1 /* Implicit rule searching for GNU Make.
2 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
3 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software
4 Foundation, Inc.
5 This file is part of GNU Make.
6 
7 GNU Make is free software; you can redistribute it and/or modify it under the
8 terms of the GNU General Public License as published by the Free Software
9 Foundation; either version 2, or (at your option) any later version.
10 
11 GNU Make is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
13 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
14 
15 You should have received a copy of the GNU General Public License along with
16 GNU Make; see the file COPYING.  If not, write to the Free Software
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.  */
18 
19 #include "make.h"
20 #include "filedef.h"
21 #include "rule.h"
22 #include "dep.h"
23 #include "debug.h"
24 #include "variable.h"
25 #include "job.h"      /* struct child, used inside commands.h */
26 #include "commands.h" /* set_file_variables */
27 
28 static int
29 pattern_search PARAMS ((struct file *file, int archive,
30                         unsigned int depth, unsigned int recursions));
31 
32 /* For a FILE which has no commands specified, try to figure out some
33    from the implicit pattern rules.
34    Returns 1 if a suitable implicit rule was found,
35    after modifying FILE to contain the appropriate commands and deps,
36    or returns 0 if no implicit rule was found.  */
37 
38 int
try_implicit_rule(struct file * file,unsigned int depth)39 try_implicit_rule (struct file *file, unsigned int depth)
40 {
41   DBF (DB_IMPLICIT, _("Looking for an implicit rule for `%s'.\n"));
42 
43   /* The order of these searches was previously reversed.  My logic now is
44      that since the non-archive search uses more information in the target
45      (the archive search omits the archive name), it is more specific and
46      should come first.  */
47 
48   if (pattern_search (file, 0, depth, 0))
49     return 1;
50 
51 #ifndef	NO_ARCHIVES
52   /* If this is an archive member reference, use just the
53      archive member name to search for implicit rules.  */
54   if (ar_name (file->name))
55     {
56       DBF (DB_IMPLICIT,
57            _("Looking for archive-member implicit rule for `%s'.\n"));
58       if (pattern_search (file, 1, depth, 0))
59 	return 1;
60     }
61 #endif
62 
63   return 0;
64 }
65 
66 
67 /* Struct idep captures information about implicit prerequisites
68    that come from implicit rules. */
69 struct idep
70 {
71   struct idep *next;              /* struct dep -compatible interface */
72   char *name;                     /* name of the prerequisite */
73   struct file *intermediate_file; /* intermediate file, 0 otherwise */
74   char *intermediate_pattern;     /* pattern for intermediate file */
75   unsigned char had_stem;         /* had % substituted with stem */
76   unsigned char ignore_mtime;     /* ignore_mtime flag */
77 };
78 
79 static void
free_idep_chain(struct idep * p)80 free_idep_chain (struct idep *p)
81 {
82   struct idep *n;
83 
84   for (; p != 0; p = n)
85     {
86       n = p->next;
87 
88       if (p->name)
89         {
90           struct file *f = p->intermediate_file;
91 
92           if (f != 0
93               && (f->stem < f->name || f->stem > f->name + strlen (f->name)))
94             free (f->stem);
95 
96           free (p->name);
97         }
98 
99       free (p);
100     }
101 }
102 
103 
104 /* Scans the BUFFER for the next word with whitespace as a separator.
