Merge branch 'nd/checkout-option-parsing-fix'

The option parsing of "git checkout" had error checking, dwim and
defaulting missing options, all mixed in the code, and issuing an
appropriate error message with useful context was getting harder.
Reorganize the code and allow giving a proper diagnosis when the
user says "git checkout -b -t foo bar" (e.g. "-t" is not a good name
for a branch).

* nd/checkout-option-parsing-fix:
  checkout: reorder option handling
  checkout: move more parameters to struct checkout_opts
  checkout: pass "struct checkout_opts *" as const pointer

1 files changed, 158 insertions, 116 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index d287ee6e4..781295b2c 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -28,23 +28,25 @@ static const char * const checkout_usage[] = {
 };
 
 struct checkout_opts {
+	int patch_mode;
 	int quiet;
 	int merge;
 	int force;
 	int force_detach;
 	int writeout_stage;
-	int writeout_error;
 	int overwrite_ignore;
 
-	/* not set by parse_options */
-	int branch_exists;
-
 	const char *new_branch;
 	const char *new_branch_force;
 	const char *new_orphan_branch;
 	int new_branch_log;
 	enum branch_track track;
 	struct diff_options diff_options;
+
+	int branch_exists;
+	const char *prefix;
+	const char **pathspec;
+	struct tree *source_tree;
 };
 
 static int post_checkout_hook(struct commit *old, struct commit *new,
@@ -215,8 +217,8 @@ static int checkout_merged(int pos, struct checkout *state)
 	return status;
 }
 
-static int checkout_paths(struct tree *source_tree, const char **pathspec,
-			  const char *prefix, struct checkout_opts *opts)
+static int checkout_paths(const struct checkout_opts *opts,
+			  const char *revision)
 {
 	int pos;
 	struct checkout state;
@@ -228,37 +230,65 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	int stage = opts->writeout_stage;
 	int merge = opts->merge;
 	int newfd;
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+	struct lock_file *lock_file;
+
+	if (opts->track != BRANCH_TRACK_UNSPECIFIED)
+		die(_("'%s' cannot be used with updating paths"), "--track");
+
+	if (opts->new_branch_log)
+		die(_("'%s' cannot be used with updating paths"), "-l");
+
+	if (opts->force && opts->patch_mode)
+		die(_("'%s' cannot be used with updating paths"), "-f");
+
+	if (opts->force_detach)
+		die(_("'%s' cannot be used with updating paths"), "--detach");
+
+	if (opts->merge && opts->patch_mode)
+		die(_("'%s' cannot be used with %s"), "--merge", "--patch");
+
+	if (opts->force && opts->merge)
+		die(_("'%s' cannot be used with %s"), "-f", "-m");
+
+	if (opts->new_branch)
+		die(_("Cannot update paths and switch to branch '%s' at the same time."),
+		    opts->new_branch);
+
+	if (opts->patch_mode)
+		return run_add_interactive(revision, "--patch=checkout",
+					   opts->pathspec);
+
+	lock_file = xcalloc(1, sizeof(struct lock_file));
 
 	newfd = hold_locked_index(lock_file, 1);
-	if (read_cache_preload(pathspec) < 0)
+	if (read_cache_preload(opts->pathspec) < 0)
 		return error(_("corrupt index file"));
 
-	if (source_tree)
-		read_tree_some(source_tree, pathspec);
+	if (opts->source_tree)
+		read_tree_some(opts->source_tree, opts->pathspec);
 
-	for (pos = 0; pathspec[pos]; pos++)
+	for (pos = 0; opts->pathspec[pos]; pos++)
 		;
 	ps_matched = xcalloc(1, pos);
 
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
-		if (source_tree && !(ce->ce_flags & CE_UPDATE))
+		if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 			continue;
-		match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
+		match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
 	}
 
-	if (report_path_error(ps_matched, pathspec, prefix))
+	if (report_path_error(ps_matched, opts->pathspec, opts->prefix))
 		return 1;
 
 	/* "checkout -m path" to recreate conflicted state */
 	if (opts->merge)
-		unmerge_cache(pathspec);
+		unmerge_cache(opts->pathspec);
 
 	/* Any unmerged paths? */
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
-		if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
+		if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 			if (!ce_stage(ce))
 				continue;
 			if (opts->force) {
@@ -283,9 +313,9 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	state.refresh_cache = 1;
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
-		if (source_tree && !(ce->ce_flags & CE_UPDATE))
+		if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 			continue;
-		if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
+		if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
 			if (!ce_stage(ce)) {
 				errs |= checkout_entry(ce, &state, NULL);
 				continue;
@@ -309,7 +339,8 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	return errs;
 }
 
