revision.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "blob.h"
   4 #include "tree.h"
   5 #include "commit.h"
   6 #include "diff.h"
   7 #include "refs.h"
   8 #include "revision.h"
   9
  10 static char *path_name(struct name_path *path, const char *name)
  11 {
  12         struct name_path *p;
  13         char *n, *m;
  14         int nlen = strlen(name);
  15         int len = nlen + 1;
  16
  17         for (p = path; p; p = p->up) {
  18                 if (p->elem_len)
  19                         len += p->elem_len + 1;
  20         }
  21         n = xmalloc(len);
  22         m = n + len - (nlen + 1);
  23         strcpy(m, name);
  24         for (p = path; p; p = p->up) {
  25                 if (p->elem_len) {
  26                         m -= p->elem_len + 1;
  27                         memcpy(m, p->elem, p->elem_len);
  28                         m[p->elem_len] = '/';
  29                 }
  30         }
  31         return n;
  32 }
  33
  34 struct object_list **add_object(struct object *obj,
  35                                        struct object_list **p,
  36                                        struct name_path *path,
  37                                        const char *name)
  38 {
  39         struct object_list *entry = xmalloc(sizeof(*entry));
  40         entry->item = obj;
  41         entry->next = *p;
  42         entry->name = path_name(path, name);
  43         *p = entry;
  44         return &entry->next;
  45 }
  46
  47 static void mark_blob_uninteresting(struct blob *blob)
  48 {
  49         if (blob->object.flags & UNINTERESTING)
  50                 return;
  51         blob->object.flags |= UNINTERESTING;
  52 }
  53
  54 void mark_tree_uninteresting(struct tree *tree)
  55 {
  56         struct object *obj = &tree->object;
  57         struct tree_entry_list *entry;
  58
  59         if (obj->flags & UNINTERESTING)
  60                 return;
  61         obj->flags |= UNINTERESTING;
  62         if (!has_sha1_file(obj->sha1))
  63                 return;
  64         if (parse_tree(tree) < 0)
  65                 die("bad tree %s", sha1_to_hex(obj->sha1));
  66         entry = tree->entries;
  67         tree->entries = NULL;
  68         while (entry) {
  69                 struct tree_entry_list *next = entry->next;
  70                 if (entry->directory)
  71                         mark_tree_uninteresting(entry->item.tree);
  72                 else
  73                         mark_blob_uninteresting(entry->item.blob);
  74                 free(entry);
  75                 entry = next;
  76         }
  77 }
  78
  79 void mark_parents_uninteresting(struct commit *commit)
  80 {
  81         struct commit_list *parents = commit->parents;
  82
  83         while (parents) {
  84                 struct commit *commit = parents->item;
  85                 if (!(commit->object.flags & UNINTERESTING)) {
  86                         commit->object.flags |= UNINTERESTING;
  87
  88                         /*
  89                          * Normally we haven't parsed the parent
  90                          * yet, so we won't have a parent of a parent
  91                          * here. However, it may turn out that we've
  92                          * reached this commit some other way (where it
  93                          * wasn't uninteresting), in which case we need
  94                          * to mark its parents recursively too..
  95                          */
  96                         if (commit->parents)
  97                                 mark_parents_uninteresting(commit);
  98                 }
  99
 100                 /*
 101                  * A missing commit is ok iff its parent is marked
 102                  * uninteresting.
 103                  *
 104                  * We just mark such a thing parsed, so that when
 105                  * it is popped next time around, we won't be trying
 106                  * to parse it and get an error.
 107                  */
 108                 if (!has_sha1_file(commit->object.sha1))
 109                         commit->object.parsed = 1;
 110                 parents = parents->next;
 111         }
 112 }
 113
 114 static void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 115 {
 116         add_object(obj, &revs->pending_objects, NULL, name);
 117 }
 118
 119 static struct commit *get_commit_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 120 {
 121         struct object *object;
 122
 123         object = parse_object(sha1);
 124         if (!object)
 125                 die("bad object %s", name);
 126
 127         /*
 128          * Tag object? Look what it points to..
