Merge branch 'dg/local-mod-error-messages'

* dg/local-mod-error-messages:
  t7609: test merge and checkout error messages
  unpack_trees: group error messages by type
  merge-recursive: distinguish "removed" and "overwritten" messages
  merge-recursive: porcelain messages for checkout
  Turn unpack_trees_options.msgs into an array + enum

Conflicts:
	t/t3400-rebase.sh

13 files changed, 340 insertions, 81 deletions

diff --git a/Documentation/technical/api-tree-walking.txt b/Documentation/technical/api-tree-walking.txt
index 55b728632c..14af37c3f1 100644
--- a/Documentation/technical/api-tree-walking.txt
+++ b/Documentation/technical/api-tree-walking.txt
@@ -42,6 +42,8 @@ information.
 
 * `data` can be anything the `fn` callback would want to use.
 
+* `show_all_errors` tells whether to stop at the first error or not.
+
 Initializing
 ------------
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 7f81120c72..7250e5c23c 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -376,7 +376,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 		topts.src_index = &the_index;
 		topts.dst_index = &the_index;
 
-		topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
+		set_porcelain_error_msgs(topts.msgs, "checkout");
 
 		refresh_cache(REFRESH_QUIET);
 
@@ -395,6 +395,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 		topts.dir = xcalloc(1, sizeof(*topts.dir));
 		topts.dir->flags |= DIR_SHOW_IGNORED;
 		topts.dir->exclude_per_dir = ".gitignore";
+		topts.show_all_errors = 1;
 		tree = parse_tree_indirect(old->commit ?
 					   old->commit->object.sha1 :
 					   (unsigned char *)EMPTY_TREE_SHA1_BIN);
diff --git a/builtin/merge.c b/builtin/merge.c
index 37ce4f589f..1bcf7fd9d5 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -704,7 +704,8 @@ int checkout_fast_forward(const unsigned char *head, const unsigned char *remote
 	opts.verbose_update = 1;
 	opts.merge = 1;
 	opts.fn = twoway_merge;
-	opts.msgs = get_porcelain_error_msgs();
+	opts.show_all_errors = 1;
+	set_porcelain_error_msgs(opts.msgs, "merge");
 
 	trees[nr_trees] = parse_tree_indirect(head);
 	if (!trees[nr_trees++])
diff --git a/merge-recursive.c b/merge-recursive.c
index 6cff9cdc86..656e769b44 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -179,7 +179,7 @@ static int git_merge_trees(int index_only,
 	opts.fn = threeway_merge;
 	opts.src_index = &the_index;
 	opts.dst_index = &the_index;
-	opts.msgs = get_porcelain_error_msgs();
+	set_porcelain_error_msgs(opts.msgs, "merge");
 
 	init_tree_desc_from_tree(t+0, common);
 	init_tree_desc_from_tree(t+1, head);
@@ -1173,26 +1173,48 @@ static int process_entry(struct merge_options *o,
 	return clean_merge;
 }
 
-struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
+void set_porcelain_error_msgs(const char **msgs, const char *cmd)
 {
-	struct unpack_trees_error_msgs msgs = {
-		/* would_overwrite */
-		"Your local changes to '%s' would be overwritten by merge.  Aborting.",
-		/* not_uptodate_file */
-		"Your local changes to '%s' would be overwritten by merge.  Aborting.",
-		/* not_uptodate_dir */
-		"Updating '%s' would lose untracked files in it.  Aborting.",
-		/* would_lose_untracked */
-		"Untracked working tree file '%s' would be %s by merge.  Aborting",
-		/* bind_overlap -- will not happen here */
-		NULL,
-	};
-	if (advice_commit_before_merge) {
-		msgs.would_overwrite = msgs.not_uptodate_file =
-			"Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
-			"Please, commit your changes or stash them before you can merge.";
-	}
-	return msgs;
+	const char *msg;
+	char *tmp;
+	const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
+	if (advice_commit_before_merge)
+		msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
+			"Please, commit your changes or stash them before you can %s.";
+	else
+		msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
+	tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen(cmd2) - 2);
+	sprintf(tmp, msg, cmd, cmd2);
+	msgs[ERROR_WOULD_OVERWRITE] = tmp;
+	msgs[ERROR_NOT_UPTODATE_FILE] = tmp;
+
+	msgs[ERROR_NOT_UPTODATE_DIR] =
+		"Updating the following directories would lose untracked files in it:\n%s";
+
+	if (advice_commit_before_merge)
+		msg = "The following untracked working tree files would be %s by %s:\n%%s"
+			"Please move or remove them before you can %s.";
+	else
+		msg = "The following untracked working tree files would be %s by %s:\n%%s";
+	tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("removed") + strlen(cmd2) - 4);
+	sprintf(tmp, msg, "removed", cmd, cmd2);
+	msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = tmp;
+	tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("overwritten") + strlen(cmd2) - 4);
+	sprintf(tmp, msg, "overwritten", cmd, cmd2);
+	msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = tmp;
+
+	/*
+	 * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
+	 * cannot easily display it as a list.
+	 */
+	msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
+
+	msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
+		"Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
+	msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
+		"The following Working tree files would be overwritten by sparse checkout update:\n%s";
+	msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
+		"The following Working tree files would be removed by sparse checkout update:\n%s";
 }
 