-static void show_local_changes(struct object *head, struct diff_options *opts)
+static void show_local_changes(struct object *head,
+			       const struct diff_options *opts)
 {
 	struct rev_info rev;
 	/* I think we want full paths, even if we're in a subdirectory. */
@@ -331,7 +362,8 @@ static void describe_detached_head(const char *msg, struct commit *commit)
 	strbuf_release(&sb);
 }
 
-static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
+static int reset_tree(struct tree *tree, const struct checkout_opts *o,
+		      int worktree, int *writeout_error)
 {
 	struct unpack_trees_options opts;
 	struct tree_desc tree_desc;
@@ -350,7 +382,7 @@ static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
 	init_tree_desc(&tree_desc, tree->buffer, tree->size);
 	switch (unpack_trees(1, &tree_desc, &opts)) {
 	case -2:
-		o->writeout_error = 1;
+		*writeout_error = 1;
 		/*
 		 * We return 0 nevertheless, as the index is all right
 		 * and more importantly we have made best efforts to
@@ -381,8 +413,10 @@ static void setup_branch_path(struct branch_info *branch)
 	branch->path = strbuf_detach(&buf, NULL);
 }
 
-static int merge_working_tree(struct checkout_opts *opts,
-			      struct branch_info *old, struct branch_info *new)
+static int merge_working_tree(const struct checkout_opts *opts,
+			      struct branch_info *old,
+			      struct branch_info *new,
+			      int *writeout_error)
 {
 	int ret;
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
@@ -393,7 +427,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 
 	resolve_undo_clear();
 	if (opts->force) {
-		ret = reset_tree(new->commit->tree, opts, 1);
+		ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 		if (ret)
 			return ret;
 	} else {
@@ -479,7 +513,8 @@ static int merge_working_tree(struct checkout_opts *opts,
 			o.verbosity = 0;
 			work = write_tree_from_memory(&o);
 
-			ret = reset_tree(new->commit->tree, opts, 1);
+			ret = reset_tree(new->commit->tree, opts, 1,
+					 writeout_error);
 			if (ret)
 				return ret;
 			o.ancestor = old->name;
@@ -487,7 +522,8 @@ static int merge_working_tree(struct checkout_opts *opts,
 			o.branch2 = "local";
 			merge_trees(&o, new->commit->tree, work,
 				old->commit->tree, &result);
-			ret = reset_tree(new->commit->tree, opts, 0);
+			ret = reset_tree(new->commit->tree, opts, 0,
+					 writeout_error);
 			if (ret)
 				return ret;
 		}
@@ -514,7 +550,7 @@ static void report_tracking(struct branch_info *new)
 	strbuf_release(&sb);
 }
 
-static void update_refs_for_switch(struct checkout_opts *opts,
+static void update_refs_for_switch(const struct checkout_opts *opts,
 				   struct branch_info *old,
 				   struct branch_info *new)
 {
@@ -701,13 +737,14 @@ static void orphaned_commit_warning(struct commit *old, struct commit *new)
 	free(refs.objects);
 }
 
-static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
+static int switch_branches(const struct checkout_opts *opts,
+			   struct branch_info *new)
 {
 	int ret = 0;
 	struct branch_info old;
 	void *path_to_free;
 	unsigned char rev[20];
-	int flag;
+	int flag, writeout_error = 0;
 	memset(&old, 0, sizeof(old));
 	old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
 	old.commit = lookup_commit_reference_gently(rev, 1);
@@ -725,7 +762,7 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 		parse_commit(new->commit);
 	}
 
-	ret = merge_working_tree(opts, &old, new);
+	ret = merge_working_tree(opts, &old, new, &writeout_error);
 	if (ret) {
 		free(path_to_free);
 		return ret;
@@ -738,7 +775,7 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 
 	ret = post_checkout_hook(old.commit, new->commit, 1);
 	free(path_to_free);
-	return ret || opts->writeout_error;
+	return ret || writeout_error;
 }
 
 static int git_checkout_config(const char *var, const char *value, void *cb)
@@ -755,12 +792,6 @@ static int git_checkout_config(const char *var, const char *value, void *cb)
 	return git_xmerge_config(var, value, NULL);
 }
 
