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Make all methods of std::net::Ipv6Addr const #76206

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merged 4 commits into from
Sep 2, 2020
Merged

Make all methods of std::net::Ipv6Addr const #76206

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b31cc8f
Make all methods of `std::net::Ipv6Addr` const
Sep 1, 2020
cd08def
Add test for `Ipv6Addr` methods in a const context
Sep 1, 2020
a43dd4f
Change implementation of `Ipv6Addr::is_unspecified` and `is_loopback`…
Sep 1, 2020
9afe97c
Add trailing newline to `ipv6.rs`
CDirkx Sep 1, 2020
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1 change: 1 addition & 0 deletions library/std/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,6 +238,7 @@
#![feature(concat_idents)]
#![feature(const_cstr_unchecked)]
#![feature(const_fn_transmute)]
#![feature(const_ipv6)]
#![feature(const_raw_ptr_deref)]
#![feature(container_error_extra)]
#![feature(core_intrinsics)]
Expand Down
46 changes: 30 additions & 16 deletions library/std/src/net/ip.rs
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Expand Up @@ -1102,8 +1102,9 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).segments(),
/// [0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff]);
/// ```
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn segments(&self) -> [u16; 8] {
pub const fn segments(&self) -> [u16; 8] {
// All elements in `s6_addr` must be big endian.
// SAFETY: `[u8; 16]` is always safe to transmute to `[u16; 8]`.
let [a, b, c, d, e, f, g, h] = unsafe { transmute::<_, [u16; 8]>(self.inner.s6_addr) };
Expand Down Expand Up @@ -1135,9 +1136,10 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unspecified(), false);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0).is_unspecified(), true);
/// ```
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[stable(since = "1.7.0", feature = "ip_17")]
pub fn is_unspecified(&self) -> bool {
self.segments() == [0, 0, 0, 0, 0, 0, 0, 0]
pub const fn is_unspecified(&self) -> bool {
matches!(self.segments(), [0, 0, 0, 0, 0, 0, 0, 0])
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@ecstatic-morse ecstatic-morse Sep 1, 2020 •
edited
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As a general rule, matches! won't optimize as well as comparison to an array. I don't think the performance of is_unspecified and is_loopback is terribly important for real code, so this is fine for now. It would be good to look into constifying slice equality, making memcmp callable in a const context, or generating better code for array patterns in match statements.

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Yeah, which is a shame. I was looking into this for the Ipv4Addr methods as well, most of which can be written very elegantly using matches!. If performance is a concern, the same implementation could be used as in Ipv4Addr::is_global:

u128::from_be_bytes(self.octets()) == 0

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@ecstatic-morse ecstatic-morse Sep 1, 2020 •
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Yeah, let's do it that way. Instead of comparing with an integer literal, however, you should convert the LOOPBACK and UNSPECIFIED associated constants to a u128 and compare with those.

}

/// Returns [`true`] if this is a loopback address (::1).
Expand All @@ -1155,9 +1157,10 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_loopback(), false);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1).is_loopback(), true);
/// ```
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[stable(since = "1.7.0", feature = "ip_17")]
pub fn is_loopback(&self) -> bool {
self.segments() == [0, 0, 0, 0, 0, 0, 0, 1]
pub const fn is_loopback(&self) -> bool {
matches!(self.segments(), [0, 0, 0, 0, 0, 0, 0, 1])
}

/// Returns [`true`] if the address appears to be globally routable.
Expand All @@ -1182,7 +1185,8 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1).is_global(), false);
/// assert_eq!(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1).is_global(), true);
/// ```
pub fn is_global(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_global(&self) -> bool {
match self.multicast_scope() {
Some(Ipv6MulticastScope::Global) => true,
None => self.is_unicast_global(),
Expand All @@ -1208,7 +1212,8 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unique_local(), false);
/// assert_eq!(Ipv6Addr::new(0xfc02, 0, 0, 0, 0, 0, 0, 0).is_unique_local(), true);
/// ```
pub fn is_unique_local(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_unique_local(&self) -> bool {
(self.segments()[0] & 0xfe00) == 0xfc00
}

Expand Down Expand Up @@ -1263,7 +1268,8 @@ impl Ipv6Addr {
/// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
/// [IETF RFC 4291 section 2.5.6]: https://tools.ietf.org/html/rfc4291#section-2.5.6
/// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
pub fn is_unicast_link_local_strict(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_unicast_link_local_strict(&self) -> bool {
(self.segments()[0] & 0xffff) == 0xfe80
&& (self.segments()[1] & 0xffff) == 0
&& (self.segments()[2] & 0xffff) == 0
Expand Down Expand Up @@ -1320,7 +1326,8 @@ impl Ipv6Addr {
///
/// [IETF RFC 4291 section 2.4]: https://tools.ietf.org/html/rfc4291#section-2.4
/// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
pub fn is_unicast_link_local(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_unicast_link_local(&self) -> bool {
(self.segments()[0] & 0xffc0) == 0xfe80
}

Expand Down Expand Up @@ -1359,7 +1366,8 @@ impl Ipv6Addr {
/// addresses.
///
/// [RFC 3879]: https://tools.ietf.org/html/rfc3879
pub fn is_unicast_site_local(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_unicast_site_local(&self) -> bool {
(self.segments()[0] & 0xffc0) == 0xfec0
}

Expand All @@ -1381,7 +1389,8 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_documentation(), false);
/// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_documentation(), true);
/// ```
pub fn is_documentation(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_documentation(&self) -> bool {
(self.segments()[0] == 0x2001) && (self.segments()[1] == 0xdb8)
}

Expand Down Expand Up @@ -1416,7 +1425,8 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast_global(), false);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unicast_global(), true);
/// ```
pub fn is_unicast_global(&self) -> bool {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn is_unicast_global(&self) -> bool {
!self.is_multicast()
&& !self.is_loopback()
&& !self.is_unicast_link_local()
Expand All @@ -1440,7 +1450,8 @@ impl Ipv6Addr {
/// );
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).multicast_scope(), None);
/// ```
pub fn multicast_scope(&self) -> Option<Ipv6MulticastScope> {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn multicast_scope(&self) -> Option<Ipv6MulticastScope> {
if self.is_multicast() {
match self.segments()[0] & 0x000f {
1 => Some(Ipv6MulticastScope::InterfaceLocal),
Expand Down Expand Up @@ -1472,8 +1483,9 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).is_multicast(), true);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_multicast(), false);
/// ```
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[stable(since = "1.7.0", feature = "ip_17")]
pub fn is_multicast(&self) -> bool {
pub const fn is_multicast(&self) -> bool {
(self.segments()[0] & 0xff00) == 0xff00
}

Expand All @@ -1498,7 +1510,8 @@ impl Ipv6Addr {
/// Some(Ipv4Addr::new(192, 10, 2, 255)));
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4_mapped(), None);
/// ```
pub fn to_ipv4_mapped(&self) -> Option<Ipv4Addr> {
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
pub const fn to_ipv4_mapped(&self) -> Option<Ipv4Addr> {
match self.octets() {
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, a, b, c, d] => {
Some(Ipv4Addr::new(a, b, c, d))
Expand All @@ -1525,8 +1538,9 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4(),
/// Some(Ipv4Addr::new(0, 0, 0, 1)));
/// ```
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn to_ipv4(&self) -> Option<Ipv4Addr> {
pub const fn to_ipv4(&self) -> Option<Ipv4Addr> {
if let [0, 0, 0, 0, 0, 0 | 0xffff, ab, cd] = self.segments() {
let [a, b] = ab.to_be_bytes();
let [c, d] = cd.to_be_bytes();
Expand Down