Make second expansion optional (partial implementation).

I decided this feature was too impacting to make the permanent default
behavior.  This set of changes makes the default behavior of make the
old behavior (no second expansion).  If you want second expansion, you
must define the .SECONDEXPANSION: special target before the first target
that needs it.

This set of changes ONLY fixes explicit and static pattern rules to work
like this.  Implicit rules still have second expansion enabled all the
time: I'll work on that next.

Note that there is still a backward-incompatibility: now to get the old
SysV behavior using $$@ etc. in the prerequisites list you need to set
.SECONDEXPANSION: as well.

1 files changed, 50 insertions, 80 deletions

diff --git a/read.c b/read.c
index 0f07ee9..bad07eb 100644
--- a/read.c
+++ b/read.c
@@ -258,6 +258,7 @@ read_all_makefiles (char **makefiles)
 	      d->file = enter_file (*p);
 	      d->file->dontcare = 1;
               d->ignore_mtime = 0;
+              d->staticpattern = 0;
               d->need_2nd_expansion = 0;
 	      /* Tell update_goal_chain to bail out as soon as this file is
 		 made, and main not to die if we can't make this file.  */
@@ -378,6 +379,7 @@ eval_makefile (char *filename, int flags)
   filename = deps->file->name;
   deps->changed = flags;
   deps->ignore_mtime = 0;
+  deps->staticpattern = 0;
   deps->need_2nd_expansion = 0;
   if (flags & RM_DONTCARE)
     deps->file->dontcare = 1;
@@ -1160,7 +1162,7 @@ eval (struct ebuffer *ebuf, int set_default)
             pattern_percent = find_percent (pattern);
             if (pattern_percent == 0)
               fatal (fstart, _("target pattern contains no `%%'"));
-            free((char *)target);
+            free ((char *)target);
           }
         else
           pattern = 0;
@@ -1172,21 +1174,12 @@ eval (struct ebuffer *ebuf, int set_default)
 
         if (beg <= end && *beg != '\0')
           {
-            char *top;
-            const char *fromp = beg;
-
-            /* Make a copy of the dependency string.  Note if we find '$'.  */
-            deps = (struct dep*) xmalloc (sizeof (struct dep));
+            /* Put all the prerequisites here; they'll be parsed later.  */
+            deps = (struct dep *) xmalloc (sizeof (struct dep));
             deps->next = 0;
-            deps->name = top = (char *) xmalloc (end - beg + 2);
+            deps->name = xstrdup (beg);
+            deps->staticpattern = 0;
             deps->need_2nd_expansion = 0;
-            while (fromp <= end)
-              {
-                if (*fromp == '$')
-                  deps->need_2nd_expansion = 1;
-                *(top++) = *(fromp++);
-              }
-            *top = '\0';
             deps->file = 0;
           }
         else
@@ -1918,19 +1911,19 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
     {
       char *name = filenames->name;
       struct file *f;
-      struct dep *d;
-      struct dep *this;
+      struct dep *this = 0;
       char *implicit_percent;
 
       nextf = filenames->next;
       free (filenames);
 
-      /* Check for .POSIX.  We used to do this in snap_deps() but that's not
-         good enough: it doesn't happen until after the makefile is read,
-         which means we cannot use its value during parsing.  */
+      /* Check for special targets.  Do it here instead of, say, snap_deps()
+         so that we can immediately use the value.  */
 
       if (streq (name, ".POSIX"))
         posix_pedantic = 1;
+      else if (streq (name, ".SECONDEXPANSION"))
+        second_expansion = 1;
 
       implicit_percent = find_percent (name);
       implicit |= implicit_percent != 0;
@@ -1965,40 +1958,19 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
 	  continue;
 	}
 
-      /* If there are multiple filenames, copy the chain DEPS
-	 for all but the last one.  It is not safe for the same deps
-	 to go in more than one place in the database.  */
-      this = nextf != 0 ? copy_dep_chain (deps) : deps;
-
-      if (pattern != 0)
-	{
-	  /* If this is an extended static rule:
-	     `targets: target%pattern: dep%pattern; cmds',
-	     translate each dependency pattern into a plain filename
-	     using the target pattern and this target's name.  */
-	  if (!pattern_matches (pattern, pattern_percent, name))
-	    {
-	      /* Give a warning if the rule is meaningless.  */
-	      error (flocp,
-		     _("target `%s' doesn't match the target pattern"), name);
-	      this = 0;
-	    }
-	  else
-            /* We use subst_expand to do the work of translating % to $* in
-               the dependency line.  */
-
-            if (this != 0 && find_percent (this->name) != 0)
-              {
-                char *o;
-                char *buffer = variable_expand ("");
-
-                o = subst_expand (buffer, this->name, "%", "$*", 1, 2, 0);
-
-                free (this->name);
-                this->name = savestring (buffer, o - buffer);
-                this->need_2nd_expansion = 1;
-              }
-	}
+      /* If this is a static pattern rule:
+         `targets: target%pattern: dep%pattern; cmds',
+         make sure the pattern matches this target name.  */
+      if (pattern && !pattern_matches (pattern, pattern_percent, name))
+        error (flocp, _("target `%s' doesn't match the target pattern"), name);
+      else if (deps)
+        {
+          /* If there are multiple filenames, copy the chain DEPS for all but
+             the last one.  It is not safe for the same deps to go in more
+             than one place in the database.  */
+          this = nextf != 0 ? copy_dep_chain (deps) : deps;
+          this->need_2nd_expansion = second_expansion;
+        }
 