-static int interactive_checkout(const char *revision, const char **pathspec,
-				struct checkout_opts *opts)
-{
-	return run_add_interactive(revision, "--patch=checkout", pathspec);
-}
-
 struct tracking_name_data {
 	const char *name;
 	char *remote;
@@ -910,7 +941,7 @@ static int parse_branchname_arg(int argc, const char **argv,
 	return argcount;
 }
 
-static int switch_unborn_to_new_branch(struct checkout_opts *opts)
+static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 {
 	int status;
 	struct strbuf branch_ref = STRBUF_INIT;
@@ -923,14 +954,56 @@ static int switch_unborn_to_new_branch(struct checkout_opts *opts)
 	return status;
 }
 
+static int checkout_branch(struct checkout_opts *opts,
+			   struct branch_info *new)
+{
+	if (opts->pathspec)
+		die(_("paths cannot be used with switching branches"));
+
+	if (opts->patch_mode)
+		die(_("'%s' cannot be used with switching branches"),
+		    "--patch");
+
+	if (opts->writeout_stage)
+		die(_("'%s' cannot be used with switching branches"),
+		    "--ours/--theirs");
+
+	if (opts->force && opts->merge)
+		die(_("'%s' cannot be used with '%s'"), "-f", "-m");
+
+	if (opts->force_detach && opts->new_branch)
+		die(_("'%s' cannot be used with '%s'"),
+		    "--detach", "-b/-B/--orphan");
+
+	if (opts->new_orphan_branch) {
+		if (opts->track != BRANCH_TRACK_UNSPECIFIED)
+			die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
+	} else if (opts->force_detach) {
+		if (opts->track != BRANCH_TRACK_UNSPECIFIED)
+			die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
+	} else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
+		opts->track = git_branch_track;
+
+	if (new->name && !new->commit)
+		die(_("Cannot switch branch to a non-commit '%s'"),
+		    new->name);
+
+	if (!new->commit && opts->new_branch) {
+		unsigned char rev[20];
+		int flag;
+
+		if (!read_ref_full("HEAD", rev, 0, &flag) &&
+		    (flag & REF_ISSYMREF) && is_null_sha1(rev))
+			return switch_unborn_to_new_branch(opts);
+	}
+	return switch_branches(opts, new);
+}
+
 int cmd_checkout(int argc, const char **argv, const char *prefix)
 {
 	struct checkout_opts opts;
-	unsigned char rev[20];
 	struct branch_info new;
-	struct tree *source_tree = NULL;
 	char *conflict_style = NULL;
-	int patch_mode = 0;
 	int dwim_new_local_branch = 1;
 	struct option options[] = {
 		OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
@@ -952,7 +1025,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
 		OPT_STRING(0, "conflict", &conflict_style, N_("style"),
 			   N_("conflict style (merge or diff3)")),
-		OPT_BOOLEAN('p', "patch", &patch_mode, N_("select hunks interactively")),
+		OPT_BOOLEAN('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
 		{ OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
 		  N_("second guess 'git checkout no-such-branch'"),
 		  PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
@@ -962,6 +1035,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	memset(&opts, 0, sizeof(opts));
 	memset(&new, 0, sizeof(new));
 	opts.overwrite_ignore = 1;
+	opts.prefix = prefix;
 
 	gitmodules_config();
 	git_config(git_checkout_config, &opts);
@@ -971,26 +1045,27 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, checkout_usage,
 			     PARSE_OPT_KEEP_DASHDASH);
 
-	/* we can assume from now on new_branch = !new_branch_force */
-	if (opts.new_branch && opts.new_branch_force)
-		die(_("-B cannot be used with -b"));
+	if (conflict_style) {
+		opts.merge = 1; /* implied */
+		git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
+	}
+
+	if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
+		die(_("-b, -B and --orphan are mutually exclusive"));
 
-	/* copy -B over to -b, so that we can just check the latter */
+	/*
+	 * From here on, new_branch will contain the branch to be checked out,
+	 * and new_branch_force and new_orphan_branch will tell us which one of
+	 * -b/-B/--orphan is being used.
+	 */
 	if (opts.new_branch_force)
 		opts.new_branch = opts.new_branch_force;
 
-	if (patch_mode && (opts.track > 0 || opts.new_branch
-			   || opts.new_branch_log || opts.merge || opts.force
-			   || opts.force_detach))
-		die (_("--patch is incompatible with all other options"));
-
-	if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
-		die(_("--detach cannot be used with -b/-B/--orphan"));
-	if (opts.force_detach && 0 < opts.track)
-		die(_("--detach cannot be used with -t"));
+	if (opts.new_orphan_branch)
+		opts.new_branch = opts.new_orphan_branch;
 
