Unify and deduplicate From<T> float tests #150611

augustocesarperin · 2026-01-02T18:54:18Z

Unify the From tests from f16.rs and f128.rs into a single float_test! in mod.rs.

rustbot · 2026-01-02T18:54:23Z

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jieyouxu · 2026-01-03T05:16:14Z

@rustbot reroll

hkBst · 2026-01-03T09:27:35Z

cc @RalfJung @tgross35

hkBst

lgtm

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Mark-Simulacrum · 2026-01-04T14:42:57Z

library/coretests/tests/floats/f16.rs

    assert_biteq!(f16::from(u8::MAX), 255.0);
    assert_biteq!(f16::from(i8::MIN), -128.0);
    assert_biteq!(f16::from(42_i8), 42.0);
    assert_biteq!(f16::from(i8::MAX), 127.0);


Why only the bools, and not the rest of the cases here?

Probably because they want to know whether they are on the right track, given this is their first PR here.

Are you saying they are on the right track and should add more?

Tried to keep it minimal at first.
Added the u8/i8 cases now

rustbot · 2026-01-04T14:43:32Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

tgross35 · 2026-01-05T01:41:35Z

I believe this will be superseded by #148206

augustocesarperin · 2026-01-06T03:36:38Z

@rustbot ready

augustocesarperin · 2026-01-06T04:03:31Z

@tgross35 I believe both PRs contribute to #141726 but address different categories of tests. Please let me know if I'm missing something or if there's a better way to coordinate these changes.

tgross35

@tgross35 I believe both PRs contribute to #141726 but address different categories of tests. Please let me know if I'm missing something or if there's a better way to coordinate these changes.

Ah sorry, you're right!

View changes since this review

tgross35 · 2026-01-11T06:29:31Z

library/coretests/tests/floats/mod.rs

+float_test! {
+    name: from_bool,
+    attrs: {
+        f16: #[cfg(any(miri, target_has_reliable_f16))],
+        f128: #[cfg(any(miri, target_has_reliable_f128))],
+    },
+    test<Float> {
+        assert_biteq!(Float::from(false), Float::ZERO);
+        assert_biteq!(Float::from(true), Float::ONE);
+    }
+}
+
+float_test! {
+    name: from_u8,
+    attrs: {
+        f16: #[cfg(any(miri, target_has_reliable_f16))],
+        f128: #[cfg(any(miri, target_has_reliable_f128))],
+    },
+    test<Float> {
+        assert_biteq!(Float::from(u8::MIN), Float::ZERO);
+        assert_biteq!(Float::from(42_u8), 42.0);
+        assert_biteq!(Float::from(u8::MAX), 255.0);
+    }
+}
+
+float_test! {
+    name: from_i8,
+    attrs: {
+        f16: #[cfg(any(miri, target_has_reliable_f16))],
+        f128: #[cfg(any(miri, target_has_reliable_f128))],
+    },
+    test<Float> {
+        assert_biteq!(Float::from(i8::MIN), -128.0);
+        assert_biteq!(Float::from(42_i8), 42.0);
+        assert_biteq!(Float::from(i8::MAX), 127.0);
+    }
+}


No need to split the tests up, leaving them in a single function as they are currently is fine.

I kept bool/u8/i8 together, but had to split u16/u32 since f16/f32 lack those From impls, otherwise it fails with E0277.

tgross35 · 2026-01-11T06:31:11Z

library/coretests/tests/floats/f128.rs

    assert_biteq!(f128::from(u16::MIN), 0.0);
    assert_biteq!(f128::from(42_u16), 42.0);
    assert_biteq!(f128::from(u16::MAX), 65535.0);
    assert_biteq!(f128::from(i16::MIN), -32768.0);
    assert_biteq!(f128::from(42_i16), 42.0);
    assert_biteq!(f128::from(i16::MAX), 32767.0);
    assert_biteq!(f128::from(u32::MIN), 0.0);
    assert_biteq!(f128::from(42_u32), 42.0);
    assert_biteq!(f128::from(u32::MAX), 4294967295.0);
    assert_biteq!(f128::from(i32::MIN), -2147483648.0);
    assert_biteq!(f128::from(42_i32), 42.0);
    assert_biteq!(f128::from(i32::MAX), 2147483647.0);
    // FIXME(f16_f128): Uncomment these tests once the From<{u64,i64}> impls are added.
    // assert_eq!(f128::from(u64::MIN), 0.0);
    // assert_eq!(f128::from(42_u64), 42.0);
    // assert_eq!(f128::from(u64::MAX), 18446744073709551615.0);
    // assert_eq!(f128::from(i64::MIN), -9223372036854775808.0);
    // assert_eq!(f128::from(42_i64), 42.0);
    // assert_eq!(f128::from(i64::MAX), 9223372036854775807.0);


Bring these tests over as well. Just gate them as needed:

if Float::BITS >= 32 { // ... } if Float::BITS >= 64 { // ... } if Float::BITS >= 128 { // ... }

I see RawFloat has BITS but TestableFloat doesn't, and the f16 lacks From<u16/u32> so trait bounds still fail. Is cfg(false) ok here?

tgross35 · 2026-01-11T06:31:42Z

library/coretests/tests/floats/f16.rs

This entire file can be deleted since it is no longer used. Ditto for f128 with the above change.

Done! Also I'll update the PR title since it's not only From<bool>

tgross35 · 2026-01-11T06:32:21Z

r? tgross35

Co-authored-by: ericinB <[email protected]>

augustocesarperin · 2026-01-13T20:37:37Z

@rustbot ready

rustbot assigned jieyouxu Jan 2, 2026

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augustocesarperin force-pushed the from-bool-float-test branch from 3f94742 to 357ec46 Compare January 2, 2026 18:56

rustbot assigned Mark-Simulacrum and unassigned jieyouxu Jan 3, 2026

hkBst approved these changes Jan 3, 2026

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rustbot assigned tgross35 and unassigned Mark-Simulacrum Jan 11, 2026

Unify and deduplicate From<T> float tests

1123177

Co-authored-by: ericinB <[email protected]>

augustocesarperin force-pushed the from-bool-float-test branch from 6085df8 to 1123177 Compare January 13, 2026 02:57

augustocesarperin changed the title ~~Unify and deduplicate From<bool> float tests~~ Unify and deduplicate From float tests Jan 13, 2026

augustocesarperin changed the title ~~Unify and deduplicate From float tests~~ Unify and deduplicate From<T> float tests Jan 13, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 13, 2026

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Unify and deduplicate From<T> float tests #150611

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