git.oblomov.eu Git - git/blob - diffcore-rename.c

   1 /*
   2  *
   3  * Copyright (C) 2005 Junio C Hamano
   4  */
   5 #include "cache.h"
   6 #include "diff.h"
   7 #include "diffcore.h"
   8 #include "object-store.h"
   9 #include "hashmap.h"
  10 #include "progress.h"
  11 #include "promisor-remote.h"
  12
  13 /* Table of rename/copy destinations */
  14
  15 static struct diff_rename_dst {
  16         struct diff_filespec *two;
  17         struct diff_filepair *pair;
  18 } *rename_dst;
  19 static int rename_dst_nr, rename_dst_alloc;
  20
  21 static int find_rename_dst(struct diff_filespec *two)
  22 {
  23         int first, last;
  24
  25         first = 0;
  26         last = rename_dst_nr;
  27         while (last > first) {
  28                 int next = first + ((last - first) >> 1);
  29                 struct diff_rename_dst *dst = &(rename_dst[next]);
  30                 int cmp = strcmp(two->path, dst->two->path);
  31                 if (!cmp)
  32                         return next;
  33                 if (cmp < 0) {
  34                         last = next;
  35                         continue;
  36                 }
  37                 first = next+1;
  38         }
  39         return -first - 1;
  40 }
  41
  42 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
  43 {
  44         int ofs = find_rename_dst(two);
  45         return ofs < 0 ? NULL : &rename_dst[ofs];
  46 }
  47
  48 /*
  49  * Returns 0 on success, -1 if we found a duplicate.
  50  */
  51 static int add_rename_dst(struct diff_filespec *two)
  52 {
  53         int first = find_rename_dst(two);
  54
  55         if (first >= 0)
  56                 return -1;
  57         first = -first - 1;
  58
  59         /* insert to make it at "first" */
  60         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
  61         rename_dst_nr++;
  62         if (first < rename_dst_nr)
  63                 MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
  64                            rename_dst_nr - first - 1);
  65         rename_dst[first].two = alloc_filespec(two->path);
  66         fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
  67                       two->mode);
  68         rename_dst[first].pair = NULL;
  69         return 0;
  70 }
  71
  72 /* Table of rename/copy src files */
  73 static struct diff_rename_src {
  74         struct diff_filepair *p;
  75         unsigned short score; /* to remember the break score */
  76 } *rename_src;
  77 static int rename_src_nr, rename_src_alloc;
  78
  79 static void register_rename_src(struct diff_filepair *p)
  80 {
  81         /*
  82          * If we have multiple entries at the same path in the source tree
  83          * (an invalid tree, to be sure), avoid using more more than one
  84          * such entry in rename detection.  Once upon a time, doing so
  85          * caused segfaults; see commit 25d5ea410f ("[PATCH] Redo
  86          * rename/copy detection logic.", 2005-05-24).
  87          */
  88         if (rename_src_nr > 0 &&
  89             !strcmp(rename_src[rename_src_nr-1].p->one->path, p->one->path))
  90                 return;
  91
  92         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  93         rename_src[rename_src_nr].p = p;
  94         rename_src[rename_src_nr].score = p->score;
  95         rename_src_nr++;
  96 }
  97
  98 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
  99 {
 100         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 101         while (src_len && dst_len) {
 102                 char c1 = src->path[--src_len];
 103                 char c2 = dst->path[--dst_len];
 104                 if (c1 != c2)
 105                         return 0;
 106                 if (c1 == '/')
 107                         return 1;
 108         }
 109         return (!src_len || src->path[src_len - 1] == '/') &&
 110                 (!dst_len || dst->path[dst_len - 1] == '/');
 111 }
 112
 113 struct diff_score {
 114         int src; /* index in rename_src */
 115         int dst; /* index in rename_dst */
 116         unsigned short score;
 117         short name_score;
 118 };
 119
 120 struct prefetch_options {
 121         struct repository *repo;
 122         int skip_unmodified;
 123 };
 124 static void prefetch(void *prefetch_options)
 125 {
 126         struct prefetch_options *options = prefetch_options;
 127         int i;
 128         struct oid_array to_fetch = OID_ARRAY_INIT;
 129
 130         for (i = 0; i < rename_dst_nr; i++) {
 131                 if (rename_dst[i].pair)
 132                         /*
 133                          * The loop in diffcore_rename() will not need these
 134                          * blobs, so skip prefetching.