105    Returns the pointer to the beginning of the word. LENGTH hold the
106    length of the word.  */
107 
108 static char *
get_next_word(char * buffer,unsigned int * length)109 get_next_word (char *buffer, unsigned int *length)
110 {
111   char *p = buffer, *beg;
112   char c;
113 
114   /* Skip any leading whitespace.  */
115   while (isblank ((unsigned char)*p))
116     ++p;
117 
118   beg = p;
119   c = *(p++);
120 
121   if (c == '\0')
122     return 0;
123 
124 
125   /* We already found the first value of "c", above.  */
126   while (1)
127     {
128       char closeparen;
129       int count;
130 
131       switch (c)
132         {
133         case '\0':
134         case ' ':
135         case '\t':
136           goto done_word;
137 
138         case '$':
139           c = *(p++);
140           if (c == '$')
141             break;
142 
143           /* This is a variable reference, so read it to the matching
144              close paren.  */
145 
146           if (c == '(')
147             closeparen = ')';
148           else if (c == '{')
149             closeparen = '}';
150           else
151             /* This is a single-letter variable reference.  */
152             break;
153 
154           for (count = 0; *p != '\0'; ++p)
155             {
156               if (*p == c)
157                 ++count;
158               else if (*p == closeparen && --count < 0)
159                 {
160                   ++p;
161                   break;
162                 }
163             }
164           break;
165 
166         case '|':
167           goto done;
168 
169         default:
170           break;
171         }
172 
173       c = *(p++);
174     }
175  done_word:
176   --p;
177 
178  done:
179   if (length)
180     *length = p - beg;
181 
182   return beg;
183 }
184 
185 /* Search the pattern rules for a rule with an existing dependency to make
186    FILE.  If a rule is found, the appropriate commands and deps are put in FILE
187    and 1 is returned.  If not, 0 is returned.
188 
189    If ARCHIVE is nonzero, FILE->name is of the form "LIB(MEMBER)".  A rule for
190    "(MEMBER)" will be searched for, and "(MEMBER)" will not be chopped up into
191    directory and filename parts.
192 
193    If an intermediate file is found by pattern search, the intermediate file
194    is set up as a target by the recursive call and is also made a dependency
195    of FILE.
196 
197    DEPTH is used for debugging messages.  */
198 
199 static int
pattern_search(struct file * file,int archive,unsigned int depth,unsigned int recursions)200 pattern_search (struct file *file, int archive,
201                 unsigned int depth, unsigned int recursions)
202 {
203   /* Filename we are searching for a rule for.  */
204   char *filename = archive ? strchr (file->name, '(') : file->name;
205 
206   /* Length of FILENAME.  */
207   unsigned int namelen = strlen (filename);
208 
209   /* The last slash in FILENAME (or nil if there is none).  */
210   char *lastslash;
211 
212   /* This is a file-object used as an argument in
213      recursive calls.  It never contains any data
214      except during a recursive call.  */
215   struct file *intermediate_file = 0;
216 
217   /* This linked list records all the prerequisites actually
218      found for a rule along with some other useful information
219      (see struct idep for details). */
220   struct idep* deps = 0;
221 
222   /* 1 if we need to remove explicit prerequisites, 0 otherwise. */
223   unsigned int remove_explicit_deps = 0;
224 
225   /* Names of possible dependencies are constructed in this buffer.  */
226   register char *depname = (char *) alloca (namelen + max_pattern_dep_length);
227 
228   /* The start and length of the stem of FILENAME for the current rule.  */
229   register char *stem = 0;
230   register unsigned int stemlen = 0;
231   register unsigned int fullstemlen = 0;
232 
233   /* Buffer in which we store all the rules that are possibly applicable.  */
234   struct rule **tryrules
235     = (struct rule **) xmalloc (num_pattern_rules * max_pattern_targets
236                                 * sizeof (struct rule *));
237 
238   /* Number of valid elements in TRYRULES.  */
239   unsigned int nrules;
240 
241   /* The numbers of the rule targets of each rule
242      in TRYRULES that matched the target file.  */
243   unsigned int *matches
244     = (unsigned int *) alloca (num_pattern_rules * sizeof (unsigned int));
245 
246   /* Each element is nonzero if LASTSLASH was used in
247      matching the corresponding element of TRYRULES.  */
248   char *checked_lastslash
