From b5c7468f3a6603ee2f707417181c60a4fbd00995 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pedro=20T=C3=B4rres?= <t0rr3sp3dr0@gmail.com>
Date: Sat, 1 Jun 2024 20:20:15 -0700
Subject: [PATCH] fix: decoding struct and union fields with ambiguous types
 (#59)

---
 types/objc/type_encoding.go      |  9 +++++++++
 types/objc/type_encoding_test.go | 14 ++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/types/objc/type_encoding.go b/types/objc/type_encoding.go
index 3e64c5c..1384c11 100644
--- a/types/objc/type_encoding.go
+++ b/types/objc/type_encoding.go
@@ -446,6 +446,15 @@ func decodeStructOrUnion(typ, kind string) string {
 	field, rest, ok := CutType(rest)
 
 	for ok {
+		// Although technically possible, binaries produced by clang never have a
+		// mix of named and unnamed fields in the same struct. This assumption is
+		// necessary to disambiguate {"x0"@"x1"c}.
+		if fieldName != "" && rest != "" && strings.HasSuffix(field, `"`) && !strings.HasPrefix(rest, `"`) {
+			penultQuoteIdx := strings.LastIndex(strings.TrimRight(field, `"`), `"`)
+			rest = field[penultQuoteIdx:] + rest
+			field = field[:penultQuoteIdx]
+		}
+
 		if fieldName == "" {
 			fieldName = fmt.Sprintf("x%d", idx)
 		}
diff --git a/types/objc/type_encoding_test.go b/types/objc/type_encoding_test.go
index 01b94be..6c4f6fd 100644
--- a/types/objc/type_encoding_test.go
+++ b/types/objc/type_encoding_test.go
@@ -74,6 +74,13 @@ func Test_decodeType(t *testing.T) {
 			},
 			want: "struct __CFRuntimeBase { unsigned long long x0; _Atomic unsigned long long x1; }",
 		},
+		{
+			name: "Test struct 4",
+			args: args{
+				encType: "{__cfobservers_t=\"slot\"@\"next\"^{__cfobservers_t}}",
+			},
+			want: "struct __cfobservers_t { id slot; struct __cfobservers_t *next; }",
+		},
 		{
 			name: "Test union 0",
 			args: args{
@@ -95,6 +102,13 @@ func Test_decodeType(t *testing.T) {
 			},
 			want: "void * /* union */",
 		},
+		{
+			name: "Test union 3",
+			args: args{
+				encType: "(?=\"xpc\"@\"NSObject<OS_xpc_object>\"\"remote\"@\"OS_xpc_remote_connection\")",
+			},
+			want: "union { NSObject<OS_xpc_object> *xpc; OS_xpc_remote_connection *remote; }",
+		},
 		{
 			name: "Test block",
 			args: args{