Jeff King <peff@xxxxxxxx> writes:
> Want to do a proof-of-concept patch? Then we can get some real timings.
This was about
> > 2. When leaving the detached state, notice that we have commits not
> > contained in any other ref and pop up an "are you sure you want to
> > lose these commits" dialog, with an option to create a branch. This
> > is something we considered and rejected for the CLI, but I wonder
> > if it makes more sense for git-gui.
I thought about counting remaining commits, but decided against it. The
cost has already paid (the "limited" traversal already has happend), so it
may not be too bad to show each of them in oneline format if somebody
really wanted to to tell the user "here are the stuff you are about to
lose".
Also it might make sense to have a training wheel option of forcing
"checkout -f branch-I-wanted-to-go" in this case as an extra safety valve,
and it would be even Ok to enable the training wheel by default, as long
as annoyed experts can turn it off via configuration.
builtin/checkout.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 60 insertions(+), 6 deletions(-)
diff --git a/builtin/checkout.c b/builtin/checkout.c
index cd7f56e..1f5376f 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -503,6 +503,17 @@ static void detach_advice(const char *old_path, const char *new_name)
fprintf(stderr, fmt, new_name);
}
+static void suggest_reattach(struct commit *commit)
+{
+ const char fmt[] =
+ "Note: you are about to abandon commit %1$s\n\n"
+ "None of your branches nor tags refer to this commit. If you want to\n"
+ "keep this commit, you can do so by creating a new branch. Example:\n\n"
+ " git branch new_branch_name %1$s\n\n";
+
+ fprintf(stderr, fmt, sha1_to_hex(commit->object.sha1));
+}
+
static void update_refs_for_switch(struct checkout_opts *opts,
struct branch_info *old,
struct branch_info *new)
@@ -578,6 +589,54 @@ static void update_refs_for_switch(struct checkout_opts *opts,
report_tracking(new);
}
+struct rev_list_args {
+ int argc;
+ int alloc;
+ const char **argv;
+};
+
+static void add_one_rev_list_arg(struct rev_list_args *args, const char *s)
+{
+ ALLOC_GROW(args->argv, args->argc + 1, args->alloc);
+ args->argv[args->argc++] = s;
+}
+
+static int add_one_ref_to_rev_list_arg(const char *refname,
+ const unsigned char *sha1,
+ int flags,
+ void *cb_data)
+{
+ add_one_rev_list_arg(cb_data, refname);
+ return 0;
+}
+
+/*
+ * We are about to leave commit that was at the tip of a detached
+ * HEAD. If it is not reachable from any ref, this is the last chance
+ * for the user to do so without resorting to reflog.
+ */
+static void orphaned_commit_warning(struct commit *commit)
+{
+ struct rev_list_args args = { 0, 0, NULL };
+ struct rev_info revs;
+
+ add_one_rev_list_arg(&args, "(internal)");
+ add_one_rev_list_arg(&args, sha1_to_hex(commit->object.sha1));
+ add_one_rev_list_arg(&args, "--not");
+ for_each_ref(add_one_ref_to_rev_list_arg, &args);
+ add_one_rev_list_arg(&args, "--");
+ add_one_rev_list_arg(&args, NULL);
+
+ init_revisions(&revs, NULL);
+ if (setup_revisions(args.argc - 1, args.argv, &revs, NULL) != 1)
+ die("internal error: only -- alone should have been left");
+ if (prepare_revision_walk(&revs))
+ die("internal error in revision walk");
+ if (!(commit->object.flags & UNINTERESTING))
+ suggest_reattach(commit);
+ describe_detached_head("Previous HEAD position was", commit);
+}
+
static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
{
int ret = 0;
@@ -605,13 +664,8 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
if (ret)
return ret;
- /*
- * If we were on a detached HEAD, but have now moved to
- * a new commit, we want to mention the old commit once more
- * to remind the user that it might be lost.
- */
if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
- describe_detached_head("Previous HEAD position was", old.commit);
+ orphaned_commit_warning(old.commit);
update_refs_for_switch(opts, &old, new);
--
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