thodg/libgit2

diff --git a/include/git2/diff.h b/include/git2/diff.h
index 9fcc3bb..cac3b26 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -124,6 +124,11 @@ typedef enum {
 	/** Use case insensitive filename comparisons */
 	GIT_DIFF_IGNORE_CASE = (1u << 10),
 
+	/** May be combined with `GIT_DIFF_IGNORE_CASE` to specify that a file
+	 *  that has changed case will be returned as an add/delete pair.
+	 */
+	GIT_DIFF_INCLUDE_CASECHANGE = (1u << 11),
+
 	/** If the pathspec is set in the diff options, this flags means to
 	 *  apply it as an exact match instead of as an fnmatch pattern.
 	 */
@@ -220,7 +225,7 @@ typedef struct git_diff git_diff;
 typedef enum {
 	GIT_DIFF_FLAG_BINARY     = (1u << 0), /**< file(s) treated as binary data */
 	GIT_DIFF_FLAG_NOT_BINARY = (1u << 1), /**< file(s) treated as text data */
-	GIT_DIFF_FLAG_VALID_ID  = (1u << 2), /**< `id` value is known correct */
+	GIT_DIFF_FLAG_VALID_ID   = (1u << 2), /**< `id` value is known correct */
 } git_diff_flag_t;
 
 /**
diff --git a/src/checkout.c b/src/checkout.c
index 4781308..a647ce0 100644
--- a/src/checkout.c
+++ b/src/checkout.c
@@ -409,6 +409,14 @@ static bool submodule_is_config_only(
 	return rval;
 }
 
+static bool checkout_is_empty_dir(checkout_data *data, const char *path)
+{
+	git_buf_truncate(&data->path, data->workdir_len);
+	if (git_buf_puts(&data->path, path) < 0)
+		return false;
+	return git_path_is_empty_dir(data->path.ptr);
+}
+
 static int checkout_action_with_wd(
 	int *action,
 	checkout_data *data,
@@ -526,6 +534,7 @@ static int checkout_action_with_wd_dir(
 			checkout_notify(data, GIT_CHECKOUT_NOTIFY_DIRTY, delta, NULL));
 		GITERR_CHECK_ERROR(
 			checkout_notify(data, GIT_CHECKOUT_NOTIFY_UNTRACKED, NULL, wd));
+		*action = CHECKOUT_ACTION_IF(FORCE, REMOVE_AND_UPDATE, NONE);
 		break;
 	case GIT_DELTA_ADDED:/* case 4 (and 7 for dir) */
 	case GIT_DELTA_MODIFIED: /* case 20 (or 37 but not really) */
@@ -550,8 +559,6 @@ static int checkout_action_with_wd_dir(
 			 * dir and it will succeed if no children are left.
 			 */
 			*action = CHECKOUT_ACTION_IF(SAFE, UPDATE_BLOB, NONE);
-			if (*action != CHECKOUT_ACTION__NONE)
-				*action |= CHECKOUT_ACTION__DEFER_REMOVE;
 		}
 		else if (delta->new_file.mode != GIT_FILEMODE_TREE)
 			/* For typechange to dir, dir is already created so no action */
@@ -564,6 +571,20 @@ static int checkout_action_with_wd_dir(
 	return checkout_action_common(action, data, delta, wd);
 }
 
+static int checkout_action_with_wd_dir_empty(
+	int *action,
+	checkout_data *data,
+	const git_diff_delta *delta)
+{
+	int error = checkout_action_no_wd(action, data, delta);
+
+	/* We can always safely remove an empty directory. */
+	if (error == 0 && *action != CHECKOUT_ACTION__NONE)
+		*action |= CHECKOUT_ACTION__REMOVE;
+
+	return error;
+}
+
 static int checkout_action(
 	int *action,
 	checkout_data *data,
@@ -653,7 +674,9 @@ static int checkout_action(
 				}
 			}
 
