portage.package.ebuild.config: Always export filtered USE_EXPAND vars

Ensure that all USE_EXPAND variables are always exported with filtered
USE flags inside, even if none of those flags are declared in IUSE.
This is the behavior required for EAPI 5+ by the PMS.

Since the behavior for earlier EAPIs is left undefined and having
different behavior would be confusing to users, apply it in earlier
EAPIs as well.

Bug: https://bugs.gentoo.org/582140
Closes: https://github.com/gentoo/portage/pull/254
Reviewed-by: Zac Medico <zmedico@gentoo.org>

2 files changed, 4 insertions, 59 deletions

diff --git a/bin/ebuild.sh b/bin/ebuild.sh
index 4a80fdd06..d63b0a0ba 100755
--- a/bin/ebuild.sh
+++ b/bin/ebuild.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 1999-2015 Gentoo Foundation
+# Copyright 1999-2018 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
 # Prevent aliases from causing portage to act inappropriately.
@@ -704,12 +704,6 @@ if ! has "$EBUILD_PHASE" clean cleanrm ; then
 	fi
 fi
 
-# unset USE_EXPAND variables that contain only the special "*" token
-for x in ${USE_EXPAND} ; do
-	[ "${!x}" == "*" ] && unset ${x}
-done
-unset x
-
 if has nostrip ${FEATURES} ${RESTRICT} || has strip ${RESTRICT}
 then
 	export DEBUGBUILD=1
diff --git a/pym/portage/package/ebuild/config.py b/pym/portage/package/ebuild/config.py
index 35cf4f614..432520ba8 100644
--- a/pym/portage/package/ebuild/config.py
+++ b/pym/portage/package/ebuild/config.py
@@ -1359,47 +1359,7 @@ class config(object):
 					filtered_var_split.append(x)
 			var_split = filtered_var_split
 
-			if var_split:
-				value = ' '.join(var_split)
-			else:
-				# Don't export empty USE_EXPAND vars unless the user config
-				# exports them as empty.  This is required for vars such as
-				# LINGUAS, where unset and empty have different meanings.
-				# The special '*' token is understood by ebuild.sh, which
-				# will unset the variable so that things like LINGUAS work
-				# properly (see bug #459350).
-				if has_wildcard:
-					value = '*'
-				else:
-					if has_iuse:
-						already_set = False
-						# Skip the first 'env' configdict, in order to
-						# avoid infinite recursion here, since that dict's
-						# __getitem__ calls the current __getitem__.
-						for d in self._settings.lookuplist[1:]:
-							if key in d:
-								already_set = True
-								break
-
-						if not already_set:
-							for x in self._unfiltered_use:
-								if x[:prefix_len] == prefix:
-									already_set = True
-									break
-
-						if already_set:
-							value = ''
-						else:
-							value = '*'
-					else:
-						# It's not in IUSE, so just allow the variable content
-						# to pass through if it is defined somewhere.  This
-						# allows packages that support LINGUAS but don't
-						# declare it in IUSE to use the variable outside of the
-						# USE_EXPAND context.
-						value = None
-
-			return value
+			return ' '.join(var_split)
 
 	def _setcpv_recursion_gate(f):
 		"""
@@ -1775,7 +1735,7 @@ class config(object):
 			self, unfiltered_use, use, self.usemask,
 			portage_iuse, use_expand_split, self._use_expand_dict)
 
-		use_expand_iuses = {}
+		use_expand_iuses = dict((k, set()) for k in use_expand_split)
 		for x in portage_iuse:
 			x_split = x.split('_')
 			if len(x_split) == 1:
@@ -1783,18 +1743,9 @@ class config(object):
 			for i in range(len(x_split) - 1):
 				k = '_'.join(x_split[:i+1])
 				if k in use_expand_split:
-					v = use_expand_iuses.get(k)
-					if v is None:
-						v = set()
-						use_expand_iuses[k] = v
-					v.add(x)
+					use_expand_iuses[k].add(x)
 					break
 
-		# If it's not in IUSE, variable content is allowed
-		# to pass through if it is defined somewhere.  This
-		# allows packages that support LINGUAS but don't
-		# declare it in IUSE to use the variable outside of the
-		# USE_EXPAND context.
 		for k, use_expand_iuse in use_expand_iuses.items():
 			if k + '_*' in use:
 				use.update( x for x in use_expand_iuse if x not in usemask )