Re: What's cooking in git.git (Aug 2008, #05; Tue, 19)

[Miklos Vajna <vmiklos@frugalware.org>]

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On Tue, Aug 19, 2008 at 03:00:27PM -0700, Junio C Hamano <gitster@pobox.com> wrote:
> and the call chain would become:
> (...)
>     cmd_revert(), cmd_am(), cmd_checkout(), cmd_stash(), ...
>     -> merge_trees()

I tried to let cmd_revert() use merge_trees() only and not
merge_recursive_generic(), but something is fishy with it.

t3501-revert-cherry-pick passes fine, but t3404-rebase-interactive fail,
becase once we have a conflict, git diff --name-status says 'M' for the
given file and not 'U', which is obviously wrong.

I'm sending both patches: the one that works properly using
merge_recursive_generic() - and which one passes the testsuite here, and
the one that is elegant as it uses merge_trees(), but actually not
complete, at least regarding not adding the unmerged entries to the
index.

So, first here is my failed attempt to use merge_trees() inside
builtin-revert:

diff --git a/builtin-revert.c b/builtin-revert.c
index 3667705..3071518 100644
--- a/builtin-revert.c
+++ b/builtin-revert.c
@@ -12,6 +12,7 @@
 #include "diff.h"
 #include "revision.h"
 #include "rerere.h"
+#include "merge-recursive.h"
 
 /*
  * This implements the builtins revert and cherry-pick.
@@ -201,36 +202,6 @@ static void set_author_ident_env(const char *message)
 			sha1_to_hex(commit->object.sha1));
 }
 
-static int merge_recursive(const char *base_sha1,
-		const char *head_sha1, const char *head_name,
-		const char *next_sha1, const char *next_name)
-{
-	char buffer[256];
-	const char *argv[6];
-	int i = 0;
-
-	sprintf(buffer, "GITHEAD_%s", head_sha1);
-	setenv(buffer, head_name, 1);
-	sprintf(buffer, "GITHEAD_%s", next_sha1);
-	setenv(buffer, next_name, 1);
-
-	/*
-	 * This three way merge is an interesting one.  We are at
-	 * $head, and would want to apply the change between $commit
-	 * and $prev on top of us (when reverting), or the change between
-	 * $prev and $commit on top of us (when cherry-picking or replaying).
-	 */
-	argv[i++] = "merge-recursive";
-	if (base_sha1)
-		argv[i++] = base_sha1;
-	argv[i++] = "--";
-	argv[i++] = head_sha1;
-	argv[i++] = next_sha1;
-	argv[i++] = NULL;
-
-	return run_command_v_opt(argv, RUN_COMMAND_NO_STDIN | RUN_GIT_CMD);
-}
-
 static char *help_msg(const unsigned char *sha1)
 {
 	static char helpbuf[1024];
@@ -271,6 +242,8 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 	char *oneline, *reencoded_message = NULL;
 	const char *message, *encoding;
 	const char *defmsg = xstrdup(git_path("MERGE_MSG"));
+	struct merge_options o;
+	struct tree *result;
 
 	git_config(git_default_config, NULL);
 	me = action == REVERT ? "revert" : "cherry-pick";
@@ -374,13 +347,16 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 		}
 	}
 
-	if (merge_recursive(base == NULL ?
-				NULL : sha1_to_hex(base->object.sha1),
-				sha1_to_hex(head), "HEAD",
-				sha1_to_hex(next->object.sha1), oneline) ||
-			write_cache_as_tree(head, 0, NULL)) {
+	read_cache();
+	init_merge_options(&o);
+	o.branch1 = "HEAD";
+	o.branch2 = oneline;
+	parse_commit(next);
+	parse_commit(base);
+	if (!merge_trees(&o, lookup_commit_reference_gently(head, 0)->tree,
+				next->tree, base->tree, &result) ||
+		write_cache_as_tree(head, 0, NULL)) {
 		add_to_msg("\nConflicts:\n\n");
-		read_cache();
 		for (i = 0; i < active_nr;) {
 			struct cache_entry *ce = active_cache[i++];
 			if (ce_stage(ce)) {

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