-			return checkout_action_with_wd_dir(action, data, delta, workdir, wd);
+			return checkout_is_empty_dir(data, wd->path) ?
+				checkout_action_with_wd_dir_empty(action, data, delta) :
+				checkout_action_with_wd_dir(action, data, delta, workdir, wd);
 		}
 
 		/* case 6 - wd is after delta */
@@ -2462,7 +2485,8 @@ int git_checkout_iterator(
 		GIT_DIFF_INCLUDE_IGNORED |
 		GIT_DIFF_INCLUDE_TYPECHANGE |
 		GIT_DIFF_INCLUDE_TYPECHANGE_TREES |
-		GIT_DIFF_SKIP_BINARY_CHECK;
+		GIT_DIFF_SKIP_BINARY_CHECK |
+		GIT_DIFF_INCLUDE_CASECHANGE;
 	if (data.opts.checkout_strategy & GIT_CHECKOUT_DISABLE_PATHSPEC_MATCH)
 		diff_opts.flags |= GIT_DIFF_DISABLE_PATHSPEC_MATCH;
 	if (data.opts.paths.count > 0)
@@ -2643,7 +2667,7 @@ int git_checkout_tree(
 	if ((error = git_repository_index(&index, repo)) < 0)
 		return error;
 
-	if (!(error = git_iterator_for_tree(&tree_i, tree, GIT_ITERATOR_DONT_IGNORE_CASE, NULL, NULL)))
+	if (!(error = git_iterator_for_tree(&tree_i, tree, 0, NULL, NULL)))
 		error = git_checkout_iterator(tree_i, index, opts);
 
 	git_iterator_free(tree_i);
diff --git a/src/diff.c b/src/diff.c
index 08e218c..f7e1c8e 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -822,6 +822,19 @@ static int maybe_modified(
 			status = GIT_DELTA_UNMODIFIED;
 	}
 
+	/* If we want case changes, then break this into a delete of the old
+	 * and an add of the new so that consumers can act accordingly (eg,
+	 * checkout will update the case on disk.)
+	 */
+	if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_CASE) &&
+		DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_CASECHANGE) &&
+		strcmp(oitem->path, nitem->path) != 0) {
+
+		if (!(error = diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem)))
+			error = diff_delta__from_one(diff, GIT_DELTA_ADDED, nitem);
+		return error;
+	}
+
 	return diff_delta__from_two(
 		diff, status, oitem, omode, nitem, nmode,
 		git_oid_iszero(&noid) ? NULL : &noid, matched_pathspec);
diff --git a/tests/checkout/icase.c b/tests/checkout/icase.c
index 2117380..510f542 100644
--- a/tests/checkout/icase.c
+++ b/tests/checkout/icase.c
@@ -1,10 +1,13 @@
 #include "clar_libgit2.h"
 
 #include "git2/checkout.h"
+#include "refs.h"
 #include "path.h"
 
 #ifdef GIT_WIN32
 # include <windows.h>
+#else
+# include <dirent.h>
 #endif
 
 static git_repository *repo;
@@ -14,14 +17,23 @@ static git_checkout_options checkout_opts;
 void test_checkout_icase__initialize(void)
 {
 	git_oid id;
+	git_config *cfg;
+	int icase = 0;
 
 	repo = cl_git_sandbox_init("testrepo");
 
+	cl_git_pass(git_repository_config_snapshot(&cfg, repo));
+	git_config_get_bool(&icase, cfg, "core.ignorecase");
+	git_config_free(cfg);
+
+	if (!icase)
+		cl_skip();
+
 	cl_git_pass(git_reference_name_to_id(&id, repo, "refs/heads/dir"));
 	cl_git_pass(git_object_lookup(&obj, repo, &id, GIT_OBJ_ANY));
 
 	git_checkout_init_options(&checkout_opts, GIT_CHECKOUT_OPTIONS_VERSION);
-	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_NONE;
 }
 
 void test_checkout_icase__cleanup(void)
@@ -30,7 +42,7 @@ void test_checkout_icase__cleanup(void)
 	cl_git_sandbox_cleanup();
 }
 
