Check for component use, fix sanity checks

Lib/ufo2ft/filters/optimizeAnchors.py

@@ -10,21 +10,30 @@ class OptimizeAnchorsFilter(TransformationsFilter):
     def set_context(self, font, glyphSet):
         self.context = BaseFilter.set_context(self, font, glyphSet)
 
+        self.context.component_use = {}
+        for g in font.layers["public.default"]:
+            for comp in g.components:
+                self.context.component_use[comp.baseGlyph] = True
+
         return self.context
 
+
     def filter(self, glyph):
-        if len(glyph.anchors) == 0 or any(
-            not (a.name.startswith("_")) for a in glyph.anchors
-        ):
+        if not any(a.name.startswith("_") for a in glyph.anchors):
             # We're a base!
             return False
 
-        # More sanity checks: skip over spacing marks
+        # Are we a spacing mark?
         if glyph.width != 0:
             return False
+
+       # Are we anywhere used as a component?
+        if glyph.name in self.context.component_use:
+            return False
+
         # Also skip over marks which are deliberately positioned over the
         # previous glyphs
-        if glyph.getBounds().xMax < 0:
+        if len(glyph.components) or glyph.getBounds().xMax < 0:
             return False
 
         # We are a mark glyph with (at least) one attachment point.