diff options
| -rw-r--r-- | library/core/src/num/f32.rs | 116 | ||||
| -rw-r--r-- | library/core/src/num/f64.rs | 103 | ||||
| -rw-r--r-- | src/test/ui/consts/const-float-bits-conv.rs | 30 | ||||
| -rw-r--r-- | src/test/ui/consts/const-float-bits-reject-conv.rs | 62 | ||||
| -rw-r--r-- | src/test/ui/consts/const-float-bits-reject-conv.stderr | 119 |
5 files changed, 392 insertions, 38 deletions
diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs index 6cd95272ea4..d3d8bd1bf48 100644 --- a/library/core/src/num/f32.rs +++ b/library/core/src/num/f32.rs @@ -623,6 +623,23 @@ impl f32 { } } + // This operates on bits, and only bits, so it can ignore concerns about weird FPUs. + // FIXME(jubilee): In a just world, this would be the entire impl for classify, + // plus a transmute. We do not live in a just world, but we can make it more so. + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + const fn classify_bits(b: u32) -> FpCategory { + const EXP_MASK: u32 = 0x7f800000; + const MAN_MASK: u32 = 0x007fffff; + + match (b & MAN_MASK, b & EXP_MASK) { + (0, EXP_MASK) => FpCategory::Infinite, + (_, EXP_MASK) => FpCategory::Nan, + (0, 0) => FpCategory::Zero, + (_, 0) => FpCategory::Subnormal, + _ => FpCategory::Normal, + } + } + /// Returns `true` if `self` has a positive sign, including `+0.0`, `NaN`s with /// positive sign bit and positive infinity. /// @@ -874,8 +891,59 @@ impl f32 { #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] #[inline] pub const fn to_bits(self) -> u32 { - // SAFETY: `u32` is a plain old datatype so we can always transmute to it - unsafe { mem::transmute(self) } + // SAFETY: `u32` is a plain old datatype so we can always transmute to it. + // ...sorta. + // + // It turns out that at runtime, it is possible for a floating point number + // to be subject to a floating point mode that alters nonzero subnormal numbers + // to zero on reads and writes, aka "denormals are zero" and "flush to zero". + // This is not a problem per se, but at least one tier2 platform for Rust + // actually exhibits this behavior by default. + // + // In addition, on x86 targets with SSE or SSE2 disabled and the x87 FPU enabled, + // i.e. not soft-float, the way Rust does parameter passing can actually alter + // a number that is "not infinity" to have the same exponent as infinity, + // in a slightly unpredictable manner. + // + // And, of course evaluating to a NaN value is fairly nondeterministic. + // More precisely: when NaN should be returned is knowable, but which NaN? + // So far that's defined by a combination of LLVM and the CPU, not Rust. + // This function, however, allows observing the bitstring of a NaN, + // thus introspection on CTFE. + // + // In order to preserve, at least for the moment, const-to-runtime equivalence, + // we reject any of these possible situations from happening. + #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] + const fn ct_f32_to_u32(ct: f32) -> u32 { + match ct.classify() { + FpCategory::Nan => { + panic!("const-eval error: cannot use f32::to_bits on a NaN") + } + FpCategory::Subnormal => { + panic!("const-eval error: cannot use f32::to_bits on a subnormal number") + } + FpCategory::Infinite => + // SAFETY: Infinity per se is fine + unsafe { mem::transmute::<f32, u32>(ct) }, + FpCategory::Zero | FpCategory::Normal => { + // SAFETY: We have a normal floating point number. Now we transmute, i.e. do a bitcopy. + let bits: u32 = unsafe { mem::transmute::<f32, u32>(ct) }; + // Let's doublecheck to make sure it wasn't a weird float by truncating it. + if bits >> 23 & 0xFF == 0xFF { + panic!( + "const-eval error: an unusually large x87 floating point value should not leak into const eval" + ) + }; + bits + } + } + } + // SAFETY: `u32` is a plain old datatype so we can always... uh... + // ...look, just pretend you forgot what you just read. + // Stability concerns. + let rt_f32_to_u32 = |rt| unsafe { mem::transmute::<f32, u32>(rt) }; + // SAFETY: We use internal implementations that either always work or fail at compile time. + unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) } } /// Raw transmutation from `u32`. @@ -919,9 +987,49 @@ impl f32 { #[must_use] #[inline] pub const fn from_bits(v: u32) -> Self { - // SAFETY: `u32` is a plain old datatype so we can always transmute from it // It turns out the safety issues with sNaN were overblown! Hooray! - unsafe { mem::transmute::<u32, f32>(v) } + // SAFETY: `u32` is a plain old datatype so we can always transmute from it + // ...sorta. + // + // It