-static char *test_realpath(const char *in)
+static char *get_filename(const char *in)
 {
 #ifdef GIT_WIN32
 	HANDLE fh;
@@ -55,7 +67,31 @@ static char *test_realpath(const char *in)
 
 	return filename;
 #else
-	return realpath(in, NULL);
+	char *search_dirname, *search_filename, *filename = NULL;
+	git_buf out = GIT_BUF_INIT;
+	DIR *dir;
+	struct dirent *de;
+
+	cl_assert(search_dirname = git_path_dirname(in));
+	cl_assert(search_filename = git_path_basename(in));
+
+	cl_assert(dir = opendir(search_dirname));
+
+	while ((de = readdir(dir))) {
+		if (strcasecmp(de->d_name, search_filename) == 0) {
+			git_buf_join(&out, '/', search_dirname, de->d_name);
+			filename = git_buf_detach(&out);
+			break;
+		}
+	}
+
+	closedir(dir);
+
+	git__free(search_dirname);
+	git__free(search_filename);
+	git_buf_free(&out);
+
+	return filename;
 #endif
 }
 
@@ -64,7 +100,7 @@ static void assert_name_is(const char *expected)
 	char *actual;
 	size_t actual_len, expected_len, start;
 
-	cl_assert(actual = test_realpath(expected));
+	cl_assert(actual = get_filename(expected));
 
 	expected_len = strlen(expected);
 	actual_len = strlen(actual);
@@ -79,8 +115,21 @@ static void assert_name_is(const char *expected)
 	free(actual);
 }
 
-void test_checkout_icase__overwrites_files_for_files(void)
+void test_checkout_icase__refuses_to_overwrite_files_for_files(void)
 {
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
+	cl_git_write2file("testrepo/BRANCH_FILE.txt", "neue file\n", 10, \
+		O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+	cl_git_fail(git_checkout_tree(repo, obj, &checkout_opts));
+	assert_name_is("testrepo/BRANCH_FILE.txt");
+}
+
+void test_checkout_icase__overwrites_files_for_files_when_forced(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
 	cl_git_write2file("testrepo/NEW.txt", "neue file\n", 10, \
 		O_WRONLY | O_CREAT | O_TRUNC, 0644);
 
@@ -88,8 +137,22 @@ void test_checkout_icase__overwrites_files_for_files(void)
 	assert_name_is("testrepo/new.txt");
 }
 
-void test_checkout_icase__overwrites_links_for_files(void)
+void test_checkout_icase__refuses_to_overwrite_links_for_files(void)
 {
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
+	cl_must_pass(p_symlink("../tmp", "testrepo/BRANCH_FILE.txt"));
+
+	cl_git_fail(git_checkout_tree(repo, obj, &checkout_opts));
+
+	cl_assert(!git_path_exists("tmp"));
+	assert_name_is("testrepo/BRANCH_FILE.txt");
+}
+
+void test_checkout_icase__overwrites_links_for_files_when_forced(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
 	cl_must_pass(p_symlink("../tmp", "testrepo/NEW.txt"));
 
 	cl_git_pass(git_checkout_tree(repo, obj, &checkout_opts));
@@ -98,8 +161,10 @@ void test_checkout_icase__overwrites_links_for_files(void)
 	assert_name_is("testrepo/new.txt");
 }
 
-void test_checkout_icase__overwites_folders_for_files(void)
+void test_checkout_icase__overwrites_empty_folders_for_files(void)
 {
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
 	cl_must_pass(p_mkdir("testrepo/NEW.txt", 0777));
 
 	cl_git_pass(git_checkout_tree(repo, obj, &checkout_opts));
@@ -108,8 +173,50 @@ void test_checkout_icase__overwites_folders_for_files(void)
 	cl_assert(!git_path_isdir("testrepo/new.txt"));
 }
 
