ra_ap_rustc_serialize/
int_overflow.rs

1// This would belong to `rustc_data_structures`, but `rustc_serialize` needs it too.
2
3/// Addition, but only overflow checked when `cfg(debug_assertions)` is set
4/// instead of respecting `-Coverflow-checks`.
5///
6/// This exists for performance reasons, as we ship rustc with overflow checks.
7/// While overflow checks are perf neutral in almost all of the compiler, there
8/// are a few particularly hot areas where we don't want overflow checks in our
9/// dist builds. Overflow is still a bug there, so we want overflow check for
10/// builds with debug assertions.
11///
12/// That's a long way to say that this should be used in areas where overflow
13/// is a bug but overflow checking is too slow.
14pub trait DebugStrictAdd {
15    /// See [`DebugStrictAdd`].
16    fn debug_strict_add(self, other: Self) -> Self;
17}
18
19macro_rules! impl_debug_strict_add {
20    ($( $ty:ty )*) => {
21        $(
22            impl DebugStrictAdd for $ty {
23                fn debug_strict_add(self, other: Self) -> Self {
24                    if cfg!(debug_assertions) {
25                        self + other
26                    } else {
27                        self.wrapping_add(other)
28                    }
29                }
30            }
31        )*
32    };
33}
34
35/// See [`DebugStrictAdd`].
36pub trait DebugStrictSub {
37    /// See [`DebugStrictAdd`].
38    fn debug_strict_sub(self, other: Self) -> Self;
39}
40
41macro_rules! impl_debug_strict_sub {
42    ($( $ty:ty )*) => {
43        $(
44            impl DebugStrictSub for $ty {
45                fn debug_strict_sub(self, other: Self) -> Self {
46                    if cfg!(debug_assertions) {
47                        self - other
48                    } else {
49                        self.wrapping_sub(other)
50                    }
51                }
52            }
53        )*
54    };
55}
56
57impl_debug_strict_add! {
58    u8 u16 u32 u64 u128 usize
59    i8 i16 i32 i64 i128 isize
60}
61
62impl_debug_strict_sub! {
63    u8 u16 u32 u64 u128 usize
64    i8 i16 i32 i64 i128 isize
65}
ra_ap_rustc_serialize/int_overflow.rs

ra_ap_rustc_serialize/
int_overflow.rs
