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Fix {f16,f32,f64,f128}::div_euclid #133755

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Fix {f16,f32,f64,f128}::div_euclid #133755

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17 changes: 15 additions & 2 deletions library/std/src/f128.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -309,8 +309,21 @@ impl f128 {
#[unstable(feature = "f128", issue = "116909")]
#[must_use = "method returns a new number and does not mutate the original value"]
pub fn rem_euclid(self, rhs: f128) -> f128 {
let r = self % rhs;
if r < 0.0 { r + rhs.abs() } else { r }
if rhs.is_infinite() {
if self.is_infinite() || self.is_nan() {
return f128::NAN;
} else {
return self;
}
}
// FIXME(#133755): Though `self % rhs` is documented to be
// equivalent to this, it is not, and the distinction matters
// here.
let r = self - rhs * (self / rhs).trunc();
if r < 0.0 {
return if rhs > 0.0 { r + rhs } else { r - rhs };
}
r
Comment on lines +323 to +326
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nit: is there a reason this has a return instead of

Suggested change
if r < 0.0 {
return if rhs > 0.0 { r + rhs } else { r - rhs };
}
r
if r < 0.0 {
if rhs > 0.0 { r + rhs } else { r - rhs }
} else {
r
}

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For consistency (both stylistic and as it makes the mathematically analogy more clear), I followed the style of the existing div_euclid implementation:

    pub fn div_euclid(self, rhs: f64) -> f64 {
        let q = (self / rhs).trunc();
        if self % rhs < 0.0 {
            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
        }
        q
    }

}

/// Raises a number to an integer power.
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17 changes: 15 additions & 2 deletions library/std/src/f16.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -309,8 +309,21 @@ impl f16 {
#[unstable(feature = "f16", issue = "116909")]
#[must_use = "method returns a new number and does not mutate the original value"]
pub fn rem_euclid(self, rhs: f16) -> f16 {
let r = self % rhs;
if r < 0.0 { r + rhs.abs() } else { r }
if rhs.is_infinite() {
if self.is_infinite() || self.is_nan() {
return f16::NAN;
} else {
return self;
}
}
// FIXME(#133755): Though `self % rhs` is documented to be
// equivalent to this, it is not, and the distinction matters
// here.
let r = self - rhs * (self / rhs).trunc();
if r < 0.0 {
return if rhs > 0.0 { r + rhs } else { r - rhs };
}
r
}

/// Raises a number to an integer power.
Expand Down
17 changes: 15 additions & 2 deletions library/std/src/f32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -285,8 +285,21 @@ impl f32 {
#[inline]
#[stable(feature = "euclidean_division", since = "1.38.0")]
pub fn rem_euclid(self, rhs: f32) -> f32 {
let r = self % rhs;
if r < 0.0 { r + rhs.abs() } else { r }
if rhs.is_infinite() {
if self.is_infinite() || self.is_nan() {
return f32::NAN;
} else {
return self;
}
}
// FIXME(#133755): Though `self % rhs` is documented to be
// equivalent to this, it is not, and the distinction matters
// here.
let r = self - rhs * (self / rhs).trunc();
if r < 0.0 {
return if rhs > 0.0 { r + rhs } else { r - rhs };
}
r
}

/// Raises a number to an integer power.
Expand Down
17 changes: 15 additions & 2 deletions library/std/src/f64.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -285,8 +285,21 @@ impl f64 {
#[inline]
#[stable(feature = "euclidean_division", since = "1.38.0")]
pub fn rem_euclid(self, rhs: f64) -> f64 {
let r = self % rhs;
if r < 0.0 { r + rhs.abs() } else { r }
if rhs.is_infinite() {
if self.is_infinite() || self.is_nan() {
return f64::NAN;
} else {
return self;
}
}
// FIXME(#133755): Though `self % rhs` is documented to be
// equivalent to this, it is not, and the distinction matters
// here.
let r = self - rhs * (self / rhs).trunc();
if r < 0.0 {
return if rhs > 0.0 { r + rhs } else { r - rhs };
}
r
}

/// Raises a number to an integer power.
Expand Down
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