249     = (char *) alloca (num_pattern_rules * sizeof (char));
250 
251   /* The index in TRYRULES of the rule we found.  */
252   unsigned int foundrule;
253 
254   /* Nonzero if should consider intermediate files as dependencies.  */
255   int intermed_ok;
256 
257   /* Nonzero if we have matched a pattern-rule target
258      that is not just `%'.  */
259   int specific_rule_matched = 0;
260 
261   unsigned int i = 0;  /* uninit checks OK */
262   struct rule *rule;
263   struct dep *dep, *expl_d;
264 
265   char *p, *vname;
266 
267   struct idep *d;
268   struct idep **id_ptr;
269   struct dep **d_ptr;
270 
271   PATH_VAR (stem_str); /* @@ Need to get rid of stem, stemlen, etc. */
272 
273 #ifndef	NO_ARCHIVES
274   if (archive || ar_name (filename))
275     lastslash = 0;
276   else
277 #endif
278     {
279       /* Set LASTSLASH to point at the last slash in FILENAME
280 	 but not counting any slash at the end.  (foo/bar/ counts as
281 	 bar/ in directory foo/, not empty in directory foo/bar/.)  */
282 #ifdef VMS
283       lastslash = strrchr (filename, ']');
284       if (lastslash == 0)
285 	lastslash = strrchr (filename, ':');
286 #else
287       lastslash = strrchr (filename, '/');
288 #ifdef HAVE_DOS_PATHS
289       /* Handle backslashes (possibly mixed with forward slashes)
290 	 and the case of "d:file".  */
291       {
292 	char *bslash = strrchr (filename, '\\');
293 	if (lastslash == 0 || bslash > lastslash)
294 	  lastslash = bslash;
295 	if (lastslash == 0 && filename[0] && filename[1] == ':')
296 	  lastslash = filename + 1;
297       }
298 #endif
299 #endif
300       if (lastslash != 0 && lastslash[1] == '\0')
301 	lastslash = 0;
302     }
303 
304   /* First see which pattern rules match this target
305      and may be considered.  Put them in TRYRULES.  */
306 
307   nrules = 0;
308   for (rule = pattern_rules; rule != 0; rule = rule->next)
309     {
310       /* If the pattern rule has deps but no commands, ignore it.
311 	 Users cancel built-in rules by redefining them without commands.  */
312       if (rule->deps != 0 && rule->cmds == 0)
313 	continue;
314 
315       /* If this rule is in use by a parent pattern_search,
316 	 don't use it here.  */
317       if (rule->in_use)
318 	{
319 	  DBS (DB_IMPLICIT, (_("Avoiding implicit rule recursion.\n")));
320 	  continue;
321 	}
322 
323       for (i = 0; rule->targets[i] != 0; ++i)
324 	{
325 	  char *target = rule->targets[i];
326 	  char *suffix = rule->suffixes[i];
327 	  int check_lastslash;
328 
329 	  /* Rules that can match any filename and are not terminal
330 	     are ignored if we're recursing, so that they cannot be
331 	     intermediate files.  */
332 	  if (recursions > 0 && target[1] == '\0' && !rule->terminal)
333 	    continue;
334 
335 	  if (rule->lens[i] > namelen)
336 	    /* It can't possibly match.  */
337 	    continue;
338 
339 	  /* From the lengths of the filename and the pattern parts,
340 	     find the stem: the part of the filename that matches the %.  */
341 	  stem = filename + (suffix - target - 1);
342 	  stemlen = namelen - rule->lens[i] + 1;
343 
344 	  /* Set CHECK_LASTSLASH if FILENAME contains a directory
345 	     prefix and the target pattern does not contain a slash.  */
346 
347           check_lastslash = 0;
348           if (lastslash)
349             {
350 #ifdef VMS
351               check_lastslash = (strchr (target, ']') == 0
352                                  && strchr (target, ':') == 0);
353 #else
354               check_lastslash = strchr (target, '/') == 0;
355 #ifdef HAVE_DOS_PATHS
356               /* Didn't find it yet: check for DOS-type directories.  */
357               if (check_lastslash)
358                 {
359                   char *b = strchr (target, '\\');
360                   check_lastslash = !(b || (target[0] && target[1] == ':'));
361                 }
362 #endif
363 #endif
364             }
365 	  if (check_lastslash)
366 	    {
367 	      /* If so, don't include the directory prefix in STEM here.  */
368 	      unsigned int difference = lastslash - filename + 1;
369 	      if (difference > stemlen)
370 		continue;
371 	      stemlen -= difference;
372 	      stem += difference;
373 	    }
374 
375 	  /* Check that the rule pattern matches the text before the stem.  */
376 	  if (check_lastslash)
377 	    {
378 	      if (stem > (lastslash + 1)
379 		  && !strneq (target, lastslash + 1, stem - lastslash - 1))
380 		continue;
381 	    }
382 	  else if (stem > filename
383 		   && !strneq (target, filename, stem - filename))
384 	    continue;
385 
386 	  /* Check that the rule pattern matches the text after the stem.
