[update]Fix compilation warnings.

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[0x822a5b87]

This repository contains some trivial warnings (such as unused import and mutable reference to a mutable static), which continuously output warning messages that obscure the actual logs. This PR resolves these annoying warnings.

unused import

 --> src/bin/ch7b_pipe_large_test.rs:10:29
|
10 | use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};

mutable reference to mutable static

 --> src/bin/ch8b_race_adder_mutex_spin.rs:20:17
|
20 | let a = &mut A as *mut usize;
| ^^^^^^ mutable reference to mutable static

unsupported in naked functions

 --> src/bin/ch8b_stackful_coroutine.rs:259:1
|
259 | unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^