Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

13 files changed, 2252 insertions, 0 deletions

diff --git a/third_party/rust/time/src/format_description/borrowed_format_item.rs b/third_party/rust/time/src/format_description/borrowed_format_item.rs
new file mode 100644
index 0000000000..425b902878
--- /dev/null
+++ b/third_party/rust/time/src/format_description/borrowed_format_item.rs
@@ -0,0 +1,106 @@
+//! A format item with borrowed data.
+
+#[cfg(feature = "alloc")]
+use alloc::string::String;
+#[cfg(feature = "alloc")]
+use core::fmt;
+
+use crate::error;
+use crate::format_description::Component;
+
+/// A complete description of how to format and parse a type.
+#[non_exhaustive]
+#[cfg_attr(not(feature = "alloc"), derive(Debug))]
+#[derive(Clone, PartialEq, Eq)]
+pub enum BorrowedFormatItem<'a> {
+    /// Bytes that are formatted as-is.
+    ///
+    /// **Note**: If you call the `format` method that returns a `String`, these bytes will be
+    /// passed through `String::from_utf8_lossy`.
+    Literal(&'a [u8]),
+    /// A minimal representation of a single non-literal item.
+    Component(Component),
+    /// A series of literals or components that collectively form a partial or complete
+    /// description.
+    Compound(&'a [Self]),
+    /// A `FormatItem` that may or may not be present when parsing. If parsing fails, there
+    /// will be no effect on the resulting `struct`.
+    ///
+    /// This variant has no effect on formatting, as the value is guaranteed to be present.
+    Optional(&'a Self),
+    /// A series of `FormatItem`s where, when parsing, the first successful parse is used. When
+    /// formatting, the first element of the slice is used.  An empty slice is a no-op when
+    /// formatting or parsing.
+    First(&'a [Self]),
+}
+
+#[cfg(feature = "alloc")]
+impl fmt::Debug for BorrowedFormatItem<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Literal(literal) => f.write_str(&String::from_utf8_lossy(literal)),
+            Self::Component(component) => component.fmt(f),
+            Self::Compound(compound) => compound.fmt(f),
+            Self::Optional(item) => f.debug_tuple("Optional").field(item).finish(),
+            Self::First(items) => f.debug_tuple("First").field(items).finish(),
+        }
+    }
+}
+
+impl From<Component> for BorrowedFormatItem<'_> {
+    fn from(component: Component) -> Self {
+        Self::Component(component)
+    }
+}
+
+impl TryFrom<BorrowedFormatItem<'_>> for Component {
+    type Error = error::DifferentVariant;
+
+    fn try_from(value: BorrowedFormatItem<'_>) -> Result<Self, Self::Error> {
+        match value {
+            BorrowedFormatItem::Component(component) => Ok(component),
+            _ => Err(error::DifferentVariant),
+        }
+    }
+}
+
+impl<'a> From<&'a [BorrowedFormatItem<'_>]> for BorrowedFormatItem<'a> {
+    fn from(items: &'a [BorrowedFormatItem<'_>]) -> Self {
+        Self::Compound(items)
+    }
+}
+
+impl<'a> TryFrom<BorrowedFormatItem<'a>> for &[BorrowedFormatItem<'a>] {
+    type Error = error::DifferentVariant;
+
+    fn try_from(value: BorrowedFormatItem<'a>) -> Result<Self, Self::Error> {
+        match value {
+            BorrowedFormatItem::Compound(items) => Ok(items),
+            _ => Err(error::DifferentVariant),
+        }
+    }
+}
+
+impl PartialEq<Component> for BorrowedFormatItem<'_> {
+    fn eq(&self, rhs: &Component) -> bool {
+        matches!(self, Self::Component(component) if component == rhs)
+    }
+}
+
+impl PartialEq<BorrowedFormatItem<'_>> for Component {
+    fn eq(&self, rhs: &BorrowedFormatItem<'_>) -> bool {
+        rhs == self
+    }
+}
+
+impl PartialEq<&[Self]> for BorrowedFormatItem<'_> {
+    fn eq(&self, rhs: &&[Self]) -> bool {
+        matches!(self, Self::Compound(compound) if compound == rhs)
+    }
+}
+
+impl PartialEq<BorrowedFormatItem<'_>> for &[BorrowedFormatItem<'_>] {
+    fn eq(&self, rhs: &BorrowedFormatItem<'_>) -> bool {
+        rhs == self
+    }
+}
diff --git a/third_party/rust/time/src/format_description/component.rs b/third_party/rust/time/src/format_description/component.rs
new file mode 100644
index 0000000000..68d162e260
--- /dev/null
+++ b/third_party/rust/time/src/format_description/component.rs
@@ -0,0 +1,37 @@
+//! Part of a format description.
+
+use crate::format_description::modifier;
+
+/// A component of a larger format description.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Component {
+    /// Day of the month.
+    Day(modifier::Day),
+    /// Month of the year.
+    Month(modifier::Month),
+    /// Ordinal day of the year.
+    Ordinal(modifier::Ordinal),
+    /// Day of the week.
+    Weekday(modifier::Weekday),
+    /// Week within the year.
+    WeekNumber(modifier::WeekNumber),
+    /// Year of the date.
+    Year(modifier::Year),
+    /// Hour of the day.
+    Hour(modifier::Hour),
+    /// Minute within the hour.
+    Minute(modifier::Minute),
+    /// AM/PM part of the time.
+    Period(modifier::Period),
+    /// Second within the minute.
+    Second(modifier::Second),
+    /// Subsecond within the second.
+    Subsecond(modifier::Subsecond),
+    /// Hour of the UTC offset.
+    OffsetHour(modifier::OffsetHour),
+    /// Minute within the hour of the UTC offset.
+    OffsetMinute(modifier::OffsetMinute),
+    /// Second within the minute of the UTC offset.
+    OffsetSecond(modifier::OffsetSecond),
+}
diff --git a/third_party/rust/time/src/format_description/mod.rs b/third_party/rust/time/src/format_description/mod.rs
new file mode 100644
index 0000000000..7712288e74
--- /dev/null
+++ b/third_party/rust/time/src/format_description/mod.rs
@@ -0,0 +1,34 @@
+//! Description of how types should be formatted and parsed.
+//!
+//! The formatted value will be output to the provided writer. Format descriptions can be
+//! [well-known](crate::format_description::well_known) or obtained by using the
+//! [`format_description!`](crate::macros::format_description) macro, the
+//! [`format_description::parse`](crate::format_description::parse()) function.
+
+mod borrowed_format_item;
+mod component;
+pub mod modifier;
+#[cfg(feature = "alloc")]
+mod owned_format_item;
+#[cfg(feature = "alloc")]
+mod parse;
+
+pub use borrowed_format_item::BorrowedFormatItem as FormatItem;
+#[cfg(feature = "alloc")]
+pub use owned_format_item::OwnedFormatItem;
+
+pub use self::component::Component;
+#[cfg(feature = "alloc")]
+pub use self::parse::{parse, parse_owned};
+
+/// Well-known formats, typically standards.
+pub mod well_known {
+    pub mod iso8601;
+    mod rfc2822;
+    mod rfc3339;
+
+    #[doc(inline)]
+    pub use iso8601::Iso8601;
+    pub use rfc2822::Rfc2822;
+    pub use rfc3339::Rfc3339;
+}
diff --git a/third_party/rust/time/src/format_description/modifier.rs b/third_party/rust/time/src/format_description/modifier.rs
new file mode 100644
index 0000000000..e01c18fda4
--- /dev/null
+++ b/third_party/rust/time/src/format_description/modifier.rs
@@ -0,0 +1,355 @@
+//! Various modifiers for components.
+
+// region: date modifiers
+/// Day of the month.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Day {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// The representation of a month.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MonthRepr {
+    /// The number of the month (January is 1, December is 12).
+    Numerical,
+    /// The long form of the month name (e.g. "January").
+    Long,
+    /// The short form of the month name (e.g. "Jan").
+    Short,
+}
+
+/// Month of the year.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Month {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+    /// What form of representation should be used?
+    pub repr: MonthRepr,
+    /// Is the value case sensitive when parsing?
+    pub case_sensitive: bool,
+}
+
+/// Ordinal day of the year.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Ordinal {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// The representation used for the day of the week.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum WeekdayRepr {
+    /// The short form of the weekday (e.g. "Mon").
+    Short,
+    /// The long form of the weekday (e.g. "Monday").
+    Long,
+    /// A numerical representation using Sunday as the first day of the week.
+    ///
+    /// Sunday is either 0 or 1, depending on the other modifier's value.
+    Sunday,
+    /// A numerical representation using Monday as the first day of the week.
+    ///
+    /// Monday is either 0 or 1, depending on the other modifier's value.
+    Monday,
+}
+
+/// Day of the week.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Weekday {
+    /// What form of representation should be used?
+    pub repr: WeekdayRepr,
+    /// When using a numerical representation, should it be zero or one-indexed?
+    pub one_indexed: bool,
+    /// Is the value case sensitive when parsing?
+    pub case_sensitive: bool,
+}
+
+/// The representation used for the week number.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum WeekNumberRepr {
+    /// Week 1 is the week that contains January 4.
+    Iso,
+    /// Week 1 begins on the first Sunday of the calendar year.
+    Sunday,
+    /// Week 1 begins on the first Monday of the calendar year.
+    Monday,
+}
+
+/// Week within the year.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct WeekNumber {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+    /// What kind of representation should be used?