387 	     We could test simply use streq, but this way we compare the
388 	     first two characters immediately.  This saves time in the very
389 	     common case where the first character matches because it is a
390 	     period.  */
391 	  if (*suffix != stem[stemlen]
392 	      || (*suffix != '\0' && !streq (&suffix[1], &stem[stemlen + 1])))
393 	    continue;
394 
395 	  /* Record if we match a rule that not all filenames will match.  */
396 	  if (target[1] != '\0')
397 	    specific_rule_matched = 1;
398 
399 	  /* A rule with no dependencies and no commands exists solely to set
400 	     specific_rule_matched when it matches.  Don't try to use it.  */
401 	  if (rule->deps == 0 && rule->cmds == 0)
402 	    continue;
403 
404 	  /* Record this rule in TRYRULES and the index of the matching
405 	     target in MATCHES.  If several targets of the same rule match,
406 	     that rule will be in TRYRULES more than once.  */
407 	  tryrules[nrules] = rule;
408 	  matches[nrules] = i;
409 	  checked_lastslash[nrules] = check_lastslash;
410 	  ++nrules;
411 	}
412     }
413 
414   /* If we have found a matching rule that won't match all filenames,
415      retroactively reject any non-"terminal" rules that do always match.  */
416   if (specific_rule_matched)
417     for (i = 0; i < nrules; ++i)
418       if (!tryrules[i]->terminal)
419 	{
420 	  register unsigned int j;
421 	  for (j = 0; tryrules[i]->targets[j] != 0; ++j)
422 	    if (tryrules[i]->targets[j][1] == '\0')
423 	      break;
424 	  if (tryrules[i]->targets[j] != 0)
425 	    tryrules[i] = 0;
426 	}
427 
428   /* We are going to do second expansion so initialize file variables
429      for the rule. */
430   initialize_file_variables (file, 0);
431 
432   /* Try each rule once without intermediate files, then once with them.  */
433   for (intermed_ok = 0; intermed_ok == !!intermed_ok; ++intermed_ok)
434     {
435       /* Try each pattern rule till we find one that applies.
436 	 If it does, expand its dependencies (as substituted)
437 	 and chain them in DEPS.  */
438 
439       for (i = 0; i < nrules; i++)
440 	{
441           struct file *f;
442           unsigned int failed = 0;
443 	  int check_lastslash;
444           int file_variables_set = 0;
445 
446 	  rule = tryrules[i];
447 
448           remove_explicit_deps = 0;
449 
450 	  /* RULE is nil when we discover that a rule,
451 	     already placed in TRYRULES, should not be applied.  */
452 	  if (rule == 0)
453 	    continue;
454 
455 	  /* Reject any terminal rules if we're
456 	     looking to make intermediate files.  */
457 	  if (intermed_ok && rule->terminal)
458 	    continue;
459 
460 	  /* Mark this rule as in use so a recursive
461 	     pattern_search won't try to use it.  */
462 	  rule->in_use = 1;
463 
464 	  /* From the lengths of the filename and the matching pattern parts,
465 	     find the stem: the part of the filename that matches the %.  */
466 	  stem = filename
467 	    + (rule->suffixes[matches[i]] - rule->targets[matches[i]]) - 1;
468 	  stemlen = namelen - rule->lens[matches[i]] + 1;
469 	  check_lastslash = checked_lastslash[i];
470 	  if (check_lastslash)
471 	    {
472 	      stem += lastslash - filename + 1;
473 	      stemlen -= (lastslash - filename) + 1;
474 	    }
475 
476 	  DBS (DB_IMPLICIT, (_("Trying pattern rule with stem `%.*s'.\n"),
477                              (int) stemlen, stem));
478 
479           strncpy (stem_str, stem, stemlen);
480           stem_str[stemlen] = '\0';
481 
482           /* Temporary assign STEM to file->stem (needed to set file
483              variables below).   */
484           file->stem = stem_str;
485 
486 	  /* Try each dependency; see if it "exists".  */
487 
488 	  for (dep = rule->deps; dep != 0; dep = dep->next)
489 	    {
490               unsigned int len;
491               char *p2;
492               unsigned int order_only = 0; /* Set if '|' was seen. */
493 
494               /* In an ideal world we would take the dependency line,
495                  substitute the stem, re-expand the whole line and chop it
496                  into individual prerequisites. Unfortunately this won't work
497                  because of the "check_lastslash" twist.  Instead, we will
498                  have to go word by word, taking $()'s into account, for each
499                  word we will substitute the stem, re-expand, chop it up, and,
500                  if check_lastslash != 0, add the directory part to each
501                  resulting prerequisite.  */
502 
503               p = get_next_word (dep->name, &len);
504 
505               while (1)
506                 {
507                   int add_dir = 0;
508                   int had_stem = 0;
509 
510                   if (p == 0)
511                     break; /* No more words */
512 
