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Miri: non-deterministic floating point operations in foreign_items #143906

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5a5027a
Move float non determinism helpers to math.rs
LorrensP-2158466 Jul 7, 2025
f391acb
Implement nondet behaviour and change/add tests.
LorrensP-2158466 Jul 7, 2025
ba59bff
Change stdlib float tests to account for miri nondet floats.
LorrensP-2158466 Jul 13, 2025
11247c0
use pi/4 instead of pi/2 for asin tests
LorrensP-2158466 Jul 25, 2025
92cbc7c
change std f32 tests
LorrensP-2158466 Jul 31, 2025
d132189
change std f64 tests
LorrensP-2158466 Jul 31, 2025
4462568
address review and fix test failures
LorrensP-2158466 Aug 3, 2025
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8 changes: 4 additions & 4 deletions library/core/src/num/f32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1879,7 +1879,7 @@ pub mod math {
///
/// let x = 2.0_f32;
/// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
/// assert!(abs_difference <= 1e-5);
/// assert!(abs_difference <= 1e-4);
///
/// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
/// ```
Expand Down Expand Up @@ -1942,8 +1942,8 @@ pub mod math {
/// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
/// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
///
/// assert!(abs_difference_x <= f32::EPSILON);
/// assert!(abs_difference_y <= f32::EPSILON);
/// assert!(abs_difference_x <= 1e-4);
/// assert!(abs_difference_y <= 1e-4);
/// ```
///
/// _This standalone function is for testing only.
Expand Down Expand Up @@ -1988,7 +1988,7 @@ pub mod math {
/// // x^(1/3) - 2 == 0
/// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-4);
/// ```
///
/// _This standalone function is for testing only.
Expand Down
42 changes: 21 additions & 21 deletions library/std/src/num/f32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -582,8 +582,8 @@ impl f32 {
/// let abs_difference_x = (x.abs_sub(1.0) - 2.0).abs();
/// let abs_difference_y = (y.abs_sub(1.0) - 0.0).abs();
///
/// assert!(abs_difference_x <= f32::EPSILON);
/// assert!(abs_difference_y <= f32::EPSILON);
/// assert!(abs_difference_x <= 1e-6);
/// assert!(abs_difference_y <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -621,7 +621,7 @@ impl f32 {
/// // x^(1/3) - 2 == 0
/// let abs_difference = (x.cbrt() - 2.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -652,7 +652,7 @@ impl f32 {
/// // sqrt(x^2 + y^2)
/// let abs_difference = (x.hypot(y) - (x.powi(2) + y.powi(2)).sqrt()).abs();
///
/// assert!(abs_difference <= 1e-6);
/// assert!(abs_difference <= 1e-5);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -725,7 +725,7 @@ impl f32 {
/// let x = std::f32::consts::FRAC_PI_4;
/// let abs_difference = (x.tan() - 1.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand All @@ -749,12 +749,12 @@ impl f32 {
/// # Examples
///
/// ```
/// let f = std::f32::consts::FRAC_PI_2;
/// let f = std::f32::consts::FRAC_PI_4;
///
/// // asin(sin(pi/2))
/// let abs_difference = (f.sin().asin() - std::f32::consts::FRAC_PI_2).abs();
/// let abs_difference = (f.sin().asin() - f).abs();
///
/// assert!(abs_difference <= 1e-3);
/// assert!(abs_difference <= 1e-6);
/// ```
#[doc(alias = "arcsin")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -813,7 +813,7 @@ impl f32 {
/// // atan(tan(1))
/// let abs_difference = (f.tan().atan() - 1.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[doc(alias = "arctan")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -854,8 +854,8 @@ impl f32 {
/// let abs_difference_1 = (y1.atan2(x1) - (-std::f32::consts::FRAC_PI_4)).abs();
/// let abs_difference_2 = (y2.atan2(x2) - (3.0 * std::f32::consts::FRAC_PI_4)).abs();
///
/// assert!(abs_difference_1 <= f32::EPSILON);
/// assert!(abs_difference_2 <= f32::EPSILON);
/// assert!(abs_difference_1 <= 1e-5);
/// assert!(abs_difference_2 <= 1e-5);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -884,8 +884,8 @@ impl f32 {
/// let abs_difference_0 = (f.0 - x.sin()).abs();
/// let abs_difference_1 = (f.1 - x.cos()).abs();
///
/// assert!(abs_difference_0 <= 1e-6);
/// assert!(abs_difference_1 <= 1e-6);
/// assert!(abs_difference_0 <= 1e-4);
/// assert!(abs_difference_1 <= 1e-4);
/// ```
#[doc(alias = "sincos")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -982,7 +982,7 @@ impl f32 {
/// let g = ((e * e) - 1.0) / (2.0 * e);
/// let abs_difference = (f - g).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -1012,7 +1012,7 @@ impl f32 {
/// let abs_difference = (f - g).abs();
///
/// // Same result
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -1042,7 +1042,7 @@ impl f32 {
/// let g = (1.0 - e.powi(-2)) / (1.0 + e.powi(-2));
/// let abs_difference = (f - g).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand All @@ -1067,7 +1067,7 @@ impl f32 {
///
/// let abs_difference = (f - x).abs();
///
/// assert!(abs_difference <= 1e-7);
/// assert!(abs_difference <= 1e-6);
/// ```
#[doc(alias = "arcsinh")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -1095,7 +1095,7 @@ impl f32 {
///
/// let abs_difference = (f - x).abs();
///
/// assert!(abs_difference <= 1e-6);
/// assert!(abs_difference <= 1e-5);
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@RalfJung RalfJung Aug 3, 2025 •
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Why did this change again? It's super hard to keep track when you just keep doing random-looking changes without explanation...

