[lldb] Fix AppleObjCDeclVendor for classes which have no methods (llvm#145452)

Fix the rare case where an ObjC class has ivars but no methods. The fix is to not early
return when a class has no method list.

Author: kastiglione

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp

@@ -552,9 +552,8 @@ bool ClassDescriptorV2::Describe(
     } else {
       std::optional<method_list_t> base_method_list =
           GetMethodList(process, class_ro->m_baseMethods_ptr);
-      if (!base_method_list)
-        return false;
-      if (!ProcessMethodList(instance_method_func, *base_method_list))
+      if (base_method_list &&
+          !ProcessMethodList(instance_method_func, *base_method_list))
         return false;
     }
   }

lldb/test/API/lang/objc/class-without-methods/Makefile

@@ -0,0 +1,5 @@
+OBJC_SOURCES := Point.m main.m
+include Makefile.rules
+
+# Only objc metadata, no debug info, for Point.m
+Point.o: CFLAGS_EXTRAS += -g0

lldb/test/API/lang/objc/class-without-methods/Point.h

@@ -0,0 +1,4 @@
+#import <objc/NSObject.h>
+
+@interface Point : NSObject
+@end

lldb/test/API/lang/objc/class-without-methods/Point.m

@@ -0,0 +1,7 @@
+#import "Point.h"
+
+@implementation Point {
+  float _x;
+  float _y;
+}
+@end

lldb/test/API/lang/objc/class-without-methods/TestObjCClassWithoutMethods.py

@@ -0,0 +1,11 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.m"))
+        self.expect("frame var -P1 p", substrs=["_x = 0", "_y = 0"])

lldb/test/API/lang/objc/class-without-methods/main.m

@@ -0,0 +1,7 @@
+#import "Point.h"
+
+int main() {
+  Point *p = [Point new];
+  // break here
+  return 0;
+}