+    pub repr: WeekNumberRepr,
+}
+
+/// The representation used for a year value.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum YearRepr {
+    /// The full value of the year.
+    Full,
+    /// Only the last two digits of the year.
+    LastTwo,
+}
+
+/// Year of the date.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Year {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+    /// What kind of representation should be used?
+    pub repr: YearRepr,
+    /// Whether the value is based on the ISO week number or the Gregorian calendar.
+    pub iso_week_based: bool,
+    /// Whether the `+` sign is present when a positive year contains fewer than five digits.
+    pub sign_is_mandatory: bool,
+}
+// endregion date modifiers
+
+// region: time modifiers
+/// Hour of the day.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Hour {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+    /// Is the hour displayed using a 12 or 24-hour clock?
+    pub is_12_hour_clock: bool,
+}
+
+/// Minute within the hour.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Minute {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// AM/PM part of the time.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Period {
+    /// Is the period uppercase or lowercase?
+    pub is_uppercase: bool,
+    /// Is the value case sensitive when parsing?
+    ///
+    /// Note that when `false`, the `is_uppercase` field has no effect on parsing behavior.
+    pub case_sensitive: bool,
+}
+
+/// Second within the minute.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Second {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// The number of digits present in a subsecond representation.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SubsecondDigits {
+    /// Exactly one digit.
+    One,
+    /// Exactly two digits.
+    Two,
+    /// Exactly three digits.
+    Three,
+    /// Exactly four digits.
+    Four,
+    /// Exactly five digits.
+    Five,
+    /// Exactly six digits.
+    Six,
+    /// Exactly seven digits.
+    Seven,
+    /// Exactly eight digits.
+    Eight,
+    /// Exactly nine digits.
+    Nine,
+    /// Any number of digits (up to nine) that is at least one. When formatting, the minimum digits
+    /// necessary will be used.
+    OneOrMore,
+}
+
+/// Subsecond within the second.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Subsecond {
+    /// How many digits are present in the component?
+    pub digits: SubsecondDigits,
+}
+// endregion time modifiers
+
+// region: offset modifiers
+/// Hour of the UTC offset.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OffsetHour {
+    /// Whether the `+` sign is present on positive values.
+    pub sign_is_mandatory: bool,
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// Minute within the hour of the UTC offset.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OffsetMinute {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+
+/// Second within the minute of the UTC offset.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OffsetSecond {
+    /// The padding to obtain the minimum width.
+    pub padding: Padding,
+}
+// endregion offset modifiers
+
+/// Type of padding to ensure a minimum width.
+#[non_exhaustive]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Padding {
+    /// A space character (` `) should be used as padding.
+    Space,
+    /// A zero character (`0`) should be used as padding.
+    Zero,
+    /// There is no padding. This can result in a width below the otherwise minimum number of
+    /// characters.
+    None,
+}
+
+/// Generate the provided code if and only if `pub` is present.
+macro_rules! if_pub {
+    (pub $(#[$attr:meta])*; $($x:tt)*) => {
+        $(#[$attr])*
+        ///
+        /// This function exists since [`Default::default()`] cannot be used in a `const` context.
+        /// It may be removed once that becomes possible. As the [`Default`] trait is in the
+        /// prelude, removing this function in the future will not cause any resolution failures for
+        /// the overwhelming majority of users; only users who use `#![no_implicit_prelude]` will be
+        /// affected. As such it will not be considered a breaking change.
+        $($x)*
+    };
+    ($($_:tt)*) => {};
+}
+
+/// Implement `Default` for the given type. This also generates an inherent implementation of a
+/// `default` method that is `const fn`, permitting the default value to be used in const contexts.
+// Every modifier should use this macro rather than a derived `Default`.
+macro_rules! impl_const_default {
+    ($($(#[$doc:meta])* $(@$pub:ident)? $type:ty => $default:expr;)*) => {$(
+        impl $type {
+            if_pub! {
+                $($pub)?
+                $(#[$doc])*;
+                pub const fn default() -> Self {
+                    $default
+                }
+            }
+        }
+
+        $(#[$doc])*
+        impl Default for $type {
+            fn default() -> Self {
+                $default
+            }
+        }
+    )*};
+}
+
+impl_const_default! {
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub Day => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the value uses the
+    /// [`Numerical`](Self::Numerical) representation.
+    MonthRepr => Self::Numerical;
+    /// Creates an instance of this type that indicates the value uses the
+    /// [`Numerical`](MonthRepr::Numerical) representation, is [padded with zeroes](Padding::Zero),
+    /// and is case-sensitive when parsing.
+    @pub Month => Self {
+        padding: Padding::Zero,
+        repr: MonthRepr::Numerical,
+        case_sensitive: true,
+    };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub Ordinal => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the value uses the [`Long`](Self::Long) representation.
+    WeekdayRepr => Self::Long;
+    /// Creates a modifier that indicates the value uses the [`Long`](WeekdayRepr::Long)
+    /// representation and is case-sensitive when parsing. If the representation is changed to a
+    /// numerical one, the instance defaults to one-based indexing.
+    @pub Weekday => Self {
+        repr: WeekdayRepr::Long,
+        one_indexed: true,
+        case_sensitive: true,
+    };
+    /// Creates a modifier that indicates that the value uses the [`Iso`](Self::Iso) representation.
+    WeekNumberRepr => Self::Iso;
+    /// Creates a modifier that indicates that the value is [padded with zeroes](Padding::Zero)
+            /// and uses the [`Iso`](WeekNumberRepr::Iso) representation.
+    @pub WeekNumber => Self {
+        padding: Padding::Zero,
+        repr: WeekNumberRepr::Iso,
+    };
+    /// Creates a modifier that indicates the value uses the [`Full`](Self::Full) representation.
+    YearRepr => Self::Full;
+    /// Creates a modifier that indicates the value uses the [`Full`](YearRepr::Full)
+    /// representation, is [padded with zeroes](Padding::Zero), uses the Gregorian calendar as its
+    /// base, and only includes the year's sign if necessary.
+    @pub Year => Self {
+        padding: Padding::Zero,
+        repr: YearRepr::Full,
+        iso_week_based: false,
+        sign_is_mandatory: false,
+    };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero) and
+    /// has the 24-hour representation.
+    @pub Hour => Self {
+        padding: Padding::Zero,
+        is_12_hour_clock: false,
+    };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub Minute => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the value uses the upper-case representation and is
+    /// case-sensitive when parsing.
+    @pub Period => Self {
+        is_uppercase: true,
+        case_sensitive: true,
+    };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub Second => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the stringified value contains [one or more
+    /// digits](Self::OneOrMore).
+    SubsecondDigits => Self::OneOrMore;
+    /// Creates a modifier that indicates the stringified value contains [one or more
+    /// digits](SubsecondDigits::OneOrMore).
+    @pub Subsecond => Self { digits: SubsecondDigits::OneOrMore };
+    /// Creates a modifier that indicates the value uses the `+` sign for all positive values
+    /// and is [padded with zeroes](Padding::Zero).
+    @pub OffsetHour => Self {
+        sign_is_mandatory: true,
+        padding: Padding::Zero,
+    };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub OffsetMinute => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Padding::Zero).
+    @pub OffsetSecond => Self { padding: Padding::Zero };
+    /// Creates a modifier that indicates the value is [padded with zeroes](Self::Zero).
+    Padding => Self::Zero;
+}
diff --git a/third_party/rust/time/src/format_description/owned_format_item.rs b/third_party/rust/time/src/format_description/owned_format_item.rs
new file mode 100644
index 0000000000..6f7f7c2337
--- /dev/null
+++ b/third_party/rust/time/src/format_description/owned_format_item.rs
@@ -0,0 +1,162 @@
+//! A format item with owned data.
+
+use alloc::boxed::Box;
+use alloc::string::String;
+use alloc::vec::Vec;
+use core::fmt;
+
+use crate::error;
+use crate::format_description::{Component, FormatItem};
+
+/// A complete description of how to format and parse a type.
+#[non_exhaustive]
+#[derive(Clone, PartialEq, Eq)]
+pub enum OwnedFormatItem {
+    /// Bytes that are formatted as-is.
+    ///
+    /// **Note**: If you call the `format` method that returns a `String`, these bytes will be
+    /// passed through `String::from_utf8_lossy`.
+    Literal(Box<[u8]>),
+    /// A minimal representation of a single non-literal item.
+    Component(Component),
+    /// A series of literals or components that collectively form a partial or complete
+    /// description.
+    Compound(Box<[Self]>),
+    /// A `FormatItem` that may or may not be present when parsing. If parsing fails, there
+    /// will be no effect on the resulting `struct`.
+    ///
+    /// This variant has no effect on formatting, as the value is guaranteed to be present.
+    Optional(Box<Self>),
+    /// A series of `FormatItem`s where, when parsing, the first successful parse is used. When
+    /// formatting, the first element of the [`Vec`] is used. An empty [`Vec`] is a no-op when
+    /// formatting or parsing.
