Bug #124041 - Make emerge show an informative warning message when one

or more eclasses override eclasses from PORTDIR. The warning can be
permanently disabled by setting PORTAGE_ECLASS_WARNING_ENABLE="0" in
/etc/make.conf. (trunk r8668)

svn path=/main/branches/2.1.2/; revision=8669

3 files changed, 50 insertions, 6 deletions

diff --git a/bin/emerge b/bin/emerge
index a527c26cc..49204d9be 100755
--- a/bin/emerge
+++ b/bin/emerge
@@ -6313,10 +6313,39 @@ def emerge_main():
 
 	portage.deprecated_profile_check()
 
-	#Freeze the portdbapi for enhanced performance:
-	for myroot in trees:
-		trees[myroot]["porttree"].dbapi.freeze()
-		del myroot
+	eclasses_overridden = {}
+	for mytrees in trees.itervalues():
+		mydb = mytrees["porttree"].dbapi
+		# Freeze the portdbapi for performance (memoize all xmatch results).
+		mydb.freeze()
+		eclasses_overridden.update(mydb.eclassdb._master_eclasses_overridden)
+	del mytrees, mydb
+
+	if eclasses_overridden and \
+		settings.get("PORTAGE_ECLASS_WARNING_ENABLE") != "0":
+		prefix = bad(" * ")
+		if len(eclasses_overridden) == 1:
+			writemsg(prefix + "Overlay eclass overrides " + \
+				"eclass from PORTDIR:\n", noiselevel=-1)
+		else:
+			writemsg(prefix + "Overlay eclasses override " + \
+				"eclasses from PORTDIR:\n", noiselevel=-1)
+		writemsg(prefix + "\n", noiselevel=-1)
+		for eclass_name in sorted(eclasses_overridden):
+			writemsg(prefix + "  '%s/%s.eclass'\n" % \
+				(eclasses_overridden[eclass_name], eclass_name),
+				noiselevel=-1)
+		writemsg(prefix + "\n", noiselevel=-1)
+		msg = "It is best to avoid overridding eclasses from PORTDIR " + \
+		"because it will trigger invalidation of cached ebuild metadata " + \
+		"that is distributed with the portage tree. If you must " + \
+		"override eclasses from PORTDIR then you are advised to run " + \
+		"`emerge --regen` after each time that you run `emerge --sync`. " + \
+		"Set PORTAGE_ECLASS_WARNING_ENABLE=\"0\" in /etc/make.conf if " + \
+		"you would like to disable this warning."
+		from textwrap import wrap
+		for line in wrap(msg, 72):
+			writemsg("%s%s\n" % (prefix, line), noiselevel=-1)
 
 	if "moo" in myfiles:
 		print """
diff --git a/pym/eclass_cache.py b/pym/eclass_cache.py
index ede081d9c..b8d849368 100644
--- a/pym/eclass_cache.py
+++ b/pym/eclass_cache.py
@@ -23,6 +23,7 @@ class cache:
 		self.porttrees = [self.porttree_root]+overlays
 		self.porttrees = tuple(map(normalize_path, self.porttrees))
 		self._master_eclass_root = os.path.join(self.porttrees[0],"eclass")
+		self._master_eclasses_overridden = {}
 		self.update_eclasses()
 
 	def close_caches(self):
@@ -41,6 +42,7 @@ class cache:
 	def update_eclasses(self):
 		self.eclasses = {}
 		self._eclass_locations = {}
+		master_eclasses = {}
 		eclass_len = len(".eclass")
 		ignored_listdir_errnos = (errno.ENOENT, errno.ENOTDIR)
 		for x in [normalize_path(os.path.join(y,"eclass")) for y in self.porttrees]:
@@ -63,7 +65,13 @@ class cache:
 				ys=y[:-eclass_len]
 				self.eclasses[ys] = (x, long(mtime))
 				self._eclass_locations[ys] = x
-	
+				if x == self._master_eclass_root:
+					master_eclasses[ys] = mtime
+				else:
+					master_mtime = master_eclasses.get(ys)
+					if master_mtime and master_mtime != mtime:
+						self._master_eclasses_overridden[ys] = x
+
 	def is_eclass_data_valid(self, ec_dict):
 		if not isinstance(ec_dict, dict):
 			return False
diff --git a/pym/portage.py b/pym/portage.py
index f82074f74..bbaee8027 100644
--- a/pym/portage.py
+++ b/pym/portage.py
@@ -961,7 +961,11 @@ class config:
 	Generally if you need data like USE flags, FEATURES, environment variables,
 	virtuals ...etc you look in here.
 	"""
-	
+
+	# Filter selected variables in the config.environ() method so that
+	# they don't needlessly propagate down into the ebuild environment.
+	_environ_filter = frozenset(["PORTAGE_ECLASS_WARNING_ENABLE"])
+
 	def __init__(self, clone=None, mycpv=None, config_profile_path=None,
 		config_incrementals=None, config_root=None, target_root=None,
 		local_config=True):
@@ -2429,7 +2433,10 @@ class config:
 	def environ(self):
 		"return our locally-maintained environment"
 		mydict={}
+		environ_filter = self._environ_filter
 		for x in self:
+			if x in environ_filter:
+				continue
 			myvalue = self[x]
 			if not isinstance(myvalue, basestring):
 				writemsg("!!! Non-string value in config: %s=%s\n" % \