From 29b4a4cbe337b91f0543dc919f4a43e3783e89f2 Mon Sep 17 00:00:00 2001
From: Mark Rowe <mrowe@bdash.net.nz>
Date: Sun, 6 Apr 2025 21:34:12 -0700
Subject: [PATCH] [ObjC] Handle Objective-C ivars with an offset of 0

objc-runtime-new.mm mentions an offset of 0 is used for anonymous
bitfields.

Previously this would throw an exception when attempting to read from
offset 0 and the types would not be applied.
---
 objectivec/objc.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/objectivec/objc.cpp b/objectivec/objc.cpp
index 7d11045052..9bdd61c3c6 100644
--- a/objectivec/objc.cpp
+++ b/objectivec/objc.cpp
@@ -936,8 +936,17 @@ void ObjCProcessor::ReadIvarList(ObjCReader* reader, ClassBase& cls, std::string
 			ivarStruct.alignmentRaw = reader->Read32();
 			ivarStruct.size = reader->Read32();
 
-			reader->Seek(ivarStruct.offset);
-			ivar.offset = reader->Read32();
+			if (ivarStruct.offset)
+			{
+				reader->Seek(ivarStruct.offset);
+				ivar.offset = reader->Read32();
+			}
+			else
+			{
+				// `offset` can be 0 if the ivar is an anonymous bitfield.
+				ivar.offset = 0;
+			}
+
 			reader->Seek(ivarStruct.name);
 			ivar.name = reader->ReadCString();
 			reader->Seek(ivarStruct.type);