+    First(Box<[Self]>),
+}
+
+impl fmt::Debug for OwnedFormatItem {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Literal(literal) => f.write_str(&String::from_utf8_lossy(literal)),
+            Self::Component(component) => component.fmt(f),
+            Self::Compound(compound) => compound.fmt(f),
+            Self::Optional(item) => f.debug_tuple("Optional").field(item).finish(),
+            Self::First(items) => f.debug_tuple("First").field(items).finish(),
+        }
+    }
+}
+
+// region: conversions from FormatItem
+impl From<FormatItem<'_>> for OwnedFormatItem {
+    fn from(item: FormatItem<'_>) -> Self {
+        (&item).into()
+    }
+}
+
+impl From<&FormatItem<'_>> for OwnedFormatItem {
+    fn from(item: &FormatItem<'_>) -> Self {
+        match item {
+            FormatItem::Literal(literal) => Self::Literal(literal.to_vec().into_boxed_slice()),
+            FormatItem::Component(component) => Self::Component(*component),
+            FormatItem::Compound(compound) => Self::Compound(
+                compound
+                    .iter()
+                    .cloned()
+                    .map(Into::into)
+                    .collect::<Vec<_>>()
+                    .into_boxed_slice(),
+            ),
+            FormatItem::Optional(item) => Self::Optional(Box::new((*item).into())),
+            FormatItem::First(items) => Self::First(
+                items
+                    .iter()
+                    .cloned()
+                    .map(Into::into)
+                    .collect::<Vec<_>>()
+                    .into_boxed_slice(),
+            ),
+        }
+    }
+}
+
+impl From<Vec<FormatItem<'_>>> for OwnedFormatItem {
+    fn from(items: Vec<FormatItem<'_>>) -> Self {
+        items.as_slice().into()
+    }
+}
+
+impl<'a, T: AsRef<[FormatItem<'a>]> + ?Sized> From<&T> for OwnedFormatItem {
+    fn from(items: &T) -> Self {
+        Self::Compound(
+            items
+                .as_ref()
+                .iter()
+                .cloned()
+                .map(Into::into)
+                .collect::<Vec<_>>()
+                .into_boxed_slice(),
+        )
+    }
+}
+// endregion conversions from FormatItem
+
+// region: from variants
+impl From<Component> for OwnedFormatItem {
+    fn from(component: Component) -> Self {
+        Self::Component(component)
+    }
+}
+
+impl TryFrom<OwnedFormatItem> for Component {
+    type Error = error::DifferentVariant;
+
+    fn try_from(value: OwnedFormatItem) -> Result<Self, Self::Error> {
+        match value {
+            OwnedFormatItem::Component(component) => Ok(component),
+            _ => Err(error::DifferentVariant),
+        }
+    }
+}
+
+impl From<Vec<Self>> for OwnedFormatItem {
+    fn from(items: Vec<Self>) -> Self {
+        Self::Compound(items.into_boxed_slice())
+    }
+}
+
+impl TryFrom<OwnedFormatItem> for Vec<OwnedFormatItem> {
+    type Error = error::DifferentVariant;
+
+    fn try_from(value: OwnedFormatItem) -> Result<Self, Self::Error> {
+        match value {
+            OwnedFormatItem::Compound(items) => Ok(items.into_vec()),
+            _ => Err(error::DifferentVariant),
+        }
+    }
+}
+// endregion from variants
+
+// region: equality
+impl PartialEq<Component> for OwnedFormatItem {
+    fn eq(&self, rhs: &Component) -> bool {
+        matches!(self, Self::Component(component) if component == rhs)
+    }
+}
+
+impl PartialEq<OwnedFormatItem> for Component {
+    fn eq(&self, rhs: &OwnedFormatItem) -> bool {
+        rhs == self
+    }
+}
+
+impl PartialEq<&[Self]> for OwnedFormatItem {
+    fn eq(&self, rhs: &&[Self]) -> bool {
+        matches!(self, Self::Compound(compound) if &&**compound == rhs)
+    }
+}
+
+impl PartialEq<OwnedFormatItem> for &[OwnedFormatItem] {
+    fn eq(&self, rhs: &OwnedFormatItem) -> bool {
+        rhs == self
+    }
+}
+// endregion equality
diff --git a/third_party/rust/time/src/format_description/parse/ast.rs b/third_party/rust/time/src/format_description/parse/ast.rs
new file mode 100644
index 0000000000..6977cc9cda
--- /dev/null
+++ b/third_party/rust/time/src/format_description/parse/ast.rs
@@ -0,0 +1,278 @@
+//! AST for parsing format descriptions.
+
+use alloc::string::String;
+use alloc::vec::Vec;
+use core::iter;
+use core::iter::Peekable;
+
+use super::{lexer, Error, Location, Span};
+
+/// One part of a complete format description.
+#[allow(variant_size_differences)]
+pub(super) enum Item<'a> {
+    /// A literal string, formatted and parsed as-is.
+    Literal {
+        /// The string itself.
+        value: &'a [u8],
+        /// Where the string originates from in the format string.
+        _span: Span,
+    },
+    /// A sequence of brackets. The first acts as the escape character.
+    EscapedBracket {
+        /// The first bracket.
+        _first: Location,
+        /// The second bracket.
+        _second: Location,
+    },
+    /// Part of a type, along with its modifiers.
+    Component {
+        /// Where the opening bracket was in the format string.
+        _opening_bracket: Location,
+        /// Whitespace between the opening bracket and name.
+        _leading_whitespace: Option<Whitespace<'a>>,
+        /// The name of the component.
+        name: Name<'a>,
+        /// The modifiers for the component.
+        modifiers: Vec<Modifier<'a>>,
+        /// Whitespace between the modifiers and closing bracket.
+        _trailing_whitespace: Option<Whitespace<'a>>,
+        /// Where the closing bracket was in the format string.
+        _closing_bracket: Location,
+    },
+}
+
+/// Whitespace within a component.
+pub(super) struct Whitespace<'a> {
+    /// The whitespace itself.
+    pub(super) _value: &'a [u8],
+    /// Where the whitespace was in the format string.
+    pub(super) span: Span,
+}
+
+/// The name of a component.
+pub(super) struct Name<'a> {
+    /// The name itself.
+    pub(super) value: &'a [u8],
+    /// Where the name was in the format string.
+    pub(super) span: Span,
+}
+
+/// A modifier for a component.
+pub(super) struct Modifier<'a> {
+    /// Whitespace preceding the modifier.
+    pub(super) _leading_whitespace: Whitespace<'a>,
+    /// The key of the modifier.
+    pub(super) key: Key<'a>,
+    /// Where the colon of the modifier was in the format string.
+    pub(super) _colon: Location,
+    /// The value of the modifier.
+    pub(super) value: Value<'a>,
+}
+
+/// The key of a modifier.
+pub(super) struct Key<'a> {
+    /// The key itself.
+    pub(super) value: &'a [u8],
+    /// Where the key was in the format string.
+    pub(super) span: Span,
+}
+
+/// The value of a modifier.
+pub(super) struct Value<'a> {
+    /// The value itself.
+    pub(super) value: &'a [u8],
+    /// Where the value was in the format string.
+    pub(super) span: Span,
+}
+
+/// Parse the provided tokens into an AST.
+pub(super) fn parse<'a>(
+    tokens: impl Iterator<Item = lexer::Token<'a>>,
+) -> impl Iterator<Item = Result<Item<'a>, Error>> {
+    let mut tokens = tokens.peekable();
+    iter::from_fn(move || {
+        Some(match tokens.next()? {
+            lexer::Token::Literal { value, span } => Ok(Item::Literal { value, _span: span }),
+            lexer::Token::Bracket {
+                kind: lexer::BracketKind::Opening,
+                location,
+            } => {
+                // escaped bracket
+                if let Some(&lexer::Token::Bracket {
+                    kind: lexer::BracketKind::Opening,
+                    location: second_location,
+                }) = tokens.peek()
+                {
+                    tokens.next(); // consume
+                    Ok(Item::EscapedBracket {
+                        _first: location,
+                        _second: second_location,
+                    })
+                }
+                // component
+                else {
+                    parse_component(location, &mut tokens)
+                }
+            }
+            lexer::Token::Bracket {
+                kind: lexer::BracketKind::Closing,
+                location: _,
+            } => unreachable!(
+                "internal error: closing bracket should have been consumed by `parse_component`",
+            ),
+            lexer::Token::ComponentPart {
+                kind: _,
+                value: _,
+                span: _,
+            } => unreachable!(
+                "internal error: component part should have been consumed by `parse_component`",
+            ),
+        })
+    })
+}
+
+/// Parse a component. This assumes that the opening bracket has already been consumed.