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Excuse me, it shouldn't. I should not be implementing this while sick :).

I confused it with cosh, which is a foreign_item that should be changed in this pr, I just thought I forgot this one. I should've mentioned it.

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So, does 1e-6 work here or not?

Get well soon. :)

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According to the many-seeds runs on the extracted doctests it should change to 1e-5, but it did pass CI multiple times, while asin doesn't. You mentioned "minimizing the diff" if previous values already worked.

/// ```
#[doc(alias = "arccosh")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -1125,7 +1125,7 @@ impl f32 {
///
/// let abs_difference = (f - e).abs();
///
/// assert!(abs_difference <= 1e-5);
/// assert!(abs_difference <= 1e-4);
/// ```
#[doc(alias = "arctanh")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -1153,7 +1153,7 @@ impl f32 {
///
/// let abs_difference = (x.gamma() - 24.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-4);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -1248,7 +1248,7 @@ impl f32 {
/// let one = x.erf() + x.erfc();
/// let abs_difference = (one - 1.0).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference <= 1e-6);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down
10 changes: 5 additions & 5 deletions library/std/src/num/f64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -749,12 +749,12 @@ impl f64 {
/// # Examples
///
/// ```
/// let f = std::f64::consts::FRAC_PI_2;
/// let f = std::f64::consts::FRAC_PI_4;
///
/// // asin(sin(pi/2))
/// let abs_difference = (f.sin().asin() - std::f64::consts::FRAC_PI_2).abs();
/// let abs_difference = (f.sin().asin() - f).abs();
///
/// assert!(abs_difference < 1e-7);
/// assert!(abs_difference < 1e-14);
/// ```
#[doc(alias = "arcsin")]
#[rustc_allow_incoherent_impl]
Expand Down Expand Up @@ -1153,7 +1153,7 @@ impl f64 {
///
/// let abs_difference = (x.gamma() - 24.0).abs();
///
/// assert!(abs_difference <= f64::EPSILON);
/// assert!(abs_difference <= 1e-10);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down Expand Up @@ -1248,7 +1248,7 @@ impl f64 {
/// let one = x.erf() + x.erfc();
/// let abs_difference = (one - 1.0).abs();
///
/// assert!(abs_difference <= f64::EPSILON);
/// assert!(abs_difference <= 1e-10);
/// ```
#[rustc_allow_incoherent_impl]
#[must_use = "method returns a new number and does not mutate the original value"]