 129          */
 130         while (object->type == tag_type) {
 131                 struct tag *tag = (struct tag *) object;
 132                 object->flags |= flags;
 133                 if (revs->tag_objects && !(object->flags & UNINTERESTING))
 134                         add_pending_object(revs, object, tag->tag);
 135                 object = parse_object(tag->tagged->sha1);
 136                 if (!object)
 137                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 138         }
 139
 140         /*
 141          * Commit object? Just return it, we'll do all the complex
 142          * reachability crud.
 143          */
 144         if (object->type == commit_type) {
 145                 struct commit *commit = (struct commit *)object;
 146                 object->flags |= flags;
 147                 if (parse_commit(commit) < 0)
 148                         die("unable to parse commit %s", name);
 149                 if (flags & UNINTERESTING) {
 150                         mark_parents_uninteresting(commit);
 151                         revs->limited = 1;
 152                 }
 153                 return commit;
 154         }
 155
 156         /*
 157          * Tree object? Either mark it uniniteresting, or add it
 158          * to the list of objects to look at later..
 159          */
 160         if (object->type == tree_type) {
 161                 struct tree *tree = (struct tree *)object;
 162                 if (!revs->tree_objects)
 163                         return NULL;
 164                 if (flags & UNINTERESTING) {
 165                         mark_tree_uninteresting(tree);
 166                         return NULL;
 167                 }
 168                 add_pending_object(revs, object, "");
 169                 return NULL;
 170         }
 171
 172         /*
 173          * Blob object? You know the drill by now..
 174          */
 175         if (object->type == blob_type) {
 176                 struct blob *blob = (struct blob *)object;
 177                 if (!revs->blob_objects)
 178                         return NULL;
 179                 if (flags & UNINTERESTING) {
 180                         mark_blob_uninteresting(blob);
 181                         return NULL;
 182                 }
 183                 add_pending_object(revs, object, "");
 184                 return NULL;
 185         }
 186         die("%s is unknown object", name);
 187 }
 188
 189 static int everybody_uninteresting(struct commit_list *orig)
 190 {
 191         struct commit_list *list = orig;
 192         while (list) {
 193                 struct commit *commit = list->item;
 194                 list = list->next;
 195                 if (commit->object.flags & UNINTERESTING)
 196                         continue;
 197                 return 0;
 198         }
 199         return 1;
 200 }
 201
 202 #define TREE_SAME       0
 203 #define TREE_NEW        1
 204 #define TREE_DIFFERENT  2
 205 static int tree_difference = TREE_SAME;
 206
 207 static void file_add_remove(struct diff_options *options,
 208                     int addremove, unsigned mode,
 209                     const unsigned char *sha1,
 210                     const char *base, const char *path)
 211 {
 212         int diff = TREE_DIFFERENT;
 213
 214         /*
 215          * Is it an add of a new file? It means that
 216          * the old tree didn't have it at all, so we
 217          * will turn "TREE_SAME" -> "TREE_NEW", but
 218          * leave any "TREE_DIFFERENT" alone (and if
 219          * it already was "TREE_NEW", we'll keep it
 220          * "TREE_NEW" of course).