+fn parse_component<'a>(
+    opening_bracket: Location,
+    tokens: &mut Peekable<impl Iterator<Item = lexer::Token<'a>>>,
+) -> Result<Item<'a>, Error> {
+    let leading_whitespace = if let Some(&lexer::Token::ComponentPart {
+        kind: lexer::ComponentKind::Whitespace,
+        value,
+        span,
+    }) = tokens.peek()
+    {
+        tokens.next(); // consume
+        Some(Whitespace {
+            _value: value,
+            span,
+        })
+    } else {
+        None
+    };
+
+    let name = if let Some(&lexer::Token::ComponentPart {
+        kind: lexer::ComponentKind::NotWhitespace,
+        value,
+        span,
+    }) = tokens.peek()
+    {
+        tokens.next(); // consume
+        Name { value, span }
+    } else {
+        let span = leading_whitespace.map_or_else(
+            || Span {
+                start: opening_bracket,
+                end: opening_bracket,
+            },
+            |whitespace| whitespace.span.shrink_to_end(),
+        );
+        return Err(Error {
+            _inner: span.error("expected component name"),
+            public: crate::error::InvalidFormatDescription::MissingComponentName {
+                index: span.start_byte(),
+            },
+        });
+    };
+
+    let mut modifiers = Vec::new();
+    let trailing_whitespace = loop {
+        let whitespace = if let Some(&lexer::Token::ComponentPart {
+            kind: lexer::ComponentKind::Whitespace,
+            value,
+            span,
+        }) = tokens.peek()
+        {
+            tokens.next(); // consume
+            Whitespace {
+                _value: value,
+                span,
+            }
+        } else {
+            break None;
+        };
+
+        if let Some(&lexer::Token::ComponentPart {
+            kind: lexer::ComponentKind::NotWhitespace,
+            value,
+            span,
+        }) = tokens.peek()
+        {
+            tokens.next(); // consume
+
+            let colon_index = match value.iter().position(|&b| b == b':') {
+                Some(index) => index,
+                None => {
+                    return Err(Error {
+                        _inner: span.error("modifier must be of the form `key:value`"),
+                        public: crate::error::InvalidFormatDescription::InvalidModifier {
+                            value: String::from_utf8_lossy(value).into_owned(),
+                            index: span.start_byte(),
+                        },
+                    });
+                }
+            };
+            let key = &value[..colon_index];
+            let value = &value[colon_index + 1..];
+
+            if key.is_empty() {
+                return Err(Error {
+                    _inner: span.shrink_to_start().error("expected modifier key"),
+                    public: crate::error::InvalidFormatDescription::InvalidModifier {
+                        value: String::new(),
+                        index: span.start_byte(),
+                    },
+                });
+            }
+            if value.is_empty() {
+                return Err(Error {
+                    _inner: span.shrink_to_end().error("expected modifier value"),
+                    public: crate::error::InvalidFormatDescription::InvalidModifier {
+                        value: String::new(),
+                        index: span.shrink_to_end().start_byte(),
+                    },
+                });
+            }
+
+            modifiers.push(Modifier {
+                _leading_whitespace: whitespace,
+                key: Key {
+                    value: key,
+                    span: span.subspan(..colon_index),
+                },
+                _colon: span.start.offset(colon_index),
+                value: Value {
+                    value,
+                    span: span.subspan(colon_index + 1..),
+                },
+            });
+        } else {
+            break Some(whitespace);
+        }
+    };
+
+    let closing_bracket = if let Some(&lexer::Token::Bracket {
+        kind: lexer::BracketKind::Closing,
+        location,
+    }) = tokens.peek()
+    {
+        tokens.next(); // consume
+        location
+    } else {
+        return Err(Error {
+            _inner: opening_bracket.error("unclosed bracket"),
+            public: crate::error::InvalidFormatDescription::UnclosedOpeningBracket {
+                index: opening_bracket.byte,
+            },
+        });
+    };
+
+    Ok(Item::Component {
+        _opening_bracket: opening_bracket,
+        _leading_whitespace: leading_whitespace,
+        name,
+        modifiers,
+        _trailing_whitespace: trailing_whitespace,
+        _closing_bracket: closing_bracket,
+    })
+}
diff --git a/third_party/rust/time/src/format_description/parse/format_item.rs b/third_party/rust/time/src/format_description/parse/format_item.rs
new file mode 100644
index 0000000000..53146d5228
--- /dev/null
+++ b/third_party/rust/time/src/format_description/parse/format_item.rs
@@ -0,0 +1,386 @@
+//! Typed, validated representation of a parsed format description.
+
+use alloc::string::String;
+
+use super::{ast, Error};
+
+/// Parse an AST iterator into a sequence of format items.
+pub(super) fn parse<'a>(
+    ast_items: impl Iterator<Item = Result<ast::Item<'a>, Error>>,
+) -> impl Iterator<Item = Result<Item<'a>, Error>> {
+    ast_items.map(|ast_item| ast_item.and_then(Item::from_ast))
+}
+
+/// A description of how to format and parse one part of a type.
+#[allow(variant_size_differences)]
+pub(super) enum Item<'a> {
+    /// A literal string.
+    Literal(&'a [u8]),
+    /// Part of a type, along with its modifiers.
+    Component(Component),
+}
+
+impl Item<'_> {
+    /// Parse an AST item into a format item.
+    pub(super) fn from_ast(ast_item: ast::Item<'_>) -> Result<Item<'_>, Error> {
+        Ok(match ast_item {
+            ast::Item::Component {
+                _opening_bracket: _,
+                _leading_whitespace: _,
+                name,
+                modifiers,
+                _trailing_whitespace: _,
+                _closing_bracket: _,
+            } => Item::Component(component_from_ast(&name, &modifiers)?),
+            ast::Item::Literal { value, _span: _ } => Item::Literal(value),
+            ast::Item::EscapedBracket {
+                _first: _,
+                _second: _,
+            } => Item::Literal(b"["),
+        })
+    }
+}
+
+impl<'a> From<Item<'a>> for crate::format_description::FormatItem<'a> {
+    fn from(item: Item<'a>) -> Self {
+        match item {
+            Item::Literal(literal) => Self::Literal(literal),
+            Item::Component(component) => Self::Component(component.into()),
+        }
+    }
+}
+
+impl From<Item<'_>> for crate::format_description::OwnedFormatItem {
+    fn from(item: Item<'_>) -> Self {
+        match item {
+            Item::Literal(literal) => Self::Literal(literal.to_vec().into_boxed_slice()),
+            Item::Component(component) => Self::Component(component.into()),
+        }
+    }
+}
+
+/// Declare the `Component` struct.
+macro_rules! component_definition {
+    ($vis:vis enum $name:ident {
+        $($variant:ident = $parse_variant:literal {
+            $($field:ident = $parse_field:literal:
+                Option<$field_type:ty> => $target_field:ident),* $(,)?
+        }),* $(,)?
+    }) => {
+        $vis enum $name {
+            $($variant($variant),)*
+        }
+
+        $($vis struct $variant {
+            $($field: Option<$field_type>),*
+        })*
+
+        $(impl $variant {
+            /// Parse the component from the AST, given its modifiers.
+            fn with_modifiers(modifiers: &[ast::Modifier<'_>]) -> Result<Self, Error> {
+                let mut this = Self {
+                    $($field: None),*
+                };
+
+                for modifier in modifiers {
+                    $(if modifier.key.value.eq_ignore_ascii_case($parse_field) {
+                        this.$field = <$field_type>::from_modifier_value(&modifier.value)?;
+                        continue;
+                    })*
+                    return Err(Error {
+                        _inner: modifier.key.span.error("invalid modifier key"),
+                        public: crate::error::InvalidFormatDescription::InvalidModifier {
+                            value: String::from_utf8_lossy(modifier.key.value).into_owned(),
+                            index: modifier.key.span.start_byte(),
+                        }
+                    });
+                }
+
+                Ok(this)
+            }
+        })*
+
+        impl From<$name> for crate::format_description::Component {
+            fn from(component: $name) -> Self {
+                match component {$(
+                    $name::$variant($variant { $($field),* }) => {
+                        $crate::format_description::component::Component::$variant(
+                            $crate::format_description::modifier::$variant {$(
+                                $target_field: $field.unwrap_or_default().into()
+                            ),*}
+                        )
+                    }
+                )*}
+            }
+        }
+
+        /// Parse a component from the AST, given its name and modifiers.
+        fn component_from_ast(
+            name: &ast::Name<'_>,
+            modifiers: &[ast::Modifier<'_>],
+        ) -> Result<Component, Error> {
+            $(if name.value.eq_ignore_ascii_case($parse_variant) {
+                return Ok(Component::$variant($variant::with_modifiers(&modifiers)?));
+            })*
+            Err(Error {
+                _inner: name.span.error("invalid component"),
+                public: crate::error::InvalidFormatDescription::InvalidComponentName {
+                    name: String::from_utf8_lossy(name.value).into_owned(),
+                    index: name.span.start_byte(),
+                },
+            })
+        }
+    }
+}
+
+// Keep in alphabetical order.
+component_definition! {
+    pub(super) enum Component {
+        Day = b"day" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        Hour = b"hour" {
+            padding = b"padding": Option<Padding> => padding,
+            base = b"repr": Option<HourBase> => is_12_hour_clock,
+        },
+        Minute = b"minute" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        Month = b"month" {
+            padding = b"padding": Option<Padding> => padding,
+            repr = b"repr": Option<MonthRepr> => repr,
+            case_sensitive = b"case_sensitive": Option<MonthCaseSensitive> => case_sensitive,
+        },
+        OffsetHour = b"offset_hour" {
+            sign_behavior = b"sign": Option<SignBehavior> => sign_is_mandatory,
+            padding = b"padding": Option<Padding> => padding,
+        },
+        OffsetMinute = b"offset_minute" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        OffsetSecond = b"offset_second" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        Ordinal = b"ordinal" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        Period = b"period" {
+            case = b"case": Option<PeriodCase> => is_uppercase,
+            case_sensitive = b"case_sensitive": Option<PeriodCaseSensitive> => case_sensitive,
+        },
+        Second = b"second" {
+            padding = b"padding": Option<Padding> => padding,
+        },
+        Subsecond = b"subsecond" {
+            digits = b"digits": Option<SubsecondDigits> => digits,
+        },
+        Weekday = b"weekday" {
+            repr = b"repr": Option<WeekdayRepr> => repr,
+            one_indexed = b"one_indexed": Option<WeekdayOneIndexed> => one_indexed,
+            case_sensitive = b"case_sensitive": Option<WeekdayCaseSensitive> => case_sensitive,
+        },
+        WeekNumber = b"week_number" {
+            padding = b"padding": Option<Padding> => padding,
+            repr = b"repr": Option<WeekNumberRepr> => repr,
+        },
+        Year = b"year" {
+            padding = b"padding": Option<Padding> => padding,
+            repr = b"repr": Option<YearRepr> => repr,
+            base = b"base": Option<YearBase> => iso_week_based,
+            sign_behavior = b"sign": Option<SignBehavior> => sign_is_mandatory,
+        },
+    }
+}
+
+/// Get the target type for a given enum.