 int merge_trees(struct merge_options *o,
diff --git a/merge-recursive.h b/merge-recursive.h
index b831293b38..08f9850367 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -23,8 +23,11 @@ struct merge_options {
 	struct string_list current_directory_set;
 };
 
-/* Return a list of user-friendly error messages to be used by merge */
-struct unpack_trees_error_msgs get_porcelain_error_msgs(void);
+/*
+ * Sets the list of user-friendly error messages to be used by the
+ * command "cmd" (either merge or checkout)
+ */
+void set_porcelain_error_msgs(const char **msgs, const char *cmd);
 
 /* merge_trees() but with recursive ancestor consolidation */
 int merge_recursive(struct merge_options *o,
diff --git a/t/t3030-merge-recursive.sh b/t/t3030-merge-recursive.sh
index d541544537..efe2900a37 100755
--- a/t/t3030-merge-recursive.sh
+++ b/t/t3030-merge-recursive.sh
@@ -294,7 +294,7 @@ test_expect_success 'fail if the index has unresolved entries' '
 	grep "You have not concluded your merge" out &&
 	rm -f .git/MERGE_HEAD &&
 	test_must_fail git merge "$c5" 2> out &&
-	grep "Your local changes to .* would be overwritten by merge." out
+	grep "Your local changes to the following files would be overwritten by merge:" out
 '
 
 test_expect_success 'merge-recursive remove conflict' '
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index a19aeb6441..349eebd542 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -153,7 +153,8 @@ test_expect_success 'setup: recover' '
 test_expect_success 'Show verbose error when HEAD could not be detached' '
 	>B &&
 	test_must_fail git rebase topic 2>output.err >output.out &&
-	grep "Untracked working tree file .B. would be overwritten" output.err
+	grep "The following untracked working tree files would be overwritten by checkout:" output.err &&
+	grep B output.err
 '
 rm -f B
 
