checkout -p: handle new files correctly

The original patch selection code was written for `git add -p`, and the
fundamental unit on which it works is a hunk.

We hacked around that to handle deletions back in 24ab81ae4d
(add-interactive: handle deletion of empty files, 2009-10-27). But `git
add -p` would never see a new file, since we only consider the set of
tracked files in the index.

However, since the same machinery was used for `git checkout -p` &
friends, we can see new files.

Handle this case specifically, adding a new prompt for it that is
modeled after the `deleted file` case.

This also fixes the problem where added _empty_ files could not be
staged via `git checkout -p`.

Reported-by: Merlin Büge <toni@bluenox07.de>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 23 insertions, 7 deletions

diff --git a/add-patch.c b/add-patch.c
index d8dafa8..eaace1b 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -9,7 +9,7 @@
 #include "compat/terminal.h"
 
 enum prompt_mode_type {
-	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,
+	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_ADDITION, PROMPT_HUNK,
 	PROMPT_MODE_MAX, /* must be last */
 };
 
@@ -32,6 +32,7 @@ static struct patch_mode patch_mode_add = {
 	.prompt_mode = {
 		N_("Stage mode change [y,n,q,a,d%s,?]? "),
 		N_("Stage deletion [y,n,q,a,d%s,?]? "),
+		N_("Stage addition [y,n,q,a,d%s,?]? "),
 		N_("Stage this hunk [y,n,q,a,d%s,?]? ")
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -53,6 +54,7 @@ static struct patch_mode patch_mode_stash = {
 	.prompt_mode = {
 		N_("Stash mode change [y,n,q,a,d%s,?]? "),
 		N_("Stash deletion [y,n,q,a,d%s,?]? "),
+		N_("Stash addition [y,n,q,a,d%s,?]? "),
 		N_("Stash this hunk [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -76,6 +78,7 @@ static struct patch_mode patch_mode_reset_head = {
 	.prompt_mode = {
 		N_("Unstage mode change [y,n,q,a,d%s,?]? "),
 		N_("Unstage deletion [y,n,q,a,d%s,?]? "),
+		N_("Unstage addition [y,n,q,a,d%s,?]? "),
 		N_("Unstage this hunk [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -98,6 +101,7 @@ static struct patch_mode patch_mode_reset_nothead = {
 	.prompt_mode = {
 		N_("Apply mode change to index [y,n,q,a,d%s,?]? "),
 		N_("Apply deletion to index [y,n,q,a,d%s,?]? "),
+		N_("Apply addition to index [y,n,q,a,d%s,?]? "),
 		N_("Apply this hunk to index [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -120,6 +124,7 @@ static struct patch_mode patch_mode_checkout_index = {
 	.prompt_mode = {
 		N_("Discard mode change from worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard deletion from worktree [y,n,q,a,d%s,?]? "),
+		N_("Discard addition from worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard this hunk from worktree [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -142,6 +147,7 @@ static struct patch_mode patch_mode_checkout_head = {
 	.prompt_mode = {
 		N_("Discard mode change from index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard deletion from index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Discard addition from index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard this hunk from index and worktree [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -163,6 +169,7 @@ static struct patch_mode patch_mode_checkout_nothead = {
 	.prompt_mode = {
 		N_("Apply mode change to index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Apply deletion to index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Apply addition to index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Apply this hunk to index and worktree [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -185,6 +192,7 @@ static struct patch_mode patch_mode_worktree_head = {
 	.prompt_mode = {
 		N_("Discard mode change from index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard deletion from index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Discard addition from index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Discard this hunk from index and worktree [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -206,6 +214,7 @@ static struct patch_mode patch_mode_worktree_nothead = {
 	.prompt_mode = {
 		N_("Apply mode change to index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Apply deletion to index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Apply addition to index and worktree [y,n,q,a,d%s,?]? "),
 		N_("Apply this hunk to index and worktree [y,n,q,a,d%s,?]? "),
 	},
 	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
@@ -247,7 +256,7 @@ struct add_p_state {
 		struct hunk head;
 		struct hunk *hunk;
 		size_t hunk_nr, hunk_alloc;
-		unsigned deleted:1, mode_change:1,binary:1;
+		unsigned deleted:1, added:1, mode_change:1,binary:1;
 	} *file_diff;
 	size_t file_diff_nr;
 
@@ -441,7 +450,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 	pend = p + plain->len;
 	while (p != pend) {
 		char *eol = memchr(p, '\n', pend - p);
-		const char *deleted = NULL, *mode_change = NULL;
+		const char *deleted = NULL, *added = NULL, *mode_change = NULL;
 
 		if (!eol)
 			eol = pend;
@@ -460,11 +469,12 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		} else if (p == plain->buf)
 			BUG("diff starts with unexpected line:\n"
 			    "%.*s\n", (int)(eol - p), p);
-		else if (file_diff->deleted)
+		else if (file_diff->deleted || file_diff->added)
 			; /* keep the rest of the file in a single "hunk" */
 		else if (starts_with(p, "@@ ") ||
 			 (hunk == &file_diff->head &&
-			  skip_prefix(p, "deleted file", &deleted))) {
+			  (skip_prefix(p, "deleted file", &deleted) ||
+			   skip_prefix(p, "new file", &added)))) {
 			if (marker == '-' || marker == '+')
 				/*
 				 * Should not happen; previous hunk did not end
@@ -484,6 +494,8 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 
 			if (deleted)
 				file_diff->deleted = 1;
+			else if (added)
+				file_diff->added = 1;
 			else if (parse_hunk_header(s, hunk) < 0)
 				return -1;
 
@@ -536,8 +548,10 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 			   starts_with(p, "Binary files "))
 			file_diff->binary = 1;
 
-		if (file_diff->deleted && file_diff->mode_change)
-			BUG("diff contains delete *and* a mode change?!?\n%.*s",
+		if (!!file_diff->deleted + !!file_diff->added +
+		    !!file_diff->mode_change > 1)
+			BUG("diff can only contain delete *or* add *or* a "
+			    "mode change?!?\n%.*s",
 			    (int)(eol - (plain->buf + file_diff->head.start)),
 			    plain->buf + file_diff->head.start);
 
@@ -1397,6 +1411,8 @@ static int patch_update_file(struct add_p_state *s,
 
 		if (file_diff->deleted)
 			prompt_mode_type = PROMPT_DELETION;
+		else if (file_diff->added)
+			prompt_mode_type = PROMPT_ADDITION;
 		else if (file_diff->mode_change && !hunk_index)
 			prompt_mode_type = PROMPT_MODE_CHANGE;
 		else