+macro_rules! target_ty {
+    ($name:ident $type:ty) => {
+        $type
+    };
+    ($name:ident) => {
+        $crate::format_description::modifier::$name
+    };
+}
+
+/// Get the target value for a given enum.
+macro_rules! target_value {
+    ($name:ident $variant:ident $value:expr) => {
+        $value
+    };
+    ($name:ident $variant:ident) => {
+        $crate::format_description::modifier::$name::$variant
+    };
+}
+
+// TODO use `#[derive(Default)]` on enums once MSRV is 1.62 (NET 2022-12-30)
+/// Simulate `#[derive(Default)]` on enums.
+macro_rules! derived_default_on_enum {
+    ($type:ty; $default:expr) => {};
+    ($attr:meta $type:ty; $default:expr) => {
+        impl Default for $type {
+            fn default() -> Self {
+                $default
+            }
+        }
+    };
+}
+
+/// Declare the various modifiers.
+///
+/// For the general case, ordinary syntax can be used. Note that you _must_ declare a default
+/// variant. The only significant change is that the string representation of the variant must be
+/// provided after the variant name. For example, `Numerical = b"numerical"` declares a variant
+/// named `Numerical` with the string representation `b"numerical"`. This is the value that will be
+/// used when parsing the modifier. The value is not case sensitive.
+///
+/// If the type in the public API does not have the same name as the type in the internal
+/// representation, then the former must be specified in parenthesis after the internal name. For
+/// example, `HourBase(bool)` has an internal name "HourBase", but is represented as a boolean in
+/// the public API.
+///
+/// By default, the internal variant name is assumed to be the same as the public variant name. If
+/// this is not the case, the qualified path to the variant must be specified in parenthesis after
+/// the internal variant name. For example, `Twelve(true)` has an internal variant name "Twelve",
+/// but is represented as `true` in the public API.
+macro_rules! modifier {
+    ($(
+        enum $name:ident $(($target_ty:ty))? {
+            $(
+                $(#[$attr:meta])?
+                $variant:ident $(($target_value:expr))? = $parse_variant:literal
+            ),* $(,)?
+        }
+    )+) => {$(
+        enum $name {
+            $($variant),*
+        }
+
+        $(derived_default_on_enum! {
+            $($attr)? $name; $name::$variant
+        })*
+
+        impl $name {
+            /// Parse the modifier from its string representation.
+            fn from_modifier_value(value: &ast::Value<'_>) -> Result<Option<Self>, Error> {
+                $(if value.value.eq_ignore_ascii_case($parse_variant) {
+                    return Ok(Some(Self::$variant));
+                })*
+                Err(Error {
+                    _inner: value.span.error("invalid modifier value"),
+                    public: crate::error::InvalidFormatDescription::InvalidModifier {
+                        value: String::from_utf8_lossy(value.value).into_owned(),
+                        index: value.span.start_byte(),
+                    },
+                })
+            }
+        }
+
+        impl From<$name> for target_ty!($name $($target_ty)?) {
+            fn from(modifier: $name) -> Self {
+                match modifier {
+                    $($name::$variant => target_value!($name $variant $($target_value)?)),*
+                }
+            }
+        }
+    )+};
+}
+
+// Keep in alphabetical order.
+modifier! {
+    enum HourBase(bool) {
+        Twelve(true) = b"12",
+        #[default]
+        TwentyFour(false) = b"24",
+    }
+
+    enum MonthCaseSensitive(bool) {
+        False(false) = b"false",
+        #[default]
+        True(true) = b"true",
+    }
+
+    enum MonthRepr {
+        #[default]
+        Numerical = b"numerical",
+        Long = b"long",
+        Short = b"short",
+    }
+
+    enum Padding {
+        Space = b"space",
+        #[default]
+        Zero = b"zero",
+        None = b"none",
+    }
+
+    enum PeriodCase(bool) {
+        Lower(false) = b"lower",
+        #[default]
+        Upper(true) = b"upper",
+    }
+
+    enum PeriodCaseSensitive(bool) {
+        False(false) = b"false",
+        #[default]
+        True(true) = b"true",
+    }
+
+    enum SignBehavior(bool) {
+        #[default]
+        Automatic(false) = b"automatic",
+        Mandatory(true) = b"mandatory",
+    }
+
+    enum SubsecondDigits {
+        One = b"1",
+        Two = b"2",
+        Three = b"3",
+        Four = b"4",
+        Five = b"5",
+        Six = b"6",
+        Seven = b"7",
+        Eight = b"8",
+        Nine = b"9",
+        #[default]
+        OneOrMore = b"1+",
+    }
+
+    enum WeekNumberRepr {
+        #[default]
+        Iso = b"iso",
+        Sunday = b"sunday",
+        Monday = b"monday",
+    }
+
+    enum WeekdayCaseSensitive(bool) {
+        False(false) = b"false",
+        #[default]
+        True(true) = b"true",
+    }
+
+    enum WeekdayOneIndexed(bool) {
+        False(false) = b"false",
+        #[default]
+        True(true) = b"true",
+    }
+
+    enum WeekdayRepr {
+        Short = b"short",
+        #[default]
+        Long = b"long",
+        Sunday = b"sunday",
+        Monday = b"monday",
+    }
+
+    enum YearBase(bool) {
+        #[default]
+        Calendar(false) = b"calendar",
+        IsoWeek(true) = b"iso_week",
+    }
+
+    enum YearRepr {
+        #[default]
+        Full = b"full",
+        LastTwo = b"last_two",
+    }
+}
diff --git a/third_party/rust/time/src/format_description/parse/lexer.rs b/third_party/rust/time/src/format_description/parse/lexer.rs
new file mode 100644
index 0000000000..e405ea8c85
--- /dev/null
+++ b/third_party/rust/time/src/format_description/parse/lexer.rs
@@ -0,0 +1,159 @@
+//! Lexer for parsing format descriptions.
+
+use core::iter;
+
+use super::{Location, Span};
+
+/// A token emitted by the lexer. There is no semantic meaning at this stage.
+pub(super) enum Token<'a> {
+    /// A literal string, formatted and parsed as-is.
+    Literal {
+        /// The string itself.
+        value: &'a [u8],
+        /// Where the string was in the format string.
+        span: Span,
+    },
+    /// An opening or closing bracket. May or may not be the start or end of a component.
+    Bracket {
+        /// Whether the bracket is opening or closing.
+        kind: BracketKind,
+        /// Where the bracket was in the format string.
+        location: Location,
+    },
+    /// One part of a component. This could be its name, a modifier, or whitespace.
+    ComponentPart {
+        /// Whether the part is whitespace or not.
+        kind: ComponentKind,
+        /// The part itself.
+        value: &'a [u8],
+        /// Where the part was in the format string.
+        span: Span,
+    },
+}
+
+/// What type of bracket is present.
+pub(super) enum BracketKind {
+    /// An opening bracket: `[`
+    Opening,
+    /// A closing bracket: `]`
+    Closing,
+}
+
+/// Indicates whether the component is whitespace or not.
+pub(super) enum ComponentKind {
+    #[allow(clippy::missing_docs_in_private_items)]
+    Whitespace,
+    #[allow(clippy::missing_docs_in_private_items)]
+    NotWhitespace,
+}
+
+/// Attach [`Location`] information to each byte in the iterator.
+fn attach_location(iter: impl Iterator<Item = u8>) -> impl Iterator<Item = (u8, Location)> {
+    let mut line = 1;
+    let mut column = 1;
+    let mut byte_pos = 0;
+
+    iter.map(move |byte| {
+        let location = Location {
+            line,
+            column,
+            byte: byte_pos,
+        };
+        column += 1;
+        byte_pos += 1;
+
+        if byte == b'\n' {
+            line += 1;
+            column = 1;
+        }
+
+        (byte, location)
+    })
+}
+
+/// Parse the string into a series of [`Token`]s.
+pub(super) fn lex(mut input: &[u8]) -> impl Iterator<Item = Token<'_>> {
+    let mut depth: u8 = 0;
+    let mut iter = attach_location(input.iter().copied()).peekable();
+    let mut second_bracket_location = None;
+
+    iter::from_fn(move || {
+        // There is a flag set to emit the second half of an escaped bracket pair.
