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// compile-flags: -Zmir-opt-level=0
// error-pattern: cannot use f32::to_bits on a NaN
#![feature(const_float_bits_conv)]
#![feature(const_float_classify)]
// Don't promote
const fn nop<T>(x: T) -> T { x }
macro_rules! const_assert {
($a:expr) => {
{
const _: () = assert!($a);
assert!(nop($a));
}
};
($a:expr, $b:expr) => {
{
const _: () = assert!($a == $b);
assert_eq!(nop($a), nop($b));
}
};
}
fn f32() {
// Check that NaNs roundtrip their bits regardless of signalingness
// 0xA is 0b1010; 0x5 is 0b0101 -- so these two together clobbers all the mantissa bits
// ...actually, let's just check that these break. :D
const MASKED_NAN1: u32 = f32::NAN.to_bits() ^ 0x002A_AAAA;
//~^ inside
const MASKED_NAN2: u32 = f32::NAN.to_bits() ^ 0x0055_5555;
//~^ inside
// The rest of the code is dead because the constants already fail to evaluate.
const_assert!(f32::from_bits(MASKED_NAN1).is_nan());
const_assert!(f32::from_bits(MASKED_NAN1).is_nan());
// LLVM does not guarantee that loads and stores of NaNs preserve their exact bit pattern.
// In practice, this seems to only cause a problem on x86, since the most widely used calling
// convention mandates that floating point values are returned on the x87 FPU stack. See #73328.
// However, during CTFE we still preserve bit patterns (though that is not a guarantee).
const_assert!(f32::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1);
const_assert!(f32::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
}
fn f64() {
// Check that NaNs roundtrip their bits regardless of signalingness
// 0xA is 0b1010; 0x5 is 0b0101 -- so these two together clobbers all the mantissa bits
// ...actually, let's just check that these break. :D
const MASKED_NAN1: u64 = f64::NAN.to_bits() ^ 0x000A_AAAA_AAAA_AAAA;
//~^ inside
const MASKED_NAN2: u64 = f64::NAN.to_bits() ^ 0x0005_5555_5555_5555;
//~^ inside
// The rest of the code is dead because the constants already fail to evaluate.
const_assert!(f64::from_bits(MASKED_NAN1).is_nan());
const_assert!(f64::from_bits(MASKED_NAN1).is_nan());
// See comment above.
const_assert!(f64::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1);
const_assert!(f64::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
}
fn main() {
f32();
f64();
}
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