blob: 9e37120bc69c20c056851c1977de3dc80120823b (
plain)
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
|
// SPDX-License-Identifier: GPL-2.0
//! Build-time assert.
/// Fails the build if the code path calling `build_error!` can possibly be executed.
///
/// If the macro is executed in const context, `build_error!` will panic.
/// If the compiler or optimizer cannot guarantee that `build_error!` can never
/// be called, a build error will be triggered.
///
/// # Examples
///
/// ```
/// # use kernel::build_error;
/// #[inline]
/// fn foo(a: usize) -> usize {
/// a.checked_add(1).unwrap_or_else(|| build_error!("overflow"))
/// }
///
/// assert_eq!(foo(usize::MAX - 1), usize::MAX); // OK.
/// // foo(usize::MAX); // Fails to compile.
/// ```
#[macro_export]
macro_rules! build_error {
() => {{
$crate::build_error("")
}};
($msg:expr) => {{
$crate::build_error($msg)
}};
}
/// Asserts that a boolean expression is `true` at compile time.
///
/// If the condition is evaluated to `false` in const context, `build_assert!`
/// will panic. If the compiler or optimizer cannot guarantee the condition will
/// be evaluated to `true`, a build error will be triggered.
///
/// [`static_assert!`] should be preferred to `build_assert!` whenever possible.
///
/// # Examples
///
/// These examples show that different types of [`assert!`] will trigger errors
/// at different stage of compilation. It is preferred to err as early as
/// possible, so [`static_assert!`] should be used whenever possible.
/// ```ignore
/// fn foo() {
/// static_assert!(1 > 1); // Compile-time error
/// build_assert!(1 > 1); // Build-time error
/// assert!(1 > 1); // Run-time error
/// }
/// ```
///
/// When the condition refers to generic parameters or parameters of an inline function,
/// [`static_assert!`] cannot be used. Use `build_assert!` in this scenario.
/// ```
/// fn foo<const N: usize>() {
/// // `static_assert!(N > 1);` is not allowed
/// build_assert!(N > 1); // Build-time check
/// assert!(N > 1); // Run-time check
/// }
///
/// #[inline]
/// fn bar(n: usize) {
/// // `static_assert!(n > 1);` is not allowed
/// build_assert!(n > 1); // Build-time check
/// assert!(n > 1); // Run-time check
/// }
/// ```
///
/// [`static_assert!`]: crate::static_assert!
#[macro_export]
macro_rules! build_assert {
($cond:expr $(,)?) => {{
if !$cond {
$crate::build_error(concat!("assertion failed: ", stringify!($cond)));
}
}};
($cond:expr, $msg:expr) => {{
if !$cond {
$crate::build_error($msg);
}
}};
}
|