-	/* --track without -b should DWIM */
-	if (0 < opts.track && !opts.new_branch) {
+	/* --track without -b/-B/--orphan should DWIM */
+	if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
 		const char *argv0 = argv[0];
 		if (!argc || !strcmp(argv0, "--"))
 			die (_("--track needs a branch name"));
@@ -1004,22 +1079,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 		opts.new_branch = argv0 + 1;
 	}
 
-	if (opts.new_orphan_branch) {
-		if (opts.new_branch)
-			die(_("--orphan and -b|-B are mutually exclusive"));
-		if (opts.track > 0)
-			die(_("--orphan cannot be used with -t"));
-		opts.new_branch = opts.new_orphan_branch;
-	}
-
-	if (conflict_style) {
-		opts.merge = 1; /* implied */
-		git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
-	}
-
-	if (opts.force && opts.merge)
-		die(_("git checkout: -f and -m are incompatible"));
-
 	/*
 	 * Extract branch name from command line arguments, so
 	 * all that is left is pathspecs.
@@ -1034,73 +1093,56 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	 * remote branches, erroring out for invalid or ambiguous cases.
 	 */
 	if (argc) {
+		unsigned char rev[20];
 		int dwim_ok =
-			!patch_mode &&
+			!opts.patch_mode &&
 			dwim_new_local_branch &&
 			opts.track == BRANCH_TRACK_UNSPECIFIED &&
 			!opts.new_branch;
 		int n = parse_branchname_arg(argc, argv, dwim_ok,
-				&new, &source_tree, rev, &opts.new_branch);
+					     &new, &opts.source_tree,
+					     rev, &opts.new_branch);
 		argv += n;
 		argc -= n;
 	}
 
-	if (opts.track == BRANCH_TRACK_UNSPECIFIED)
-		opts.track = git_branch_track;
-
 	if (argc) {
-		const char **pathspec = get_pathspec(prefix, argv);
+		opts.pathspec = get_pathspec(prefix, argv);
 
-		if (!pathspec)
+		if (!opts.pathspec)
 			die(_("invalid path specification"));
 
-		if (patch_mode)
-			return interactive_checkout(new.name, pathspec, &opts);
-
-		/* Checkout paths */
-		if (opts.new_branch) {
-			if (argc == 1) {
-				die(_("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?"), argv[0]);
-			} else {
-				die(_("git checkout: updating paths is incompatible with switching branches."));
-			}
-		}
+		/*
+		 * Try to give more helpful suggestion.
+		 * new_branch && argc > 1 will be caught later.
+		 */
+		if (opts.new_branch && argc == 1)
+			die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
+			      "Did you intend to checkout '%s' which can not be resolved as commit?"),
+			    opts.new_branch, argv[0]);
 
 		if (opts.force_detach)
-			die(_("git checkout: --detach does not take a path argument"));
+			die(_("git checkout: --detach does not take a path argument '%s'"),
+			    argv[0]);
 
 		if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
-			die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index."));
-
-		return checkout_paths(source_tree, pathspec, prefix, &opts);
+			die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
+			      "checking out of the index."));
 	}
 
-	if (patch_mode)
-		return interactive_checkout(new.name, NULL, &opts);
-
 	if (opts.new_branch) {
 		struct strbuf buf = STRBUF_INIT;
 
-		opts.branch_exists = validate_new_branchname(opts.new_branch, &buf,
-							     !!opts.new_branch_force,
-							     !!opts.new_branch_force);
+		opts.branch_exists =
+			validate_new_branchname(opts.new_branch, &buf,
+						!!opts.new_branch_force,
+						!!opts.new_branch_force);
 
 		strbuf_release(&buf);
 	}
 
-	if (new.name && !new.commit) {
-		die(_("Cannot switch branch to a non-commit."));
-	}
-	if (opts.writeout_stage)
-		die(_("--ours/--theirs is incompatible with switching branches."));
-
-	if (!new.commit && opts.new_branch) {
-		unsigned char rev[20];
-		int flag;
-
-		if (!read_ref_full("HEAD", rev, 0, &flag) &&
-		    (flag & REF_ISSYMREF) && is_null_sha1(rev))
-			return switch_unborn_to_new_branch(&opts);
-	}
-	return switch_branches(&opts, &new);
+	if (opts.patch_mode || opts.pathspec)
+		return checkout_paths(&opts, new.name);
+	else
+		return checkout_branch(&opts, &new);
 }