git-commit-vandalism/rebase-interactive.c
Elijah Newren d48e5e21da rebase (interactive-backend): make --keep-empty the default
Different rebase backends have different treatment for commits which
start empty (i.e. have no changes relative to their parent), and the
--keep-empty option was added at some point to allow adjusting behavior.
The handling of commits which start empty is actually quite similar to
commit b00bf1c9a8 (git-rebase: make --allow-empty-message the default,
2018-06-27), which pointed out that the behavior for various backends is
often more happenstance than design.  The specific change made in that
commit is actually quite relevant as well and much of the logic there
directly applies here.

It makes a lot of sense in 'git commit' to error out on the creation of
empty commits, unless an override flag is provided.  However, once
someone determines that there is a rare case that merits using the
manual override to create such a commit, it is somewhere between
annoying and harmful to have to take extra steps to keep such
intentional commits around.  Granted, empty commits are quite rare,
which is why handling of them doesn't get considered much and folks tend
to defer to existing (accidental) behavior and assume there was a reason
for it, leading them to just add flags (--keep-empty in this case) that
allow them to override the bad defaults.  Fix the interactive backend so
that --keep-empty is the default, much like we did with
--allow-empty-message.  The am backend should also be fixed to have
--keep-empty semantics for commits that start empty, but that is not
included in this patch other than a testcase documenting the failure.

Note that there was one test in t3421 which appears to have been written
expecting --keep-empty to not be the default as correct behavior.  This
test was introduced in commit 00b8be5a4d ("add tests for rebasing of
empty commits", 2013-06-06), which was part of a series focusing on
rebase topology and which had an interesting original cover letter at
https://lore.kernel.org/git/1347949878-12578-1-git-send-email-martinvonz@gmail.com/
which noted
    Your input especially appreciated on whether you agree with the
    intent of the test cases.
and then went into a long example about how one of the many tests added
had several questions about whether it was correct.  As such, I believe
most the tests in that series were about testing rebase topology with as
many different flags as possible and were not trying to state in general
how those flags should behave otherwise.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00

