merge-recursive --patience

Teach the merge-recursive strategy a --patience option to use the
"patience diff" algorithm, which tends to improve results when
cherry-picking a patch that reorders functions at the same time as
refactoring them.

To support this, struct merge_options and ll_merge_options gain an
xdl_opts member, so programs can use arbitrary xdiff flags (think
"XDF_IGNORE_WHITESPACE") in a git-aware merge.

git merge and git rebase can be passed the -Xpatience option to
use this.

[jn: split from --ignore-space patch; with documentation]

Signed-off-by: Justin Frankel <justin@cockos.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/merge-strategies.txt b/Documentation/merge-strategies.txt
index 049313d..a5ae14f 100644 (file)
--- a/Documentation/merge-strategies.txt
+++ b/Documentation/merge-strategies.txt
@@ -40,6 +40,13 @@ the other tree did, declaring 'our' history contains all that happened in it.
 theirs;;
        This is opposite of 'ours'.
 
+patience;;
+       With this option, 'merge-recursive' spends a little extra time
+       to avoid mismerges that sometimes occur due to unimportant
+       matching lines (e.g., braces from distinct functions).  Use
+       this when the branches to be merged have diverged wildly.
+       See also linkgit:git-diff[1] `--patience`.
+
 renormalize;;
        This runs a virtual check-out and check-in of all three stages
        of a file when resolving a three-way merge.  This option is

diff --git a/builtin/merge-recursive.c b/builtin/merge-recursive.c
index 5a52f3d..70e1d25 100644 (file)
--- a/builtin/merge-recursive.c
+++ b/builtin/merge-recursive.c
@@ -2,6 +2,7 @@
 #include "commit.h"
 #include "tag.h"
 #include "merge-recursive.h"
+#include "xdiff-interface.h"
 
 static const char *better_branch_name(const char *branch)
 {

diff --git a/ll-merge.c b/ll-merge.c
index 4d8e321..007dd3e 100644 (file)
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -86,6 +86,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
        memset(&xmp, 0, sizeof(xmp));
        xmp.level = XDL_MERGE_ZEALOUS;
        xmp.favor = opts->variant;
+       xmp.xpp.flags = opts->xdl_opts;
        if (git_xmerge_style >= 0)
                xmp.style = git_xmerge_style;
        if (marker_size > 0)

diff --git a/ll-merge.h b/ll-merge.h
index 4b707f0..244a31f 100644 (file)
--- a/ll-merge.h
+++ b/ll-merge.h
@@ -9,6 +9,7 @@ struct ll_merge_options {
        unsigned virtual_ancestor : 1;
        unsigned variant : 2;   /* favor ours, favor theirs, or union merge */
        unsigned renormalize : 1;
+       long xdl_opts;
 };
 
 int ll_merge(mmbuffer_t *result_buf,

diff --git a/merge-recursive.c b/merge-recursive.c
index 0e9a29d..3e67f81 100644 (file)
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -613,6 +613,7 @@ static int merge_3way(struct merge_options *o,
        int merge_status;
 
        ll_opts.renormalize = o->renormalize;
+       ll_opts.xdl_opts = o->xdl_opts;
 
        if (o->call_depth) {
                ll_opts.virtual_ancestor = 1;
@@ -1512,6 +1513,8 @@ int parse_merge_opt(struct merge_options *o, const char *s)
                o->subtree_shift = "";
        else if (!prefixcmp(s, "subtree="))
                o->subtree_shift = s + strlen("subtree=");
+       else if (!strcmp(s, "patience"))
+               o->xdl_opts |= XDF_PATIENCE_DIFF;
        else if (!strcmp(s, "renormalize"))
                o->renormalize = 1;
        else if (!strcmp(s, "no-renormalize"))

diff --git a/merge-recursive.h b/merge-recursive.h
index 37ff99a..d21b446 100644 (file)
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -15,6 +15,7 @@ struct merge_options {
        const char *subtree_shift;
        unsigned buffer_output : 1;
        unsigned renormalize : 1;
+       long xdl_opts;
        int verbosity;
        int diff_rename_limit;
        int merge_rename_limit;