[PATCH v3 09/12] revision.c: --all adds HEAD from all worktrees

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Unless single_worktree is set, --all now adds HEAD from all worktrees.

Since reachable.c code does not use setup_revisions(), we need to call
other_head_refs_submodule() explicitly there to have the same effect on
"git prune", so that we won't accidentally delete objects needed by some
other HEADs.

A new FIXME is added because we would need something like

    int refs_other_head_refs(struct ref_store *, each_ref_fn, cb_data);

in addition to other_head_refs() to handle it, which might require

    int get_submodule_worktrees(const char *submodule, int flags);

It could be a separate topic to reduce the scope of this one.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 reachable.c      |  1 +
 refs.c           | 22 ++++++++++++++++++++++
 refs.h           |  1 +
 revision.c       | 13 +++++++++++++
 submodule.c      |  2 ++
 t/t5304-prune.sh | 12 ++++++++++++
 6 files changed, 51 insertions(+)

diff --git a/reachable.c b/reachable.c
index a8a979bd4f..a3b938b46c 100644
--- a/reachable.c
+++ b/reachable.c
@@ -177,6 +177,7 @@ void mark_reachable_objects(struct rev_info *revs, int mark_reflog,
 
 	/* detached HEAD is not included in the list above */
 	head_ref(add_one_ref, revs);
+	other_head_refs(add_one_ref, revs);
 
 	/* Add all reflog info */
 	if (mark_reflog)
diff --git a/refs.c b/refs.c
index 537052f7ba..23e3607674 100644
--- a/refs.c
+++ b/refs.c
@@ -1780,3 +1780,25 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 {
 	return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
 }
+
+int other_head_refs(each_ref_fn fn, void *cb_data)
+{
+	struct worktree **worktrees, **p;
+	int ret = 0;
+
+	worktrees = get_worktrees(0);
+	for (p = worktrees; *p; p++) {
+		struct worktree *wt = *p;
+		struct ref_store *refs;
+
+		if (wt->is_current)
+			continue;
+
+		refs = get_worktree_ref_store(wt);
+		ret = refs_head_ref(refs, fn, cb_data);
+		if (ret)
+			break;
+	}
+	free_worktrees(worktrees);
+	return ret;
+}
diff --git a/refs.h b/refs.h
index e06db37118..cc71b6c7a0 100644
--- a/refs.h
+++ b/refs.h
@@ -247,6 +247,7 @@ int refs_for_each_remote_ref(struct ref_store *refs,
 			     each_ref_fn fn, void *cb_data);
 
 int head_ref(each_ref_fn fn, void *cb_data);
+int other_head_refs(each_ref_fn fn, void *cb_data);
 int for_each_ref(each_ref_fn fn, void *cb_data);
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data);
 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data,
diff --git a/revision.c b/revision.c
index c329070c89..040a0064f6 100644
--- a/revision.c
+++ b/revision.c
@@ -2105,6 +2105,13 @@ static int handle_revision_pseudo_opt(const char *submodule,
 	int argcount;
 
 	if (submodule) {
+		/*
+		 * We need some something like get_submodule_worktrees()
+		 * before we can go through all worktrees of a submodule,
+		 * .e.g with adding all HEADs from --all, which is not
+		 * supported right now, so stick to single worktree.
+		 */
+		assert(revs->single_worktree != 0);
 		refs = get_submodule_ref_store(submodule);
 	} else
 		refs = get_main_ref_store();
@@ -2122,6 +2129,12 @@ static int handle_revision_pseudo_opt(const char *submodule,
 	if (!strcmp(arg, "--all")) {
 		handle_refs(refs, revs, *flags, refs_for_each_ref);
 		handle_refs(refs, revs, *flags, refs_head_ref);
+		if (!revs->single_worktree) {
+			struct all_refs_cb cb;
+
+			init_all_refs_cb(&cb, revs, *flags);
+			other_head_refs(handle_one_ref, &cb);
+		}
 		clear_ref_exclusion(&revs->ref_excludes);
 	} else if (!strcmp(arg, "--branches")) {
 		handle_refs(refs, revs, *flags, refs_for_each_branch_ref);
diff --git a/submodule.c b/submodule.c
index a31f68812c..8c5af6e7f3 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1225,6 +1225,8 @@ static int find_first_merges(struct object_array *result, const char *path,
 			oid_to_hex(&a->object.oid));
 	init_revisions(&revs, NULL);
 	rev_opts.submodule = path;
+	/* FIXME: can't handle linked worktrees in submodules yet */
+	revs.single_worktree = path != NULL;
 	setup_revisions(ARRAY_SIZE(rev_args)-1, rev_args, &revs, &rev_opts);
 
 	/* save all revisions from the above list that contain b */
diff --git a/t/t5304-prune.sh b/t/t5304-prune.sh
index cba45c7be9..683bdb031c 100755
--- a/t/t5304-prune.sh
+++ b/t/t5304-prune.sh
@@ -292,4 +292,16 @@ test_expect_success 'prune: handle index in multiple worktrees' '
 	test_cmp second-worktree/blob actual
 '
 
+test_expect_success 'prune: handle HEAD in multiple worktrees' '
+	git worktree add --detach third-worktree &&
+	echo "new blob for third-worktree" >third-worktree/blob &&
+	git -C third-worktree add blob &&
+	git -C third-worktree commit -m "third" &&
+	rm .git/worktrees/third-worktree/index &&
+	test_must_fail git -C third-worktree show :blob &&
+	git prune --expire=now &&
+	git -C third-worktree show HEAD:blob >actual &&
+	test_cmp third-worktree/blob actual
+'
+
 test_done
-- 
2.11.0.157.gd943d85