diff --git a/library/alloc/src/fmt.rs b/library/alloc/src/fmt.rs index 695dddb25ee..e40de13f3d4 100644 --- a/library/alloc/src/fmt.rs +++ b/library/alloc/src/fmt.rs @@ -596,6 +596,8 @@ pub use core::fmt::{Arguments, write}; pub use core::fmt::{Binary, Octal}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::fmt::{Debug, Display}; +#[unstable(feature = "formatting_options", issue = "118117")] +pub use core::fmt::{DebugAsHex, FormattingOptions, Sign}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::fmt::{DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple}; #[stable(feature = "rust1", since = "1.0.0")] diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs index 84f4202c02a..927c3aa23b9 100644 --- a/library/alloc/src/lib.rs +++ b/library/alloc/src/lib.rs @@ -117,6 +117,7 @@ #![feature(extend_one_unchecked)] #![feature(fmt_internals)] #![feature(fn_traits)] +#![feature(formatting_options)] #![feature(hasher_prefixfree_extras)] #![feature(inplace_iteration)] #![feature(iter_advance_by)] diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs index e0576c25515..d0d0276c55e 100644 --- a/library/alloc/src/string.rs +++ b/library/alloc/src/string.rs @@ -43,6 +43,7 @@ #![stable(feature = "rust1", since = "1.0.0")] use core::error::Error; +use core::fmt::FormattingOptions; use core::iter::FusedIterator; #[cfg(not(no_global_oom_handling))] use core::iter::from_fn; @@ -2682,7 +2683,7 @@ impl ToString for T { #[inline] default fn to_string(&self) -> String { let mut buf = String::new(); - let mut formatter = core::fmt::Formatter::new(&mut buf); + let mut formatter = core::fmt::Formatter::new(&mut buf, FormattingOptions::new()); // Bypass format_args!() to avoid write_str with zero-length strs fmt::Display::fmt(self, &mut formatter) .expect("a Display implementation returned an error unexpectedly"); diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs index 1023fad8037..8e08b7fe983 100644 --- a/library/core/src/fmt/mod.rs +++ b/library/core/src/fmt/mod.rs @@ -33,6 +33,19 @@ pub enum Alignment { Center, } +#[doc(hidden)] +#[unstable(feature = "fmt_internals", reason = "internal to standard library", issue = "none")] +impl From for Option { + fn from(value: rt::Alignment) -> Self { + match value { + rt::Alignment::Left => Some(Alignment::Left), + rt::Alignment::Right => Some(Alignment::Right), + rt::Alignment::Center => Some(Alignment::Center), + rt::Alignment::Unknown => None, + } + } +} + #[stable(feature = "debug_builders", since = "1.2.0")] pub use self::builders::{DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple}; #[unstable(feature = "debug_closure_helpers", issue = "117729")] @@ -247,6 +260,243 @@ impl Write for &mut W { } } +/// The signedness of a [`Formatter`] (or of a [`FormattingOptions`]). +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +#[unstable(feature = "formatting_options", issue = "118117")] +pub enum Sign { + /// Represents the `+` flag. + Plus, + /// Represents the `-` flag. + Minus, +} + +/// Specifies whether the [`Debug`] trait should use lower-/upper-case +/// hexadecimal or normal integers. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +#[unstable(feature = "formatting_options", issue = "118117")] +pub enum DebugAsHex { + /// Use lower-case hexadecimal integers for the `Debug` trait (like [the `x?` type](../../std/fmt/index.html#formatting-traits)). + Lower, + /// Use upper-case hexadecimal integers for the `Debug` trait (like [the `x?` type](../../std/fmt/index.html#formatting-traits)). + Upper, +} + +/// Options for formatting. +/// +/// `FormattingOptions` is a [`Formatter`] without an attached [`Write`] trait. +/// It is mainly used to construct `Formatter` instances. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +#[unstable(feature = "formatting_options", issue = "118117")] +pub struct FormattingOptions { + sign: Option, + sign_aware_zero_pad: bool, + alternate: bool, + fill: char, + alignment: Option, + width: Option, + precision: Option, + debug_as_hex: Option, +} + +impl FormattingOptions { + /// Construct a new `FormatterBuilder` with the supplied `Write` trait + /// object for output that is equivalent to the `{}` formatting + /// specifier: + /// + /// - no flags, + /// - filled with spaces, + /// - no alignment, + /// - no width, + /// - no precision, and + /// - no [`DebugAsHex`] output mode. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn new() -> Self { + Self { + sign: None, + sign_aware_zero_pad: false, + alternate: false, + fill: ' ', + alignment: None, + width: None, + precision: None, + debug_as_hex: None, + } + } + + /// Sets or removes the sign (the `+` or the `-` flag). + /// + /// - `+`: This is intended for numeric types and indicates that the sign + /// should always be printed. By default only the negative sign of signed + /// values is printed, and the sign of positive or unsigned values is + /// omitted. This flag indicates that the correct sign (+ or -) should + /// always be printed. + /// - `-`: Currently not used + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn sign(&mut self, sign: Option) -> &mut Self { + self.sign = sign; + self + } + /// Sets or unsets the `0` flag. + /// + /// This is used to indicate for integer formats that the padding to width should both be done with a 0 character as well as be sign-aware + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn sign_aware_zero_pad(&mut self, sign_aware_zero_pad: bool) -> &mut Self { + self.sign_aware_zero_pad = sign_aware_zero_pad; + self + } + /// Sets or unsets the `#` flag. + /// + /// This flag indicates that the "alternate" form of printing should be + /// used. The alternate forms are: + /// - [`Debug`] : pretty-print the [`Debug`] formatting (adds linebreaks and indentation) + /// - [`LowerHex`] as well as [`UpperHex`] - precedes the argument with a `0x` + /// - [`Octal`] - precedes the argument with a `0b` + /// - [`Binary`] - precedes the argument with a `0o` + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn alternate(&mut self, alternate: bool) -> &mut Self { + self.alternate = alternate; + self + } + /// Sets the fill character. + /// + /// The optional fill character and alignment is provided normally in + /// conjunction with the width parameter. This indicates that if the value + /// being formatted is smaller than width some extra characters will be + /// printed around it. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn fill(&mut self, fill: char) -> &mut Self { + self.fill = fill; + self + } + /// Sets or removes the alignment. + /// + /// The alignment specifies how the value being formatted should be + /// positioned if it is smaller than the width of the formatter. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn alignment(&mut self, alignment: Option) -> &mut Self { + self.alignment = alignment; + self + } + /// Sets or removes the width. + /// + /// This is a parameter for the “minimum width” that the format should take + /// up. If the value’s string does not fill up this many characters, then + /// the padding specified by [`FormattingOptions::fill`]/[`FormattingOptions::alignment`] + /// will be used to take up the required space. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn width(&mut self, width: Option) -> &mut Self { + self.width = width; + self + } + /// Sets or removes the precision. + /// + /// - For non-numeric types, this can be considered a “maximum width”. If + /// the resulting string is longer than this width, then it is truncated + /// down to this many characters and that truncated value is emitted with + /// proper fill, alignment and width if those parameters are set. + /// - For integral types, this is ignored. + /// - For floating-point types, this indicates how many digits after the + /// decimal point should be printed. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn precision(&mut self, precision: Option) -> &mut Self { + self.precision = precision; + self + } + /// Specifies whether the [`Debug`] trait should use lower-/upper-case + /// hexadecimal or normal integers + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn debug_as_hex(&mut self, debug_as_hex: Option) -> &mut Self { + self.debug_as_hex = debug_as_hex; + self + } + + /// Returns the current sign (the `+` or the `-` flag). + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_sign(&self) -> Option { + self.sign + } + /// Returns the current `0` flag. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_sign_aware_zero_pad(&self) -> bool { + self.sign_aware_zero_pad + } + /// Returns the current `#` flag. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_alternate(&self) -> bool { + self.alternate + } + /// Returns the current fill character. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_fill(&self) -> char { + self.fill + } + /// Returns the current alignment. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_alignment(&self) -> Option { + self.alignment + } + /// Returns the current width. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_width(&self) -> Option { + self.width + } + /// Returns the current precision. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_precision(&self) -> Option { + self.precision + } + /// Returns the current precision. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn get_debug_as_hex(&self) -> Option { + self.debug_as_hex + } + + /// Creates a [`Formatter`] that writes its output to the given [`Write`] trait. + /// + /// You may alternatively use [`Formatter::new()`]. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn create_formatter<'a>(self, write: &'a mut (dyn Write + 'a)) -> Formatter<'a> { + Formatter { options: self, buf: write } + } + + #[doc(hidden)] + #[unstable(feature = "fmt_internals", reason = "internal to standard library", issue = "none")] + /// Flags for formatting + pub fn flags(&mut self, flags: u32) { + self.sign = if flags & (1 << rt::Flag::SignPlus as u32) != 0 { + Some(Sign::Plus) + } else if flags & (1 << rt::Flag::SignMinus as u32) != 0 { + Some(Sign::Minus) + } else { + None + }; + self.alternate = (flags & (1 << rt::Flag::Alternate as u32)) != 0; + self.sign_aware_zero_pad = (flags & (1 << rt::Flag::SignAwareZeroPad as u32)) != 0; + self.debug_as_hex = if flags & (1 << rt::Flag::DebugLowerHex as u32) != 0 { + Some(DebugAsHex::Lower) + } else if flags & (1 << rt::Flag::DebugUpperHex as u32) != 0 { + Some(DebugAsHex::Upper) + } else { + None + }; + } + #[doc(hidden)] + #[unstable(feature = "fmt_internals", reason = "internal to standard library", issue = "none")] + /// Flags for formatting + pub fn get_flags(&self) -> u32 { + >::into(self.get_sign() == Some(Sign::Plus)) << rt::Flag::SignPlus as u32 + | >::into(self.get_sign() == Some(Sign::Minus)) + << rt::Flag::SignMinus as u32 + | >::into(self.get_alternate()) << rt::Flag::Alternate as u32 + | >::into(self.get_sign_aware_zero_pad()) + << rt::Flag::SignAwareZeroPad as u32 + | >::into(self.debug_as_hex == Some(DebugAsHex::Lower)) + << rt::Flag::DebugLowerHex as u32 + | >::into(self.debug_as_hex == Some(DebugAsHex::Upper)) + << rt::Flag::DebugUpperHex as u32 + } +} + /// Configuration for formatting. /// /// A `Formatter` represents various options related to formatting. Users do not @@ -260,34 +510,28 @@ impl Write for &mut W { #[stable(feature = "rust1", since = "1.0.0")] #[rustc_diagnostic_item = "Formatter"] pub struct Formatter<'a> { - flags: u32, - fill: char, - align: rt::Alignment, - width: Option, - precision: Option, + options: FormattingOptions, buf: &'a mut (dyn Write + 'a), } impl<'a> Formatter<'a> { - /// Creates a new formatter with default settings. + /// Creates a new formatter with given [`FormattingOptions`]. /// - /// This can be used as a micro-optimization in cases where a full `Arguments` - /// structure (as created by `format_args!`) is not necessary; `Arguments` - /// is a little more expensive to use in simple formatting scenarios. + /// If `write` is a reference to a formatter, it is recommended to use + /// [`Formatter::with_options`] instead as this can borrow the underlying + /// `write`, thereby bypassing one layer of indirection. /// - /// Currently not intended for use outside of the standard library. - #[unstable(feature = "fmt_internals", reason = "internal to standard library", issue = "none")] - #[doc(hidden)] - pub fn new(buf: &'a mut (dyn Write + 'a)) -> Formatter<'a> { - Formatter { - flags: 0, - fill: ' ', - align: rt::Alignment::Unknown, - width: None, - precision: None, - buf, - } + /// You may alternatively use [`FormattingOptions::create_formatter()`]. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn new(write: &'a mut (dyn Write + 'a), options: FormattingOptions) -> Self { + Formatter { options, buf: write } + } + + /// Creates a new formatter based on this one with given [`FormattingOptions`]. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn with_options(&'a mut self, options: FormattingOptions) -> Self { + Formatter { options, buf: self.buf } } } @@ -1165,7 +1409,7 @@ pub trait UpperExp { /// [`write!`]: crate::write! #[stable(feature = "rust1", since = "1.0.0")] pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result { - let mut formatter = Formatter::new(output); + let mut formatter = Formatter::new(output, FormattingOptions::new()); let mut idx = 0; match args.fmt { @@ -1214,14 +1458,14 @@ pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result { } unsafe fn run(fmt: &mut Formatter<'_>, arg: &rt::Placeholder, args: &[rt::Argument<'_>]) -> Result { - fmt.fill = arg.fill; - fmt.align = arg.align; - fmt.flags = arg.flags; + fmt.options.fill(arg.fill); + fmt.options.alignment(arg.align.into()); + fmt.options.flags(arg.flags); // SAFETY: arg and args come from the same Arguments, // which guarantees the indexes are always within bounds. unsafe { - fmt.width = getcount(args, &arg.width); - fmt.precision = getcount(args, &arg.precision); + fmt.options.width(getcount(args, &arg.width)); + fmt.options.precision(getcount(args, &arg.precision)); } // Extract the correct argument @@ -1280,11 +1524,7 @@ impl<'a> Formatter<'a> { buf: wrap(self.buf), // And preserve these - flags: self.flags, - fill: self.fill, - align: self.align, - width: self.width, - precision: self.precision, + options: self.options, } } @@ -1381,14 +1621,15 @@ impl<'a> Formatter<'a> { // The sign and prefix goes before the padding if the fill character // is zero Some(min) if self.sign_aware_zero_pad() => { - let old_fill = crate::mem::replace(&mut self.fill, '0'); - let old_align = crate::mem::replace(&mut self.align, rt::Alignment::Right); + let old_fill = crate::mem::replace(&mut self.options.fill, '0'); + let old_align = + crate::mem::replace(&mut self.options.alignment, Some(Alignment::Right)); write_prefix(self, sign, prefix)?; let post_padding = self.padding(min - width, Alignment::Right)?; self.buf.write_str(buf)?; post_padding.write(self)?; - self.fill = old_fill; - self.align = old_align; + self.options.fill = old_fill; + self.options.alignment = old_align; Ok(()) } // Otherwise, the sign and prefix goes after the padding @@ -1487,12 +1728,7 @@ impl<'a> Formatter<'a> { padding: usize, default: Alignment, ) -> result::Result { - let align = match self.align { - rt::Alignment::Unknown => default, - rt::Alignment::Left => Alignment::Left, - rt::Alignment::Right => Alignment::Right, - rt::Alignment::Center => Alignment::Center, - }; + let align = self.align().unwrap_or(default); let (pre_pad, post_pad) = match align { Alignment::Left => (0, padding), @@ -1530,8 +1766,8 @@ impl<'a> Formatter<'a> { // remove the sign from the formatted parts formatted.sign = ""; width = width.saturating_sub(sign.len()); - self.fill = '0'; - self.align = rt::Alignment::Right; + self.options.fill('0'); + self.options.alignment(Some(Alignment::Right)); } // remaining parts go through the ordinary padding process. @@ -1548,8 +1784,8 @@ impl<'a> Formatter<'a> { } post_padding.write(self) }; - self.fill = old_fill; - self.align = old_align; + self.options.fill(old_fill); + self.options.alignment(old_align); ret } else { // this is the common case and we take a shortcut @@ -1675,7 +1911,7 @@ impl<'a> Formatter<'a> { or `sign_aware_zero_pad` methods instead" )] pub fn flags(&self) -> u32 { - self.flags + self.options.get_flags() } /// Returns the character used as 'fill' whenever there is alignment. @@ -1708,7 +1944,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn fill(&self) -> char { - self.fill + self.options.get_fill() } /// Returns a flag indicating what form of alignment was requested. @@ -1743,12 +1979,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags_align", since = "1.28.0")] pub fn align(&self) -> Option { - match self.align { - rt::Alignment::Left => Some(Alignment::Left), - rt::Alignment::Right => Some(Alignment::Right), - rt::Alignment::Center => Some(Alignment::Center), - rt::Alignment::Unknown => None, - } + self.options.get_alignment() } /// Returns the optionally specified integer width that the output should be. @@ -1778,7 +2009,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn width(&self) -> Option { - self.width + self.options.get_width() } /// Returns the optionally specified precision for numeric types. @@ -1809,7 +2040,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn precision(&self) -> Option { - self.precision + self.options.get_precision() } /// Determines if the `+` flag was specified. @@ -1841,7 +2072,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn sign_plus(&self) -> bool { - self.flags & (1 << rt::Flag::SignPlus as u32) != 0 + self.options.get_sign() == Some(Sign::Plus) } /// Determines if the `-` flag was specified. @@ -1870,7 +2101,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn sign_minus(&self) -> bool { - self.flags & (1 << rt::Flag::SignMinus as u32) != 0 + self.options.get_sign() == Some(Sign::Minus) } /// Determines if the `#` flag was specified. @@ -1898,7 +2129,7 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn alternate(&self) -> bool { - self.flags & (1 << rt::Flag::Alternate as u32) != 0 + self.options.get_alternate() } /// Determines if the `0` flag was specified. @@ -1924,17 +2155,17 @@ impl<'a> Formatter<'a> { #[must_use] #[stable(feature = "fmt_flags", since = "1.5.0")] pub fn sign_aware_zero_pad(&self) -> bool { - self.flags & (1 << rt::Flag::SignAwareZeroPad as u32) != 0 + self.options.get_sign_aware_zero_pad() } // FIXME: Decide what public API we want for these two flags. // https://github.com/rust-lang/rust/issues/48584 fn debug_lower_hex(&self) -> bool { - self.flags & (1 << rt::Flag::DebugLowerHex as u32) != 0 + self.options.debug_as_hex == Some(DebugAsHex::Lower) } fn debug_upper_hex(&self) -> bool { - self.flags & (1 << rt::Flag::DebugUpperHex as u32) != 0 + self.options.debug_as_hex == Some(DebugAsHex::Upper) } /// Creates a [`DebugStruct`] builder designed to assist with creation of @@ -2350,6 +2581,18 @@ impl<'a> Formatter<'a> { pub fn debug_map<'b>(&'b mut self) -> DebugMap<'b, 'a> { builders::debug_map_new(self) } + + /// Returns the sign of this formatter (`+` or `-`). + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn sign(&self) -> Option { + self.options.get_sign() + } + + /// Returns the formatting options this formatter