1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
use autocfg::AutoCfg;
const CONST_THREAD_LOCAL_PROBE: &str = r#"
{
thread_local! {
static MY_PROBE: usize = const { 10 };
}
MY_PROBE.with(|val| *val)
}
"#;
const CONST_MUTEX_NEW_PROBE: &str = r#"
{
static MY_MUTEX: ::std::sync::Mutex<i32> = ::std::sync::Mutex::new(1);
*MY_MUTEX.lock().unwrap()
}
"#;
const AS_FD_PROBE: &str = r#"
{
#[allow(unused_imports)]
#[cfg(unix)]
use std::os::unix::prelude::AsFd as _;
#[allow(unused_imports)]
#[cfg(windows)]
use std::os::windows::prelude::AsSocket as _;
#[allow(unused_imports)]
#[cfg(target_os = "wasi")]
use std::os::wasi::prelude::AsFd as _;
}
"#;
const TARGET_HAS_ATOMIC_PROBE: &str = r#"
{
#[cfg(target_has_atomic = "ptr")]
let _ = ();
}
"#;
const TARGET_ATOMIC_U64_PROBE: &str = r#"
{
#[allow(unused_imports)]
use std::sync::atomic::AtomicU64 as _;
}
"#;
fn main() {
let mut enable_const_thread_local = false;
let mut enable_target_has_atomic = false;
let mut enable_const_mutex_new = false;
let mut enable_as_fd = false;
let mut target_needs_atomic_u64_fallback = false;
match AutoCfg::new() {
Ok(ac) => {
// These checks prefer to call only `probe_rustc_version` if that is
// enough to determine whether the feature is supported. This is
// because the `probe_expression` call involves a call to rustc,
// which the `probe_rustc_version` call avoids.
// Const-initialized thread locals were stabilized in 1.59.
if ac.probe_rustc_version(1, 60) {
enable_const_thread_local = true;
} else if ac.probe_rustc_version(1, 59) {
// This compiler claims to be 1.59, but there are some nightly
// compilers that claim to be 1.59 without supporting the
// feature. Explicitly probe to check if code using them
// compiles.
//
// The oldest nightly that supports the feature is 2021-12-06.
if ac.probe_expression(CONST_THREAD_LOCAL_PROBE) {
enable_const_thread_local = true;
}
}
// The `target_has_atomic` cfg was stabilized in 1.60.
if ac.probe_rustc_version(1, 61) {
enable_target_has_atomic = true;
} else if ac.probe_rustc_version(1, 60) {
// This compiler claims to be 1.60, but there are some nightly
// compilers that claim to be 1.60 without supporting the
// feature. Explicitly probe to check if code using them
// compiles.
//
// The oldest nightly that supports the feature is 2022-02-11.
if ac.probe_expression(TARGET_HAS_ATOMIC_PROBE) {
enable_target_has_atomic = true;
}
}
// If we can't tell using `target_has_atomic`, tell if the target
// has `AtomicU64` by trying to use it.
if !enable_target_has_atomic && !ac.probe_expression(TARGET_ATOMIC_U64_PROBE) {
target_needs_atomic_u64_fallback = true;
}
// The `Mutex::new` method was made const in 1.63.
if ac.probe_rustc_version(1, 64) {
enable_const_mutex_new = true;
} else if ac.probe_rustc_version(1, 63) {
// This compiler claims to be 1.63, but there are some nightly
// compilers that claim to be 1.63 without supporting the
// feature. Explicitly probe to check if code using them
// compiles.
//
// The oldest nightly that supports the feature is 2022-06-20.
if ac.probe_expression(CONST_MUTEX_NEW_PROBE) {
enable_const_mutex_new = true;
}
}
// The `AsFd` family of traits were made stable in 1.63.
if ac.probe_rustc_version(1, 64) {
enable_as_fd = true;
} else if ac.probe_rustc_version(1, 63) {
// This compiler claims to be 1.63, but there are some nightly
// compilers that claim to be 1.63 without supporting the
// feature. Explicitly probe to check if code using them
// compiles.
//
// The oldest nightly that supports the feature is 2022-06-16.
if ac.probe_expression(AS_FD_PROBE) {
enable_as_fd = true;
}
}
}
Err(e) => {
// If we couldn't detect the compiler version and features, just
// print a warning. This isn't a fatal error: we can still build
// Tokio, we just can't enable cfgs automatically.
println!(
"cargo:warning=tokio: failed to detect compiler features: {}",
e
);
}
}
if !enable_const_thread_local {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_const_thread_local"
autocfg::emit("tokio_no_const_thread_local")
}
if !enable_target_has_atomic {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_target_has_atomic"
autocfg::emit("tokio_no_target_has_atomic")
}
if !enable_const_mutex_new {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_const_mutex_new"
autocfg::emit("tokio_no_const_mutex_new")
}
if !enable_as_fd {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_as_fd"
autocfg::emit("tokio_no_as_fd");
}
if target_needs_atomic_u64_fallback {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_atomic_u64"
autocfg::emit("tokio_no_atomic_u64")
}
let target = ::std::env::var("TARGET").unwrap_or_default();
// We emit cfgs instead of using `target_family = "wasm"` that requires Rust 1.54.
// Note that these cfgs are unavailable in `Cargo.toml`.
if target.starts_with("wasm") {
autocfg::emit("tokio_wasm");
if target.contains("wasi") {
autocfg::emit("tokio_wasi");
} else {
autocfg::emit("tokio_wasm_not_wasi");
}
}
}
|
