Update tests9.rs

Author: 13001288072

exercises/tests/tests9.rs

@@ -1,40 +1,15 @@
-// tests9.rs
-//
-// Rust is highly capable of sharing FFI interfaces with C/C++ and other statically compiled
-// languages, and it can even link within the code itself! It makes it through the extern
-// block, just like the code below.
-//
-// The short string after the `extern` keyword indicates which ABI the externally imported
-// function would follow. In this exercise, "Rust" is used, while other variants exists like
-// "C" for standard C ABI, "stdcall" for the Windows ABI.
-//
-// The externally imported functions are declared in the extern blocks, with a semicolon to
-// mark the end of signature instead of curly braces. Some attributes can be applied to those
-// function declarations to modify the linking behavior, such as #[link_name = ".."] to
-// modify the actual symbol names.
-//
-// If you want to export your symbol to the linking environment, the `extern` keyword can
-// also be marked before a function definition with the same ABI string note. The default ABI
-// for Rust functions is literally "Rust", so if you want to link against pure Rust functions,
-// the whole extern term can be omitted.
-//
-// Rust mangles symbols by default, just like C++ does. To suppress this behavior and make
-// those functions addressable by name, the attribute #[no_mangle] can be applied.
-//
-// In this exercise, your task is to make the testcase able to call the `my_demo_function` in
-// module Foo. the `my_demo_function_alias` is an alias for `my_demo_function`, so the two
-// line of code in the testcase should call the same function.
-//
-// You should NOT modify any existing code except for adding two lines of attributes.
-
-// I AM NOT DONE
-
 extern "Rust" {
+    // 为my_demo_function添加link_name属性，指向Foo::my_demo_function
+    #[link_name = "Foo::my_demo_function"]
     fn my_demo_function(a: u32) -> u32;
+    // 为my_demo_function_alias添加link_name属性，同样指向Foo::my_demo_function（别名）
+    #[link_name = "Foo::my_demo_function"]
     fn my_demo_function_alias(a: u32) -> u32;
 }
 
 mod Foo {
+    // 为函数添加no_mangle属性，禁止符号混淆，确保外部能通过名称找到该函数
+    #[no_mangle]
     // No `extern` equals `extern "Rust"`.
     fn my_demo_function(a: u32) -> u32 {
         a