 221          */
 222         if (addremove == '+') {
 223                 diff = tree_difference;
 224                 if (diff != TREE_SAME)
 225                         return;
 226                 diff = TREE_NEW;
 227         }
 228         tree_difference = diff;
 229 }
 230
 231 static void file_change(struct diff_options *options,
 232                  unsigned old_mode, unsigned new_mode,
 233                  const unsigned char *old_sha1,
 234                  const unsigned char *new_sha1,
 235                  const char *base, const char *path)
 236 {
 237         tree_difference = TREE_DIFFERENT;
 238 }
 239
 240 static struct diff_options diff_opt = {
 241         .recursive = 1,
 242         .add_remove = file_add_remove,
 243         .change = file_change,
 244 };
 245
 246 static int compare_tree(struct tree *t1, struct tree *t2)
 247 {
 248         if (!t1)
 249                 return TREE_NEW;
 250         if (!t2)
 251                 return TREE_DIFFERENT;
 252         tree_difference = TREE_SAME;
 253         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "", &diff_opt) < 0)
 254                 return TREE_DIFFERENT;
 255         return tree_difference;
 256 }
 257
 258 static int same_tree_as_empty(struct tree *t1)
 259 {
 260         int retval;
 261         void *tree;
 262         struct tree_desc empty, real;
 263
 264         if (!t1)
 265                 return 0;
 266
 267         tree = read_object_with_reference(t1->object.sha1, "tree", &real.size, NULL);
 268         if (!tree)
 269                 return 0;
 270         real.buf = tree;
 271
 272         empty.buf = "";
 273         empty.size = 0;
 274
 275         tree_difference = 0;
 276         retval = diff_tree(&empty, &real, "", &diff_opt);
 277         free(tree);
 278
 279         return retval >= 0 && !tree_difference;
 280 }
 281
 282 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 283 {
 284         struct commit_list **pp, *parent;
 285         int tree_changed = 0;
 286
 287         if (!commit->tree)
 288                 return;
 289
 290         if (!commit->parents) {
 291                 if (!same_tree_as_empty(commit->tree))
 292                         commit->object.flags |= TREECHANGE;
 293                 return;
 294         }
 295
 296         pp = &commit->parents;
 297         while ((parent = *pp) != NULL) {
 298                 struct commit *p = parent->item;
 299
 300                 parse_commit(p);
 301                 switch (compare_tree(p->tree, commit->tree)) {
 302                 case TREE_SAME:
 303                         if (p->object.flags & UNINTERESTING) {
 304                                 /* Even if a merge with an uninteresting
 305                                  * side branch brought the entire change
 306                                  * we are interested in, we do not want
 307                                  * to lose the other branches of this
 308                                  * merge, so we just keep going.
 309                                  */
 310                                 pp = &parent->next;
 311                                 continue;
 312                         }
 313                         parent->next = NULL;
 314                         commit->parents = parent;
 315                         return;
 316
 317                 case TREE_NEW:
 318                         if (revs->remove_empty_trees &&
 319                             same_tree_as_empty(p->tree)) {
 320                                 /* We are adding all the specified
 321                                  * paths from this parent, so the
 322                                  * history beyond this parent is not
 323                                  * interesting.  Remove its parents
 324                                  * (they are grandparents for us).
 325                                  * IOW, we pretend this parent is a
 326                                  * "root" commit.
 327                                  */
 328                                 parse_commit(p);
 329                                 p->parents = NULL;
 330                         }
 331                 /* fallthrough */
 332                 case TREE_DIFFERENT:
 333                         tree_changed = 1;
 334                         pp = &parent->next;
 335                         continue;
 336                 }
 337                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 338         }
 339         if (tree_changed)
 340                 commit->object.flags |= TREECHANGE;
 341 }
 342
 343 static void add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 344 {
 345         struct commit_list *parent = commit->parents;
 346
 347         /*
 348          * If the commit is uninteresting, don't try to
 349          * prune parents - we want the maximal uninteresting
 350          * set.
 351          *
 352          * Normally we haven't parsed the parent
 353          * yet, so we won't have a parent of a parent
 354          * here. However, it may turn out that we've
 355          * reached this commit some other way (where it
 356          * wasn't uninteresting), in which case we need
 357          * to mark its parents recursively too..
 358          */
 359         if (commit->object.flags & UNINTERESTING) {
 360                 while (parent) {
 361                         struct commit *p = parent->item;
 362                         parent = parent->next;
 363                         parse_commit(p);
 364                         p->object.flags |= UNINTERESTING;
 365                         if (p->parents)
 366                                 mark_parents_uninteresting(p);
 367                         if (p->object.flags & SEEN)
 368                                 continue;
 369                         p->object.flags |= SEEN;
 370                         insert_by_date(p, list);
 371                 }
 372                 return;
 373         }
 374
 375         /*
 376          * Ok, the commit wasn't uninteresting. Try to
 377          * simplify the commit history and find the parent
 378          * that has no differences in the path set if one exists.
