Fix: ObjC-bridged Kotlin fields rendered as None

LLDBPlugin/touchlab_kotlin_lldb/types/base.py

@@ -76,6 +76,22 @@ def obj_header_pointer(valobj: lldb.SBValue) -> lldb.SBValue:
     return single_pointer(valobj).Cast(obj_header_type())
 
 
+def objc_bridged_obj_header(cast_value: lldb.SBValue) -> Optional[lldb.SBValue]:
+    """If cast_value points at an ObjC instance wrapping a Kotlin object,
+    return the corresponding ObjHeader*. Otherwise, return None."""
+    if cast_value.unsigned == 0:
+        return None
+    bridged = evaluate(
+        'void* __result = 0; (ObjHeader*)Kotlin_ObjCExport_refFromObjC((void*){:#x}, &__result)',
+        cast_value.unsigned,
+    )
+    if bridged is None or not bridged.IsValid() or bridged.error.Fail():
+        return None
+    if bridged.unsigned == 0 or bridged.unsigned == cast_value.unsigned:
+        return None
+    return bridged
+
+
 def get_runtime_type(variable):
     return strip_quotes(evaluate("(char *)Konan_DebugGetTypeName({:#x})", variable.unsigned).summary)
 

LLDBPlugin/touchlab_kotlin_lldb/types/proxy.py

@@ -6,7 +6,7 @@
 from .KonanNotInitializedObjectSyntheticProvider import KonanNotInitializedObjectSyntheticProvider
 from .KonanBaseSyntheticProvider import KonanBaseSyntheticProvider
 from .KonanZerroSyntheticProvider import KonanZerroSyntheticProvider
-from .base import get_type_info, obj_header_pointer, single_pointer
+from .base import get_type_info, obj_header_pointer, objc_bridged_obj_header, single_pointer
 from .select_provider import select_provider
 
 
@@ -20,11 +20,16 @@ def __getattr__(self, item):
             cast_value = obj_header_pointer(self._valobj)
             type_info = get_type_info(cast_value)
 
-            if not type_info:
-                self._proxy = KonanNotInitializedObjectSyntheticProvider(self._valobj)
-                return
-
-            self._proxy = select_provider(cast_value, type_info)
+            if type_info:
+                self._proxy = select_provider(cast_value, type_info)
+            else:
+                bridged = objc_bridged_obj_header(cast_value)
+                bridged_type_info = get_type_info(bridged) if bridged is not None else None
+                if bridged_type_info:
+                    self._proxy = select_provider(bridged, bridged_type_info)
+                else:
+                    self._proxy = KonanNotInitializedObjectSyntheticProvider(self._valobj)
+                    return
 
         return getattr(self._proxy, item)
 

LLDBPlugin/touchlab_kotlin_lldb/types/summary.py

@@ -1,8 +1,41 @@
+from typing import Optional
+
 import lldb
 
 from .select_provider import select_provider
-from .base import get_type_info, obj_header_pointer, single_pointer
-from ..util import log, evaluate
+from .base import get_type_info, obj_header_pointer, objc_bridged_obj_header, single_pointer
+from ..util import log, evaluate, strip_quotes
+
+
+def _objc_class_name(objc_ptr: int) -> Optional[str]:
+    """Return the ObjC class name for an instance pointer, or None if it can't
+    be read. Used to label a bridged Kotlin object with the class the user
+    actually wrote (e.g. their Swift type) instead of a bare address."""
+    name = evaluate('(const char*)object_getClassName((void*){:#x})', objc_ptr)
+    if name is None or not name.IsValid() or name.error.Fail():
+        return None
+    return strip_quotes(name.summary) or None
+
+
+def _objc_bridge_summary_fallback(cast_value: lldb.SBValue) -> str:
+    """Build a summary for a Kotlin object that the Kotlin runtime can't
+    describe via Konan_DebugObjectToUtf8Array (typically a Kotlin wrapper
+    around a Swift class implementing a Kotlin interface). It looks up the
+    underlying ObjC pointer via Kotlin_ObjCExport_refToObjC and the instance's
+    ObjC class name so the user sees something like `SwiftCallback objc@0x…`
+    instead of `None`."""
+    if cast_value.unsigned == 0:
+        return "@0x0"
+    objc_ptr = evaluate(
+        '(void*)Kotlin_ObjCExport_refToObjC((ObjHeader*){:#x})',
+        cast_value.unsigned,
+    )
+    if objc_ptr is not None and objc_ptr.error.Success() and objc_ptr.unsigned != 0:
+        class_name = _objc_class_name(objc_ptr.unsigned)
+        if class_name:
+            return "{} objc@{:#x}".format(class_name, objc_ptr.unsigned)
+        return "objc@{:#x}".format(objc_ptr.unsigned)
+    return "@{:#x}".format(cast_value.unsigned)
 
 
 def kotlin_object_type_summary(valobj: lldb.SBValue, internal_dict):
@@ -13,20 +46,35 @@ def kotlin_object_type_summary(valobj: lldb.SBValue, internal_dict):
     type_info = internal_dict["type_info"] if "type_info" in internal_dict.keys() else get_type_info(cast_value)
 
     if not type_info:
+        bridged = objc_bridged_obj_header(cast_value)
+        if bridged is not None:
+            bridged_type_info = get_type_info(bridged)
+            if bridged_type_info:
+                log(lambda: "kotlin_object_type_summary: bridged ObjC->Kotlin {:#x}->{:#x}".format(
+                    cast_value.unsigned, bridged.unsigned))
+                provider = select_provider(bridged, bridged_type_info)
+                provider.update()
+                bridged_summary = provider.to_string()
+                if bridged_summary is not None:
+                    return bridged_summary
+            return _objc_bridge_summary_fallback(bridged)
         return cast_value.GetValue()
 
     provider = select_provider(cast_value, type_info)
     log(lambda: "kotlin_object_type_summary({:#x} - {})".format(cast_value.unsigned, type(provider).__name__))
     provider.update()
-    return provider.to_string()
+    summary = provider.to_string()
+    if summary is None and cast_value.unsigned != 0:
+        return _objc_bridge_summary_fallback(cast_value)
+    return summary
 
 
 def kotlin_objc_class_summary(objc_obj: lldb.SBValue, internal_dict):
-    # """Hook that is run by lldb to display a Kotlin ObjC class wrapper."""
+    """Hook that is run by lldb to display a Kotlin ObjC class wrapper."""
     objc_obj = single_pointer(objc_obj)
 
     konan_obj = evaluate(
         'void* __result = 0; (ObjHeader*)Kotlin_ObjCExport_refFromObjC((void*){:#x}, &__result)',
         objc_obj.unsigned
     )
-    return kotlin_object_type_summary(konan_obj, internal_dict)
+    return kotlin_object_type_summary(konan_obj, internal_dict)