 135                          */
 136                         continue; /* already found exact match */
 137                 diff_add_if_missing(options->repo, &to_fetch,
 138                                     rename_dst[i].two);
 139         }
 140         for (i = 0; i < rename_src_nr; i++) {
 141                 if (options->skip_unmodified &&
 142                     diff_unmodified_pair(rename_src[i].p))
 143                         /*
 144                          * The loop in diffcore_rename() will not need these
 145                          * blobs, so skip prefetching.
 146                          */
 147                         continue;
 148                 diff_add_if_missing(options->repo, &to_fetch,
 149                                     rename_src[i].p->one);
 150         }
 151         promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
 152         oid_array_clear(&to_fetch);
 153 }
 154
 155 static int estimate_similarity(struct repository *r,
 156                                struct diff_filespec *src,
 157                                struct diff_filespec *dst,
 158                                int minimum_score,
 159                                int skip_unmodified)
 160 {
 161         /* src points at a file that existed in the original tree (or
 162          * optionally a file in the destination tree) and dst points
 163          * at a newly created file.  They may be quite similar, in which
 164          * case we want to say src is renamed to dst or src is copied into
 165          * dst, and then some edit has been applied to dst.
 166          *
 167          * Compare them and return how similar they are, representing
 168          * the score as an integer between 0 and MAX_SCORE.
 169          *
 170          * When there is an exact match, it is considered a better
 171          * match than anything else; the destination does not even
 172          * call into this function in that case.
 173          */
 174         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 175         int score;
 176         struct diff_populate_filespec_options dpf_options = {
 177                 .check_size_only = 1
 178         };
 179         struct prefetch_options prefetch_options = {r, skip_unmodified};
 180
 181         if (r == the_repository && has_promisor_remote()) {
 182                 dpf_options.missing_object_cb = prefetch;
 183                 dpf_options.missing_object_data = &prefetch_options;
 184         }
 185
 186         /* We deal only with regular files.  Symlink renames are handled
 187          * only when they are exact matches --- in other words, no edits
 188          * after renaming.
 189          */
 190         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 191                 return 0;
 192
 193         /*
 194          * Need to check that source and destination sizes are
 195          * filled in before comparing them.
 196          *
 197          * If we already have "cnt_data" filled in, we know it's
 198          * all good (avoid checking the size for zero, as that
 199          * is a possible size - we really should have a flag to
 200          * say whether the size is valid or not!)
 201          */
 202         if (!src->cnt_data &&
 203             diff_populate_filespec(r, src, &dpf_options))
 204                 return 0;
 205         if (!dst->cnt_data &&
 206             diff_populate_filespec(r, dst, &dpf_options))
 207                 return 0;
 208
 209         max_size = ((src->size > dst->size) ? src->size : dst->size);
 210         base_size = ((src->size < dst->size) ? src->size : dst->size);
 211         delta_size = max_size - base_size;
 212
 213         /* We would not consider edits that change the file size so
 214          * drastically.  delta_size must be smaller than
 215          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 216          *
 217          * Note that base_size == 0 case is handled here already
 218          * and the final score computation below would not have a
 219          * divide-by-zero issue.
 220          */
 221         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 222                 return 0;
 223
 224         dpf_options.check_size_only = 0;
 225
 226         if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
 227                 return 0;
 228         if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
 229                 return 0;
 230
 231         if (diffcore_count_changes(r, src, dst,
 232                                    &src->cnt_data, &dst->cnt_data,
 233                                    &src_copied, &literal_added))
 234                 return 0;
 235
 236         /* How similar are they?
 237          * what percentage of material in dst are from source?
