Merge pull request #1281 from undingen/deinitFrame_exc

deinitFrame: don't modify CAPI exception state

src/runtime/frame.cpp

@@ -253,16 +253,24 @@ void FrameInfo::disableDeinit(FrameInfo* replacement_frame) {
     assert(isDisabledFrame());
 }
 
-extern "C" void deinitFrameMaybe(FrameInfo* frame_info) {
+extern "C" void deinitFrameMaybe(FrameInfo* frame_info) noexcept {
     // Note: this has to match FrameInfo::disableDeinit
     if (!frame_info->isDisabledFrame())
         deinitFrame(frame_info);
 }
 
-extern "C" void deinitFrame(FrameInfo* frame_info) {
+extern "C" void deinitFrame(FrameInfo* frame_info) noexcept {
     // This can fire if we have a call to deinitFrame() that should be to deinitFrameMaybe() instead
     assert(!frame_info->isDisabledFrame());
 
+    Box* err_type, *err_value, *err_tb;
+    bool restore_exc = cur_thread_state.curexc_type != NULL;
+    if (restore_exc) {
+        // preserve the existing exception
+        PyErr_Fetch(&err_type, &err_value, &err_tb);
+        PyErr_Clear();
+    }
+
     assert(cur_thread_state.frame_info == frame_info);
     cur_thread_state.frame_info = frame_info->back;
     BoxedFrame* frame = frame_info->frame_obj;
@@ -288,6 +296,10 @@ extern "C" void deinitFrame(FrameInfo* frame_info) {
     }
 
     Py_CLEAR(frame_info->globals);
+
+    assert(!PyErr_Occurred());
+    if (restore_exc)
+        PyErr_Restore(err_type, err_value, err_tb);
 }
 
 int frameinfo_traverse(FrameInfo* frame_info, visitproc visit, void* arg) noexcept {

src/runtime/types.h

@@ -1307,8 +1307,8 @@ FunctionMetadata* metadataFromCode(Box* code);
 BORROWED(Box*) getFrame(FrameInfo* frame_info);
 BORROWED(Box*) getFrame(int depth);
 void frameInvalidateBack(BoxedFrame* frame);
-extern "C" void deinitFrame(FrameInfo* frame_info);
-extern "C" void deinitFrameMaybe(FrameInfo* frame_info);
+extern "C" void deinitFrame(FrameInfo* frame_info) noexcept;
+extern "C" void deinitFrameMaybe(FrameInfo* frame_info) noexcept;
 int frameinfo_traverse(FrameInfo* frame_info, visitproc visit, void* arg) noexcept;
 extern "C" void initFrame(FrameInfo* frame_info);
 extern "C" void setFrameExcInfo(FrameInfo* frame_info, STOLEN(Box*) type, STOLEN(Box*) value, STOLEN(Box*) tb);