       if (!two_colon)
 	{
@@ -2038,18 +2010,11 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
 	  if (cmds != 0)
 	    f->cmds = cmds;
 
-	  /* Defining .SUFFIXES with no dependencies
-	     clears out the list of suffixes.  */
+	  /* Defining .SUFFIXES with no dependencies clears out the list of
+	     suffixes.  */
 	  if (f == suffix_file && this == 0)
 	    {
-	      d = f->deps;
-	      while (d != 0)
-		{
-		  struct dep *nextd = d->next;
- 		  free (d->name);
- 		  free ((char *)d);
-		  d = nextd;
-		}
+              free_dep_chain (f->deps);
 	      f->deps = 0;
 	    }
           else if (this != 0)
@@ -2109,38 +2074,40 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
 	}
       else
 	{
-	  /* Double-colon.  Make a new record
-	     even if the file already has one.  */
+	  /* Double-colon.  Make a new record even if there already is one.  */
 	  f = lookup_file (name);
+
 	  /* Check for both : and :: rules.  Check is_target so
 	     we don't lose on default suffix rules or makefiles.  */
 	  if (f != 0 && f->is_target && !f->double_colon)
 	    fatal (flocp,
                    _("target file `%s' has both : and :: entries"), f->name);
 	  f = enter_file (name);
-	  /* If there was an existing entry and it was a double-colon
-	     entry, enter_file will have returned a new one, making it the
-	     prev pointer of the old one, and setting its double_colon
-	     pointer to the first one.  */
+	  /* If there was an existing entry and it was a double-colon entry,
+	     enter_file will have returned a new one, making it the prev
+	     pointer of the old one, and setting its double_colon pointer to
+	     the first one.  */
 	  if (f->double_colon == 0)
-	    /* This is the first entry for this name, so we must
-	       set its double_colon pointer to itself.  */
+	    /* This is the first entry for this name, so we must set its
+	       double_colon pointer to itself.  */
 	    f->double_colon = f;
 	  f->is_target = 1;
 	  f->deps = this;
 	  f->cmds = cmds;
 	}
 
-      /* If this is a static pattern rule, set the file's stem to
-         the part of its name that matched the `%' in the pattern,
-         so you can use $* in the commands.  */
-      if (pattern != 0)
+      /* If this is a static pattern rule, set the stem to the part of its
+         name that matched the `%' in the pattern, so you can use $* in the
+         commands.  */
+      if (pattern)
         {
           static char *percent = "%";
           char *buffer = variable_expand ("");
           char *o = patsubst_expand (buffer, name, pattern, percent,
                                      pattern_percent+1, percent+1);
           f->stem = savestring (buffer, o - buffer);
+          if (this)
+            this->staticpattern = 1;
         }
 
       /* Free name if not needed further.  */
@@ -2152,9 +2119,9 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
 	}
 
       /* If this target is a default target, update DEFAULT_GOAL_FILE.  */
-      if (strcmp (*default_goal_name, name) == 0
+      if (streq (*default_goal_name, name)
           && (default_goal_file == 0
-              || strcmp (default_goal_file->name, name) != 0))
+              || ! streq (default_goal_file->name, name)))
         default_goal_file = f;
     }
 
@@ -2162,6 +2129,9 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
     {
       targets[target_idx] = 0;
       target_percents[target_idx] = 0;
+      deps->need_2nd_expansion = second_expansion;
+      /* We set this to indicate we've not yet parsed the prereq string.  */
+      deps->staticpattern = 1;
       create_pattern_rule (targets, target_percents, two_colon, deps, cmds, 1);
       free ((char *) target_percents);
     }
@@ -2291,9 +2261,9 @@ find_percent (char *pattern)
 struct nameseq *
 parse_file_seq (char **stringp, int stopchar, unsigned int size, int strip)
 {
-  register struct nameseq *new = 0;
-  register struct nameseq *new1, *lastnew1;
-  register char *p = *stringp;
+  struct nameseq *new = 0;
+  struct nameseq *new1, *lastnew1;
+  char *p = *stringp;
   char *q;
   char *name;