 238          */
 239         if (!dst->size)
 240                 score = 0; /* should not happen */
 241         else
 242                 score = (int)(src_copied * MAX_SCORE / max_size);
 243         return score;
 244 }
 245
 246 static void record_rename_pair(int dst_index, int src_index, int score)
 247 {
 248         struct diff_filespec *src, *dst;
 249         struct diff_filepair *dp;
 250
 251         if (rename_dst[dst_index].pair)
 252                 die("internal error: dst already matched.");
 253
 254         src = rename_src[src_index].p->one;
 255         src->rename_used++;
 256         src->count++;
 257
 258         dst = rename_dst[dst_index].two;
 259         dst->count++;
 260
 261         dp = diff_queue(NULL, src, dst);
 262         dp->renamed_pair = 1;
 263         if (!strcmp(src->path, dst->path))
 264                 dp->score = rename_src[src_index].score;
 265         else
 266                 dp->score = score;
 267         rename_dst[dst_index].pair = dp;
 268 }
 269
 270 /*
 271  * We sort the rename similarity matrix with the score, in descending
 272  * order (the most similar first).
 273  */
 274 static int score_compare(const void *a_, const void *b_)
 275 {
 276         const struct diff_score *a = a_, *b = b_;
 277
 278         /* sink the unused ones to the bottom */
 279         if (a->dst < 0)
 280                 return (0 <= b->dst);
 281         else if (b->dst < 0)
 282                 return -1;
 283
 284         if (a->score == b->score)
 285                 return b->name_score - a->name_score;
 286
 287         return b->score - a->score;
 288 }
 289
 290 struct file_similarity {
 291         struct hashmap_entry entry;
 292         int index;
 293         struct diff_filespec *filespec;
 294 };
 295
 296 static unsigned int hash_filespec(struct repository *r,
 297                                   struct diff_filespec *filespec)
 298 {
 299         if (!filespec->oid_valid) {
 300                 if (diff_populate_filespec(r, filespec, NULL))
 301                         return 0;
 302                 hash_object_file(r->hash_algo, filespec->data, filespec->size,
 303                                  "blob", &filespec->oid);
 304         }
 305         return oidhash(&filespec->oid);
 306 }
 307
 308 static int find_identical_files(struct hashmap *srcs,
 309                                 int dst_index,
 310                                 struct diff_options *options)
 311 {
 312         int renames = 0;
 313         struct diff_filespec *target = rename_dst[dst_index].two;
 314         struct file_similarity *p, *best = NULL;
 315         int i = 100, best_score = -1;
 316         unsigned int hash = hash_filespec(options->repo, target);
 317
 318         /*
 319          * Find the best source match for specified destination.
 320          */
 321         p = hashmap_get_entry_from_hash(srcs, hash, NULL,
 322                                         struct file_similarity, entry);
 323         hashmap_for_each_entry_from(srcs, p, entry) {
 324                 int score;
 325                 struct diff_filespec *source = p->filespec;
 326
 327                 /* False hash collision? */
 328                 if (!oideq(&source->oid, &target->oid))
 329                         continue;
 330                 /* Non-regular files? If so, the modes must match! */
 331                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 332                         if (source->mode != target->mode)
 333                                 continue;
 334                 }
 335                 /* Give higher scores to sources that haven't been used already */
 336                 score = !source->rename_used;
 337                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 338                         continue;
 339                 score += basename_same(source, target);
 340                 if (score > best_score) {
 341                         best = p;
 342                         best_score = score;
 343                         if (score == 2)
 344                                 break;
 345                 }
 346
 347                 /* Too many identical alternatives? Pick one */
 348                 if (!--i)
 349                         break;
 350         }
 351         if (best) {
 352                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 353                 renames++;
 354         }
 355         return renames;
 356 }
 357
 358 static void insert_file_table(struct repository *r,
 359                               struct hashmap *table, int index,
 360                               struct diff_filespec *filespec)
 361 {
 362         struct file_similarity *entry = xmalloc(sizeof(*entry));
 363
 364         entry->index = index;
 365         entry->filespec = filespec;
 366
 367         hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
 368         hashmap_add(table, &entry->entry);
 369 }
 370
 371 /*
 372  * Find exact renames first.
 373  *
 374  * The first round matches up the up-to-date entries,
 375  * and then during the second round we try to match
 376  * cache-dirty entries as well.
 377  */
 378 static int find_exact_renames(struct diff_options *options)
 379 {
 380         int i, renames = 0;
 381         struct hashmap file_table;
 382
 383         /* Add all sources to the hash table in reverse order, because
 384          * later on they will be retrieved in LIFO order.
 385          */
 386         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
 387         for (i = rename_src_nr-1; i >= 0; i--)
 388                 insert_file_table(options->repo,
 389                                   &file_table, i,
 390                                   rename_src[i].p->one);
 391
 392         /* Walk the destinations and find best source match */
 393         for (i = 0; i < rename_dst_nr; i++)
 394                 renames += find_identical_files(&file_table, i, options);
 395
 396         /* Free the hash data structure and entries */
 397         hashmap_clear_and_free(&file_table, struct file_similarity, entry);
 398
 399         return renames;
 400 }
 401
 402 #define NUM_CANDIDATE_PER_DST 4
 403 static void record_if_better(struct diff_score m[], struct diff_score *o)
 404 {
 405         int i, worst;
 406
 407         /* find the worst one */
 408         worst = 0;
 409         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 410                 if (score_compare(&m[i], &m[worst]) > 0)
 411                         worst = i;
 412
 413         /* is it better than the worst one? */
 414         if (score_compare(&m[worst], o) > 0)
 415                 m[worst] = *o;
 416 }
 417
 418 /*
 419  * Returns:
 420  * 0 if we are under the limit;
 421  * 1 if we need to disable inexact rename detection;
 422  * 2 if we would be under the limit if we were given -C instead of -C -C.
 423  */
 424 static int too_many_rename_candidates(int num_destinations, int num_sources,
 425                                       struct diff_options *options)
 426 {
 427         int rename_limit = options->rename_limit;
 428         int i, limited_sources;
 429
 430         options->needed_rename_limit = 0;
 431
 432         /*
 433          * This basically does a test for the rename matrix not
 434          * growing larger than a "rename_limit" square matrix, ie:
 435          *
 436          *    num_destinations * num_sources > rename_limit * rename_limit
 437          *
 438          * We use st_mult() to check overflow conditions; in the
 439          * exceptional circumstance that size_t isn't large enough to hold
 440          * the multiplication, the system won't be able to allocate enough
 441          * memory for the matrix anyway.
 442          */
 443         if (rename_limit <= 0)
 444                 rename_limit = 32767;
 445         if (st_mult(num_destinations, num_sources)
 446             <= st_mult(rename_limit, rename_limit))
 447                 return 0;
 448
 449         options->needed_rename_limit =
 450                 num_sources > num_destinations ? num_sources : num_destinations;
 451
 452         /* Are we running under -C -C? */
 453         if (!options->flags.find_copies_harder)
 454                 return 1;
 455
 456         /* Would we bust the limit if we were running under -C? */
 457         for (limited_sources = i = 0; i < num_sources; i++) {
 458                 if (diff_unmodified_pair(rename_src[i].p))
 459                         continue;
 460                 limited_sources++;
 461         }
 462         if (st_mult(num_destinations, limited_sources)
 463             <= st_mult(rename_limit, rename_limit))
 464                 return 2;
 465         return 1;
 466 }
 467
 468 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 469 {
 470         int count = 0, i;
 471
 472         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 473                 struct diff_rename_dst *dst;
 474
 475                 if ((mx[i].dst < 0) ||
 476                     (mx[i].score < minimum_score))
 477                         break; /* there is no more usable pair. */
 478                 dst = &rename_dst[mx[i].dst];
 479                 if (dst->pair)
 480                         continue; /* already done, either exact or fuzzy. */
 481                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 482                         continue;
 483                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 484                 count++;
 485         }
 486         return count;
 487 }
 488
 489 void diffcore_rename(struct diff_options *options)
 490 {
 491         int detect_rename = options->detect_rename;
 492         int minimum_score = options->rename_score;
 493         struct diff_queue_struct *q = &diff_queued_diff;
 494         struct diff_queue_struct outq;
 495         struct diff_score *mx;
 496         int i, j, rename_count, skip_unmodified = 0;
 497         int num_destinations, dst_cnt;
 498         struct progress *progress = NULL;
 499
 500         if (!minimum_score)
 501                 minimum_score = DEFAULT_RENAME_SCORE;
 502
 503         for (i = 0; i < q->nr; i++) {
 504                 struct diff_filepair *p = q->queue[i];
 505                 if (!DIFF_FILE_VALID(p->one)) {
 506                         if (!DIFF_FILE_VALID(p->two))
