Hi,
On Tue, 2 Jan 2007, Jakub Narebski wrote:
> On Sun, 31 Dec 2006, Johannes Schindelin wrote:
>
> > On Sat, 30 Dec 2006, Jakub Narebski wrote:
> >
> >> Johannes Schindelin wrote:
> >>
> >>> Of course, you can hit mismerges like the illustrated one _without_
> >>> being marked as conflict (e.g. if the chunk of identical code is _not_
> >>> added, but only the increments), but we should at least avoid them
> >>> where possible.
> >>
> >> Perhaps you could make it even more conservating merge conflicts option
> >> (to tighten merge conflicts even more) to xdl_merge, but not used by
> >> default because as it removes accidental conflicts it increases
> >> mismerges (falsely not conflicted).
> >
> > There is no way to do this sanely. If you want to catch these mismerges,
> > you have to mark _all_ modifications as conflicting.
>
> Currently you have:
> - a level value of 0 means that all overlapping changes are treated
> as conflicts,
> - a value of 1 means that if the overlapping changes are identical,
> it is not treated as a conflict.
> - If you set level to 2, overlapping changes will be analyzed, so that
> almost identical changes will not result in huge conflicts. Rather,
> only the conflicting lines will be shown inside conflict markers.
>
> I was thinking about:
> - If you set level to 3, if one part after overlapping changes analysis
> in level 2 has empty conflict region, resolve this conflict as second
> side. WARNING: this reduces number of merge conflicts, but might give
> mismerges!
That is certainly a possibility! But how would you specify it? If you
do it as a command line option, you'd have to add it to git-merge,
git-pull, git-merge-recursive and git-merge-file. Ugly.
You could do it as a config variable, but git-merge-file operates without
a git repository. And you'd want it to be overrideable anyway.
Environment variable? Too unfriendly to users, because it is not really a
proper UI.
It is certainly easy enough to teach the code (but might introduce
unwanted side effects, when the _deletion_, not the _addition_ was what
you wanted):
xdiff/xdiff.h | 1 +
xdiff/xmerge.c | 21 ++++++++++++++++++---
2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index fa409d5..bdf12e3 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -52,6 +52,7 @@ extern "C" {
#define XDL_MERGE_MINIMAL 0
#define XDL_MERGE_EAGER 1
#define XDL_MERGE_ZEALOUS 2
+#define XDL_MERGE_OVERZEALOUS 3
typedef struct s_mmfile {
char *ptr;
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index b83b334..e7b740f 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -180,7 +180,7 @@ static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
* lines. Try hard to show only these few lines as conflicting.
*/
static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
- xpparam_t const *xpp)
+ int level, xpparam_t const *xpp)
{
for (; m; m = m->next) {
mmfile_t t1, t2;
@@ -225,6 +225,12 @@ static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
m->chg1 = xscr->chg1;
m->i2 = xscr->i2 + i2;
m->chg2 = xscr->chg2;
+ if (level >= XDL_MERGE_OVERZEALOUS) {
+ if (!m->chg1)
+ m->mode = 2;
+ else if (!m->chg2)
+ m->mode = 1;
+ }
while (xscr->next) {
xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
if (!m2) {
@@ -241,6 +247,12 @@ static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
m->chg1 = xscr->chg1;
m->i2 = xscr->i2 + i2;
m->chg2 = xscr->chg2;
+ if (level >= XDL_MERGE_OVERZEALOUS) {
+ if (!m->chg1)
+ m->mode = 2;
+ else if (!m->chg2)
+ m->mode = 1;
+ }
}
xdl_free_env(&xe);
xdl_free_script(x);
@@ -252,6 +264,7 @@ static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
* level == 0: mark all overlapping changes as conflict
* level == 1: mark overlapping changes as conflict only if not identical
* level == 2: analyze non-identical changes for minimal conflict set
+ * level == 3: if one side in the analysis is empty, assume no conflict
*
* returns < 0 on error, == 0 for no conflicts, else number of conflicts
*/
@@ -290,7 +303,7 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
xscr2 = xscr2->next;
continue;
}
- if (level < 1 || xscr1->i1 != xscr2->i1 ||
+ if (level < XDL_MERGE_EAGER || xscr1->i1 != xscr2->i1 ||
xscr1->chg1 != xscr2->chg1 ||
xscr1->chg2 != xscr2->chg2 ||
xdl_merge_cmp_lines(xe1, xscr1->i2,
@@ -355,7 +368,9 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
if (!changes)
changes = c;
/* refine conflicts */
- if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
+ if (level >= XDL_MERGE_ZEALOUS &&
+ xdl_refine_conflicts(xe1, xe2, changes,
+ xpp, level) < 0) {
xdl_cleanup_merge(changes);
return -1;
}
-
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