[pypy-commit] cffi default: Improve the error message.

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r926:da8b284ba665
Date: 2012-09-13 08:49 +0200
http://bitbucket.org/cffi/cffi/changeset/da8b284ba665/

Log:	Improve the error message.

diff --git a/cffi/model.py b/cffi/model.py
--- a/cffi/model.py
+++ b/cffi/model.py
@@ -38,7 +38,7 @@
         return 'void' + replace_with
 
     def finish_backend_type(self, ffi):
-        return global_cache(ffi, 'new_void_type')
+        return global_cache(self, ffi, 'new_void_type')
 
 void_type = VoidType()
 
@@ -64,7 +64,7 @@
         return self.name in ('double', 'float')
 
     def finish_backend_type(self, ffi):
-        return global_cache(ffi, 'new_primitive_type', self.name)
+        return global_cache(self, ffi, 'new_primitive_type', self.name)
 
 
 class BaseFunctionType(BaseType):
@@ -108,7 +108,7 @@
         args = []
         for tp in self.args:
             args.append(ffi._get_cached_btype(tp))
-        return global_cache(ffi, 'new_function_type',
+        return global_cache(self, ffi, 'new_function_type',
                             tuple(args), result, self.ellipsis)
 
 
@@ -123,7 +123,7 @@
 
     def finish_backend_type(self, ffi):
         BItem = ffi._get_cached_btype(self.totype)
-        return global_cache(ffi, 'new_pointer_type', BItem)
+        return global_cache(self, ffi, 'new_pointer_type', BItem)
 
 
 class ConstPointerType(PointerType):
@@ -166,7 +166,7 @@
 
     def finish_backend_type(self, ffi):
         BPtrItem = ffi._get_cached_btype(PointerType(self.item))
-        return global_cache(ffi, 'new_array_type', BPtrItem, self.length)
+        return global_cache(self, ffi, 'new_array_type', BPtrItem, self.length)
 
 
 class StructOrUnionOrEnum(BaseType):
@@ -313,7 +313,7 @@
     tp = StructType('*$%s' % name, None, None, None)
     return NamedPointerType(tp, name)
 
-def global_cache(ffi, funcname, *args):
+def global_cache(srctype, ffi, funcname, *args):
     try:
         return ffi._backend.__typecache[args]
     except KeyError:
@@ -327,6 +327,9 @@
             ffi._backend.__typecache = weakref.WeakValueDictionary()
         else:
             type(ffi._backend).__typecache = weakref.WeakValueDictionary()
-    res = getattr(ffi._backend, funcname)(*args)
+    try:
+        res = getattr(ffi._backend, funcname)(*args)
+    except NotImplementedError, e:
+        raise NotImplementedError("%r: %s" % (srctype, e))
     ffi._backend.__typecache[args] = res
     return res
diff --git a/testing/test_ffi_backend.py b/testing/test_ffi_backend.py
--- a/testing/test_ffi_backend.py
+++ b/testing/test_ffi_backend.py
@@ -1,4 +1,6 @@
+import py
 from testing import backend_tests, test_function, test_ownlib
+from cffi import FFI
 import _cffi_backend
 
 
@@ -10,3 +12,11 @@
     @staticmethod
     def Backend():
         return _cffi_backend
+
+    def test_not_supported_bitfield_in_result(self):
+        ffi = FFI(backend=self.Backend())
+        ffi.cdef("struct foo_s { int x:1; };")
+        e = py.test.raises(NotImplementedError, ffi.callback,
+                           "struct foo_s foo(void)", lambda: 42)
+        assert str(e.value) == ("<struct foo_s(*)(void)>: "
+            "cannot pass as argument or return value a struct with bit fields")