+        if let Some(location) = second_bracket_location.take() {
+            return Some(Token::Bracket {
+                kind: BracketKind::Opening,
+                location,
+            });
+        }
+
+        Some(match iter.next()? {
+            (b'[', location) => {
+                if let Some((_, second_location)) = iter.next_if(|&(byte, _)| byte == b'[') {
+                    // escaped bracket
+                    second_bracket_location = Some(second_location);
+                    input = &input[2..];
+                } else {
+                    // opening bracket
+                    depth += 1;
+                    input = &input[1..];
+                }
+
+                Token::Bracket {
+                    kind: BracketKind::Opening,
+                    location,
+                }
+            }
+            // closing bracket
+            (b']', location) if depth > 0 => {
+                depth -= 1;
+                input = &input[1..];
+                Token::Bracket {
+                    kind: BracketKind::Closing,
+                    location,
+                }
+            }
+            // literal
+            (_, start_location) if depth == 0 => {
+                let mut bytes = 1;
+                let mut end_location = start_location;
+
+                while let Some((_, location)) = iter.next_if(|&(byte, _)| byte != b'[') {
+                    end_location = location;
+                    bytes += 1;
+                }
+
+                let value = &input[..bytes];
+                input = &input[bytes..];
+                Token::Literal {
+                    value,
+                    span: Span::start_end(start_location, end_location),
+                }
+            }
+            // component part
+            (byte, start_location) => {
+                let mut bytes = 1;
+                let mut end_location = start_location;
+                let is_whitespace = byte.is_ascii_whitespace();
+
+                while let Some((_, location)) = iter.next_if(|&(byte, _)| {
+                    byte != b'[' && byte != b']' && is_whitespace == byte.is_ascii_whitespace()
+                }) {
+                    end_location = location;
+                    bytes += 1;
+                }
+
+                let value = &input[..bytes];
+                input = &input[bytes..];
+                Token::ComponentPart {
+                    kind: if is_whitespace {
+                        ComponentKind::Whitespace
+                    } else {
+                        ComponentKind::NotWhitespace
+                    },
+                    value,
+                    span: Span::start_end(start_location, end_location),
+                }
+            }
+        })
+    })
+}
diff --git a/third_party/rust/time/src/format_description/parse/mod.rs b/third_party/rust/time/src/format_description/parse/mod.rs
new file mode 100644
index 0000000000..c73a674494
--- /dev/null
+++ b/third_party/rust/time/src/format_description/parse/mod.rs
@@ -0,0 +1,193 @@
+//! Parser for format descriptions.
+
+use alloc::vec::Vec;
+use core::ops::{RangeFrom, RangeTo};
+
+mod ast;
+mod format_item;
+mod lexer;
+
+/// Parse a sequence of items from the format description.
+///
+/// The syntax for the format description can be found in [the
+/// book](https://time-rs.github.io/book/api/format-description.html).
+pub fn parse(
+    s: &str,
+) -> Result<Vec<crate::format_description::FormatItem<'_>>, crate::error::InvalidFormatDescription>
+{
+    let lexed = lexer::lex(s.as_bytes());
+    let ast = ast::parse(lexed);
+    let format_items = format_item::parse(ast);
+    Ok(format_items
+        .map(|res| res.map(Into::into))
+        .collect::<Result<Vec<_>, _>>()?)
+}
+
+/// Parse a sequence of items from the format description.
+///
+/// The syntax for the format description can be found in [the
+/// book](https://time-rs.github.io/book/api/format-description.html).
+///
+/// Unlike [`parse`], this function returns [`OwnedFormatItem`], which owns its contents. This means
+/// that there is no lifetime that needs to be handled.
+///
+/// [`OwnedFormatItem`]: crate::format_description::OwnedFormatItem
+pub fn parse_owned(
+    s: &str,
+) -> Result<crate::format_description::OwnedFormatItem, crate::error::InvalidFormatDescription> {
+    let lexed = lexer::lex(s.as_bytes());
+    let ast = ast::parse(lexed);
+    let format_items = format_item::parse(ast);
+    let items = format_items
+        .map(|res| res.map(Into::into))
+        .collect::<Result<Vec<_>, _>>()?
+        .into_boxed_slice();
+    Ok(crate::format_description::OwnedFormatItem::Compound(items))
+}
+
+/// A location within a string.
+#[derive(Clone, Copy)]
+struct Location {
+    /// The one-indexed line of the string.
+    line: usize,
+    /// The one-indexed column of the string.
+    column: usize,
+    /// The zero-indexed byte of the string.
+    byte: usize,
+}
+
+impl Location {
+    /// Offset the location by the provided amount.
+    ///
+    /// Note that this assumes the resulting location is on the same line as the original location.
+    #[must_use = "this does not modify the original value"]
+    const fn offset(&self, offset: usize) -> Self {
+        Self {
+            line: self.line,
+            column: self.column + offset,
+            byte: self.byte + offset,
+        }
+    }
+
+    /// Create an error with the provided message at this location.
+    const fn error(self, message: &'static str) -> ErrorInner {
+        ErrorInner {
+            _message: message,
+            _span: Span {
+                start: self,
+                end: self,
+            },
+        }
+    }
+}
+
+/// A start and end point within a string.
+#[derive(Clone, Copy)]
+struct Span {
+    #[allow(clippy::missing_docs_in_private_items)]
+    start: Location,
+    #[allow(clippy::missing_docs_in_private_items)]
+    end: Location,
+}
+
+impl Span {
+    /// Create a new `Span` from the provided start and end locations.
+    const fn start_end(start: Location, end: Location) -> Self {
+        Self { start, end }
+    }
+
+    /// Reduce this span to the provided range.
+    #[must_use = "this does not modify the original value"]
+    fn subspan(&self, range: impl Subspan) -> Self {
+        range.subspan(self)
+    }
+
+    /// Obtain a `Span` pointing at the start of the pre-existing span.
+    #[must_use = "this does not modify the original value"]
+    const fn shrink_to_start(&self) -> Self {
+        Self {
+            start: self.start,
+            end: self.start,
+        }
+    }
+
+    /// Obtain a `Span` pointing at the end of the pre-existing span.
+    #[must_use = "this does not modify the original value"]
+    const fn shrink_to_end(&self) -> Self {
+        Self {
+            start: self.end,
+            end: self.end,
+        }
+    }
+
+    /// Create an error with the provided message at this span.
+    const fn error(self, message: &'static str) -> ErrorInner {
+        ErrorInner {
+            _message: message,
+            _span: self,
+        }
+    }
+
+    /// Get the byte index that the span starts at.
+    const fn start_byte(&self) -> usize {
+        self.start.byte
+    }
+}
+
+/// A trait for types that can be used to reduce a `Span`.
+trait Subspan {
+    /// Reduce the provided `Span` to a new `Span`.
+    fn subspan(self, span: &Span) -> Span;
+}
+
+impl Subspan for RangeFrom<usize> {
+    fn subspan(self, span: &Span) -> Span {
+        assert_eq!(span.start.line, span.end.line);
+
+        Span {
+            start: Location {
+                line: span.start.line,
+                column: span.start.column + self.start,
+                byte: span.start.byte + self.start,
+            },
+            end: span.end,
+        }
+    }
+}
+
+impl Subspan for RangeTo<usize> {
+    fn subspan(self, span: &Span) -> Span {
+        assert_eq!(span.start.line, span.end.line);
+
+        Span {
+            start: span.start,
+            end: Location {
+                line: span.start.line,
+                column: span.start.column + self.end - 1,
+                byte: span.start.byte + self.end - 1,
+            },
+        }
+    }
+}
+
+/// The internal error type.
+struct ErrorInner {
+    /// The message displayed to the user.
+    _message: &'static str,
+    /// Where the error originated.
+    _span: Span,
+}
+
+/// A complete error description.
+struct Error {
+    /// The internal error.
+    _inner: ErrorInner,
+    /// The error needed for interoperability with the rest of `time`.
+    public: crate::error::InvalidFormatDescription,
+}
+
+impl From<Error> for crate::error::InvalidFormatDescription {
+    fn from(error: Error) -> Self {
+        error.public
+    }
+}
diff --git a/third_party/rust/time/src/format_description/well_known/iso8601.rs b/third_party/rust/time/src/format_description/well_known/iso8601.rs
new file mode 100644
index 0000000000..f19181a926
--- /dev/null
+++ b/third_party/rust/time/src/format_description/well_known/iso8601.rs
@@ -0,0 +1,233 @@
+//! The format described in ISO 8601.
+
+mod adt_hack;
+
+use core::num::NonZeroU8;
+
+pub use self::adt_hack::{DoNotRelyOnWhatThisIs, EncodedConfig};
+
+/// A configuration for [`Iso8601`] that only parses values.
+const PARSING_ONLY: EncodedConfig = Config {
+    formatted_components: FormattedComponents::None,
+    use_separators: false,
+    year_is_six_digits: false,
+    date_kind: DateKind::Calendar,
+    time_precision: TimePrecision::Hour {
+        decimal_digits: None,
+    },
+    offset_precision: OffsetPrecision::Hour,
+}
+.encode();
+
+/// The default configuration for [`Iso8601`].
+const DEFAULT_CONFIG: EncodedConfig = Config::DEFAULT.encode();
+
+/// The format described in [ISO 8601](https://www.iso.org/iso-8601-date-and-time-format.html).
+///
+/// This implementation is of ISO 8601-1:2019. It may not be compatible with other versions.
+///
+/// The const parameter `CONFIG` **must** be a value that was returned by [`Config::encode`].
+/// Passing any other value is **unspecified behavior**.
+///
+/// Example: 1997-11-21T09:55:06.000000000-06:00
+///
+/// # Examples
+#[cfg_attr(feature = "formatting", doc = "```rust")]
+#[cfg_attr(not(feature = "formatting"), doc = "```rust,ignore")]
+/// # use time::format_description::well_known::Iso8601;
+/// # use time_macros::datetime;
+/// assert_eq!(
+///     datetime!(1997-11-12 9:55:06 -6:00).format(&Iso8601::DEFAULT)?,
+///     "1997-11-12T09:55:06.000000000-06:00"
+/// );
+/// # Ok::<_, time::Error>(())
+/// ```
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct Iso8601<const CONFIG: EncodedConfig = DEFAULT_CONFIG>;
+
+impl<const CONFIG: EncodedConfig> core::fmt::Debug for Iso8601<CONFIG> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.debug_struct("Iso8601")
+            .field("config", &Config::decode(CONFIG))
+            .finish()
+    }
+}
+
+impl Iso8601<DEFAULT_CONFIG> {
+    /// An [`Iso8601`] with the default configuration.
