Add a registry for builtin exception models. Close pylint-dev/pylint#1432

Author: PCManticore

ChangeLog

@@ -7,6 +7,8 @@ What's New in astroid 2.2.0?
 Release Date: TBA
 
 
+* Add a registry for builtin exception models. Close PyCQA/pylint#1432
+
 * Add brain tips for `http.client`. Close PyCQA/pylint#2687
 
 * Prevent crashing when processing ``enums`` with mixed single and double quotes.

astroid/interpreter/objectmodel.py

@@ -601,6 +601,9 @@ def py__dict__(self):
         return _dunder_dict(self._instance, self._instance.instance_attrs)
 
 
+# Exception instances
+
+
 class ExceptionInstanceModel(InstanceModel):
     @property
     def pyargs(self):
@@ -616,6 +619,15 @@ def py__traceback__(self):
         return traceback_type.instantiate_class()
 
 
+class SyntaxErrorInstanceModel(ExceptionInstanceModel):
+    @property
+    def pytext(self):
+        return node_classes.Const("")
+
+
+BUILTIN_EXCEPTIONS = {"builtins.SyntaxError": SyntaxErrorInstanceModel}
+
+
 class DictModel(ObjectModel):
     @property
     def py__class__(self):

astroid/objects.py

@@ -210,10 +210,13 @@ class ExceptionInstance(bases.Instance):
     the case of .args.
     """
 
-    # pylint: disable=unnecessary-lambda
-    special_attributes = util.lazy_descriptor(
-        lambda: objectmodel.ExceptionInstanceModel()
-    )
+    @decorators.cachedproperty
+    def special_attributes(self):
+        qname = self.qname()
+        instance = objectmodel.BUILTIN_EXCEPTIONS.get(
+            qname, objectmodel.ExceptionInstanceModel
+        )
+        return instance()
 
 
 class DictInstance(bases.Instance):

astroid/tests/unittest_object_model.py

@@ -585,6 +585,18 @@ def test_model_py3(self):
         with self.assertRaises(exceptions.InferenceError):
             next(ast_nodes[2].infer())
 
+    def test_syntax_error(self):
+        ast_node = builder.extract_node(
+            """
+        try:
+            x[42]
+        except SyntaxError as err:
+           err.text #@
+        """
+        )
+        inferred = next(ast_node.infer())
+        assert isinstance(inferred, astroid.Const)
+
 
 class DictObjectModelTest(unittest.TestCase):
     def test__class__(self):