Expand Down
14 changes: 7 additions & 7 deletions library/std/tests/floats/f32.rs
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Expand Up @@ -79,7 +79,7 @@ fn test_log() {
let nan: f32 = f32::NAN;
let inf: f32 = f32::INFINITY;
let neg_inf: f32 = f32::NEG_INFINITY;
assert_approx_eq!(10.0f32.log(10.0), 1.0);
assert_approx_eq!(10.0f32.log(10.0), 1.0, APPROX_DELTA);
assert_approx_eq!(2.3f32.log(3.5), 0.664858);
assert_approx_eq!(1.0f32.exp().log(1.0f32.exp()), 1.0, APPROX_DELTA);
assert!(1.0f32.log(1.0).is_nan());
Expand Down Expand Up @@ -140,10 +140,10 @@ fn test_asinh() {
assert_approx_eq!(2.0f32.asinh(), 1.443635475178810342493276740273105f32);
assert_approx_eq!((-2.0f32).asinh(), -1.443635475178810342493276740273105f32);
// regression test for the catastrophic cancellation fixed in 72486
assert_approx_eq!((-3000.0f32).asinh(), -8.699514775987968673236893537700647f32);
assert_approx_eq!((-3000.0f32).asinh(), -8.699514775987968673236893537700647f32, APPROX_DELTA);

// test for low accuracy from issue 104548
assert_approx_eq!(60.0f32, 60.0f32.sinh().asinh());
assert_approx_eq!(60.0f32, 60.0f32.sinh().asinh(), APPROX_DELTA);
// mul needed for approximate comparison to be meaningful
assert_approx_eq!(1.0f32, 1e-15f32.sinh().asinh() * 1e15f32);
}
Expand Down Expand Up @@ -196,10 +196,10 @@ fn test_gamma() {
assert_approx_eq!(1.0f32.gamma(), 1.0f32);
assert_approx_eq!(2.0f32.gamma(), 1.0f32);
assert_approx_eq!(3.0f32.gamma(), 2.0f32);
assert_approx_eq!(4.0f32.gamma(), 6.0f32);
assert_approx_eq!(5.0f32.gamma(), 24.0f32);
assert_approx_eq!(4.0f32.gamma(), 6.0f32, APPROX_DELTA);
assert_approx_eq!(5.0f32.gamma(), 24.0f32, APPROX_DELTA);
assert_approx_eq!(0.5f32.gamma(), consts::PI.sqrt());
assert_approx_eq!((-0.5f32).gamma(), -2.0 * consts::PI.sqrt());
assert_approx_eq!((-0.5f32).gamma(), -2.0 * consts::PI.sqrt(), APPROX_DELTA);
assert_eq!(0.0f32.gamma(), f32::INFINITY);
assert_eq!((-0.0f32).gamma(), f32::NEG_INFINITY);
assert!((-1.0f32).gamma().is_nan());
Expand All @@ -218,7 +218,7 @@ fn test_ln_gamma() {
assert_eq!(2.0f32.ln_gamma().1, 1);
assert_approx_eq!(3.0f32.ln_gamma().0, 2.0f32.ln());
assert_eq!(3.0f32.ln_gamma().1, 1);
assert_approx_eq!((-0.5f32).ln_gamma().0, (2.0 * consts::PI.sqrt()).ln());
assert_approx_eq!((-0.5f32).ln_gamma().0, (2.0 * consts::PI.sqrt()).ln(), APPROX_DELTA);
assert_eq!((-0.5f32).ln_gamma().1, -1);
}

Expand Down
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