513                   /* Is there a pattern in this prerequisite?  */
514 
515                   for (p2 = p; p2 < p + len && *p2 != '%'; ++p2)
516                     ;
517 
518                   if (dep->need_2nd_expansion)
519                     {
520                       /* If the dependency name has %, substitute the stem.
521 
522                          Watch out, we are going to do something tricky
523                          here. If we just replace % with the stem value,
524                          later, when we do the second expansion, we will
525                          re-expand this stem value once again. This is not
526                          good especially if you have certain characters in
527                          your stem (like $).
528 
529                          Instead, we will replace % with $* and allow the
530                          second expansion to take care of it for us. This way
531                          (since $* is a simple variable) there won't be
532                          additional re-expansion of the stem.  */
533 
534                       if (p2 < p + len)
535                         {
536                           register unsigned int i = p2 - p;
537                           bcopy (p, depname, i);
538                           bcopy ("$*", depname + i, 2);
539                           bcopy (p2 + 1, depname + i + 2, len - i - 1);
540                           depname[len + 2 - 1] = '\0';
541 
542                           if (check_lastslash)
543                             add_dir = 1;
544 
545                           had_stem = 1;
546                         }
547                       else
548                         {
549                           bcopy (p, depname, len);
550                           depname[len] = '\0';
551                         }
552 
553                       /* Set file variables. Note that we cannot do it once
554                          at the beginning of the function because of the stem
555                          value.  */
556                       if (!file_variables_set)
557                         {
558                           set_file_variables (file);
559                           file_variables_set = 1;
560                         }
561 
562                       p2 = variable_expand_for_file (depname, file);
563                     }
564                   else
565                     {
566                        if (p2 < p + len)
567                         {
568                           register unsigned int i = p2 - p;
569                           bcopy (p, depname, i);
570                           bcopy (stem_str, depname + i, stemlen);
571                           bcopy (p2 + 1, depname + i + stemlen, len - i - 1);
572                           depname[len + stemlen - 1] = '\0';
573 
574                           if (check_lastslash)
575                             add_dir = 1;
576 
577                           had_stem = 1;
578                         }
579                       else
580                         {
581                           bcopy (p, depname, len);
582                           depname[len] = '\0';
583                         }
584 
585                        p2 = depname;
586                     }
587 
588                   /* Parse the dependencies. */
589 
590                   while (1)
591                     {
592                       id_ptr = &deps;
593 
594                       for (; *id_ptr; id_ptr = &(*id_ptr)->next)
595                         ;
596 
597                       *id_ptr = (struct idep *)
598                         multi_glob (
599                           parse_file_seq (&p2,
600                                           order_only ? '\0' : '|',
601                                           sizeof (struct idep),
602                                           1), sizeof (struct idep));
603 
604                       /* @@ It would be nice to teach parse_file_seq or
605                          multi_glob to add prefix. This would save us some
606                          reallocations. */
607 
608                       if (order_only || add_dir || had_stem)
609                         {
610                           unsigned long l = lastslash - filename + 1;
611 
612                           for (d = *id_ptr; d != 0; d = d->next)
613                             {
614                               if (order_only)
615                                 d->ignore_mtime = 1;
616 
617                               if (add_dir)
618                                 {
619                                   char *p = d->name;
620 
621                                   d->name = xmalloc (strlen (p) + l + 1);
622 
623                                   bcopy (filename, d->name, l);