+    ///
+    /// The following is the default behavior:
+    ///
+    /// - The configuration can be used for both formatting and parsing.
+    /// - The date, time, and UTC offset are all formatted.
+    /// - Separators (such as `-` and `:`) are included.
+    /// - The year contains four digits, such that the year must be between 0 and 9999.
+    /// - The date uses the calendar format.
+    /// - The time has precision to the second and nine decimal digits.
+    /// - The UTC offset has precision to the minute.
+    ///
+    /// If you need different behavior, use [`Config::DEFAULT`] and [`Config`]'s methods to create
+    /// a custom configuration.
+    pub const DEFAULT: Self = Self;
+}
+
+impl Iso8601<PARSING_ONLY> {
+    /// An [`Iso8601`] that can only be used for parsing. Using this to format a value is
+    /// unspecified behavior.
+    pub const PARSING: Self = Self;
+}
+
+/// Which components to format.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum FormattedComponents {
+    /// The configuration can only be used for parsing. Using this to format a value is
+    /// unspecified behavior.
+    None,
+    /// Format only the date.
+    Date,
+    /// Format only the time.
+    Time,
+    /// Format only the UTC offset.
+    Offset,
+    /// Format the date and time.
+    DateTime,
+    /// Format the date, time, and UTC offset.
+    DateTimeOffset,
+    /// Format the time and UTC offset.
+    TimeOffset,
+}
+
+/// Which format to use for the date.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum DateKind {
+    /// Use the year-month-day format.
+    Calendar,
+    /// Use the year-week-weekday format.
+    Week,
+    /// Use the week-ordinal format.
+    Ordinal,
+}
+
+/// The precision and number of decimal digits present for the time.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum TimePrecision {
+    /// Format the hour only. Minutes, seconds, and nanoseconds will be represented with the
+    /// specified number of decimal digits, if any.
+    Hour {
+        #[allow(clippy::missing_docs_in_private_items)]
+        decimal_digits: Option<NonZeroU8>,
+    },
+    /// Format the hour and minute. Seconds and nanoseconds will be represented with the specified
+    /// number of decimal digits, if any.
+    Minute {
+        #[allow(clippy::missing_docs_in_private_items)]
+        decimal_digits: Option<NonZeroU8>,
+    },
+    /// Format the hour, minute, and second. Nanoseconds will be represented with the specified
+    /// number of decimal digits, if any.
+    Second {
+        #[allow(clippy::missing_docs_in_private_items)]
+        decimal_digits: Option<NonZeroU8>,
+    },
+}
+
+/// The precision for the UTC offset.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OffsetPrecision {
+    /// Format only the offset hour. Requires the offset minute to be zero.
+    Hour,
+    /// Format both the offset hour and minute.
+    Minute,
+}
+
+/// Configuration for [`Iso8601`].
+// This is only used as a const generic, so there's no need to have a number of implementations on
+// it.
+#[allow(missing_copy_implementations)]
+#[doc(alias = "EncodedConfig")] // People will likely search for `EncodedConfig`, so show them this.
+#[derive(Debug)]
+pub struct Config {
+    /// Which components, if any, will be formatted.
+    pub(crate) formatted_components: FormattedComponents,
+    /// Whether the format contains separators (such as `-` or `:`).
+    pub(crate) use_separators: bool,
+    /// Whether the year is six digits.
+    pub(crate) year_is_six_digits: bool,
+    /// The format used for the date.
+    pub(crate) date_kind: DateKind,
+    /// The precision and number of decimal digits present for the time.
+    pub(crate) time_precision: TimePrecision,
+    /// The precision for the UTC offset.
+    pub(crate) offset_precision: OffsetPrecision,
+}
+
+impl Config {
+    /// A configuration for the [`Iso8601`] format.
+    ///
+    /// The following is the default behavior:
+    ///
+    /// - The configuration can be used for both formatting and parsing.
+    /// - The date, time, and UTC offset are all formatted.
+    /// - Separators (such as `-` and `:`) are included.
+    /// - The year contains four digits, such that the year must be between 0 and 9999.
+    /// - The date uses the calendar format.
+    /// - The time has precision to the second and nine decimal digits.
+    /// - The UTC offset has precision to the minute.
+    ///
+    /// If you need different behavior, use the setter methods on this struct.
+    pub const DEFAULT: Self = Self {
+        formatted_components: FormattedComponents::DateTimeOffset,
+        use_separators: true,
+        year_is_six_digits: false,
+        date_kind: DateKind::Calendar,
+        time_precision: TimePrecision::Second {
+            decimal_digits: NonZeroU8::new(9),
+        },
+        offset_precision: OffsetPrecision::Minute,
+    };
+
+    /// Set whether the format the date, time, and/or UTC offset.
+    pub const fn set_formatted_components(self, formatted_components: FormattedComponents) -> Self {
+        Self {
+            formatted_components,
+            ..self
+        }
+    }
+
+    /// Set whether the format contains separators (such as `-` or `:`).
+    pub const fn set_use_separators(self, use_separators: bool) -> Self {
+        Self {
+            use_separators,
+            ..self
+        }
+    }
+
+    /// Set whether the year is six digits.
+    pub const fn set_year_is_six_digits(self, year_is_six_digits: bool) -> Self {
+        Self {
+            year_is_six_digits,
+            ..self
+        }
+    }
+
+    /// Set the format used for the date.
+    pub const fn set_date_kind(self, date_kind: DateKind) -> Self {
+        Self { date_kind, ..self }
+    }
+
+    /// Set the precision and number of decimal digits present for the time.
+    pub const fn set_time_precision(self, time_precision: TimePrecision) -> Self {
+        Self {
+            time_precision,
+            ..self
+        }
+    }
+
+    /// Set the precision for the UTC offset.
+    pub const fn set_offset_precision(self, offset_precision: OffsetPrecision) -> Self {
+        Self {
+            offset_precision,
+            ..self
+        }
+    }
+}
diff --git a/third_party/rust/time/src/format_description/well_known/iso8601/adt_hack.rs b/third_party/rust/time/src/format_description/well_known/iso8601/adt_hack.rs
new file mode 100644
index 0000000000..757a68b18f
--- /dev/null
+++ b/third_party/rust/time/src/format_description/well_known/iso8601/adt_hack.rs
@@ -0,0 +1,249 @@
+//! Hackery to work around not being able to use ADTs in const generics on stable.
+
+use core::num::NonZeroU8;
+
+#[cfg(feature = "formatting")]
+use super::Iso8601;
+use super::{Config, DateKind, FormattedComponents as FC, OffsetPrecision, TimePrecision};
+
+// This provides a way to include `EncodedConfig` in documentation without displaying the type it is
+// aliased to.
+#[doc(hidden)]
+pub type DoNotRelyOnWhatThisIs = u128;
+
+/// An encoded [`Config`] that can be used as a const parameter to [`Iso8601`].
+///
+/// The type this is aliased to must not be relied upon. It can change in any release without
+/// notice.
+pub type EncodedConfig = DoNotRelyOnWhatThisIs;
+
+#[cfg(feature = "formatting")]
+impl<const CONFIG: EncodedConfig> Iso8601<CONFIG> {
+    /// The user-provided configuration for the ISO 8601 format.
+    const CONFIG: Config = Config::decode(CONFIG);
+    /// Whether the date should be formatted.
+    pub(crate) const FORMAT_DATE: bool = matches!(
+        Self::CONFIG.formatted_components,
+        FC::Date | FC::DateTime | FC::DateTimeOffset
+    );
+    /// Whether the time should be formatted.
+    pub(crate) const FORMAT_TIME: bool = matches!(
+        Self::CONFIG.formatted_components,
+        FC::Time | FC::DateTime | FC::DateTimeOffset | FC::TimeOffset
+    );
+    /// Whether the UTC offset should be formatted.
+    pub(crate) const FORMAT_OFFSET: bool = matches!(
+        Self::CONFIG.formatted_components,
+        FC::Offset | FC::DateTimeOffset | FC::TimeOffset
+    );
+    /// Whether the year is six digits.
+    pub(crate) const YEAR_IS_SIX_DIGITS: bool = Self::CONFIG.year_is_six_digits;
+    /// Whether the format contains separators (such as `-` or `:`).
+    pub(crate) const USE_SEPARATORS: bool = Self::CONFIG.use_separators;
+    /// Which format to use for the date.
+    pub(crate) const DATE_KIND: DateKind = Self::CONFIG.date_kind;
+    /// The precision and number of decimal digits to use for the time.
+    pub(crate) const TIME_PRECISION: TimePrecision = Self::CONFIG.time_precision;
+    /// The precision for the UTC offset.
+    pub(crate) const OFFSET_PRECISION: OffsetPrecision = Self::CONFIG.offset_precision;
+}
+
+impl Config {
+    /// Encode the configuration, permitting it to be used as a const parameter of [`Iso8601`].
+    ///
+    /// The value returned by this method must only be used as a const parameter to [`Iso8601`]. Any
+    /// other usage is unspecified behavior.
