cgen: fix go call interface method (fix #10520) (#10602)

Author: yuyi98

vlib/v/gen/c/cgen.v

@@ -5935,12 +5935,29 @@ fn (mut g Gen) go_expr(node ast.GoExpr) {
 		} else {
 			g.gowrappers.write_string('\t')
 		}
-		g.gowrappers.write_string('${name}(')
 		if expr.is_method {
-			g.gowrappers.write_string('arg->arg0')
+			unwrapped_rec_type := g.unwrap_generic(expr.receiver_type)
+			typ_sym := g.table.get_type_symbol(unwrapped_rec_type)
+			if typ_sym.kind == .interface_
+				&& (typ_sym.info as ast.Interface).defines_method(expr.name) {
+				rec_cc_type := g.cc_type(unwrapped_rec_type, false)
+				receiver_type_name := util.no_dots(rec_cc_type)
+				g.gowrappers.write_string('${c_name(receiver_type_name)}_name_table[')
+				g.gowrappers.write_string('arg->arg0')
+				dot := if expr.left_type.is_ptr() { '->' } else { '.' }
+				mname := c_name(expr.name)
+				g.gowrappers.write_string('${dot}_typ]._method_${mname}(')
+				g.gowrappers.write_string('arg->arg0')
+				g.gowrappers.write_string('${dot}_object')
+			} else {
+				g.gowrappers.write_string('${name}(')
+				g.gowrappers.write_string('arg->arg0')
+			}
 			if expr.args.len > 0 {
 				g.gowrappers.write_string(', ')
 			}
+		} else {
+			g.gowrappers.write_string('${name}(')
 		}
 		if expr.args.len > 0 {
 			mut has_cast := false

vlib/v/tests/go_call_interface_method_test.v

@@ -0,0 +1,28 @@
+interface CanPerformTask {
+	task()
+}
+
+struct Task1 {}
+
+fn (task1 Task1) task() {
+	println('task1')
+}
+
+struct Task2 {}
+
+fn (task2 Task2) task() {
+	println('task2')
+}
+
+fn test_go_call_interface_method() {
+	mut tasks := []CanPerformTask{}
+
+	tasks << Task1{}
+	tasks << Task2{}
+
+	for task in tasks {
+		go task.task()
+	}
+
+	assert true
+}