Add emerge --dynamic-deps <y|n> option.

This makes it possible to disable the dynamic dependency updates that
FakeVartree performs by default.

WARNING: If --dynamic-deps is disabled, then it is necessary to
ensure that an alternative method is used to handle package moves
in dependencies of installed packages. Normally, this is handled
by FEATURES="fixpackages", which is enabled by default and may be
disabled via make.conf(5). Alternatively, in order to manually apply
package moves, run `emaint --fix moveinst` after each emerge --sync
operation (see emaint(1)).

6 files changed, 43 insertions, 6 deletions

diff --git a/man/emerge.1 b/man/emerge.1
index 62bfd5ecd..10be7895c 100644
--- a/man/emerge.1
+++ b/man/emerge.1
@@ -407,6 +407,22 @@ when FEATURES="preserve\-libs" is enabled in
 \fBmake.conf\fR(5), since any libraries that have
 consumers will simply be preserved.
 .TP
+.BR "\-\-dynamic\-deps < y | n >"
+In dependency calculations, substitute the dependencies of installed
+packages with the dependencies of corresponding unbuilt ebuilds from
+source repositories. This causes the effective dependencies of
+installed packages to vary dynamically when source ebuild dependencies
+are modified. This option is enabled by default.
+
+\fBWARNING:\fR
+If \-\-dynamic\-deps is disabled, then it is necessary to ensure that
+an alternative method is used to handle package moves in dependencies
+of installed packages. Normally, this is handled by
+FEATURES="fixpackages", which is enabled by default and may be
+disabled via \fBmake.conf\fR(5). Alternatively, in order to manually
+apply package moves, run `emaint \-\-fix moveinst` after each
+emerge \-\-sync operation (see \fBemaint\fR(1)).
+.TP
 .BR "\-\-emptytree " (\fB\-e\fR)
 Reinstalls target atoms and their entire deep
 dependency tree, as though no packages are currently
diff --git a/pym/_emerge/FakeVartree.py b/pym/_emerge/FakeVartree.py
index a11966f89..a9c1b90e0 100644
--- a/pym/_emerge/FakeVartree.py
+++ b/pym/_emerge/FakeVartree.py
@@ -37,8 +37,10 @@ class FakeVartree(vartree):
 	global updates are necessary (updates are performed when necessary if there
 	is not a matching ebuild in the tree). Instances of this class are not
 	populated until the sync() method is called."""
-	def __init__(self, root_config, pkg_cache=None, pkg_root_config=None):
+	def __init__(self, root_config, pkg_cache=None, pkg_root_config=None,
+		dynamic_deps=True):
 		self._root_config = root_config
+		self._dynamic_deps = dynamic_deps
 		if pkg_root_config is None:
 			pkg_root_config = self._root_config
 		self._pkg_root_config = pkg_root_config
@@ -60,7 +62,8 @@ class FakeVartree(vartree):
 		# metadata.  This ensures that the vardb lock is released ASAP, without
 		# being delayed in case cache generation is triggered.
 		self._aux_get = self.dbapi.aux_get
-		self.dbapi.aux_get = self._aux_get_wrapper
+		if dynamic_deps:
+			self.dbapi.aux_get = self._aux_get_wrapper
 		self._match = self.dbapi.match
 		self.dbapi.match = self._match_wrapper
 		self._aux_get_history = set()
diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index a6dd98c28..11a72f358 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -304,10 +304,11 @@ class Scheduler(PollScheduler):
 		"""
 		self._set_graph_config(graph_config)
 		self._blocker_db = {}
+		dynamic_deps = myopts.get("--dynamic-deps", "y") != "n"
 		for root in self.trees:
 			if graph_config is None:
 				fake_vartree = FakeVartree(self.trees[root]["root_config"],
-					pkg_cache=self._pkg_cache)
+					pkg_cache=self._pkg_cache, dynamic_deps=dynamic_deps)
 				fake_vartree.sync()
 			else:
 				fake_vartree = graph_config.trees[root]['vartree']
diff --git a/pym/_emerge/create_depgraph_params.py b/pym/_emerge/create_depgraph_params.py
index 42983fef3..8f15c6813 100644
--- a/pym/_emerge/create_depgraph_params.py
+++ b/pym/_emerge/create_depgraph_params.py
@@ -21,6 +21,10 @@ def create_depgraph_params(myopts, myaction):
 	if bdeps is not None:
 		myparams["bdeps"] = bdeps
 
+	dynamic_deps = myopts.get("--dynamic-deps")
+	if dynamic_deps is not None:
+		myparams["dynamic_deps"] = dynamic_deps
+
 	if myaction == "remove":
 		myparams["remove"] = True
 		myparams["complete"] = True
diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index a409bedac..ab62dc773 100644
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -109,6 +109,7 @@ class _frozen_depgraph_config(object):
 		# All Package instances
 		self._pkg_cache = {}
 		self._highest_license_masked = {}
+		dynamic_deps = myopts.get("--dynamic-deps", "y") != "n"
 		for myroot in trees:
 			self.trees[myroot] = {}
 			# Create a RootConfig instance that references
@@ -122,7 +123,8 @@ class _frozen_depgraph_config(object):
 			self.trees[myroot]["vartree"] = \
 				FakeVartree(trees[myroot]["root_config"],
 					pkg_cache=self._pkg_cache,
-					pkg_root_config=self.roots[myroot])
+					pkg_root_config=self.roots[myroot],
+					dynamic_deps=dynamic_deps)
 			self.pkgsettings[myroot] = portage.config(
 				clone=self.trees[myroot]["vartree"].settings)
 
@@ -514,6 +516,8 @@ class depgraph(object):
 
 		for myroot in self._frozen_config.trees:
 
+			dynamic_deps = self._dynamic_config.myparams.get(
+				"dynamic_deps", "y") != "n"
 			preload_installed_pkgs = \
 				"--nodeps" not in self._frozen_config.myopts
 
@@ -535,8 +539,11 @@ class depgraph(object):
 
 				for pkg in vardb:
 					self._spinner_update()
-					# This triggers metadata updates via FakeVartree.
-					vardb.aux_get(pkg.cpv, [])
+					if dynamic_deps:
+						# This causes FakeVartree to update the
+						# Package instance dependencies via
+						# PackageVirtualDbapi.aux_update()
+						vardb.aux_get(pkg.cpv, [])
 					fakedb.cpv_inject(pkg)
 
 		self._dynamic_config._vdb_loaded = True
diff --git a/pym/_emerge/main.py b/pym/_emerge/main.py
index f4ea36c7b..ed07c092d 100644
--- a/pym/_emerge/main.py
+++ b/pym/_emerge/main.py
@@ -684,6 +684,12 @@ def parse_opts(tmpcmdline, silent=False):
 			"choices" : true_y_or_n
 		},
 
+		"--dynamic-deps": {
+			"help": "substitute the dependencies of installed packages with the dependencies of unbuilt ebuilds",
+			"type": "choice",
+			"choices": y_or_n
+		},
+
 		"--exclude": {
 			"help"   :"A space separated list of package names or slot atoms. " + \
 				"Emerge won't  install any ebuild or binary package that " + \