185 lines
6.0 KiB
C

#include "cache.h"
#include "commit.h"
#include "sequencer.h"
#include "rebase-interactive.h"
#include "strbuf.h"
#include "commit-slab.h"
#include "config.h"
enum missing_commit_check_level {
MISSING_COMMIT_CHECK_IGNORE = 0,
MISSING_COMMIT_CHECK_WARN,
MISSING_COMMIT_CHECK_ERROR
};
static enum missing_commit_check_level get_missing_commit_check_level(void)
{
const char *value;
if (git_config_get_value("rebase.missingcommitscheck", &value) ||
!strcasecmp("ignore", value))
return MISSING_COMMIT_CHECK_IGNORE;
if (!strcasecmp("warn", value))
return MISSING_COMMIT_CHECK_WARN;
if (!strcasecmp("error", value))
return MISSING_COMMIT_CHECK_ERROR;
warning(_("unrecognized setting %s for option "
"rebase.missingCommitsCheck. Ignoring."), value);
return MISSING_COMMIT_CHECK_IGNORE;
}
void append_todo_help(int command_count,
const char *shortrevisions, const char *shortonto,
struct strbuf *buf)
{
const char *msg = _("\nCommands:\n"
"p, pick <commit> = use commit\n"
"r, reword <commit> = use commit, but edit the commit message\n"
"e, edit <commit> = use commit, but stop for amending\n"
"s, squash <commit> = use commit, but meld into previous commit\n"
"f, fixup <commit> = like \"squash\", but discard this commit's log message\n"
"x, exec <command> = run command (the rest of the line) using shell\n"
"b, break = stop here (continue rebase later with 'git rebase --continue')\n"
"d, drop <commit> = remove commit\n"
"l, label <label> = label current HEAD with a name\n"
"t, reset <label> = reset HEAD to a label\n"
"m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]\n"
". create a merge commit using the original merge commit's\n"
". message (or the oneline, if no original merge commit was\n"
". specified). Use -c <commit> to reword the commit message.\n"
"\n"
"These lines can be re-ordered; they are executed from top to bottom.\n");
unsigned edit_todo = !(shortrevisions && shortonto);
if (!edit_todo) {
strbuf_addch(buf, '\n');
strbuf_commented_addf(buf, Q_("Rebase %s onto %s (%d command)",
"Rebase %s onto %s (%d commands)",
command_count),
shortrevisions, shortonto, command_count);
}
strbuf_add_commented_lines(buf, msg, strlen(msg));
if (get_missing_commit_check_level() == MISSING_COMMIT_CHECK_ERROR)
msg = _("\nDo not remove any line. Use 'drop' "
"explicitly to remove a commit.\n");
else
msg = _("\nIf you remove a line here "
"THAT COMMIT WILL BE LOST.\n");
strbuf_add_commented_lines(buf, msg, strlen(msg));
if (edit_todo)
msg = _("\nYou are editing the todo file "
"of an ongoing interactive rebase.\n"
"To continue rebase after editing, run:\n"
" git rebase --continue\n\n");
else
msg = _("\nHowever, if you remove everything, "
"the rebase will be aborted.\n\n");
strbuf_add_commented_lines(buf, msg, strlen(msg));
}
int edit_todo_list(struct repository *r, struct todo_list *todo_list,
struct todo_list *new_todo, const char *shortrevisions,
const char *shortonto, unsigned flags)
{
const char *todo_file = rebase_path_todo();
unsigned initial = shortrevisions && shortonto;
/* If the user is editing the todo list, we first try to parse
* it. If there is an error, we do not return, because the user
* might want to fix it in the first place. */
if (!initial)
todo_list_parse_insn_buffer(r, todo_list->buf.buf, todo_list);
if (todo_list_write_to_file(r, todo_list, todo_file, shortrevisions, shortonto,
-1, flags | TODO_LIST_SHORTEN_IDS | TODO_LIST_APPEND_TODO_HELP))
return error_errno(_("could not write '%s'"), todo_file);
if (initial && copy_file(rebase_path_todo_backup(), todo_file, 0666))
return error(_("could not copy '%s' to '%s'."), todo_file,
rebase_path_todo_backup());
if (launch_sequence_editor(todo_file, &new_todo->buf, NULL))
return -2;
strbuf_stripspace(&new_todo->buf, 1);
if (initial && new_todo->buf.len == 0)
return -3;
/* For the initial edit, the todo list gets parsed in
* complete_action(). */
if (!initial)
return todo_list_parse_insn_buffer(r, new_todo->buf.buf, new_todo);
return 0;
}
define_commit_slab(commit_seen, unsigned char);
/*
* Check if the user dropped some commits by mistake
* Behaviour determined by rebase.missingCommitsCheck.
* Check if there is an unrecognized command or a
* bad SHA-1 in a command.
*/
int todo_list_check(struct todo_list *old_todo, struct todo_list *new_todo)
{
enum missing_commit_check_level check_level = get_missing_commit_check_level();
struct strbuf missing = STRBUF_INIT;
int res = 0, i;
struct commit_seen commit_seen;
init_commit_seen(&commit_seen);
if (check_level == MISSING_COMMIT_CHECK_IGNORE)
goto leave_check;
/* Mark the commits in git-rebase-todo as seen */
for (i = 0; i < new_todo->nr; i++) {
struct commit *commit = new_todo->items[i].commit;
if (commit)
*commit_seen_at(&commit_seen, commit) = 1;
}
/* Find commits in git-rebase-todo.backup yet unseen */
for (i = old_todo->nr - 1; i >= 0; i--) {
struct todo_item *item = old_todo->items + i;
struct commit *commit = item->commit;
if (commit && !*commit_seen_at(&commit_seen, commit)) {
strbuf_addf(&missing, " - %s %.*s\n",
find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV),
item->arg_len,
todo_item_get_arg(old_todo, item));
*commit_seen_at(&commit_seen, commit) = 1;
}
}
/* Warn about missing commits */
if (!missing.len)
goto leave_check;
if (check_level == MISSING_COMMIT_CHECK_ERROR)
res = 1;
fprintf(stderr,
_("Warning: some commits may have been dropped accidentally.\n"
"Dropped commits (newer to older):\n"));
/* Make the list user-friendly and display */
fputs(missing.buf, stderr);
strbuf_release(&missing);
fprintf(stderr, _("To avoid this message, use \"drop\" to "
"explicitly remove a commit.\n\n"
"Use 'git config rebase.missingCommitsCheck' to change "
"the level of warnings.\n"
"The possible behaviours are: ignore, warn, error.\n\n"));
leave_check:
clear_commit_seen(&commit_seen);
return res;
}