X-Git-Url: http://nitlanguage.org

diff --git a/src/ffi/extern_classes.nit b/src/ffi/extern_classes.nit
index bc4f0c4..c0e826b 100644
--- a/src/ffi/extern_classes.nit
+++ b/src/ffi/extern_classes.nit
@@ -17,7 +17,8 @@
 # Manages all extern classes and their associated foreign type.
 module extern_classes
 
-import ffi_base
+import light_ffi_base
+import modelize
 
 redef class ToolContext
 	var extern_classes_typing_phase_ast: Phase = new ExternClassesTypingPhaseAst(self, [ffi_language_assignation_phase, modelize_class_phase])
@@ -38,8 +39,8 @@ private class ExternClassesTypingPhaseAst
 		if code_block == null then return
 
 		if nclassdef.n_kwredef != null then
-			# A redef cannot specifiy a different extern type
-			toolcontext.error(nclassdef.location, "Only the introduction of a class can specify an extern type.")
+			# A redef cannot specify a different extern type
+			toolcontext.error(nclassdef.location, "FFI Error: only the introduction of a class can declare an extern type.")
 			return
 		end
 
@@ -68,10 +69,11 @@ private class ExternClassesTypingPhaseModel
 		if not nclassdef isa AStdClassdef then return
 
 		var mclassdef = nclassdef.mclassdef
-		var mclass = nclassdef.mclass
+		if mclassdef == null then return
+		var mclass = mclassdef.mclass
 
 		# We only need to do this once per class
-		if mclass.intro != mclassdef then return
+		if not mclassdef.is_intro then return
 
 		if mclass.kind != extern_kind then return
 
@@ -117,7 +119,7 @@ redef class MClass
 					else
 						# detect conflict
 						if super_ftype != ftype_b then
-							v.toolcontext.error(null, "Extern type conflict in {self}")
+							v.toolcontext.error(null, "FFI Error: extern type conflict in `{self}`.")
 							return null
 						end
 					end