624                                   bcopy (p, d->name + l, strlen (p) + 1);
625 
626                                   free (p);
627                                 }
628 
629                               if (had_stem)
630                                 d->had_stem = 1;
631                             }
632                         }
633 
634                       if (!order_only && *p2)
635                       {
636                         ++p2;
637                         order_only = 1;
638                         continue;
639                       }
640 
641                       break;
642                     }
643 
644                   p += len;
645                   p = get_next_word (p, &len);
646                 }
647 	    }
648 
649           /* Reset the stem in FILE. */
650 
651           file->stem = 0;
652 
653           /* @@ This loop can be combined with the previous one. I do
654              it separately for now for transparency.*/
655 
656           for (d = deps; d != 0; d = d->next)
657             {
658               char *name = d->name;
659 
660               if (file_impossible_p (name))
661                 {
662                   /* If this dependency has already been ruled "impossible",
663                      then the rule fails and don't bother trying it on the
664                      second pass either since we know that will fail too.  */
665                   DBS (DB_IMPLICIT,
666                        (d->had_stem
667                         ? _("Rejecting impossible implicit prerequisite `%s'.\n")
668                         : _("Rejecting impossible rule prerequisite `%s'.\n"),
669                         name));
670                   tryrules[i] = 0;
671 
672                   failed = 1;
673                   break;
674                 }
675 
676               DBS (DB_IMPLICIT,
677                    (d->had_stem
678                     ? _("Trying implicit prerequisite `%s'.\n")
679                     : _("Trying rule prerequisite `%s'.\n"), name));
680 
681               /* If this prerequisite also happened to be explicitly mentioned
682                  for FILE skip all the test below since it it has to be built
683                  anyway, no matter which implicit rule we choose. */
684 
685               for (expl_d = file->deps; expl_d != 0; expl_d = expl_d->next)
686                 if (streq (dep_name (expl_d), name))
687                   break;
688               if (expl_d != 0)
689                 continue;
690 
691               /* The DEP->changed flag says that this dependency resides in a
692                  nonexistent directory.  So we normally can skip looking for
693                  the file.  However, if CHECK_LASTSLASH is set, then the
694                  dependency file we are actually looking for is in a different
695                  directory (the one gotten by prepending FILENAME's directory),
696                  so it might actually exist.  */
697 
698               /* @@ dep->changed check is disabled. */
699               if (((f = lookup_file (name)) != 0 && f->is_target)
700                   /*|| ((!dep->changed || check_lastslash) && */
701                   || file_exists_p (name))
702                 continue;
703 
704               /* This code, given FILENAME = "lib/foo.o", dependency name
705                  "lib/foo.c", and VPATH=src, searches for "src/lib/foo.c".  */
706               vname = name;
707               if (vpath_search (&vname, (FILE_TIMESTAMP *) 0))
708                 {
709                   DBS (DB_IMPLICIT,
710                        (_("Found prerequisite `%s' as VPATH `%s'\n"),
711                         name,
712                         vname));
713 
714                   free (vname);
715                   continue;
716                 }
717 
718 
719               /* We could not find the file in any place we should look.  Try
720                  to make this dependency as an intermediate file, but only on
721                  the second pass.  */
722 
723               if (intermed_ok)
724                 {
725                   if (intermediate_file == 0)
726                     intermediate_file
727                       = (struct file *) alloca (sizeof (struct file));
728 
729                   DBS (DB_IMPLICIT,
730                        (_("Looking for a rule with intermediate file `%s'.\n"),
731                         name));
732 
733                   bzero ((char *) intermediate_file, sizeof (struct file));
734                   intermediate_file->name = name;
735                   if (pattern_search (intermediate_file,
736                                       0,
737                                       depth + 1,
738                                       recursions + 1))
739                     {
740                       d->intermediate_file = intermediate_file;