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 9f03ce699e..3af3f603fb 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -150,8 +150,9 @@ test_expect_success 'abort with error when new base cannot be checked out' '
 	git rm --cached file1 &&
 	git commit -m "remove file in base" &&
 	test_must_fail git rebase -i master > output 2>&1 &&
-	grep "Untracked working tree file .file1. would be overwritten" \
+	grep "The following untracked working tree files would be overwritten by checkout:" \
 		output &&
+	grep "file1" output &&
 	! test -d .git/rebase-merge &&
 	git reset --hard HEAD^
 '
diff --git a/t/t7609-merge-co-error-msgs.sh b/t/t7609-merge-co-error-msgs.sh
new file mode 100755
index 0000000000..1a109b41dc
--- /dev/null
+++ b/t/t7609-merge-co-error-msgs.sh
@@ -0,0 +1,125 @@
+#!/bin/sh
+
+test_description='unpack-trees error messages'
+
+. ./test-lib.sh
+
+
+test_expect_success 'setup' '
+	echo one >one &&
+	git add one &&
+	git commit -a -m First &&
+
+	git checkout -b branch &&
+	echo two >two &&
+	echo three >three &&
+	echo four >four &&
+	echo five >five &&
+	git add two three four five &&
+	git commit -m Second &&
+
+	git checkout master &&
+	echo other >two &&
+	echo other >three &&
+	echo other >four &&
+	echo other >five
+'
+
+cat >expect <<\EOF
+error: The following untracked working tree files would be overwritten by merge:
+	two
+	three
+	four
+	five
+Please move or remove them before you can merge.
+EOF
+
+test_expect_success 'untracked files overwritten by merge' '
+	test_must_fail git merge branch 2>out &&
+	test_cmp out expect
+'
+
+cat >expect <<\EOF
+error: Your local changes to the following files would be overwritten by merge:
+	two
+	three
+	four
+Please, commit your changes or stash them before you can merge.
+error: The following untracked working tree files would be overwritten by merge:
+	five
+Please move or remove them before you can merge.
+EOF
+
+test_expect_success 'untracked files or local changes ovewritten by merge' '
+	git add two &&
+	git add three &&
+	git add four &&
+	test_must_fail git merge branch 2>out &&
+	test_cmp out expect
+'
+
+cat >expect <<\EOF
+error: Your local changes to the following files would be overwritten by checkout:
+	rep/two
+	rep/one
+Please, commit your changes or stash them before you can switch branches.
+EOF
+
+test_expect_success 'cannot switch branches because of local changes' '
+	git add five &&
+	mkdir rep &&
+	echo one >rep/one &&
+	echo two >rep/two &&
+	git add rep/one rep/two &&
+	git commit -m Fourth &&
+	git checkout master &&
+	echo uno >rep/one &&
+	echo dos >rep/two &&
+	test_must_fail git checkout branch 2>out &&
+	test_cmp out expect
+'
+
+cat >expect <<\EOF
+error: Your local changes to the following files would be overwritten by checkout:
+	rep/two
+	rep/one
+Please, commit your changes or stash them before you can switch branches.
+EOF
+
+test_expect_success 'not uptodate file porcelain checkout error' '
+	git add rep/one rep/two &&
+	test_must_fail git checkout branch 2>out &&
+	test_cmp out expect
+'
+
+cat >expect <<\EOF
+error: Updating the following directories would lose untracked files in it:
+	rep2
+	rep
+
+EOF
+
+test_expect_success 'not_uptodate_dir porcelain checkout error' '
+	git init uptodate &&
+	cd uptodate &&
+	mkdir rep &&
+	mkdir rep2 &&
+	touch rep/foo &&
+	touch rep2/foo &&
+	git add rep/foo rep2/foo &&
+	git commit -m init &&
+	git checkout -b branch &&
+	git rm rep -r &&
+	git rm rep2 -r &&
+	>rep &&
+	>rep2 &&
+	git add rep rep2&&
+	git commit -m "added test as a file" &&
+	git checkout master &&
+	>rep/untracked-file &&
+	>rep2/untracked-file &&
+	test_must_fail git checkout branch 2>out &&
+	test_cmp out ../expect
+'
+
+test_done
diff --git a/tree-walk.c b/tree-walk.c
index 67a9a0c5a5..a9bbf4e235 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "tree-walk.h"
+#include "unpack-trees.h"
 #include "tree.h"
 
 static const char *get_mode(const char *str, unsigned int *modep)
@@ -310,6 +311,7 @@ static void free_extended_entry(struct tree_desc_x *t)
 int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 {
 	int ret = 0;
+	int error = 0;
 	struct name_entry *entry = xmalloc(n*sizeof(*entry));
 	int i;
 	struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
@@ -377,8 +379,11 @@ int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 		if (!mask)
 			break;
 		ret = info->fn(n, mask, dirmask, entry, info);
-		if (ret < 0)
-			break;
+		if (ret < 0) {
+			error = ret;
+			if (!info->show_all_errors)
+				break;
+		}
 		mask &= ret;
 		ret = 0;
 		for (i = 0; i < n; i++)
@@ -389,7 +394,7 @@ int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 	for (i = 0; i < n; i++)
 		free_extended_entry(tx + i);
 	free(tx);
-	return ret;
+	return error;
 }
 
 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
diff --git a/tree-walk.h b/tree-walk.h
index 42110a465f..88ea7e9298 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -45,6 +45,7 @@ struct traverse_info {
 	unsigned long conflicts;
 	traverse_callback_t fn;
 	void *data;
+	int show_all_errors;
 };
 
 int get_tree_entry(const unsigned char *, const char *, unsigned char *, unsigned *);
diff --git a/unpack-trees.c b/unpack-trees.c
index f561d88156..62852aa7fb 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -13,37 +13,42 @@
  * Error messages expected by scripts out of plumbing commands such as
  * read-tree.  Non-scripted Porcelain is not required to use these messages
  * and in fact are encouraged to reword them to better suit their particular
- * situation better.  See how "git checkout" replaces not_uptodate_file to
- * explain why it does not allow switching between branches when you have
- * local changes, for example.
+ * situation better.  See how "git checkout" and "git merge" replaces
+ * them using set_porcelain_error_msgs(), for example.
  */
-static struct unpack_trees_error_msgs unpack_plumbing_errors = {
-	/* would_overwrite */
+const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
+	/* ERROR_WOULD_OVERWRITE */
 	"Entry '%s' would be overwritten by merge. Cannot merge.",
 