 507                                 continue; /* unmerged */
 508                         else if (options->single_follow &&
 509                                  strcmp(options->single_follow, p->two->path))
 510                                 continue; /* not interested */
 511                         else if (!options->flags.rename_empty &&
 512                                  is_empty_blob_oid(&p->two->oid))
 513                                 continue;
 514                         else if (add_rename_dst(p->two) < 0) {
 515                                 warning("skipping rename detection, detected"
 516                                         " duplicate destination '%s'",
 517                                         p->two->path);
 518                                 goto cleanup;
 519                         }
 520                 }
 521                 else if (!options->flags.rename_empty &&
 522                          is_empty_blob_oid(&p->one->oid))
 523                         continue;
 524                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 525                         /*
 526                          * If the source is a broken "delete", and
 527                          * they did not really want to get broken,
 528                          * that means the source actually stays.
 529                          * So we increment the "rename_used" score
 530                          * by one, to indicate ourselves as a user
 531                          */
 532                         if (p->broken_pair && !p->score)
 533                                 p->one->rename_used++;
 534                         register_rename_src(p);
 535                 }
 536                 else if (detect_rename == DIFF_DETECT_COPY) {
 537                         /*
 538                          * Increment the "rename_used" score by
 539                          * one, to indicate ourselves as a user.
 540                          */
 541                         p->one->rename_used++;
 542                         register_rename_src(p);
 543                 }
 544         }
 545         if (rename_dst_nr == 0 || rename_src_nr == 0)
 546                 goto cleanup; /* nothing to do */
 547
 548         /*
 549          * We really want to cull the candidates list early
 550          * with cheap tests in order to avoid doing deltas.
 551          */
 552         rename_count = find_exact_renames(options);
 553
 554         /* Did we only want exact renames? */
 555         if (minimum_score == MAX_SCORE)
 556                 goto cleanup;
 557
 558         /*
 559          * Calculate how many renames are left (but all the source
 560          * files still remain as options for rename/copies!)
 561          */
 562         num_destinations = (rename_dst_nr - rename_count);
 563
 564         /* All done? */
 565         if (!num_destinations)
 566                 goto cleanup;
 567
 568         switch (too_many_rename_candidates(num_destinations, rename_src_nr,
 569                                            options)) {
 570         case 1:
 571                 goto cleanup;
 572         case 2:
 573                 options->degraded_cc_to_c = 1;
 574                 skip_unmodified = 1;
 575                 break;
 576         default:
 577                 break;
 578         }
 579
 580         if (options->show_rename_progress) {
 581                 progress = start_delayed_progress(
 582                                 _("Performing inexact rename detection"),
 583                                 (uint64_t)num_destinations * (uint64_t)rename_src_nr);
 584         }
 585
 586         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_destinations),
 587                      sizeof(*mx));
 588         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 589                 struct diff_filespec *two = rename_dst[i].two;
 590                 struct diff_score *m;
 591
 592                 if (rename_dst[i].pair)
 593                         continue; /* dealt with exact match already. */
 594
 595                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 596                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 597                         m[j].dst = -1;
 598
 599                 for (j = 0; j < rename_src_nr; j++) {
 600                         struct diff_filespec *one = rename_src[j].p->one;
 601                         struct diff_score this_src;
 602
 603                         if (skip_unmodified &&
 604                             diff_unmodified_pair(rename_src[j].p))
 605                                 continue;
 606
 607                         this_src.score = estimate_similarity(options->repo,
 608                                                              one, two,
 609                                                              minimum_score,
 610                                                              skip_unmodified);
 611                         this_src.name_score = basename_same(one, two);
 612                         this_src.dst = i;
 613                         this_src.src = j;
 614                         record_if_better(m, &this_src);
 615                         /*
 616                          * Once we run estimate_similarity,
 617                          * We do not need the text anymore.
