Fix some C/C++ capi issues

from_cpython/Include/Python.h

@@ -90,6 +90,10 @@
 #include "warnings.h"
 #include "weakrefobject.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 // Pyston additions:
 // These new APIS give access to our fast hidden-class-based attributes implementation.
 // Ideally in the future this will just be "storage strategy" of dicts and all Python
@@ -104,7 +108,7 @@ typedef struct _hcattrs PyHcAttrs;
 namespace pyston {
 class HCAttrs;
 }
-typedef int PyHcAttrs;
+typedef pyston::HCAttrs PyHcAttrs;
 #endif
 PyAPI_FUNC(void) PyObject_InitHcAttrs(PyHcAttrs*) PYSTON_NOEXCEPT;
 PyAPI_FUNC(PyObject*) PyObject_GetAttrWrapper(PyObject*) PYSTON_NOEXCEPT;
@@ -134,6 +138,10 @@ PyAPI_FUNC(PyObject*) PyGC_RegisterStaticConstant(PyObject*) PYSTON_NOEXCEPT;
 PyAPI_FUNC(void) PyGC_Enable() PYSTON_NOEXCEPT;
 PyAPI_FUNC(void) PyGC_Disable() PYSTON_NOEXCEPT;
 
+#ifdef __cplusplus
+}
+#endif
+
 #include "codecs.h"
 #include "pyerrors.h"
 

src/runtime/types.cpp

@@ -1350,7 +1350,7 @@ static void typeSubSetDict(Box* obj, Box* val, void* context) {
     abort();
 }
 
-extern "C" void PyType_SetDict(PyTypeObject* type, PyObject* dict) {
+extern "C" void PyType_SetDict(PyTypeObject* type, PyObject* dict) noexcept {
     typeSubSetDict(type, dict, NULL);
     type->tp_dict = dict;
 }
@@ -3673,8 +3673,9 @@ int BoxedClosure::clear(Box* _o) noexcept {
 #endif
 
 std::vector<Box*> constants;
-extern "C" void PyGC_RegisterStaticConstant(Box* b) {
+extern "C" PyObject* PyGC_RegisterStaticConstant(Box* b) noexcept {
     constants.push_back(b);
+    return b;
 }
 
 extern "C" void _PyUnicode_Fini(void);