+    pub const fn encode(&self) -> EncodedConfig {
+        let mut bytes = [0; EncodedConfig::BITS as usize / 8];
+
+        bytes[0] = match self.formatted_components {
+            FC::None => 0,
+            FC::Date => 1,
+            FC::Time => 2,
+            FC::Offset => 3,
+            FC::DateTime => 4,
+            FC::DateTimeOffset => 5,
+            FC::TimeOffset => 6,
+        };
+        bytes[1] = self.use_separators as _;
+        bytes[2] = self.year_is_six_digits as _;
+        bytes[3] = match self.date_kind {
+            DateKind::Calendar => 0,
+            DateKind::Week => 1,
+            DateKind::Ordinal => 2,
+        };
+        bytes[4] = match self.time_precision {
+            TimePrecision::Hour { .. } => 0,
+            TimePrecision::Minute { .. } => 1,
+            TimePrecision::Second { .. } => 2,
+        };
+        bytes[5] = match self.time_precision {
+            TimePrecision::Hour { decimal_digits }
+            | TimePrecision::Minute { decimal_digits }
+            | TimePrecision::Second { decimal_digits } => match decimal_digits {
+                None => 0,
+                Some(decimal_digits) => decimal_digits.get(),
+            },
+        };
+        bytes[6] = match self.offset_precision {
+            OffsetPrecision::Hour => 0,
+            OffsetPrecision::Minute => 1,
+        };
+
+        EncodedConfig::from_be_bytes(bytes)
+    }
+
+    /// Decode the configuration. The configuration must have been generated from
+    /// [`Config::encode`].
+    pub(super) const fn decode(encoded: EncodedConfig) -> Self {
+        let bytes = encoded.to_be_bytes();
+
+        let formatted_components = match bytes[0] {
+            0 => FC::None,
+            1 => FC::Date,
+            2 => FC::Time,
+            3 => FC::Offset,
+            4 => FC::DateTime,
+            5 => FC::DateTimeOffset,
+            6 => FC::TimeOffset,
+            _ => panic!("invalid configuration"),
+        };
+        let use_separators = match bytes[1] {
+            0 => false,
+            1 => true,
+            _ => panic!("invalid configuration"),
+        };
+        let year_is_six_digits = match bytes[2] {
+            0 => false,
+            1 => true,
+            _ => panic!("invalid configuration"),
+        };
+        let date_kind = match bytes[3] {
+            0 => DateKind::Calendar,
+            1 => DateKind::Week,
+            2 => DateKind::Ordinal,
+            _ => panic!("invalid configuration"),
+        };
+        let time_precision = match bytes[4] {
+            0 => TimePrecision::Hour {
+                decimal_digits: NonZeroU8::new(bytes[5]),
+            },
+            1 => TimePrecision::Minute {
+                decimal_digits: NonZeroU8::new(bytes[5]),
+            },
+            2 => TimePrecision::Second {
+                decimal_digits: NonZeroU8::new(bytes[5]),
+            },
+            _ => panic!("invalid configuration"),
+        };
+        let offset_precision = match bytes[6] {
+            0 => OffsetPrecision::Hour,
+            1 => OffsetPrecision::Minute,
+            _ => panic!("invalid configuration"),
+        };
+
+        // No `for` loops in `const fn`.
+        let mut idx = 7; // first unused byte
+        while idx < EncodedConfig::BITS as usize / 8 {
+            assert!(bytes[idx] == 0, "invalid configuration");
+            idx += 1;
+        }
+
+        Self {
+            formatted_components,
+            use_separators,
+            year_is_six_digits,
+            date_kind,
+            time_precision,
+            offset_precision,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    macro_rules! eq {
+        ($a:expr, $b:expr) => {{
+            let a = $a;
+            let b = $b;
+            a.formatted_components == b.formatted_components
+                && a.use_separators == b.use_separators
+                && a.year_is_six_digits == b.year_is_six_digits
+                && a.date_kind == b.date_kind
+                && a.time_precision == b.time_precision
+                && a.offset_precision == b.offset_precision
+        }};
+    }
+
+    #[test]
+    fn encoding_roundtrip() {
+        macro_rules! assert_roundtrip {
+            ($config:expr) => {
+                let config = $config;
+                let encoded = config.encode();
+                let decoded = Config::decode(encoded);
+                assert!(eq!(config, decoded));
+            };
+        }
+
+        assert_roundtrip!(Config::DEFAULT);
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::None));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::Date));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::Time));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::Offset));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::DateTime));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::DateTimeOffset));
+        assert_roundtrip!(Config::DEFAULT.set_formatted_components(FC::TimeOffset));
+        assert_roundtrip!(Config::DEFAULT.set_use_separators(false));
+        assert_roundtrip!(Config::DEFAULT.set_use_separators(true));
+        assert_roundtrip!(Config::DEFAULT.set_year_is_six_digits(false));
+        assert_roundtrip!(Config::DEFAULT.set_year_is_six_digits(true));
+        assert_roundtrip!(Config::DEFAULT.set_date_kind(DateKind::Calendar));
+        assert_roundtrip!(Config::DEFAULT.set_date_kind(DateKind::Week));
+        assert_roundtrip!(Config::DEFAULT.set_date_kind(DateKind::Ordinal));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Hour {
+            decimal_digits: None,
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Minute {
+            decimal_digits: None,
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Second {
+            decimal_digits: None,
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Hour {
+            decimal_digits: NonZeroU8::new(1),
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Minute {
+            decimal_digits: NonZeroU8::new(1),
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_time_precision(TimePrecision::Second {
+            decimal_digits: NonZeroU8::new(1),
+        }));
+        assert_roundtrip!(Config::DEFAULT.set_offset_precision(OffsetPrecision::Hour));
+        assert_roundtrip!(Config::DEFAULT.set_offset_precision(OffsetPrecision::Minute));
+    }
+
+    macro_rules! assert_decode_fail {
+        ($encoding:expr) => {
+            assert!(
+                std::panic::catch_unwind(|| {
+                    Config::decode($encoding);
+                })
+                .is_err()
+            );
+        };
+    }
+
+    #[test]
+    fn decode_fail() {
+        assert_decode_fail!(0x07_00_00_00_00_00_00_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_02_00_00_00_00_00_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_00_02_00_00_00_00_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_00_00_03_00_00_00_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_00_00_00_03_00_00_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_00_00_00_00_00_02_00_00_00_00_00_00_00_00_00);
+        assert_decode_fail!(0x00_00_00_00_00_00_00_01_00_00_00_00_00_00_00_00);
+    }
+}
diff --git a/third_party/rust/time/src/format_description/well_known/rfc2822.rs b/third_party/rust/time/src/format_description/well_known/rfc2822.rs
new file mode 100644
index 0000000000..3c890ab107
--- /dev/null
+++ b/third_party/rust/time/src/format_description/well_known/rfc2822.rs
@@ -0,0 +1,30 @@
+//! The format described in RFC 2822.
+
+/// The format described in [RFC 2822](https://tools.ietf.org/html/rfc2822#section-3.3).
+///
+/// Example: Fri, 21 Nov 1997 09:55:06 -0600
+///
+/// # Examples
+#[cfg_attr(feature = "parsing", doc = "```rust")]
+#[cfg_attr(not(feature = "parsing"), doc = "```rust,ignore")]
+/// # use time::{format_description::well_known::Rfc2822, OffsetDateTime};
+/// use time_macros::datetime;
+/// assert_eq!(
+///     OffsetDateTime::parse("Sat, 12 Jun 1993 13:25:19 GMT", &Rfc2822)?,
+///     datetime!(1993-06-12 13:25:19 +00:00)
+/// );
+/// # Ok::<_, time::Error>(())
+/// ```
+///
+#[cfg_attr(feature = "formatting", doc = "```rust")]
+#[cfg_attr(not(feature = "formatting"), doc = "```rust,ignore")]
+/// # use time::format_description::well_known::Rfc2822;
+/// # use time_macros::datetime;
+/// assert_eq!(
+///     datetime!(1997-11-21 09:55:06 -06:00).format(&Rfc2822)?,
+///     "Fri, 21 Nov 1997 09:55:06 -0600"
+/// );
+/// # Ok::<_, time::Error>(())
+/// ```
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Rfc2822;
diff --git a/third_party/rust/time/src/format_description/well_known/rfc3339.rs b/third_party/rust/time/src/format_description/well_known/rfc3339.rs
new file mode 100644
index 0000000000..f0873cbac5
--- /dev/null
+++ b/third_party/rust/time/src/format_description/well_known/rfc3339.rs
@@ -0,0 +1,30 @@
+//! The format described in RFC 3339.
+
+/// The format described in [RFC 3339](https://tools.ietf.org/html/rfc3339#section-5.6).
+///
+/// Format example: 1985-04-12T23:20:50.52Z
+///
+/// # Examples
+#[cfg_attr(feature = "parsing", doc = "```rust")]
+#[cfg_attr(not(feature = "parsing"), doc = "```rust,ignore")]
+/// # use time::{format_description::well_known::Rfc3339, OffsetDateTime};
+/// # use time_macros::datetime;
+/// assert_eq!(
+///     OffsetDateTime::parse("1985-04-12T23:20:50.52Z", &Rfc3339)?,
+///     datetime!(1985-04-12 23:20:50.52 +00:00)
+/// );
+/// # Ok::<_, time::Error>(())
+/// ```
+///
+#[cfg_attr(feature = "formatting", doc = "```rust")]
+#[cfg_attr(not(feature = "formatting"), doc = "```rust,ignore")]
+/// # use time::format_description::well_known::Rfc3339;
+/// # use time_macros::datetime;
+/// assert_eq!(
+///     datetime!(1985-04-12 23:20:50.52 +00:00).format(&Rfc3339)?,
+///     "1985-04-12T23:20:50.52Z"
+/// );
+/// # Ok::<_, time::Error>(())
+/// ```
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Rfc3339;