Merge branch 'nd/ita-empty-commit'

When new paths were added by "git add -N" to the index, it was
enough to circumvent the check by "git commit" to refrain from
making an empty commit without "--allow-empty".  The same logic
prevented "git status" to show such a path as "new file" in the
"Changes not staged for commit" section.

* nd/ita-empty-commit:
  commit: don't be fooled by ita entries when creating initial commit
  commit: fix empty commit creation when there's no changes but ita entries
  diff: add --ita-[in]visible-in-index
  diff-lib: allow ita entries treated as "not yet exist in index"

Documentation/diff-options.txt

@@ -572,5 +572,13 @@ endif::git-format-patch[]
 --line-prefix=<prefix>::
 	Prepend an additional prefix to every line of output.
 
+--ita-invisible-in-index::
+	By default entries added by "git add -N" appear as an existing
+	empty file in "git diff" and a new file in "git diff --cached".
+	This option makes the entry appear as a new file in "git diff"
+	and non-existent in "git diff --cached". This option could be
+	reverted with `--ita-visible-in-index`. Both options are
+	experimental and could be removed in future.
+
 For more detailed explanation on these common options, see also
 linkgit:gitdiffcore[7].

builtin/commit.c

@@ -894,9 +894,14 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		if (amend)
 			parent = "HEAD^1";
 
-		if (get_sha1(parent, sha1))
+		if (get_sha1(parent, sha1)) {
-			commitable = !!active_nr;
+			int i, ita_nr = 0;
-		else {
+
+			for (i = 0; i < active_nr; i++)
+				if (ce_intent_to_add(active_cache[i]))
+					ita_nr++;
+			commitable = active_nr - ita_nr > 0;
+		} else {
 			/*
 			 * Unless the user did explicitly request a submodule
 			 * ignore mode by passing a command line option we do
@@ -910,7 +915,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 			if (ignore_submodule_arg &&
 			    !strcmp(ignore_submodule_arg, "all"))
 				diff_flags |= DIFF_OPT_IGNORE_SUBMODULES;
-			commitable = index_differs_from(parent, diff_flags);
+			commitable = index_differs_from(parent, diff_flags, 1);
 		}
 	}
 	strbuf_release(&committer_ident);

diff-lib.c

@@ -214,6 +214,12 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 					       !is_null_oid(&ce->oid),
 					       ce->name, 0);
 				continue;
+			} else if (revs->diffopt.ita_invisible_in_index &&
+				   ce_intent_to_add(ce)) {
+				diff_addremove(&revs->diffopt, '+', ce->ce_mode,
+					       EMPTY_BLOB_SHA1_BIN, 0,
+					       ce->name, 0);
+				continue;
 			}
 
 			changed = match_stat_with_submodule(&revs->diffopt, ce, &st,
@@ -379,6 +385,14 @@ static void do_oneway_diff(struct unpack_trees_options *o,
 	struct rev_info *revs = o->unpack_data;
 	int match_missing, cached;
 
+	/* i-t-a entries do not actually exist in the index */
+	if (revs->diffopt.ita_invisible_in_index &&
+	    idx && ce_intent_to_add(idx)) {
+		idx = NULL;
+		if (!tree)
+			return;	/* nothing to diff.. */
+	}
+
 	/* if the entry is not checked out, don't examine work tree */
 	cached = o->index_only ||
 		(idx && ((idx->ce_flags & CE_VALID) || ce_skip_worktree(idx)));
@@ -521,7 +535,8 @@ int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 	return 0;
 }
 
-int index_differs_from(const char *def, int diff_flags)
+int index_differs_from(const char *def, int diff_flags,
+		       int ita_invisible_in_index)
 {
 	struct rev_info rev;
 	struct setup_revision_opt opt;
@@ -533,6 +548,7 @@ int index_differs_from(const char *def, int diff_flags)
 	DIFF_OPT_SET(&rev.diffopt, QUICK);
 	DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
 	rev.diffopt.flags |= diff_flags;
+	rev.diffopt.ita_invisible_in_index = ita_invisible_in_index;
 	run_diff_index(&rev, 1);
 	if (rev.pending.alloc)
 		free(rev.pending.objects);

diff.c

@@ -3987,6 +3987,10 @@ int diff_opt_parse(struct diff_options *options,
 		return parse_submodule_opt(options, arg);
 	else if (skip_prefix(arg, "--ws-error-highlight=", &arg))
 		return parse_ws_error_highlight_opt(options, arg);
+	else if (!strcmp(arg, "--ita-invisible-in-index"))
+		options->ita_invisible_in_index = 1;
+	else if (!strcmp(arg, "--ita-visible-in-index"))
+		options->ita_invisible_in_index = 0;
 
 	/* misc options */
 	else if (!strcmp(arg, "-z"))

diff.h

@@ -146,6 +146,7 @@ struct diff_options {
 	int dirstat_permille;
 	int setup;
 	int abbrev;
+	int ita_invisible_in_index;
 /* white-space error highlighting */
 #define WSEH_NEW 1
 #define WSEH_CONTEXT 2
@@ -360,7 +361,7 @@ extern int diff_result_code(struct diff_options *, int);
 
 extern void diff_no_index(struct rev_info *, int, const char **);
 
-extern int index_differs_from(const char *def, int diff_flags);
+extern int index_differs_from(const char *def, int diff_flags, int ita_invisible_in_index);
 