-void test_checkout_icase__overwrites_files_for_folders(void)
+void test_checkout_icase__refuses_to_overwrite_populated_folders_for_files(void)
 {
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
+	cl_must_pass(p_mkdir("testrepo/BRANCH_FILE.txt", 0777));
+	cl_git_write2file("testrepo/BRANCH_FILE.txt/foobar", "neue file\n", 10, \
+		O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+	cl_git_fail(git_checkout_tree(repo, obj, &checkout_opts));
+
+	assert_name_is("testrepo/BRANCH_FILE.txt");
+	cl_assert(git_path_isdir("testrepo/BRANCH_FILE.txt"));
+}
+
+void test_checkout_icase__overwrites_folders_for_files_when_forced(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
+	cl_must_pass(p_mkdir("testrepo/NEW.txt", 0777));
+	cl_git_write2file("testrepo/NEW.txt/foobar", "neue file\n", 10, \
+		O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+	cl_git_pass(git_checkout_tree(repo, obj, &checkout_opts));
+
+	assert_name_is("testrepo/new.txt");
+	cl_assert(!git_path_isdir("testrepo/new.txt"));
+}
+
+void test_checkout_icase__refuses_to_overwrite_files_for_folders(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
+	cl_git_write2file("testrepo/A", "neue file\n", 10, \
+		O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+	cl_git_fail(git_checkout_tree(repo, obj, &checkout_opts));
+	assert_name_is("testrepo/A");
+	cl_assert(!git_path_isdir("testrepo/A"));
+}
+
+void test_checkout_icase__overwrites_files_for_folders_when_forced(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
 	cl_git_write2file("testrepo/A", "neue file\n", 10, \
 		O_WRONLY | O_CREAT | O_TRUNC, 0644);
 
@@ -118,8 +225,22 @@ void test_checkout_icase__overwrites_files_for_folders(void)
 	cl_assert(git_path_isdir("testrepo/a"));
 }
 
-void test_checkout_icase__overwrites_links_for_folders(void)
+void test_checkout_icase__refuses_to_overwrite_links_for_folders(void)
+{
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE|GIT_CHECKOUT_RECREATE_MISSING;
+
+	cl_must_pass(p_symlink("..", "testrepo/A"));
+
+	cl_git_fail(git_checkout_tree(repo, obj, &checkout_opts));
+
+	cl_assert(!git_path_exists("b.txt"));
+	assert_name_is("testrepo/A");
+}
+
+void test_checkout_icase__overwrites_links_for_folders_when_forced(void)
 {
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE;
+
 	cl_must_pass(p_symlink("..", "testrepo/A"));
 
 	cl_git_pass(git_checkout_tree(repo, obj, &checkout_opts));
@@ -128,3 +249,53 @@ void test_checkout_icase__overwrites_links_for_folders(void)
 	assert_name_is("testrepo/a");
 }
 