corresponds to. + #[unstable(feature = "formatting_options", issue = "118117")] + pub fn options(&self) -> FormattingOptions { + self.options + } } #[stable(since = "1.2.0", feature = "formatter_write")] @@ -2527,25 +2770,27 @@ impl Pointer for *const T { /// [problematic]: https://github.com/rust-lang/rust/issues/95489 pub(crate) fn pointer_fmt_inner(ptr_addr: usize, f: &mut Formatter<'_>) -> Result { let old_width = f.width(); - let old_flags = f.flags(); + let old_alternate = f.alternate(); + let old_zero_pad = f.sign_aware_zero_pad(); // The alternate flag is already treated by LowerHex as being special- // it denotes whether to prefix with 0x. We use it to work out whether // or not to zero extend, and then unconditionally set it to get the // prefix. if f.alternate() { - f.flags |= 1 << (rt::Flag::SignAwareZeroPad as u32); + f.options.sign_aware_zero_pad(true); if f.width().is_none() { - f.width = Some((usize::BITS / 4) as usize + 2); + f.options.width(Some((usize::BITS / 4) as usize + 2)); } } - f.flags |= 1 << (rt::Flag::Alternate as u32); + f.options.alternate(true); let ret = LowerHex::fmt(&ptr_addr, f); - f.width = old_width; - f.flags = old_flags; + f.options.width(old_width); + f.options.alternate(old_alternate); + f.options.sign_aware_zero_pad(old_zero_pad); ret } diff --git a/library/core/tests/fmt/mod.rs b/library/core/tests/fmt/mod.rs index f7512abae38..9aedfdefa68 100644 --- a/library/core/tests/fmt/mod.rs +++ b/library/core/tests/fmt/mod.rs @@ -50,3 +50,31 @@ fn test_maybe_uninit_short() { let x = core::mem::MaybeUninit::new(0u32); assert_eq!(format!("{x:?}"), "MaybeUninit"); } + +#[test] +fn formatting_options_flags() { + use core::fmt::*; + for sign in [None, Some(Sign::Plus), Some(Sign::Minus)] { + for alternate in [true, false] { + for sign_aware_zero_pad in [true, false] { + for debug_as_hex in [None, Some(DebugAsHex::Lower), Some(DebugAsHex::Upper)] { + let mut original_formatting_options = FormattingOptions::new(); + original_formatting_options + .sign(sign) + .sign_aware_zero_pad(sign_aware_zero_pad) + .alternate(alternate) + .debug_as_hex(debug_as_hex); + + let mut formatting_options_with_flags_set_to_self = original_formatting_options; + formatting_options_with_flags_set_to_self + .flags(formatting_options_with_flags_set_to_self.get_flags()); + + assert_eq!( + original_formatting_options, formatting_options_with_flags_set_to_self, + "Reading and setting flags changes FormattingOptions; Sign({sign:?}), Alternate({alternate:?}). DebugAsHex({debug_as_hex:?})" + ) + } + } + } + } +} diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs index e0b1c21e1ec..eae6ef9e24c 100644 --- a/library/core/tests/lib.rs +++ b/library/core/tests/lib.rs @@ -31,6 +31,7 @@ #![feature(float_minimum_maximum)] #![feature(flt2dec)] #![feature(fmt_internals)] +#![feature(formatting_options)] #![feature(freeze)] #![feature(future_join)] #![feature(generic_assert_internals)] diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs index 6be27b283b2..49a03220039 100644 --- a/library/std/src/lib.rs +++ b/library/std/src/lib.rs @@ -292,6 +292,7 @@ #![feature(dropck_eyepatch)] #![feature(f128)] #![feature(f16)] +#![feature(formatting_options)] #![feature(if_let_guard)] #![feature(intra_doc_pointers)] #![feature(lang_items)] diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs index 97f800dddaa..dca5ccca0c4 100644 --- a/library/std/src/panicking.rs +++ b/library/std/src/panicking.rs @@ -623,7 +623,7 @@ pub fn begin_panic_handler(info: &core::panic::PanicInfo<'_>) -> ! { // Lazily, the first time this gets called, run the actual string formatting. self.string.get_or_insert_with(|| { let mut s = String::new(); - let mut fmt = fmt::Formatter::new(&mut s); + let mut fmt = fmt::Formatter::new(&mut s, fmt::FormattingOptions::new()); let _err = fmt::Display::fmt(&inner, &mut fmt); s })