[mono] Support array parameter types of custom attributes in Mono AOT compiler (#69759)

- mono_reflection_create_custom_attr_data_args_noalloc now supports decoding array type parameters of custom attributes
- mono_reflection_create_custom_attr_data_args_noalloc is refactored to use MonoDecodeCustomAttr 
- MonoDecodeCustomAttr encapsulates all the information of the decoded custom attribute parameters
- initial support for UnmanagedCallConvAttribute: native-to-managed wrapper generation now takes into account applied custom attributes by updating the method's signature

Fixes [#52977](#52977)

Author: ivanpovazan

src/mono/mono/component/debugger-agent.c

@@ -2944,21 +2944,14 @@ static gint32 isFixedSizeArray (MonoClassField *f)
 			MonoClass *fixed_size_class = mono_class_try_get_fixed_buffer_class ();
 			if (fixed_size_class != NULL && mono_class_has_parent (ctor_class, fixed_size_class)) {
 				attr = &cinfo->attrs [aindex];
-				gpointer *typed_args, *named_args;
-				CattrNamedArg *arginfo;
-				int num_named_args;
-
-				mono_reflection_create_custom_attr_data_args_noalloc (mono_get_corlib (), attr->ctor, attr->data, attr->data_size,
-																	&typed_args, &named_args, &num_named_args, &arginfo, error);
+				MonoDecodeCustomAttr *decoded_args = mono_reflection_create_custom_attr_data_args_noalloc (mono_get_corlib (), attr->ctor, attr->data, attr->data_size, error);
 				if (!is_ok (error)) {
 					ret = 0;
 					goto leave;
 				}
-				ret = *(gint32*)typed_args [1];
-				g_free (typed_args [1]);
-				g_free (typed_args);
-				g_free (named_args);
-				g_free (arginfo);
+
+				ret = *(gint32*)decoded_args->typed_args[1]->value.primitive;
+				mono_reflection_free_custom_attr_data_args_noalloc (decoded_args);
 				return ret;
 			}
 		}

src/mono/mono/metadata/custom-attrs-internals.h

@@ -9,6 +9,29 @@
 #include <mono/metadata/object-internals.h>
 #include <mono/metadata/reflection.h>
 
+typedef struct _MonoCustomAttrValueArray MonoCustomAttrValueArray;
+
+typedef struct _MonoCustomAttrValue {
+	union {
+		gpointer primitive; /* int/enum/MonoType/string */
+		MonoCustomAttrValueArray *array;
+	} value;
+	MonoTypeEnum type : 8;
+} MonoCustomAttrValue;
+
+struct _MonoCustomAttrValueArray {
+	int len;
+	MonoCustomAttrValue values[MONO_ZERO_LEN_ARRAY];
+};
+
+typedef struct _MonoDecodeCustomAttr {
+	int typed_args_num;
+	int named_args_num;
+	MonoCustomAttrValue **typed_args;
+	MonoCustomAttrValue **named_args;
+	CattrNamedArg *named_args_info;
+} MonoDecodeCustomAttr;
+
 MonoCustomAttrInfo*
 mono_custom_attrs_from_builders (MonoImage *alloc_img, MonoImage *image, MonoArray *cattrs);
 
@@ -33,8 +56,9 @@ MONO_COMPONENT_API void
 mono_reflection_create_custom_attr_data_args (MonoImage *image, MonoMethod *method, const guchar *data, guint32 len, MonoArrayHandleOut typed_args_out, MonoArrayHandleOut named_args_out, CattrNamedArg **named_arg_info, MonoError *error);
 
 MONO_COMPONENT_API void
-mono_reflection_create_custom_attr_data_args_noalloc (MonoImage *image, MonoMethod *method, const guchar *data, guint32 len,
-													  gpointer **typed_args_out, gpointer **named_args_out, int *num_named_args,
-													  CattrNamedArg **named_arg_info, MonoError *error);
+mono_reflection_free_custom_attr_data_args_noalloc(MonoDecodeCustomAttr* decoded_args);
+
+MONO_COMPONENT_API MonoDecodeCustomAttr*
+mono_reflection_create_custom_attr_data_args_noalloc (MonoImage *image, MonoMethod *method, const guchar *data, guint32 len, MonoError *error);
 
 #endif  /* __MONO_METADATA_REFLECTION_CUSTOM_ATTRS_INTERNALS_H__ */