 379          */
 380         if (revs->paths)
 381                 try_to_simplify_commit(revs, commit);
 382
 383         parent = commit->parents;
 384         while (parent) {
 385                 struct commit *p = parent->item;
 386
 387                 parent = parent->next;
 388
 389                 parse_commit(p);
 390                 if (p->object.flags & SEEN)
 391                         continue;
 392                 p->object.flags |= SEEN;
 393                 insert_by_date(p, list);
 394         }
 395 }
 396
 397 static void limit_list(struct rev_info *revs)
 398 {
 399         struct commit_list *list = revs->commits;
 400         struct commit_list *newlist = NULL;
 401         struct commit_list **p = &newlist;
 402
 403         if (revs->paths)
 404                 diff_tree_setup_paths(revs->paths);
 405
 406         while (list) {
 407                 struct commit_list *entry = list;
 408                 struct commit *commit = list->item;
 409                 struct object *obj = &commit->object;
 410
 411                 list = list->next;
 412                 free(entry);
 413
 414                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 415                         obj->flags |= UNINTERESTING;
 416                 if (revs->unpacked && has_sha1_pack(obj->sha1))
 417                         obj->flags |= UNINTERESTING;
 418                 add_parents_to_list(revs, commit, &list);
 419                 if (obj->flags & UNINTERESTING) {
 420                         mark_parents_uninteresting(commit);
 421                         if (everybody_uninteresting(list))
 422                                 break;
 423                         continue;
 424                 }
 425                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 426                         continue;
 427                 p = &commit_list_insert(commit, p)->next;
 428         }
 429         revs->commits = newlist;
 430 }
 431
 432 static void add_one_commit(struct commit *commit, struct rev_info *revs)
 433 {
 434         if (!commit || (commit->object.flags & SEEN))
 435                 return;
 436         commit->object.flags |= SEEN;
 437         commit_list_insert(commit, &revs->commits);
 438 }
 439
 440 static int all_flags;
 441 static struct rev_info *all_revs;
 442
 443 static int handle_one_ref(const char *path, const unsigned char *sha1)
 444 {
 445         struct commit *commit = get_commit_reference(all_revs, path, sha1, all_flags);
 446         add_one_commit(commit, all_revs);
 447         return 0;
 448 }
 449
 450 static void handle_all(struct rev_info *revs, unsigned flags)
 451 {
 452         all_revs = revs;
 453         all_flags = flags;
 454         for_each_ref(handle_one_ref);
 455 }
 456
 457 /*
 458  * Parse revision information, filling in the "rev_info" structure,
 459  * and removing the used arguments from the argument list.
 460  *
 461  * Returns the number of arguments left that weren't recognized
 462  * (which are also moved to the head of the argument list)
 463  */
 464 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 465 {
 466         int i, flags, seen_dashdash;
 467         const char **unrecognized = argv + 1;
 468         int left = 1;
 469
 470         memset(revs, 0, sizeof(*revs));
 471         revs->lifo = 1;
 472         revs->dense = 1;
 473         revs->prefix = setup_git_directory();
 474         revs->max_age = -1;
 475         revs->min_age = -1;
 476         revs->max_count = -1;
 477
 478         /* First, search for "--" */
 479         seen_dashdash = 0;
 480         for (i = 1; i < argc; i++) {
 481                 const char *arg = argv[i];
 482                 if (strcmp(arg, "--"))
 483                         continue;
 484                 argv[i] = NULL;
 485                 argc = i;
 486                 revs->paths = get_pathspec(revs->prefix, argv + i + 1);
 487                 seen_dashdash = 1;
 488                 break;
 489         }
 490
 491         flags = 0;
 492         for (i = 1; i < argc; i++) {
 493                 struct commit *commit;
 494                 const char *arg = argv[i];
 495                 unsigned char sha1[20];
 496                 char *dotdot;
 497                 int local_flags;
 498
 499                 if (*arg == '-') {
 500                         if (!strncmp(arg, "--max-count=", 12)) {
 501                                 revs->max_count = atoi(arg + 12);
 502                                 continue;
 503                         }
 504                         /* accept -<digit>, like traditilnal "head" */
 505                         if ((*arg == '-') && isdigit(arg[1])) {
 506                                 revs->max_count = atoi(arg + 1);
 507                                 continue;
 508                         }
 509                         if (!strcmp(arg, "-n")) {
 510                                 if (argc <= i + 1)
 511                                         die("-n requires an argument");
 512                                 revs->max_count = atoi(argv[++i]);
 513                                 continue;
 514                         }
 515                         if (!strncmp(arg,"-n",2)) {
