Index: clang/bindings/python/clang/cindex.py
===================================================================
--- clang/bindings/python/clang/cindex.py
+++ clang/bindings/python/clang/cindex.py
@@ -207,7 +207,7 @@
         conf.lib.clang_disposeString(self)
 
     @staticmethod
-    def from_result(res, fn, args):
+    def from_result(res, fn=None, args=None):
         assert isinstance(res, _CXString)
         return conf.lib.clang_getCString(res)
 
@@ -459,8 +459,7 @@
         """The command-line option that disables this diagnostic."""
         disable = _CXString()
         conf.lib.clang_getDiagnosticOption(self, byref(disable))
-
-        return conf.lib.clang_getCString(disable)
+        return _CXString.from_result(disable)
 
     def format(self, options=None):
         """
@@ -473,8 +472,7 @@
             options = conf.lib.clang_defaultDiagnosticDisplayOptions()
         if options & ~Diagnostic._FormatOptionsMask:
             raise ValueError('Invalid format options')
-        formatted = conf.lib.clang_formatDiagnostic(self, options)
-        return conf.lib.clang_getCString(formatted)
+        return conf.lib.clang_formatDiagnostic(self, options)
 
     def __repr__(self):
         return "<Diagnostic severity %r, location %r, spelling %r>" % (
Index: clang/bindings/python/tests/cindex/test_diagnostics.py
===================================================================
--- clang/bindings/python/tests/cindex/test_diagnostics.py
+++ clang/bindings/python/tests/cindex/test_diagnostics.py
@@ -92,3 +92,11 @@
     assert children[0].spelling.endswith('declared here')
     assert children[0].location.line == 1
     assert children[0].location.column == 1
+
+def test_diagnostic_string_repr():
+    tu = get_tu('struct MissingSemicolon{}')
+    assert len(tu.diagnostics) == 1
+    d = tu.diagnostics[0]
+
+    assert repr(d) == '<Diagnostic severity 3, location <SourceLocation file \'t.c\', line 1, column 26>, spelling "expected \';\' after struct">'
+