Support the .EXTRA_PREREQS special variable

Initial implementation by Christof Warlich <cwarlich@gmx.de>

* NEWS: Announce the new feature.
* doc/make.texi (Other Special Variables): Document .EXTRA_PREREQS.
* src/dep.h (struct dep): New flag to note extra prereq deps.
* src/filedef.h (expand_extra_prereqs): Declare a function to expand
the value of .EXTRA_PREREQS.
* src/file.c (expand_extra_prereqs): Given a struct variable lookup
of .EXTRA_PREREQS, convert it into a list of deps and for each one
make sure it has a struct file and has the new flag set.
(snap_file): A new function invoked by hash_map that will perform
per-file operations: set up second expansion, intermediate, and also
.EXTRA_PREREQS.  Manage circular dependencies by ignoring them.
(snap_deps): Defer per-file operations until the end.  Look up the
global .EXTRA_PREREQS and pass it along to snap_file for each file.
* src/implicit.c (struct patdeps): Remember the extra prereqs flag.
(pattern_search): Transfer extra prereqs flag settings into the
matched pattern rule.
* src/rule.h (snap_implicit_rules): Rename count_implicit_rules to
snap_implicit_rules since we now do more than count.
* src/rule.c (snap_implicit_rules): As we walk through all the pattern
rules, add in any global .EXTRA_PREREQS to the dep list.  Ensure we
take them into account for the max number of prereqs and name length.
* src/main.c (main): Add extra-prereqs to .FEATURES.
Call the renamed snap_implicit_rules.
* tests/scripts/variables/EXTRA_PREREQS: Add tests.

1 files changed, 39 insertions, 22 deletions

diff --git a/src/rule.c b/src/rule.c
index 6b01aa33..6645a2f7 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -60,36 +60,43 @@ struct file *suffix_file;
 
 static size_t maxsuffix;
 
-/* Compute the maximum dependency length and maximum number of
-   dependencies of all implicit rules.  Also sets the subdir
-   flag for a rule when appropriate, possibly removing the rule
-   completely when appropriate.  */
+/* Compute the maximum dependency length and maximum number of dependencies of
+   all implicit rules.  Also sets the subdir flag for a rule when appropriate,
+   possibly removing the rule completely when appropriate.
+
+   Add any global EXTRA_PREREQS here as well.  */
 
 void
-count_implicit_rule_limits (void)
+snap_implicit_rules (void)
 {
-  char *name;
-  size_t namelen;
-  struct rule *rule;
+  char *name = NULL;
+  size_t namelen = 0;
+  struct dep *prereqs = expand_extra_prereqs (lookup_variable (STRING_SIZE_TUPLE(".EXTRA_PREREQS")));
+  unsigned int pre_deps = 0;
 
-  num_pattern_rules = max_pattern_targets = max_pattern_deps = 0;
   max_pattern_dep_length = 0;
 
-  name = 0;
-  namelen = 0;
-  rule = pattern_rules;
-  while (rule != 0)
+  for (struct dep *d = prereqs; d; d = d->next)
+    {
+      size_t l = strlen (dep_name (d));
+      if (l > max_pattern_dep_length)
+        max_pattern_dep_length = l;
+      ++pre_deps;
+    }
+
+  num_pattern_rules = max_pattern_targets = max_pattern_deps = 0;
+
+  for (struct rule *rule = pattern_rules; rule; rule = rule->next)
     {
-      unsigned int ndeps = 0;
-      struct dep *dep;
-      struct rule *next = rule->next;
+      unsigned int ndeps = pre_deps;
+      struct dep *lastdep = NULL;
 
       ++num_pattern_rules;
 
       if (rule->num > max_pattern_targets)
         max_pattern_targets = rule->num;
 
-      for (dep = rule->deps; dep != 0; dep = dep->next)
+      for (struct dep *dep = rule->deps; dep != 0; dep = dep->next)
         {
           const char *dname = dep_name (dep);
           size_t len = strlen (dname);
@@ -99,17 +106,20 @@ count_implicit_rule_limits (void)
           const char *p2;
           if (p == 0)
             p = strrchr (dname, ':');
-          p2 = p != 0 ? strchr (dname, '%') : 0;
+          p2 = p ? strchr (p, '%') : 0;
 #else
           const char *p = strrchr (dname, '/');
-          const char *p2 = p != 0 ? strchr (dname, '%') : 0;
+          const char *p2 = p ? strchr (p, '%') : 0;
 #endif
           ndeps++;
 
           if (len > max_pattern_dep_length)
             max_pattern_dep_length = len;
 
-          if (p != 0 && p2 > p)
+          if (!dep->next)
+            lastdep = dep;
+
+          if (p2)
             {
               /* There is a slash before the % in the dep name.
                  Extract the directory name.  */
@@ -134,13 +144,20 @@ count_implicit_rule_limits (void)
             dep->changed = 0;
         }
 
+      if (prereqs)
+        {
+          if (lastdep)
+            lastdep->next = copy_dep_chain (prereqs);
+          else
+            rule->deps = copy_dep_chain (prereqs);
+        }
+
       if (ndeps > max_pattern_deps)
         max_pattern_deps = ndeps;
-
-      rule = next;
     }
 
   free (name);
+  free_dep_chain (prereqs);
 }
 
 /* Create a pattern rule from a suffix rule.