-	/* not_uptodate_file */
+	/* ERROR_NOT_UPTODATE_FILE */
 	"Entry '%s' not uptodate. Cannot merge.",
 
-	/* not_uptodate_dir */
+	/* ERROR_NOT_UPTODATE_DIR */
 	"Updating '%s' would lose untracked files in it",
 
-	/* would_lose_untracked */
-	"Untracked working tree file '%s' would be %s by merge.",
+	/* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
+	"Untracked working tree file '%s' would be overwritten by merge.",
 
-	/* bind_overlap */
+	/* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
+	"Untracked working tree file '%s' would be removed by merge.",
+
+	/* ERROR_BIND_OVERLAP */
 	"Entry '%s' overlaps with '%s'.  Cannot bind.",
 
-	/* sparse_not_uptodate_file */
+	/* ERROR_SPARSE_NOT_UPTODATE_FILE */
 	"Entry '%s' not uptodate. Cannot update sparse checkout.",
 
-	/* would_lose_orphaned */
-	"Working tree file '%s' would be %s by sparse checkout update.",
+	/* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
+	"Working tree file '%s' would be overwritten by sparse checkout update.",
+
+	/* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
+	"Working tree file '%s' would be removed by sparse checkout update.",
 };
 
-#define ERRORMSG(o,fld) \
-	( ((o) && (o)->msgs.fld) \
-	? ((o)->msgs.fld) \
-	: (unpack_plumbing_errors.fld) )
+#define ERRORMSG(o,type) \
+	( ((o) && (o)->msgs[(type)]) \
+	  ? ((o)->msgs[(type)])      \
+	  : (unpack_plumbing_errors[(type)]) )
 
 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 	unsigned int set, unsigned int clear)
@@ -60,6 +65,73 @@ static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 }
 
 /*
+ * add error messages on path <path>
+ * corresponding to the type <e> with the message <msg>
+ * indicating if it should be display in porcelain or not
+ */
+static int add_rejected_path(struct unpack_trees_options *o,
+			     enum unpack_trees_error_types e,
+			     const char *path)
+{
+	struct rejected_paths_list *newentry;
+	int porcelain = o && (o)->msgs[e];
+	/*
+	 * simply display the given error message if in plumbing mode
+	 */
+	if (!porcelain)
+		o->show_all_errors = 0;
+	if (!o->show_all_errors)
+		return error(ERRORMSG(o, e), path);
+
+	/*
+	 * Otherwise, insert in a list for future display by
+	 * display_error_msgs()
+	 */
+	newentry = xmalloc(sizeof(struct rejected_paths_list));
+	newentry->path = (char *)path;
+	newentry->next = o->unpack_rejects[e];
+	o->unpack_rejects[e] = newentry;
+	return -1;
+}
+
+/*
+ * free all the structures allocated for the error <e>
+ */
+static void free_rejected_paths(struct unpack_trees_options *o,
+				enum unpack_trees_error_types e)
+{
+	while (o->unpack_rejects[e]) {
+		struct rejected_paths_list *del = o->unpack_rejects[e];
+		o->unpack_rejects[e] = o->unpack_rejects[e]->next;
+		free(del);
+	}
+	free(o->unpack_rejects[e]);
+}
+
+/*
+ * display all the error messages stored in a nice way
+ */
+static void display_error_msgs(struct unpack_trees_options *o)
+{
+	int e;
+	int something_displayed = 0;
+	for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
+		if (o->unpack_rejects[e]) {
+			struct rejected_paths_list *rp;
+			struct strbuf path = STRBUF_INIT;
+			something_displayed = 1;
+			for (rp = o->unpack_rejects[e]; rp; rp = rp->next)
+				strbuf_addf(&path, "\t%s\n", rp->path);
+			error(ERRORMSG(o, e), path.buf);
+			strbuf_release(&path);
+			free_rejected_paths(o, e);
+		}
+	}
+	if (something_displayed)
+		printf("Aborting\n");
+}
+
+/*
  * Unlink the last component and schedule the leading directories for
  * removal, such that empty directories get removed.
  */
@@ -132,7 +204,7 @@ static int check_updates(struct unpack_trees_options *o)
 }
 