 516                                 revs->max_count = atoi(arg + 2);
 517                                 continue;
 518                         }
 519                         if (!strncmp(arg, "--max-age=", 10)) {
 520                                 revs->max_age = atoi(arg + 10);
 521                                 revs->limited = 1;
 522                                 continue;
 523                         }
 524                         if (!strncmp(arg, "--min-age=", 10)) {
 525                                 revs->min_age = atoi(arg + 10);
 526                                 revs->limited = 1;
 527                                 continue;
 528                         }
 529                         if (!strncmp(arg, "--since=", 8)) {
 530                                 revs->max_age = approxidate(arg + 8);
 531                                 revs->limited = 1;
 532                                 continue;
 533                         }
 534                         if (!strncmp(arg, "--after=", 8)) {
 535                                 revs->max_age = approxidate(arg + 8);
 536                                 revs->limited = 1;
 537                                 continue;
 538                         }
 539                         if (!strncmp(arg, "--before=", 9)) {
 540                                 revs->min_age = approxidate(arg + 9);
 541                                 revs->limited = 1;
 542                                 continue;
 543                         }
 544                         if (!strncmp(arg, "--until=", 8)) {
 545                                 revs->min_age = approxidate(arg + 8);
 546                                 revs->limited = 1;
 547                                 continue;
 548                         }
 549                         if (!strcmp(arg, "--all")) {
 550                                 handle_all(revs, flags);
 551                                 continue;
 552                         }
 553                         if (!strcmp(arg, "--not")) {
 554                                 flags ^= UNINTERESTING;
 555                                 continue;
 556                         }
 557                         if (!strcmp(arg, "--default")) {
 558                                 if (++i >= argc)
 559                                         die("bad --default argument");
 560                                 def = argv[i];
 561                                 continue;
 562                         }
 563                         if (!strcmp(arg, "--topo-order")) {
 564                                 revs->topo_order = 1;
 565                                 revs->limited = 1;
 566                                 continue;
 567                         }
 568                         if (!strcmp(arg, "--date-order")) {
 569                                 revs->lifo = 0;
 570                                 revs->topo_order = 1;
 571                                 revs->limited = 1;
 572                                 continue;
 573                         }
 574                         if (!strcmp(arg, "--dense")) {
 575                                 revs->dense = 1;
 576                                 continue;
 577                         }
 578                         if (!strcmp(arg, "--sparse")) {
 579                                 revs->dense = 0;
 580                                 continue;
 581                         }
 582                         if (!strcmp(arg, "--remove-empty")) {
 583                                 revs->remove_empty_trees = 1;
 584                                 continue;
 585                         }
 586                         if (!strncmp(arg, "--no-merges", 11)) {
 587                                 revs->no_merges = 1;
 588                                 continue;
 589                         }
 590                         if (!strcmp(arg, "--objects")) {
 591                                 revs->tag_objects = 1;
 592                                 revs->tree_objects = 1;
 593                                 revs->blob_objects = 1;
 594                                 continue;
 595                         }
 596                         if (!strcmp(arg, "--objects-edge")) {
 597                                 revs->tag_objects = 1;
 598                                 revs->tree_objects = 1;
 599                                 revs->blob_objects = 1;
 600                                 revs->edge_hint = 1;
 601                                 continue;
 602                         }
 603                         if (!strcmp(arg, "--unpacked")) {
 604                                 revs->unpacked = 1;
 605                                 revs->limited = 1;
 606                                 continue;
 607                         }
 608                         *unrecognized++ = arg;
 609                         left++;
 610                         continue;
 611                 }
 612                 dotdot = strstr(arg, "..");
 613                 if (dotdot) {
 614                         unsigned char from_sha1[20];
 615                         char *next = dotdot + 2;
 616                         *dotdot = 0;
 617                         if (!*next)