 /*
  * Fill the contents of the filespec "df", respecting any textconv defined by

sequencer.c

@@ -658,7 +658,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 		unborn = get_sha1("HEAD", head);
 		if (unborn)
 			hashcpy(head, EMPTY_TREE_SHA1_BIN);
-		if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD", 0))
+		if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD", 0, 0))
 			return error_dirty_index(opts);
 	}
 	discard_cache();
@@ -1312,7 +1312,7 @@ int sequencer_continue(struct replay_opts *opts)
 		if (res)
 			goto release_todo_list;
 	}
-	if (index_differs_from("HEAD", 0)) {
+	if (index_differs_from("HEAD", 0, 0)) {
 		res = error_dirty_index(opts);
 		goto release_todo_list;
 	}

t/t2203-add-intent.sh

@@ -5,10 +5,24 @@ test_description='Intent to add'
 . ./test-lib.sh
 
 test_expect_success 'intent to add' '
+	test_commit 1 &&
+	git rm 1.t &&
+	echo hello >1.t &&
 	echo hello >file &&
 	echo hello >elif &&
 	git add -N file &&
-	git add elif
+	git add elif &&
+	git add -N 1.t
+'
+
+test_expect_success 'git status' '
+	git status --porcelain | grep -v actual >actual &&
+	cat >expect <<-\EOF &&
+	DA 1.t
+	A  elif
+	 A file
+	EOF
+	test_cmp expect actual
 '
 
 test_expect_success 'check result of "add -N"' '
@@ -43,7 +57,9 @@ test_expect_success 'i-t-a entry is simply ignored' '
 	git add -N nitfol &&
 	git commit -m second &&
 	test $(git ls-tree HEAD -- nitfol | wc -l) = 0 &&
-	test $(git diff --name-only HEAD -- nitfol | wc -l) = 1
+	test $(git diff --name-only HEAD -- nitfol | wc -l) = 1 &&
+	test $(git diff --name-only --ita-invisible-in-index HEAD -- nitfol | wc -l) = 0 &&
+	test $(git diff --name-only --ita-invisible-in-index -- nitfol | wc -l) = 1
 '
 
 test_expect_success 'can commit with an unrelated i-t-a entry in index' '
@@ -113,5 +129,26 @@ test_expect_success 'cache-tree does skip dir that becomes empty' '
 	)
 '
 
+test_expect_success 'commit: ita entries ignored in empty intial commit check' '
+	git init empty-intial-commit &&
+	(
+		cd empty-intial-commit &&
+		: >one &&
+		git add -N one &&
+		test_must_fail git commit -m nothing-new-here
+	)
+'
+
+test_expect_success 'commit: ita entries ignored in empty commit check' '
+	git init empty-subsequent-commit &&
+	(
+		cd empty-subsequent-commit &&
+		test_commit one &&
+		: >two &&
+		git add -N two &&
+		test_must_fail git commit -m nothing-new-here
+	)
+'
+
 test_done
 

t/t7064-wtstatus-pv2.sh

@@ -246,8 +246,8 @@ test_expect_success 'verify --intent-to-add output' '
 	git add --intent-to-add intent1.add intent2.add &&
 
 	cat >expect <<-EOF &&
-	1 AM N... 000000 100644 100644 $_z40 $EMPTY_BLOB intent1.add
+	1 .A N... 000000 000000 100644 $_z40 $_z40 intent1.add
-	1 AM N... 000000 100644 100644 $_z40 $EMPTY_BLOB intent2.add
+	1 .A N... 000000 000000 100644 $_z40 $_z40 intent2.add
 	EOF
 
 	git status --porcelain=v2 >actual &&

wt-status.c

@@ -438,7 +438,7 @@ static void wt_status_collect_changed_cb(struct diff_queue_struct *q,
 
 		switch (p->status) {
 		case DIFF_STATUS_ADDED:
-			die("BUG: worktree status add???");
+			d->mode_worktree = p->two->mode;
 			break;
 
 		case DIFF_STATUS_DELETED:
@@ -548,6 +548,7 @@ static void wt_status_collect_changes_worktree(struct wt_status *s)
 	setup_revisions(0, NULL, &rev, NULL);
 	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
 	DIFF_OPT_SET(&rev.diffopt, DIRTY_SUBMODULES);
+	rev.diffopt.ita_invisible_in_index = 1;
 	if (!s->show_untracked_files)
 		DIFF_OPT_SET(&rev.diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 	if (s->ignore_submodule_arg) {
@@ -571,6 +572,7 @@ static void wt_status_collect_changes_index(struct wt_status *s)
 	setup_revisions(0, NULL, &rev, &opt);
 
 	DIFF_OPT_SET(&rev.diffopt, OVERRIDE_SUBMODULE_CONFIG);
+	rev.diffopt.ita_invisible_in_index = 1;
 	if (s->ignore_submodule_arg) {
 		handle_ignore_submodules_arg(&rev.diffopt, s->ignore_submodule_arg);
 	} else {
@@ -606,6 +608,8 @@ static void wt_status_collect_changes_initial(struct wt_status *s)
 
 		if (!ce_path_match(ce, &s->pathspec, NULL))
 			continue;
+		if (ce_intent_to_add(ce))
+			continue;
 		it = string_list_insert(&s->change, ce->name);
 		d = it->util;
 		if (!d) {
@@ -912,6 +916,7 @@ static void wt_longstatus_print_verbose(struct wt_status *s)
 
 	init_revisions(&rev, NULL);
 	DIFF_OPT_SET(&rev.diffopt, ALLOW_TEXTCONV);
+	rev.diffopt.ita_invisible_in_index = 1;
 
 	memset(&opt, 0, sizeof(opt));
 	opt.def = s->is_initial ? EMPTY_TREE_SHA1_HEX : s->reference;