git-read-tree: fix up two-way merge

This is starting to look better.

diff --git a/read-tree.c b/read-tree.c
index 1a575eb0d29d298ab714c7455cff5b6eced4de2f..8c9ffe123255bfeb199ea90f055ac8d1df49ddb8 100644 (file)
--- a/read-tree.c
+++ b/read-tree.c
@@ -180,6 +180,34 @@ static void trivially_merge_cache(struct cache_entry **src, int nr)
                reject_merge(old);
 }
 
+/*
+ * When we find a "stage2" entry in the two-way merge, that's
+ * the one that will remain. If we have an exact old match,
+ * we don't care whether the file is up-to-date or not, we just
+ * re-use the thing directly.
+ *
+ * If we didn't have an exact match, then we want to make sure
+ * that we've seen a stage1 that matched the old, and that the
+ * old file was up-to-date. Because it will be gone after this
+ * merge..
+ */
+static void twoway_check(struct cache_entry *old, int seen_stage1, struct cache_entry *ce)
+{
+       if (path_matches(old, ce)) {
+               /*
+                * This also removes the UPDATE flag on
+                * a match
+                */
+               if (same(old, ce)) {
+                       *ce = *old;
+                       return;
+               }
+               if (!seen_stage1)
+                       reject_merge(old);
+       }
+       verify_uptodate(old);
+}
+
 /*
  * Two-way merge.
  *
@@ -190,8 +218,8 @@ static void trivially_merge_cache(struct cache_entry **src, int nr)
  */
 static void twoway_merge(struct cache_entry **src, int nr)
 {
-       static struct cache_entry null_entry;
-       struct cache_entry *old = NULL, *stat = &null_entry;
+       int seen_stage1 = 0;
+       struct cache_entry *old = NULL;
        struct cache_entry **dst = src;
 
        while (nr--) {
@@ -203,7 +231,7 @@ static void twoway_merge(struct cache_entry **src, int nr)
                        if (old)
                                reject_merge(old);
                        old = ce;
-                       stat = ce;
+                       seen_stage1 = 0;
                        active_nr--;
                        continue;
 
@@ -213,21 +241,13 @@ static void twoway_merge(struct cache_entry **src, int nr)
                                continue;
                        if (!path_matches(old, ce) || !same(old, ce))
                                reject_merge(old);
+                       seen_stage1 = 1;
                        continue;
 
                case 2:
                        ce->ce_flags |= htons(CE_UPDATE);
                        if (old) {
-                               if (!path_matches(old, ce))
-                                       reject_merge(old);
-                               /*
-                                * This also removes the UPDATE flag on
-                                * a match
-                                */
-                               if (same(old, ce))
-                                       *ce = *old;
-                               else
-                                       verify_uptodate(old);
+                               twoway_check(old, seen_stage1, ce);
                                old = NULL;
                        }
                        ce->ce_flags &= ~htons(CE_STAGEMASK);
@@ -236,8 +256,17 @@ static void twoway_merge(struct cache_entry **src, int nr)
                }
                die("impossible two-way stage");
        }
-       if (old)
-               reject_merge(old);
+
+       /*
+        * Unmatched with a new entry? Make sure it was
+        * at least uptodate in the working directory _and_
+        * the original tree..
+        */
+       if (old) {
+               if (!seen_stage1)
+                       reject_merge(old);
+               verify_uptodate(old);
+       }
 }
 
 static void merge_stat_info(struct cache_entry **src, int nr)