 618                          */
 619                         diff_free_filespec_blob(one);
 620                         diff_free_filespec_blob(two);
 621                 }
 622                 dst_cnt++;
 623                 display_progress(progress,
 624                                  (uint64_t)dst_cnt * (uint64_t)rename_src_nr);
 625         }
 626         stop_progress(&progress);
 627
 628         /* cost matrix sorted by most to least similar pair */
 629         STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 630
 631         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 632         if (detect_rename == DIFF_DETECT_COPY)
 633                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 634         free(mx);
 635
 636  cleanup:
 637         /* At this point, we have found some renames and copies and they
 638          * are recorded in rename_dst.  The original list is still in *q.
 639          */
 640         DIFF_QUEUE_CLEAR(&outq);
 641         for (i = 0; i < q->nr; i++) {
 642                 struct diff_filepair *p = q->queue[i];
 643                 struct diff_filepair *pair_to_free = NULL;
 644
 645                 if (DIFF_PAIR_UNMERGED(p)) {
 646                         diff_q(&outq, p);
 647                 }
 648                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 649                         /*
 650                          * Creation
 651                          *
 652                          * We would output this create record if it has
 653                          * not been turned into a rename/copy already.
 654                          */
 655                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
 656                         if (dst && dst->pair) {
 657                                 diff_q(&outq, dst->pair);
 658                                 pair_to_free = p;
 659                         }
 660                         else
 661                                 /* no matching rename/copy source, so
 662                                  * record this as a creation.
 663                                  */
 664                                 diff_q(&outq, p);
 665                 }
 666                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 667                         /*
 668                          * Deletion
 669                          *
 670                          * We would output this delete record if:
 671                          *
 672                          * (1) this is a broken delete and the counterpart
 673                          *     broken create remains in the output; or
 674                          * (2) this is not a broken delete, and rename_dst
 675                          *     does not have a rename/copy to move p->one->path
 676                          *     out of existence.
 677                          *
 678                          * Otherwise, the counterpart broken create
 679                          * has been turned into a rename-edit; or
 680                          * delete did not have a matching create to
 681                          * begin with.
 682                          */
 683                         if (DIFF_PAIR_BROKEN(p)) {
 684                                 /* broken delete */
 685                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
 686                                 if (dst && dst->pair)
 687                                         /* counterpart is now rename/copy */
 688                                         pair_to_free = p;
 689                         }
 690                         else {
 691                                 if (p->one->rename_used)
 692                                         /* this path remains */
 693                                         pair_to_free = p;
 694                         }
 695
 696                         if (pair_to_free)
 697                                 ;
 698                         else
 699                                 diff_q(&outq, p);
 700                 }
 701                 else if (!diff_unmodified_pair(p))
 702                         /* all the usual ones need to be kept */
 703                         diff_q(&outq, p);
 704                 else
 705                         /* no need to keep unmodified pairs */
 706                         pair_to_free = p;
 707
 708                 if (pair_to_free)
 709                         diff_free_filepair(pair_to_free);
 710         }
 711         diff_debug_queue("done copying original", &outq);
 712
 713         free(q->queue);
 714         *q = outq;
 715         diff_debug_queue("done collapsing", q);
 716
 717         for (i = 0; i < rename_dst_nr; i++)
 718                 free_filespec(rename_dst[i].two);
 719
 720         FREE_AND_NULL(rename_dst);
 721         rename_dst_nr = rename_dst_alloc = 0;
 722         FREE_AND_NULL(rename_src);
 723         rename_src_nr = rename_src_alloc = 0;
 724         return;
 725 }