[RFC/PATCH] commit: make the error message on unmerged entries user-friendly.

[Matthieu Moy <Matthieu.Moy@imag.fr>]

The error message used to look like this:

$ git commit
foo.txt: needs merge
foo.txt: unmerged (c34a92682e0394bc0d6f4d4a67a8e2d32395c169)
foo.txt: unmerged (3afcd75de8de0bb5076942fcb17446be50451030)
foo.txt: unmerged (c9785d77b76dfe4fb038bf927ee518f6ae45ede4)
error: Error building trees

The "need merge" line is given by refresh_cache. We add the IN_PORCELAIN
option to make the output more consistant with the other porcelain
commands, and catch the error in return, to stop with a clean error
message. The next lines were displayed by a call to cache_tree_update(),
which is not reached anymore if we noticed the conflict.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
---
As usual, I try to have error messages point to the solution, not just
the origin of the problem.

Two questions:

* Did anyone actually use the 3 "file: unmerged (sha1)" lines?

* Do you like my new message?

Thanks,

 builtin-commit.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/builtin-commit.c b/builtin-commit.c
index 3dfcd77..d491a01 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -235,6 +235,18 @@ static void create_base_index(void)
 		exit(128); /* We've already reported the error, finish dying */
 }
 
+static void refresh_cache_or_die(int refresh_flags)
+{
+	/*
+	 * refresh_flags contains REFRESH_QUIET, so the only errors
+	 * are for unmerged entries.
+	*/
+	if(refresh_cache(refresh_flags | REFRESH_IN_PORCELAIN))
+		die("Commit is not possible because you have unmerged files.\n"
+		    "Please, resolve the conflicts listed above, and then mark them\n"
+		    "as resolved with 'git add <filename>', or use 'git commit -a'.");
+}
+
 static char *prepare_index(int argc, const char **argv, const char *prefix, int is_status)
 {
 	int fd;
@@ -274,7 +286,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix, int
 	if (all || (also && pathspec && *pathspec)) {
 		int fd = hold_locked_index(&index_lock, 1);
 		add_files_to_cache(also ? prefix : NULL, pathspec, 0);
-		refresh_cache(refresh_flags);
+		refresh_cache_or_die(refresh_flags);
 		if (write_cache(fd, active_cache, active_nr) ||
 		    close_lock_file(&index_lock))
 			die("unable to write new_index file");
@@ -293,7 +305,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix, int
 	 */
 	if (!pathspec || !*pathspec) {
 		fd = hold_locked_index(&index_lock, 1);
-		refresh_cache(refresh_flags);
+		refresh_cache_or_die(refresh_flags);
 		if (write_cache(fd, active_cache, active_nr) ||
 		    commit_locked_index(&index_lock))
 			die("unable to write new_index file");
-- 
1.6.6.76.gd6b23.dirty