 static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
-static int verify_absent_sparse(struct cache_entry *ce, const char *action, struct unpack_trees_options *o);
+static int verify_absent_sparse(struct cache_entry *ce, enum unpack_trees_error_types, struct unpack_trees_options *o);
 
 static int will_have_skip_worktree(const struct cache_entry *ce, struct unpack_trees_options *o)
 {
@@ -175,7 +247,7 @@ static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_opt
 		ce->ce_flags |= CE_WT_REMOVE;
 	}
 	if (was_skip_worktree && !ce_skip_worktree(ce)) {
-		if (verify_absent_sparse(ce, "overwritten", o))
+		if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 			return -1;
 		ce->ce_flags |= CE_UPDATE;
 	}
@@ -755,6 +827,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 		setup_traverse_info(&info, prefix);
 		info.fn = unpack_callback;
 		info.data = o;
+		info.show_all_errors = o->show_all_errors;
 
 		if (o->prefix) {
 			/*
@@ -834,6 +907,8 @@ done:
 	return ret;
 
 return_failed:
+	if (o->show_all_errors)
+		display_error_msgs(o);
 	mark_all_ce_unused(o->src_index);
 	ret = unpack_failed(o, NULL);
 	goto done;
@@ -843,7 +918,7 @@ return_failed:
 
 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 {
-	return error(ERRORMSG(o, would_overwrite), ce->name);
+	return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
 }
 
 static int same(struct cache_entry *a, struct cache_entry *b)
@@ -865,7 +940,7 @@ static int same(struct cache_entry *a, struct cache_entry *b)
  */
 static int verify_uptodate_1(struct cache_entry *ce,
 				   struct unpack_trees_options *o,
-				   const char *error_msg)
+				   enum unpack_trees_error_types error_type)
 {
 	struct stat st;
 
@@ -890,7 +965,7 @@ static int verify_uptodate_1(struct cache_entry *ce,
 	if (errno == ENOENT)
 		return 0;
 	return o->gently ? -1 :
-		error(error_msg, ce->name);
+		add_rejected_path(o, error_type, ce->name);
 }
 
 static int verify_uptodate(struct cache_entry *ce,
@@ -898,13 +973,13 @@ static int verify_uptodate(struct cache_entry *ce,
 {
 	if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 		return 0;
-	return verify_uptodate_1(ce, o, ERRORMSG(o, not_uptodate_file));
+	return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
 }
 
 static int verify_uptodate_sparse(struct cache_entry *ce,
 				  struct unpack_trees_options *o)
 {
-	return verify_uptodate_1(ce, o, ERRORMSG(o, sparse_not_uptodate_file));
+	return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
 }
 
 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
@@ -920,13 +995,15 @@ static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_optio
  * Currently, git does not checkout subprojects during a superproject
  * checkout, so it is not going to overwrite anything.
  */
-static int verify_clean_submodule(struct cache_entry *ce, const char *action,
+static int verify_clean_submodule(struct cache_entry *ce,
+				      enum unpack_trees_error_types error_type,
 				      struct unpack_trees_options *o)
 {
 	return 0;
 }
 
-static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
+static int verify_clean_subdirectory(struct cache_entry *ce,
+				      enum unpack_trees_error_types error_type,
 				      struct unpack_trees_options *o)
 {
 	/*
@@ -947,7 +1024,7 @@ static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 		 */
 		if (!hashcmp(sha1, ce->sha1))
 			return 0;
-		return verify_clean_submodule(ce, action, o);
+		return verify_clean_submodule(ce, error_type, o);
 	}
 
 	/*
@@ -991,7 +1068,7 @@ static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 	i = read_directory(&d, pathbuf, namelen+1, NULL);
 	if (i)
 		return o->gently ? -1 :
-			error(ERRORMSG(o, not_uptodate_dir), ce->name);
+			add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
 	free(pathbuf);
 	return cnt;
 }
@@ -1016,9 +1093,9 @@ static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst,
  * We do not want to remove or overwrite a working tree file that
  * is not tracked, unless it is ignored.
  */
-static int verify_absent_1(struct cache_entry *ce, const char *action,
-				 struct unpack_trees_options *o,
-				 const char *error_msg)
+static int verify_absent_1(struct cache_entry *ce,
+				 enum unpack_trees_error_types error_type,
+				 struct unpack_trees_options *o)
 {
 	struct stat st;
 
