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Make overflowing and wrapping negation const #58044

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Merged
merged 6 commits into from
Feb 20, 2019
Merged

Make overflowing and wrapping negation const #58044

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2f5d245
Make overflowing and wrapping negation const
Lokathor Feb 1, 2019
26a3540
Don't know why I wasn't using `self` properly there
Lokathor Feb 1, 2019
481b354
Simplify the overflowing_neg expression
Lokathor Feb 2, 2019
5256efb
const-int-overflowing.rs += overflowing_neg
Lokathor Feb 2, 2019
31bf7e1
const-int-wrapping.rs += wrapping_neg
Lokathor Feb 2, 2019
e06302f
fix the build errors
Lokathor Feb 2, 2019
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14 changes: 5 additions & 9 deletions src/libcore/num/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1175,7 +1175,7 @@ $EndFeature, "
```"),
#[stable(feature = "num_wrapping", since = "1.2.0")]
#[inline]
pub fn wrapping_neg(self) -> Self {
pub const fn wrapping_neg(self) -> Self {
self.overflowing_neg().0
}
}
Expand Down Expand Up @@ -1529,12 +1529,8 @@ assert_eq!(", stringify!($SelfT), "::MIN.overflowing_neg(), (", stringify!($Self
```"),
#[inline]
#[stable(feature = "wrapping", since = "1.7.0")]
pub fn overflowing_neg(self) -> (Self, bool) {
if self == Self::min_value() {
(Self::min_value(), true)
} else {
(-self, false)
}
pub const fn overflowing_neg(self) -> (Self, bool) {
((!self).wrapping_add(1), self == Self::min_value())
}
}

Expand Down Expand Up @@ -3017,7 +3013,7 @@ assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);
/// ```
#[stable(feature = "num_wrapping", since = "1.2.0")]
#[inline]
pub fn wrapping_neg(self) -> Self {
pub const fn wrapping_neg(self) -> Self {
self.overflowing_neg().0
}

Expand Down Expand Up @@ -3322,7 +3318,7 @@ assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!(
```"),
#[inline]
#[stable(feature = "wrapping", since = "1.7.0")]
pub fn overflowing_neg(self) -> (Self, bool) {
pub const fn overflowing_neg(self) -> (Self, bool) {
((!self).wrapping_add(1), self != 0)
}
}
Expand Down
6 changes: 6 additions & 0 deletions src/test/run-pass/const-int-overflowing.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@ const SHL_B: (u32, bool) = 0x1u32.overflowing_shl(132);
const SHR_A: (u32, bool) = 0x10u32.overflowing_shr(4);
const SHR_B: (u32, bool) = 0x10u32.overflowing_shr(132);

const NEG_A: (u32, bool) = 0u32.overflowing_neg();
const NEG_B: (u32, bool) = core::u32::MAX.overflowing_neg();

fn ident<T>(ident: T) -> T {
ident
}
Expand All @@ -32,4 +35,7 @@ fn main() {

assert_eq!(SHR_A, ident((0x1, false)));
assert_eq!(SHR_B, ident((0x1, true)));

assert_eq!(NEG_A, ident((0, false)));
assert_eq!(NEG_B, ident((1, true)));
}
6 changes: 6 additions & 0 deletions src/test/run-pass/const-int-wrapping.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@ const SHL_B: u32 = 1u32.wrapping_shl(128);
const SHR_A: u32 = 128u32.wrapping_shr(7);
const SHR_B: u32 = 128u32.wrapping_shr(128);

const NEG_A: u32 = 5u32.wrapping_neg();
const NEG_B: u32 = 1234567890u32.wrapping_neg();

fn ident<T>(ident: T) -> T {
ident
}
Expand All @@ -32,4 +35,7 @@ fn main() {

assert_eq!(SHR_A, ident(1));
assert_eq!(SHR_B, ident(128));

assert_eq!(NEG_A, ident(4294967291));
assert_eq!(NEG_B, ident(3060399406));
}