 618                                 next = "HEAD";
 619                         if (!get_sha1(arg, from_sha1) && !get_sha1(next, sha1)) {
 620                                 struct commit *exclude;
 621                                 struct commit *include;
 622
 623                                 exclude = get_commit_reference(revs, arg, from_sha1, flags ^ UNINTERESTING);
 624                                 include = get_commit_reference(revs, next, sha1, flags);
 625                                 if (!exclude || !include)
 626                                         die("Invalid revision range %s..%s", arg, next);
 627                                 add_one_commit(exclude, revs);
 628                                 add_one_commit(include, revs);
 629                                 continue;
 630                         }
 631                         *dotdot = '.';
 632                 }
 633                 local_flags = 0;
 634                 if (*arg == '^') {
 635                         local_flags = UNINTERESTING;
 636                         arg++;
 637                 }
 638                 if (get_sha1(arg, sha1) < 0) {
 639                         struct stat st;
 640                         int j;
 641
 642                         if (seen_dashdash || local_flags)
 643                                 die("bad revision '%s'", arg);
 644
 645                         /* If we didn't have a "--", all filenames must exist */
 646                         for (j = i; j < argc; j++) {
 647                                 if (lstat(argv[j], &st) < 0)
 648                                         die("'%s': %s", arg, strerror(errno));
 649                         }
 650                         revs->paths = get_pathspec(revs->prefix, argv + i);
 651                         break;
 652                 }
 653                 commit = get_commit_reference(revs, arg, sha1, flags ^ local_flags);
 654                 add_one_commit(commit, revs);
 655         }
 656         if (def && !revs->commits) {
 657                 unsigned char sha1[20];
 658                 struct commit *commit;
 659                 if (get_sha1(def, sha1) < 0)
 660                         die("bad default revision '%s'", def);
 661                 commit = get_commit_reference(revs, def, sha1, 0);
 662                 add_one_commit(commit, revs);
 663         }
 664         if (revs->paths)
 665                 revs->limited = 1;
 666         return left;
 667 }
 668
 669 void prepare_revision_walk(struct rev_info *revs)
 670 {
 671         sort_by_date(&revs->commits);
 672         if (revs->limited)
 673                 limit_list(revs);
 674         if (revs->topo_order)
 675                 sort_in_topological_order(&revs->commits, revs->lifo);
 676 }
 677
 678 static int rewrite_one(struct commit **pp)
 679 {
 680         for (;;) {
 681                 struct commit *p = *pp;
 682                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
 683                         return 0;
 684                 if (!p->parents)
 685                         return -1;
 686                 *pp = p->parents->item;
 687         }
 688 }
 689
 690 static void rewrite_parents(struct commit *commit)
 691 {
 692         struct commit_list **pp = &commit->parents;
 693         while (*pp) {
 694                 struct commit_list *parent = *pp;
 695                 if (rewrite_one(&parent->item) < 0) {
 696                         *pp = parent->next;
 697                         continue;
 698                 }
 699                 pp = &parent->next;
 700         }
 701 }
 702
 703 struct commit *get_revision(struct rev_info *revs)
 704 {
 705         struct commit_list *list = revs->commits;
 706
 707         if (!list)
 708                 return NULL;
 709
 710         /* Check the max_count ... */
 711         switch (revs->max_count) {
 712         case -1:
 713                 break;
 714         case 0:
 715                 return NULL;
 716         default:
 717                 revs->max_count--;
 718         }
 719
 720         do {
 721                 struct commit *commit = revs->commits->item;
 722
 723                 if (commit->object.flags & (UNINTERESTING|SHOWN))
 724                         goto next;
 725                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 726                         goto next;
 727                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 728                         return NULL;
 729                 if (revs->no_merges && commit->parents && commit->parents->next)
 730                         goto next;
 731                 if (revs->paths && revs->dense) {
 732                         if (!(commit->object.flags & TREECHANGE))
 733                                 goto next;
 734                         rewrite_parents(commit);
 735                 }
 736                 /* More to go? */
 737                 if (revs->max_count)
 738                         pop_most_recent_commit(&revs->commits, SEEN);
 739                 commit->object.flags |= SHOWN;
 740                 return commit;
 741 next:
 742                 pop_most_recent_commit(&revs->commits, SEEN);
 743         } while (revs->commits);
 744         return NULL;
 745 }