Use mono_mb_emit_op for CEE_LDOBJ to ensure wrapper data is added for indirect load of a ref return value. (case 1096820)

Author: joncham

mcs/class/Mono.Debugger.Soft/Test/dtest-app.cs

@@ -1755,6 +1755,11 @@ public static ref int get_ref_int() {
 	public static ref string get_ref_string() {
 		return ref ref_return_string;
 	}
+
+	static BlittableStruct ref_return_struct = new BlittableStruct () { i = 1, d = 2.0 };
+	public static ref BlittableStruct get_ref_struct () {
+		return ref ref_return_struct;
+	}
 }
 
 public class SentinelClass : MarshalByRefObject {

mcs/class/Mono.Debugger.Soft/Test/dtest.cs

@@ -4423,6 +4423,13 @@ public void InvokeRefReturnMethod () {
 		m = t.GetMethod ("get_ref_string");
 		v = t.InvokeMethod (e.Thread, m, null);
 		AssertValue ("byref", v);
+
+		m = t.GetMethod ("get_ref_struct");
+		v = t.InvokeMethod (e.Thread, m, null);
+		Assert.IsTrue(v is StructMirror);
+ 		var mirror = (StructMirror)v;
+		AssertValue (1, mirror["i"]);
+		AssertValue (2.0, mirror["d"]);
 	}
 } // class DebuggerTests
 } // namespace

mono/metadata/marshal.c

@@ -4148,10 +4148,18 @@ emit_invoke_call (MonoMethodBuilder *mb, MonoMethod *method,
 	}
 
 	if (sig->ret->byref) {
+		int ldind_op;
 		/* perform indirect load and return by value */
 		MonoType* ret_byval = &mono_class_from_mono_type (sig->ret)->byval_arg;
 		g_assert (!ret_byval->byref);
-		mono_mb_emit_byte (mb, mono_type_to_ldind (ret_byval));
+		ldind_op = mono_type_to_ldind (ret_byval);
+		/* taken from similar code in mini-generic-sharing.c
+		 * we need to use mono_mb_emit_op to add method data when loading
+		 * a structure since method-to-ir needs this data for wrapper methods */
+		if (ldind_op == CEE_LDOBJ)
+			mono_mb_emit_op (mb, CEE_LDOBJ, mono_class_from_mono_type (ret_byval));
+		else
+			mono_mb_emit_byte (mb, ldind_op);
 	}
 
 	switch (sig->ret->type) {