Some more refcounting fixes for exceptions

src/runtime/capi.cpp

@@ -848,9 +848,17 @@ extern "C" void Py_Exit(int sts) noexcept {
 }
 
 extern "C" void PyErr_Restore(PyObject* type, PyObject* value, PyObject* traceback) noexcept {
+    auto oldtype = cur_thread_state.curexc_type;
+    auto oldvalue = cur_thread_state.curexc_value;
+    auto oldtraceback = cur_thread_state.curexc_traceback;
+
     cur_thread_state.curexc_type = type;
     cur_thread_state.curexc_value = value;
     cur_thread_state.curexc_traceback = traceback;
+
+    Py_XDECREF(oldtype);
+    Py_XDECREF(oldvalue);
+    Py_XDECREF(oldtraceback);
 }
 
 extern "C" void PyErr_Clear() noexcept {

src/runtime/exceptions.cpp

@@ -28,7 +28,7 @@ namespace pyston {
 
 void raiseExc(Box* exc_obj) {
     assert(!PyErr_Occurred());
-    throw ExcInfo(exc_obj->cls, exc_obj, None);
+    throw ExcInfo(incref(exc_obj->cls), exc_obj, incref(None));
 }
 
 // Have a special helper function for syntax errors, since we want to include the location
@@ -231,8 +231,7 @@ void raiseExcHelper(BoxedClass* cls, const char* msg, ...) {
         va_end(ap);
 
         BoxedString* message = boxString(buf);
-        Box* exc_obj = runtimeCall(cls, ArgPassSpec(1), message, NULL, NULL, NULL, NULL);
-        Py_DECREF(message);
+        Box* exc_obj = runtimeCall(cls, ArgPassSpec(1), autoDecref(message), NULL, NULL, NULL, NULL);
         raiseExc(exc_obj);
     } else {
         Box* exc_obj = runtimeCall(cls, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);

src/runtime/import.cpp

@@ -515,6 +515,7 @@ Box* importModuleLevel(llvm::StringRef name, Box* globals, Box* from_imports, in
     bool again = loadNext(parent, level < 0 ? None : parent, _name, buf, &head);
     if (head == NULL)
         return NULL;
+    assert((!again) && "check refcounting");
 
     Box* tail = head;
     while (again) {

src/runtime/objmodel.h

@@ -37,7 +37,7 @@ extern "C" void raise0(ExcInfo* frame_exc_info) __attribute__((__noreturn__));
 extern "C" void raise0_capi(ExcInfo* frame_exc_info) noexcept;
 extern "C" void raise3(Box*, Box*, Box*) __attribute__((__noreturn__));
 extern "C" void raise3_capi(Box*, Box*, Box*) noexcept;
-void raiseExc(Box* exc_obj) __attribute__((__noreturn__));
+void raiseExc(STOLEN(Box*) exc_obj) __attribute__((__noreturn__));
 void _printStacktrace();
 
 extern "C" Box* deopt(AST_expr* expr, Box* value);

src/runtime/types.cpp

@@ -4150,8 +4150,8 @@ void setupRuntime() {
     setupBuiltins();
     _PyExc_Init();
     setupThread();
-    //initgc();
     setupImport();
+    initgc();
     setupPyston();
     setupAST();