fixup! Add referred parts' hash strings in __buildout_signature__, that...

fixup! Add referred parts' hash strings in __buildout_signature__, that invokes rebuild of a part when one of its (recursive) dependencies are modified.

The purpose is to make the part signature available sooner,
during recipe's __init__.

Commit 8be81fe4 already
broke detection of unused options in sections.

src/zc/buildout/buildout.py

@@ -374,6 +374,7 @@ class Buildout(DictMixin):
         self._data = {}
         self._parts = []
         self._initializing = []
+        self._signature_cache = {}
 
         # provide some defaults before options are parsed
         # because while parsing options those attributes might be
@@ -704,9 +705,7 @@ class Buildout(DictMixin):
                 _save_options(section, self[section], sys.stdout)
             print_()
 
-
-        # compute new part recipe signatures
-        self._compute_part_signatures(install_parts)
+        del self._signature_cache
 
         # uninstall parts that are no-longer used or who's configs
         # have changed
@@ -939,31 +938,7 @@ class Buildout(DictMixin):
                 self._logger.warning(
                     "Unexpected entry, %r, in develop-eggs directory.", f)
 
-    def _compute_part_signatures(self, parts):
-        # The same recipe may appear many times.
-        sig_cache= {}
-
-        # Compute recipe signature and add to options
-        for part in parts:
-            options = self.get(part)
-            if options is None:
-                options = self[part] = {}
-            recipe, entry = _recipe(options)
-
-            try:
-                # Copy cached list, because sig.append is called later
-                sig = sig_cache[recipe][:]
-            except KeyError:
-                req = pkg_resources.Requirement.parse(recipe)
-                sig_result = sig_cache[recipe] = sorted(set(_dists_sig(pkg_resources.working_set.resolve([req]))))
-                sig = sig_result[:]
-
-            for dependency in sorted(options.depends):
-                m = md5()
-                for item in sorted(self[dependency].items()):
-                    m.update(('%r\0%r\0' % item).encode())
-                sig.append('%s:%s' % (dependency, m.hexdigest()))
-            options['__buildout_signature__'] = ' '.join(sig)
+    _compute_part_signatures = None # BBB: monkey-patched by slapos.rebootstrap
 
     def _read_installed_part_options(self):
         old = self['buildout']['installed']
@@ -1306,11 +1281,19 @@ class Buildout(DictMixin):
 
     def initialize(self, options, reqs, entry):
         recipe_class = _install_and_load(reqs, 'zc.buildout', entry, self)
-        self._initializing.append(options)
         try:
-            return recipe_class(self, options.name, options)
+            sig = self._signature_cache[reqs]
+        except KeyError:
+            req = pkg_resources.Requirement.parse(reqs)
+            sig = self._signature_cache[reqs] = sorted(set(
+                _dists_sig(pkg_resources.working_set.resolve([req]))))
+        self._initializing.append((options, sig))
+        try:
+            recipe = recipe_class(self, options.name, options)
+            options['__buildout_signature__']
         finally:
             del self._initializing[-1]
+        return recipe
 
     def __getitem__(self, section):
         __doing__ = 'Getting section %s.', section
@@ -1327,9 +1310,13 @@ class Buildout(DictMixin):
             options._initialize()
 
         if self._initializing:
-            caller = self._initializing[-1]
-            if 'buildout' != section != caller.name:
-                  caller.depends.add(section)
+            caller = self._initializing[-1][0]
+            if 'buildout' != section and not (
+                  section in caller.depends or
+                  # Do not only check the caller,
+                  # because of circular dependencies during substitutions.
+                  section in (x[0].name for x in self._initializing)):
+                caller.depends.add(section)
         return options
 
     def __setitem__(self, name, data):
@@ -1441,6 +1428,11 @@ class Options(DictMixin):
             self.recipe = self.buildout.initialize(self, *_recipe(self._data))
             self.buildout._parts.append(name)
 
+        m = md5()
+        for item in sorted(self.items()):
+            m.update(('%r\0%r\0' % item).encode())
+        self.items_signature = '%s:%s' % (name, m.hexdigest())
+
     def _do_extend_raw(self, name, data, doing):
         if name == 'buildout':
             return data
@@ -1502,6 +1494,16 @@ class Options(DictMixin):
         if v is None:
             v = self._raw.get(option)
             if v is None:
+                if option == '__buildout_signature__':
+                    buildout = self.buildout
+                    options, sig = buildout._initializing[-1]
+                    if options is self:
+                        self.depends = frozenset(self.depends)
+                        v = self._data[option] = ' '.join(sig + [
+                            buildout[dependency].items_signature
+                            for dependency in sorted(self.depends)])
+                        return v
+                    raise zc.buildout.UserError("premature access to " + option)
                 return default
 
         __doing__ = 'Getting option %s:%s.', self.name, option
@@ -1559,7 +1561,7 @@ class Options(DictMixin):
                 section = self.name
                 options = self
             else:
-                self.buildout._initializing.append(self)
+                self.buildout._initializing.append((self,))
                 try:
                     options = self.buildout[section]
                 finally: