1 files changed, 32 insertions, 16 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 8afdf2b5c4..3e141fc149 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1,5 +1,5 @@
-#include "cache.h"
 #include "builtin.h"
+#include "lockfile.h"
 #include "parse-options.h"
 #include "refs.h"
 #include "commit.h"
@@ -22,8 +22,8 @@
 #include "argv-array.h"
 
 static const char * const checkout_usage[] = {
-	N_("git checkout [options] <branch>"),
-	N_("git checkout [options] [<branch>] -- <file>..."),
+	N_("git checkout [<options>] <branch>"),
+	N_("git checkout [<options>] [<branch>] -- <file>..."),
 	NULL,
 };
 
@@ -62,23 +62,41 @@ static int post_checkout_hook(struct commit *old, struct commit *new,
 
 }
 
-static int update_some(const unsigned char *sha1, const char *base, int baselen,
+static int update_some(const unsigned char *sha1, struct strbuf *base,
 		const char *pathname, unsigned mode, int stage, void *context)
 {
 	int len;
 	struct cache_entry *ce;
+	int pos;
 
 	if (S_ISDIR(mode))
 		return READ_TREE_RECURSIVE;
 
-	len = baselen + strlen(pathname);
+	len = base->len + strlen(pathname);
 	ce = xcalloc(1, cache_entry_size(len));
 	hashcpy(ce->sha1, sha1);
-	memcpy(ce->name, base, baselen);
-	memcpy(ce->name + baselen, pathname, len - baselen);
+	memcpy(ce->name, base->buf, base->len);
+	memcpy(ce->name + base->len, pathname, len - base->len);
 	ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
 	ce->ce_namelen = len;
 	ce->ce_mode = create_ce_mode(mode);
+
+	/*
+	 * If the entry is the same as the current index, we can leave the old
+	 * entry in place. Whether it is UPTODATE or not, checkout_entry will
+	 * do the right thing.
+	 */
+	pos = cache_name_pos(ce->name, ce->ce_namelen);
+	if (pos >= 0) {
+		struct cache_entry *old = active_cache[pos];
+		if (ce->ce_mode == old->ce_mode &&
+		    !hashcmp(ce->sha1, old->sha1)) {
+			old->ce_flags |= CE_UPDATE;
+			free(ce);
+			return 0;
+		}
+	}
+
 	add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 	return 0;
 }
@@ -355,7 +373,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
-	read_ref_full("HEAD", rev, 0, &flag);
+	read_ref_full("HEAD", 0, rev, &flag);
 	head = lookup_commit_reference_gently(rev, 1);
 
 	errs |= post_checkout_hook(head, head, 0);
@@ -728,7 +746,7 @@ static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 			_(
 			"If you want to keep them by creating a new branch, "
 			"this may be a good time\nto do so with:\n\n"
-			" git branch new_branch_name %s\n\n"),
+			" git branch <new-branch-name> %s\n\n"),
 			find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 }
 
@@ -775,7 +793,7 @@ static int switch_branches(const struct checkout_opts *opts,
 	unsigned char rev[20];
 	int flag, writeout_error = 0;
 	memset(&old, 0, sizeof(old));
-	old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
+	old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 	old.commit = lookup_commit_reference_gently(rev, 1);
 	if (!(flag & REF_ISSYMREF))
 		old.path = NULL;
@@ -1072,7 +1090,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		unsigned char rev[20];
 		int flag;
 
-		if (!read_ref_full("HEAD", rev, 0, &flag) &&
+		if (!read_ref_full("HEAD", 0, rev, &flag) &&
 		    (flag & REF_ISSYMREF) && is_null_sha1(rev))
 			return switch_unborn_to_new_branch(opts);
 	}
@@ -1109,7 +1127,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
 			 N_("do not limit pathspecs to sparse entries only")),
 		OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
-				N_("second guess 'git checkout no-such-branch'")),
+				N_("second guess 'git checkout <no-such-branch>'")),
 		OPT_END(),
 	};
 
@@ -1150,10 +1168,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		const char *argv0 = argv[0];
 		if (!argc || !strcmp(argv0, "--"))
 			die (_("--track needs a branch name"));
-		if (starts_with(argv0, "refs/"))
-			argv0 += 5;
-		if (starts_with(argv0, "remotes/"))
-			argv0 += 8;
+		skip_prefix(argv0, "refs/", &argv0);
+		skip_prefix(argv0, "remotes/", &argv0);
 		argv0 = strchr(argv0, '/');
 		if (!argv0 || !argv0[1])
 			die (_("Missing branch name; try -b"));