++
+This setting can be overridden with the `GIT_NOTES_REWRITE_MODE`
+environment variable.
+
+notes.rewriteRef::
+	When copying notes during a rewrite, specifies the (fully
+	qualified) ref whose notes should be copied.  The ref may be a
+	glob, in which case notes in all matching refs will be copied.
+	You may also specify this configuration several times.
++
+Does not have a default value; you must configure this variable to
+enable note rewriting.
+
 pack.window::
 	The size of the window used by linkgit:git-pack-objects[1] when no
 	window size is given on the command line. Defaults to 10.

Documentation/git-notes.txt

@@ -10,7 +10,7 @@ SYNOPSIS
 [verse]
 'git notes' [list [<object>]]
 'git notes' add [-f] [-F <file> | -m <msg> | (-c | -C) <object>] [<object>]
-'git notes' copy [-f] <from-object> <to-object>
+'git notes' copy [-f] ( --stdin | <from-object> <to-object> )
 'git notes' append [-F <file> | -m <msg> | (-c | -C) <object>] [<object>]
 'git notes' edit [<object>]
 'git notes' show [<object>]
@@ -27,12 +27,17 @@ A typical use of notes is to extend a commit message without having
 to change the commit itself. Such commit notes can be shown by `git log`
 along with the original commit message. To discern these notes from the
 message stored in the commit object, the notes are indented like the
-message, after an unindented line saying "Notes:".
+message, after an unindented line saying "Notes (<refname>):" (or
+"Notes:" for the default setting).
 
-To disable notes, you have to set the config variable core.notesRef to
-the empty string.  Alternatively, you can set it to a different ref,
-something like "refs/notes/bugzilla".  This setting can be overridden
-by the environment variable "GIT_NOTES_REF".
+This command always manipulates the notes specified in "core.notesRef"
+(see linkgit:git-config[1]), which can be overridden by GIT_NOTES_REF.
+To change which notes are shown by 'git-log', see the
+"notes.displayRef" configuration.
+
+See the description of "notes.rewrite.<command>" in
+linkgit:git-config[1] for a way of carrying your notes across commands
+that rewrite commits.
 
 
 SUBCOMMANDS
@@ -55,6 +60,16 @@ copy::
 	object has none (use -f to overwrite existing notes to the
 	second object). This subcommand is equivalent to:
 	`git notes add [-f] -C $(git notes list <from-object>) <to-object>`
++
+In `\--stdin` mode, take lines in the format
++
+----------
+<from-object> SP <to-object> [ SP <rest> ] LF
+----------
++
+on standard input, and copy the notes from each <from-object> to its
+corresponding <to-object>.  (The optional `<rest>` is ignored so that
+the command can read the input given to the `post-rewrite` hook.)
 
 append::
 	Append to the notes of an existing object (defaults to HEAD).
@@ -101,6 +116,25 @@ OPTIONS
 	Like '-C', but with '-c' the editor is invoked, so that
 	the user can further edit the note message.
 
+--ref <ref>::
+	Manipulate the notes tree in <ref>.  This overrides both
+	GIT_NOTES_REF and the "core.notesRef" configuration.  The ref
+	is taken to be in `refs/notes/` if it is not qualified.
+
+
+NOTES
+-----
+
+Every notes change creates a new commit at the specified notes ref.
+You can therefore inspect the history of the notes by invoking, e.g.,
+`git log -p notes/commits`.
+
+Currently the commit message only records which operation triggered
+the update, and the commit authorship is determined according to the
+usual rules (see linkgit:git-commit[1]).  These details may change in
+the future.
+
+
 Author
 ------
 Written by Johannes Schindelin <johannes.schindelin@gmx.de> and

Documentation/githooks.txt

@@ -317,6 +317,44 @@ This hook is invoked by 'git gc --auto'. It takes no parameter, and
 exiting with non-zero status from this script causes the 'git gc --auto'
 to abort.
 
+post-rewrite
+~~~~~~~~~~~~
+
+This hook is invoked by commands that rewrite commits (`git commit
+--amend`, 'git-rebase'; currently 'git-filter-branch' does 'not' call
+it!).  Its first argument denotes the command it was invoked by:
+currently one of `amend` or `rebase`.  Further command-dependent
+arguments may be passed in the future.
+
+The hook receives a list of the rewritten commits on stdin, in the
+format
+
+  <old-sha1> SP <new-sha1> [ SP <extra-info> ] LF
+
+The 'extra-info' is again command-dependent.  If it is empty, the
+preceding SP is also omitted.  Currently, no commands pass any
+'extra-info'.
+
+The hook always runs after the automatic note copying (see
+"notes.rewrite.<command>" in linkgit:git-config.txt) has happened, and
+thus has access to these notes.
+
+The following command-specific comments apply:
+
+rebase::
+	For the 'squash' and 'fixup' operation, all commits that were
+	squashed are listed as being rewritten to the squashed commit.
+	This means that there will be several lines sharing the same
+	'new-sha1'.
++
+The commits are guaranteed to be listed in the order that they were
+processed by rebase.
+
+There is no default 'post-rewrite' hook, but see the
+`post-receive-copy-notes` script in `contrib/hooks` for an example
+that copies your git-notes to the rewritten commits.
+
+
 GIT
 ---
 Part of the linkgit:git[1] suite

Documentation/pretty-options.txt

@@ -30,9 +30,18 @@ people using 80-column terminals.
 	defaults to UTF-8.
 