741                       d->intermediate_pattern = intermediate_file->name;
742 
743                       intermediate_file->name = xstrdup (name);
744                       intermediate_file = 0;
745 
746                       continue;
747                     }
748 
749                   /* If we have tried to find P as an intermediate
750                      file and failed, mark that name as impossible
751                      so we won't go through the search again later.  */
752                   if (intermediate_file->variables)
753                     free_variable_set (intermediate_file->variables);
754                   file_impossible (name);
755                 }
756 
757               /* A dependency of this rule does not exist. Therefore,
758                  this rule fails.  */
759               failed = 1;
760               break;
761             }
762 
763           /* This rule is no longer `in use' for recursive searches.  */
764 	  rule->in_use = 0;
765 
766           if (failed)
767             {
768               /* This pattern rule does not apply. If some of its
769                  dependencies succeeded, free the data structure
770                  describing them.  */
771               free_idep_chain (deps);
772               deps = 0;
773             }
774 	  else
775 	    /* This pattern rule does apply.  Stop looking for one.  */
776 	    break;
777 	}
778 
779       /* If we found an applicable rule without
780 	 intermediate files, don't try with them.  */
781       if (i < nrules)
782 	break;
783 
784       rule = 0;
785     }
786 
787   /* RULE is nil if the loop went all the way
788      through the list and everything failed.  */
789   if (rule == 0)
790     goto done;
791 
792   foundrule = i;
793 
794   /* If we are recursing, store the pattern that matched
795      FILENAME in FILE->name for use in upper levels.  */
796 
797   if (recursions > 0)
798     /* Kludge-o-matic */
799     file->name = rule->targets[matches[foundrule]];
800 
801   /* FOUND_FILES lists the dependencies for the rule we found.
802      This includes the intermediate files, if any.
803      Convert them into entries on the deps-chain of FILE.  */
804 
805   if (remove_explicit_deps)
806     {
807       /* Remove all the dependencies that didn't come from
808          this implicit rule. */
809 
810       dep = file->deps;
811       while (dep != 0)
812         {
813           struct dep *next = dep->next;
814           free_dep (dep);
815           dep = next;
816         }
817       file->deps = 0;
818   }
819 
820   expl_d = file->deps; /* We will add them at the end. */
821   d_ptr = &file->deps;
822 
823   for (d = deps; d != 0; d = d->next)
824     {
825       register char *s;
826 
827       if (d->intermediate_file != 0)
828 	{
829 	  /* If we need to use an intermediate file,
830 	     make sure it is entered as a target, with the info that was
831 	     found for it in the recursive pattern_search call.
832 	     We know that the intermediate file did not already exist as
833 	     a target; therefore we can assume that the deps and cmds
834 	     of F below are null before we change them.  */
835 
836 	  struct file *imf = d->intermediate_file;
837 	  register struct file *f = lookup_file (imf->name);
838 
839           /* We don't want to delete an intermediate file that happened
840              to be a prerequisite of some (other) target. Mark it as
841              precious.  */
842           if (f != 0)
843             f->precious = 1;
844           else
845             f = enter_file (imf->name);
846 
847 	  f->deps = imf->deps;
848 	  f->cmds = imf->cmds;
849 	  f->stem = imf->stem;
850           f->also_make = imf->also_make;
851           f->is_target = 1;
852 
853           if (!f->precious)
854             {
855               imf = lookup_file (d->intermediate_pattern);
856               if (imf != 0 && imf->precious)
857                 f->precious = 1;
858             }
859 
860 	  f->intermediate = 1;
861 	  f->tried_implicit = 1;
862 	  for (dep = f->deps; dep != 0; dep = dep->next)
863 	    {
864 	      dep->file = enter_file (dep->name);
865               /* enter_file uses dep->name _if_ we created a new file.  */
866               if (dep->name != dep->file->name)
867                 free (dep->name);
868 	      dep->name = 0;
869 	      dep->file->tried_implicit |= dep->changed;
870 	    }
871 	}
872 
873       dep = alloc_dep ();
874       dep->ignore_mtime = d->ignore_mtime;
875       s = d->name; /* Hijacking the name. */
876       d->name = 0;
877       if (recursions == 0)
878 	{
879 	  dep->file = lookup_file (s);
880 	  if (dep->file == 0)
881 	    /* enter_file consumes S's storage.  */
882 	    dep->file = enter_file (s);
883 	  else
884 	    /* A copy of S is already allocated in DEP->file->name.