@@ -1056,7 +1133,7 @@ static int verify_absent_1(struct cache_entry *ce, const char *action,
 			 * files that are in "foo/" we would lose
 			 * them.
 			 */
-			if (verify_clean_subdirectory(ce, action, o) < 0)
+			if (verify_clean_subdirectory(ce, error_type, o) < 0)
 				return -1;
 			return 0;
 		}
@@ -1073,22 +1150,28 @@ static int verify_absent_1(struct cache_entry *ce, const char *action,
 		}
 
 		return o->gently ? -1 :
-			error(ERRORMSG(o, would_lose_untracked), ce->name, action);
+			add_rejected_path(o, error_type, ce->name);
 	}
 	return 0;
 }
-static int verify_absent(struct cache_entry *ce, const char *action,
+static int verify_absent(struct cache_entry *ce,
+			 enum unpack_trees_error_types error_type,
 			 struct unpack_trees_options *o)
 {
 	if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 		return 0;
-	return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_untracked));
+	return verify_absent_1(ce, error_type, o);
 }
 
-static int verify_absent_sparse(struct cache_entry *ce, const char *action,
+static int verify_absent_sparse(struct cache_entry *ce,
+			 enum unpack_trees_error_types error_type,
 			 struct unpack_trees_options *o)
 {
-	return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_orphaned));
+	enum unpack_trees_error_types orphaned_error = error_type;
+	if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
+		orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
+
+	return verify_absent_1(ce, orphaned_error, o);
 }
 
 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
@@ -1097,7 +1180,7 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 	int update = CE_UPDATE;
 
 	if (!old) {
-		if (verify_absent(merge, "overwritten", o))
+		if (verify_absent(merge, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 			return -1;
 		invalidate_ce_path(merge, o);
 	} else if (!(old->ce_flags & CE_CONFLICTED)) {
@@ -1135,7 +1218,7 @@ static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 {
 	/* Did it exist in the index? */
 	if (!old) {
-		if (verify_absent(ce, "removed", o))
+		if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
 			return -1;
 		return 0;
 	}
@@ -1284,7 +1367,7 @@ int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 			if (index)
 				return deleted_entry(index, index, o);
 			if (ce && !head_deleted) {
-				if (verify_absent(ce, "removed", o))
+				if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
 					return -1;
 			}
 			return 0;
@@ -1417,7 +1500,7 @@ int bind_merge(struct cache_entry **src,
 			     o->merge_size);
 	if (a && old)
 		return o->gently ? -1 :
-			error(ERRORMSG(o, bind_overlap), a->name, old->name);
+			error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
 	if (!a)
 		return keep_entry(old, o);
 	else
diff --git a/unpack-trees.h b/unpack-trees.h
index ef70eab390..6e049b0997 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -9,14 +9,22 @@ struct exclude_list;
 typedef int (*merge_fn_t)(struct cache_entry **src,
 		struct unpack_trees_options *options);
 
-struct unpack_trees_error_msgs {
-	const char *would_overwrite;
-	const char *not_uptodate_file;
-	const char *not_uptodate_dir;
-	const char *would_lose_untracked;
-	const char *bind_overlap;
-	const char *sparse_not_uptodate_file;
-	const char *would_lose_orphaned;
+enum unpack_trees_error_types {
+	ERROR_WOULD_OVERWRITE = 0,
+	ERROR_NOT_UPTODATE_FILE,
+	ERROR_NOT_UPTODATE_DIR,
+	ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN,
+	ERROR_WOULD_LOSE_UNTRACKED_REMOVED,
+	ERROR_BIND_OVERLAP,
+	ERROR_SPARSE_NOT_UPTODATE_FILE,
+	ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN,
+	ERROR_WOULD_LOSE_ORPHANED_REMOVED,
+	NB_UNPACK_TREES_ERROR_TYPES
+};
+
+struct rejected_paths_list {
+	char *path;
+	struct rejected_paths_list *next;
 };
 
 struct unpack_trees_options {
@@ -33,12 +41,18 @@ struct unpack_trees_options {
 		     diff_index_cached,
 		     debug_unpack,
 		     skip_sparse_checkout,
-		     gently;
+		     gently,
+		     show_all_errors;
 	const char *prefix;
 	int cache_bottom;
 	struct dir_struct *dir;
 	merge_fn_t fn;
-	struct unpack_trees_error_msgs msgs;
+	const char *msgs[NB_UNPACK_TREES_ERROR_TYPES];
+	/*
+	 * Store error messages in an array, each case
+	 * corresponding to a error message type
+	 */
+	struct rejected_paths_list *unpack_rejects[NB_UNPACK_TREES_ERROR_TYPES];
 
 	int head_idx;
 	int merge_size;