 --no-notes::
---show-notes::
+--show-notes[=<ref>]::
 	Show the notes (see linkgit:git-notes[1]) that annotate the
 	commit, when showing the commit log message.  This is the default
 	for `git log`, `git show` and `git whatchanged` commands when
 	there is no `--pretty`, `--format` nor `--oneline` option is
 	given on the command line.
++
+With an optional argument, add this ref to the list of notes.  The ref
+is taken to be in `refs/notes/` if it is not qualified.
+
+--[no-]standard-notes::
+	Enable or disable populating the notes ref list from the
+	'core.notesRef' and 'notes.displayRef' variables (or
+	corresponding environment overrides).  Enabled by default.
+	See linkgit:git-config[1].

builtin.h

@@ -20,6 +20,23 @@ extern int commit_tree(const char *msg, unsigned char *tree,
 		struct commit_list *parents, unsigned char *ret,
 		const char *author);
 extern int commit_notes(struct notes_tree *t, const char *msg);
+
+struct notes_rewrite_cfg {
+	struct notes_tree **trees;
+	const char *cmd;
+	int enabled;
+	combine_notes_fn *combine;
+	struct string_list *refs;
+	int refs_from_env;
+	int mode_from_env;
+};
+
+combine_notes_fn *parse_combine_notes_fn(const char *v);
+struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd);
+int copy_note_for_rewrite(struct notes_rewrite_cfg *c,
+			  const unsigned char *from_obj, const unsigned char *to_obj);
+void finish_copy_notes_for_rewrite(struct notes_rewrite_cfg *c);
+
 extern int check_pager_config(const char *cmd);
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);

builtin/commit.c

@@ -66,6 +66,7 @@ static char *edit_message, *use_message;
 static char *author_name, *author_email, *author_date;
 static int all, edit_flag, also, interactive, only, amend, signoff;
 static int quiet, verbose, no_verify, allow_empty, dry_run, renew_authorship;
+static int no_post_rewrite;
 static char *untracked_files_arg, *force_date;
 /*
  * The default commit message cleanup mode will remove the lines
@@ -137,6 +138,7 @@ static struct option builtin_commit_options[] = {
 	OPT_BOOLEAN('z', "null", &null_termination,
 		    "terminate entries with NUL"),
 	OPT_BOOLEAN(0, "amend", &amend, "amend previous commit"),
+	OPT_BOOLEAN(0, "no-post-rewrite", &no_post_rewrite, "bypass post-rewrite hook"),
 	{ OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, "mode", "show untracked files, optional modes: all, normal, no. (Default: all)", PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
 	OPT_BOOLEAN(0, "allow-empty", &allow_empty, "ok to record an empty change"),
 	/* end commit contents options */
@@ -1160,6 +1162,40 @@ static int git_commit_config(const char *k, const char *v, void *cb)
 	return git_status_config(k, v, s);
 }
 
+static const char post_rewrite_hook[] = "hooks/post-rewrite";
+
+static int run_rewrite_hook(const unsigned char *oldsha1,
+			    const unsigned char *newsha1)
+{
+	/* oldsha1 SP newsha1 LF NUL */
+	static char buf[2*40 + 3];
+	struct child_process proc;
+	const char *argv[3];
+	int code;
+	size_t n;
+
+	if (access(git_path(post_rewrite_hook), X_OK) < 0)
+		return 0;
+
+	argv[0] = git_path(post_rewrite_hook);
+	argv[1] = "amend";
+	argv[2] = NULL;
+
+	memset(&proc, 0, sizeof(proc));
+	proc.argv = argv;
+	proc.in = -1;
+	proc.stdout_to_stderr = 1;
+
+	code = start_command(&proc);
+	if (code)
+		return code;
+	n = snprintf(buf, sizeof(buf), "%s %s\n",
+		     sha1_to_hex(oldsha1), sha1_to_hex(newsha1));
+	write_in_full(proc.in, buf, n);
+	close(proc.in);
+	return finish_command(&proc);
+}
+
 int cmd_commit(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf sb = STRBUF_INIT;
@@ -1303,6 +1339,15 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	rerere(0);
 	run_hook(get_index_file(), "post-commit", NULL);
+	if (amend && !no_post_rewrite) {
+		struct notes_rewrite_cfg *cfg;
+		cfg = init_copy_notes_for_rewrite("amend");
+		if (cfg) {
+			copy_note_for_rewrite(cfg, head_sha1, commit_sha1);
+			finish_copy_notes_for_rewrite(cfg);
+		}
+		run_rewrite_hook(head_sha1, commit_sha1);
+	}
 	if (!quiet)
 		print_summary(prefix, commit_sha1);
 

builtin/log.c

@@ -60,6 +60,8 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 
 	if (!rev->show_notes_given && !rev->pretty_given)
 		rev->show_notes = 1;
+	if (rev->show_notes)
+		init_display_notes(&rev->notes_opt);
 
 	if (rev->diffopt.pickaxe || rev->diffopt.filter)
 		rev->always_show_header = 0;
@@ -1105,6 +1107,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (!DIFF_OPT_TST(&rev.diffopt, TEXT) && !no_binary_diff)
 		DIFF_OPT_SET(&rev.diffopt, BINARY);
 
+	if (rev.show_notes)
+		init_display_notes(&rev.notes_opt);
+
 	if (!use_stdout)
 		output_directory = set_outdir(prefix, output_directory);