885 	       So we can free S.  */
886 	    free (s);
887 	}
888       else
889 	{
890 	  dep->name = s;
891 	}
892 
893       if (d->intermediate_file == 0 && tryrules[foundrule]->terminal)
894 	{
895 	  /* If the file actually existed (was not an intermediate file),
896 	     and the rule that found it was a terminal one, then we want
897 	     to mark the found file so that it will not have implicit rule
898 	     search done for it.  If we are not entering a `struct file' for
899 	     it now, we indicate this with the `changed' flag.  */
900 	  if (dep->file == 0)
901 	    dep->changed = 1;
902 	  else
903 	    dep->file->tried_implicit = 1;
904 	}
905 
906       *d_ptr = dep;
907       d_ptr = &dep->next;
908     }
909 
910   *d_ptr = expl_d;
911 
912   if (!checked_lastslash[foundrule])
913     {
914       /* Always allocate new storage, since STEM might be
915          on the stack for an intermediate file.  */
916       file->stem = savestring (stem, stemlen);
917       fullstemlen = stemlen;
918     }
919   else
920     {
921       int dirlen = (lastslash + 1) - filename;
922 
923       /* We want to prepend the directory from
924 	 the original FILENAME onto the stem.  */
925       fullstemlen = dirlen + stemlen;
926       file->stem = (char *) xmalloc (fullstemlen + 1);
927       bcopy (filename, file->stem, dirlen);
928       bcopy (stem, file->stem + dirlen, stemlen);
929       file->stem[fullstemlen] = '\0';
930     }
931 
932   file->cmds = rule->cmds;
933   file->is_target = 1;
934 
935   /* Set precious flag. */
936   {
937     struct file *f = lookup_file (rule->targets[matches[foundrule]]);
938     if (f && f->precious)
939       file->precious = 1;
940   }
941 
942   /* If this rule builds other targets, too, put the others into FILE's
943      `also_make' member.  */
944 
945   if (rule->targets[1] != 0)
946     for (i = 0; rule->targets[i] != 0; ++i)
947       if (i != matches[foundrule])
948 	{
949 	  struct file *f;
950 	  struct dep *new = alloc_dep ();
951 
952 	  /* GKM FIMXE: handle '|' here too */
953 	  new->name = p = (char *) xmalloc (rule->lens[i] + fullstemlen + 1);
954 	  bcopy (rule->targets[i], p,
955 		 rule->suffixes[i] - rule->targets[i] - 1);
956 	  p += rule->suffixes[i] - rule->targets[i] - 1;
957 	  bcopy (file->stem, p, fullstemlen);
958 	  p += fullstemlen;
959 	  bcopy (rule->suffixes[i], p,
960 		 rule->lens[i] - (rule->suffixes[i] - rule->targets[i]) + 1);
961 	  new->file = enter_file (new->name);
962 	  new->next = file->also_make;
963 
964 	  /* Set precious flag. */
965 	  f = lookup_file (rule->targets[i]);
966 	  if (f && f->precious)
967             new->file->precious = 1;
968 
969           /* Set the is_target flag so that this file is not treated
970              as intermediate by the pattern rule search algorithm and
971              file_exists_p cannot pick it up yet.  */
972           new->file->is_target = 1;
973 
974 	  file->also_make = new;
975 	}
976 
977  done:
978   free_idep_chain (deps);
979   free (tryrules);
980 
981   return rule != 0;
982 }
983