[entropy.core] implement "drop all USE" in the new dep. rewrite

conf/packages/packages.server.dep_rewrite.example

@@ -78,7 +78,8 @@
 # If present in rule, ::use_to_remove:: will be removed if dependency contains it.
 #
 # ::dep_atom:: and ::new_dep_atom:: are category/package names, without version, slot etc.
+# ::use_to_remove:: can be an asterisk (*) which means to remove all USE flags.
 #
-# Examples:
+# EXAMPLE
 #	rewrite foo/bar from-dep=app-crypt/pinentry to-dep=app-crypt/pinentry-gtk2 if-dep-has-use=gtk drop-use=gtk
 # will change foo/bar's dependency "app-crypt/pinentry[gtk,qt5]" to "app-crypt/pinentry-gtk2[qt5]".

lib/entropy/dep.py

@@ -1299,11 +1299,18 @@ class DependencyRewriter(object):
             dep_has_use_func = lambda _: True
 
         if 'drop-use' in self._rule_dict:
-            modify_use_func = lambda dep_postfix, use_flags_list, clean_use_flags_list: \
-                    DependencyRewriter._use_in_depstring_re.sub(
-                        self._filter_use(use_flags_list, clean_use_flags_list, self._rule_dict['drop-use']),
-                        dep_postfix,
-                        count=1)
+            if self._rule_dict['drop-use'] == "*":
+                modify_use_func = lambda dep_postfix, use_flags_list, clean_use_flags_list: \
+                        DependencyRewriter._use_in_depstring_re.sub(
+                            "",
+                            dep_postfix,
+                            count=1)
+            else:
+                modify_use_func = lambda dep_postfix, use_flags_list, clean_use_flags_list: \
+                        DependencyRewriter._use_in_depstring_re.sub(
+                            self._filter_use(use_flags_list, clean_use_flags_list, self._rule_dict['drop-use']),
+                            dep_postfix,
+                            count=1)
         else:
             modify_use_func = lambda dep_postfix, _1, _2: dep_postfix
 

lib/tests/dep.py

@@ -442,6 +442,18 @@ class DependencyRewriterTests(unittest.TestCase, DepsRewriteTestsMixin):
         self._expected_deps = ["x11-misc/lightdm-qt5"]
         self._validate()
 
+    def test_with_drop_use_asterisk(self):
+        self._rule = "from-dep=x11-misc/lightdm to-dep=x11-misc/lightdm-qt5 drop-use=*"
+        self._deps = ["x11-misc/lightdm[qt4?,qt5]"]
+        self._expected_deps = ["x11-misc/lightdm-qt5"]
+        self._validate()
+
+    def test_with_drop_use_asterisk_and_no_use_in_dep(self):
+        self._rule = "from-dep=x11-misc/lightdm to-dep=x11-misc/lightdm-qt5 drop-use=*"
+        self._deps = ["x11-misc/lightdm"]
+        self._expected_deps = ["x11-misc/lightdm-qt5"]
+        self._validate()
+
     def test_raises_on_unknown_key(self):
         rule = "from-dep=x11-misc/lightdm to-dep=x11-misc/lightdm-qt4 haha=true"
         deps = ["x11-misc/lightdm"]
@@ -508,6 +520,21 @@ class DependencyRewriterBasicAttrsTests(unittest.TestCase, MatchedChangedTestsMi
         self._expected_changed = False
         self._validate()
 
+    def test_matched_and_changed_with_use_asterisk(self):
+        self._rule = "from-dep=x11-misc/lightdm to-dep=x11-misc/lightdm drop-use=*"
+        self._deps = ["x11-misc/lightdm[gtk]"]
+        self._expected_matched = True
+        self._expected_changed = True
+        self._validate()
+
+    def test_matched_and_not_changed_with_use_asterisk(self):
+        self._rule = "from-dep=x11-misc/lightdm to-dep=x11-misc/lightdm drop-use=*"
+        self._deps = ["x11-misc/lightdm"]
+        self._expected_matched = True
+        self._expected_changed = False
+        self._validate()
+
+
 if __name__ == '__main__':
     unittest.main()
     raise SystemExit(0)