+void test_checkout_icase__ignores_unstaged_casechange(void)
+{
+	git_reference *orig_ref, *br2_ref;
+	git_commit *orig, *br2;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
+
+	cl_git_pass(git_reference_lookup_resolved(&orig_ref, repo, "HEAD", 100));
+	cl_git_pass(git_commit_lookup(&orig, repo, git_reference_target(orig_ref)));
+	cl_git_pass(git_reset(repo, (git_object *)orig, GIT_RESET_HARD, NULL));
+
+	cl_rename("testrepo/branch_file.txt", "testrepo/Branch_File.txt");
+
+	cl_git_pass(git_reference_lookup_resolved(&br2_ref, repo, "refs/heads/br2", 100));
+	cl_git_pass(git_commit_lookup(&br2, repo, git_reference_target(br2_ref)));
+
+	cl_git_pass(git_checkout_tree(repo, (const git_object *)br2, &checkout_opts));
+
+	git_commit_free(orig);
+	git_reference_free(orig_ref);
+}
+
+void test_checkout_icase__conflicts_with_casechanged_subtrees(void)
+{
+	git_reference *orig_ref;
+	git_object *orig, *subtrees;
+	git_oid oid;
+	git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+
+	checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
+
+	cl_git_pass(git_reference_lookup_resolved(&orig_ref, repo, "HEAD", 100));
+	cl_git_pass(git_object_lookup(&orig, repo, git_reference_target(orig_ref), GIT_OBJ_COMMIT));
+	cl_git_pass(git_reset(repo, (git_object *)orig, GIT_RESET_HARD, NULL));
+
+	cl_must_pass(p_mkdir("testrepo/AB", 0777));
+	cl_must_pass(p_mkdir("testrepo/AB/C", 0777));
+	cl_git_write2file("testrepo/AB/C/3.txt", "Foobar!\n", 8, O_RDWR|O_CREAT, 0666);
+
+	cl_git_pass(git_reference_name_to_id(&oid, repo, "refs/heads/subtrees"));
+	cl_git_pass(git_object_lookup(&subtrees, repo, &oid, GIT_OBJ_ANY));
+
+	cl_git_fail(git_checkout_tree(repo, subtrees, &checkout_opts));
+
+	git_object_free(orig);
+	git_object_free(subtrees);
+    git_reference_free(orig_ref);
+}
+
diff --git a/tests/checkout/tree.c b/tests/checkout/tree.c
index 3973d93..50541a7 100644
--- a/tests/checkout/tree.c
+++ b/tests/checkout/tree.c
@@ -646,7 +646,14 @@ void test_checkout_tree__can_cancel_checkout_from_notify(void)
 	cl_git_fail_with(git_checkout_tree(g_repo, obj, &opts), -5555);
 
 	cl_assert(!git_path_exists("testrepo/new.txt"));
-	cl_assert_equal_i(4, ca.count);
+
+	/* on case-insensitive FS = a/b.txt, branch_file.txt, new.txt */
+	/* on case-sensitive FS   = README, then above */
+
+	if (git_path_exists("testrepo/.git/CoNfIg")) /* case insensitive */
+		cl_assert_equal_i(3, ca.count);
+	else
+		cl_assert_equal_i(4, ca.count);
 
 	/* and again with a different stopping point and return code */
 	ca.filename = "README";
@@ -656,7 +663,11 @@ void test_checkout_tree__can_cancel_checkout_from_notify(void)
 	cl_git_fail_with(git_checkout_tree(g_repo, obj, &opts), 123);
 
 	cl_assert(!git_path_exists("testrepo/new.txt"));
-	cl_assert_equal_i(1, ca.count);
+
+	if (git_path_exists("testrepo/.git/CoNfIg")) /* case insensitive */
+		cl_assert_equal_i(4, ca.count);
+	else
+		cl_assert_equal_i(1, ca.count);
 
 	git_object_free(obj);
 }
diff --git a/tests/status/renames.c b/tests/status/renames.c
index 24b8aca..f482d69 100644
--- a/tests/status/renames.c
+++ b/tests/status/renames.c
@@ -73,16 +73,20 @@ static void check_status(
 
 		cl_assert_equal_i_fmt(expected->status, actual->status, "%04x");
 
-		if (oldname)
-			cl_assert(git__strcmp(oldname, expected->oldname) == 0);
-		else
-			cl_assert(expected->oldname == NULL);
+		if (expected->oldname) {
+			cl_assert(oldname != NULL);
+			cl_assert_equal_s(oldname, expected->oldname);
+		} else {
+			cl_assert(oldname == NULL);
+		}
 
 		if (actual->status & (GIT_STATUS_INDEX_RENAMED|GIT_STATUS_WT_RENAMED)) {
-			if (newname)
-				cl_assert(git__strcmp(newname, expected->newname) == 0);
-			else
-				cl_assert(expected->newname == NULL);
+			if (expected->newname) {
+				cl_assert(newname != NULL);
+				cl_assert_equal_s(newname, expected->newname);
+			} else {
+				cl_assert(newname == NULL);
+			}
 		}
 	}
 }