Add IEEE 754 compliant fmt/parse of -0, infinity, NaN

library/alloc/src/fmt.rs

@@ -157,9 +157,8 @@
 //!
 //! * `+` - This is intended for numeric types and indicates that the sign
 //! should always be printed. Positive signs are never printed by
-//! default, and the negative sign is only printed by default for the
-//! `Signed` trait. This flag indicates that the correct sign (`+` or `-`)
-//! should always be printed.
+//! default, and the negative sign is only printed by default for signed values.
+//! This flag indicates that the correct sign (`+` or `-`) should always be printed.
 //! * `-` - Currently not used
 //! * `#` - This flag indicates that the "alternate" form of printing should
 //! be used. The alternate forms are:

library/alloc/tests/fmt.rs

@@ -154,8 +154,7 @@ fn test_format_macro_interface() {
  t!(format!("{:+10.3e}", -1.2345e6f64), " -1.234e6");
 
  // Float edge cases
- t!(format!("{}", -0.0), "0");
- t!(format!("{:?}", -0.0), "-0.0");
+ t!(format!("{}", -0.0), "-0");
  t!(format!("{:?}", 0.0), "0.0");
 
  // sign aware zero padding

library/core/src/fmt/float.rs

@@ -54,21 +54,14 @@ where
 }
 
 // Common code of floating point Debug and Display.
-fn float_to_decimal_common<T>(
- fmt: &mut Formatter<'_>,
- num: &T,
- negative_zero: bool,
- min_precision: usize,
-) -> Result
+fn float_to_decimal_common<T>(fmt: &mut Formatter<'_>, num: &T, min_precision: usize) -> Result
 where
  T: flt2dec::DecodableFloat,
 {
  let force_sign = fmt.sign_plus();
- let sign = match (force_sign, negative_zero) {
- (false, false) => flt2dec::Sign::Minus,
- (false, true) => flt2dec::Sign::MinusRaw,
- (true, false) => flt2dec::Sign::MinusPlus,
- (true, true) => flt2dec::Sign::MinusPlusRaw,
+ let sign = match force_sign {
+ false => flt2dec::Sign::Minus,
+ true => flt2dec::Sign::MinusPlus,
  };
 
  if let Some(precision) = fmt.precision {
@@ -156,14 +149,14 @@ macro_rules! floating {
  #[stable(feature = "rust1", since = "1.0.0")]
  impl Debug for $ty {
  fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
- float_to_decimal_common(fmt, self, true, 1)
+ float_to_decimal_common(fmt, self, 1)
  }
  }
 
  #[stable(feature = "rust1", since = "1.0.0")]
  impl Display for $ty {
  fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
- float_to_decimal_common(fmt, self, false, 0)
+ float_to_decimal_common(fmt, self, 0)
  }
  }
 

library/core/src/num/dec2flt/mod.rs

@@ -239,13 +239,15 @@ fn dec2flt<T: RawFloat>(s: &str) -> Result<T, ParseFloatError> {
  ParseResult::Valid(decimal) => convert(decimal)?,
  ParseResult::ShortcutToInf => T::INFINITY,
  ParseResult::ShortcutToZero => T::ZERO,
- ParseResult::Invalid => match s {
- "inf" => T::INFINITY,
- "NaN" => T::NAN,
- _ => {
+ ParseResult::Invalid => {
+ if s.eq_ignore_ascii_case("nan") {
+ T::NAN
+ } else if s.eq_ignore_ascii_case("inf") || s.eq_ignore_ascii_case("infinity") {
+ T::INFINITY
+ } else {
  return Err(pfe_invalid());
  }
- },
+ }
  };
 
  match sign {

library/core/src/num/flt2dec/mod.rs

@@ -399,45 +399,25 @@ fn digits_to_exp_str<'a>(
 /// Sign formatting options.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum Sign {
- /// Prints `-` only for the negative non-zero values.
- Minus, // -inf -1 0 0 1 inf nan
- /// Prints `-` only for any negative values (including the negative zero).
- MinusRaw, // -inf -1 -0 0 1 inf nan
- /// Prints `-` for the negative non-zero values, or `+` otherwise.
- MinusPlus, // -inf -1 +0 +0 +1 +inf nan
- /// Prints `-` for any negative values (including the negative zero), or `+` otherwise.
- MinusPlusRaw, // -inf -1 -0 +0 +1 +inf nan
+ /// Prints `-` for any negative value.
+ Minus, // -inf -1 -0 0 1 inf nan
+ /// Prints `-` for any negative value, or `+` otherwise.
+ MinusPlus, // -inf -1 -0 +0 +1 +inf nan
 }
 
 /// Returns the static byte string corresponding to the sign to be formatted.
 /// It can be either `""`, `"+"` or `"-"`.
 fn determine_sign(sign: Sign, decoded: &FullDecoded, negative: bool) -> &'static str {
  match (*decoded, sign) {
  (FullDecoded::Nan, _) => "",
- (FullDecoded::Zero, Sign::Minus) => "",
- (FullDecoded::Zero, Sign::MinusRaw) => {
+ (_, Sign::Minus) => {
  if negative {
  "-"
  } else {
  ""
  }
  }
- (FullDecoded::Zero, Sign::MinusPlus) => "+",
- (FullDecoded::Zero, Sign::MinusPlusRaw) => {
- if negative {
- "-"
- } else {
- "+"
- }
- }
- (_, Sign::Minus | Sign::MinusRaw) => {
- if negative {
- "-"
- } else {
- ""
- }
- }
- (_, Sign::MinusPlus | Sign::MinusPlusRaw) => {
+ (_, Sign::MinusPlus) => {
  if negative {
  "-"
  } else {