Merge branch 'jk/no-diff-emit-common' into maint

"git merge-tree" used to mishandle "both sides added" conflict with
its own "create a fake ancestor file that has the common parts of
what both sides have added and do a 3-way merge" logic; this has
been updated to use the usual "3-way merge with an empty blob as
the fake common ancestor file" approach used in the rest of the
system.

* jk/no-diff-emit-common:
  xdiff: drop XDL_EMIT_COMMON
  merge-tree: drop generate_common strategy
  merge-one-file: use empty blob for add/add base

4 files changed, 3 insertions, 57 deletions

diff --git a/git-merge-one-file.sh b/git-merge-one-file.sh
index cdc02af517..424b034e34 100755
--- a/git-merge-one-file.sh
+++ b/git-merge-one-file.sh
@@ -120,8 +120,7 @@ case "${1:-.}${2:-.}${3:-.}" in
         case "$1" in
         '')
                 echo "Added $4 in both, but differently."
-                orig=$(git-unpack-file $2)
-                create_virtual_base "$orig" "$src2"
+                orig=$(git-unpack-file e69de29bb2d1d6434b8b29ae775ad8c2e48c5391)
                 ;;
         *)
                 echo "Auto-merging $4"
diff --git a/merge-blobs.c b/merge-blobs.c
index ddca601c77..9b6eac22e4 100644
--- a/merge-blobs.c
+++ b/merge-blobs.c
@@ -48,40 +48,6 @@ static void *three_way_filemerge(const char *path, mmfile_t *base, mmfile_t *our
         return res.ptr;
 }
 
-static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
-{
-        int i;
-        mmfile_t *dst = priv_;
-
-        for (i = 0; i < nbuf; i++) {
-                memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
-                dst->size += mb[i].size;
-        }
-        return 0;
-}
-
-static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
-{
-        unsigned long size = f1->size < f2->size ? f1->size : f2->size;
-        void *ptr = xmalloc(size);
-        xpparam_t xpp;
-        xdemitconf_t xecfg;
-        xdemitcb_t ecb;
-
-        memset(&xpp, 0, sizeof(xpp));
-        xpp.flags = 0;
-        memset(&xecfg, 0, sizeof(xecfg));
-        xecfg.ctxlen = 3;
-        xecfg.flags = XDL_EMIT_COMMON;
-        ecb.outf = common_outf;
-
-        res->ptr = ptr;
-        res->size = 0;
-
-        ecb.priv = res;
-        return xdi_diff(f1, f2, &xpp, &xecfg, &ecb);
-}
-
 void *merge_blobs(const char *path, struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
 {
         void *res = NULL;
@@ -112,8 +78,8 @@ void *merge_blobs(const char *path, struct blob *base, struct blob *our, struct
                 if (fill_mmfile_blob(&common, base) < 0)
                         goto out_free_f2_f1;
         } else {
-                if (generate_common_file(&common, &f1, &f2) < 0)
-                        goto out_free_f2_f1;
+                common.ptr = xstrdup("");
+                common.size = 0;
         }
         res = three_way_filemerge(path, &common, &f1, &f2, size);
         free_mmfile(&common);
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index c0339919cc..4fb7e79410 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -42,7 +42,6 @@ extern "C" {
 #define XDF_IGNORE_BLANK_LINES (1 << 7)
 
 #define XDL_EMIT_FUNCNAMES (1 << 0)
-#define XDL_EMIT_COMMON (1 << 1)
 #define XDL_EMIT_FUNCCONTEXT (1 << 2)
 
 #define XDL_MMB_READONLY (1 << 0)
diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 4266ada23f..993724b11c 100644
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -120,21 +120,6 @@ static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
         return -1;
 }
 
-static int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
-                           xdemitconf_t const *xecfg) {
-        xdfile_t *xdf = &xe->xdf2;
-        const char *rchg = xdf->rchg;
-        long ix;
-
-        for (ix = 0; ix < xdf->nrec; ix++) {
-                if (rchg[ix])
-                        continue;
-                if (xdl_emit_record(xdf, ix, "", ecb))
-                        return -1;
-        }
-        return 0;
-}
-
 struct func_line {
         long len;
         char buf[80];
@@ -170,9 +155,6 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
         long funclineprev = -1;
         struct func_line func_line = { 0 };
 
-        if (xecfg->flags & XDL_EMIT_COMMON)
-                return xdl_emit_common(xe, xscr, ecb, xecfg);
-
         for (xch = xscr; xch; xch = xche->next) {
                 xche = xdl_get_hunk(&xch, xecfg);
                 if (!xch)