turns out that at runtime, it is possible for a floating point number + // to be subject to a floating point mode that alters nonzero subnormal numbers + // to zero on reads and writes, aka "denormals are zero" and "flush to zero". + // This is not a problem usually, but at least one tier2 platform for Rust + // actually exhibits this behavior by default: thumbv7neon + // aka "the Neon FPU in AArch32 state" + // + // In addition, on x86 targets with SSE or SSE2 disabled and the x87 FPU enabled, + // i.e. not soft-float, the way Rust does parameter passing can actually alter + // a number that is "not infinity" to have the same exponent as infinity, + // in a slightly unpredictable manner. + // + // And, of course evaluating to a NaN value is fairly nondeterministic. + // More precisely: when NaN should be returned is knowable, but which NaN? + // So far that's defined by a combination of LLVM and the CPU, not Rust. + // This function, however, allows observing the bitstring of a NaN, + // thus introspection on CTFE. + // + // In order to preserve, at least for the moment, const-to-runtime equivalence, + // reject any of these possible situations from happening. + #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] + const fn ct_u32_to_f32(ct: u32) -> f32 { + match f32::classify_bits(ct) { + FpCategory::Subnormal => { + panic!("const-eval error: cannot use f32::from_bits on a subnormal number"); + } + FpCategory::Nan => { + panic!("const-eval error: cannot use f32::from_bits on NaN"); + } + // SAFETY: It's not a frumious number + _ => unsafe { mem::transmute::<u32, f32>(ct) }, + } + } + // SAFETY: `u32` is a plain old datatype so we can always... uh... + // ...look, just pretend you forgot what you just read. + // Stability concerns. + let rt_u32_to_f32 = |rt| unsafe { mem::transmute::<u32, f32>(rt) }; + // SAFETY: We use internal implementations that either always work or fail at compile time. + unsafe { intrinsics::const_eval_select((v,), ct_u32_to_f32, rt_u32_to_f32) } } /// Return the memory representation of this floating point number as a byte array in diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs index 53f7f3ed561..264971d586b 100644 --- a/library/core/src/num/f64.rs +++ b/library/core/src/num/f64.rs @@ -621,6 +621,23 @@ impl f64 { } } + // This operates on bits, and only bits, so it can ignore concerns about weird FPUs. + // FIXME(jubilee): In a just world, this would be the entire impl for classify, + // plus a transmute. We do not live in a just world, but we can make it more so. + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + const fn classify_bits(b: u64) -> FpCategory { + const EXP_MASK: u64 = 0x7ff0000000000000; + const MAN_MASK: u64 = 0x000fffffffffffff; + + match (b & MAN_MASK, b & EXP_MASK) { + (0, EXP_MASK) => FpCategory::Infinite, + (_, EXP_MASK) => FpCategory::Nan, + (0, 0) => FpCategory::Zero, + (_, 0) => FpCategory::Subnormal, + _ => FpCategory::Normal, + } + } + /// Returns `true` if `self` has a positive sign, including `+0.0`, `NaN`s with /// positive sign bit and positive infinity. /// @@ -891,8 +908,41 @@ impl f64 { #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] #[inline] pub const fn to_bits(self) -> u64 { - // SAFETY: `u64` is a plain old datatype so we can always transmute to it - unsafe { mem::transmute(self) } + // SAFETY: `u64` is a plain old datatype so we can always transmute to it. + // ...sorta. + // + // See the SAFETY comment in f64::from_bits for more. + #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] + const fn ct_f64_to_u64(ct: f64) -> u64 { + match ct.classify() { + FpCategory::Nan => { + panic!("const-eval error: cannot use f64::to_bits on a NaN") + } + FpCategory::Subnormal => { + panic!("const-eval error: cannot use f64::to_bits on a subnormal number") + } + FpCategory::Infinite => + // SAFETY: Infinity per se is fine + unsafe { mem::transmute::<f64, u64>(ct) }, + FpCategory::Zero | FpCategory::Normal => { + // SAFETY: We have a normal floating point number. Now we transmute, i.e. do a bitcopy. + let bits: u64 = unsafe { mem::transmute::<f64, u64>(ct) }; + // Let's doublecheck to make sure it wasn't a weird float by truncating it. + if (bits >> 52) & 0x7FF == 0x7FF { + panic!( + "const-eval error: an unusually large x87 floating point value should not leak into const eval" + ) + }; + bits + } + } + } + // SAFETY: `u64` is a plain old datatype so we can always... uh... + // ...look, just pretend you forgot what you just read. + // Stability concerns. + let rt_f64_to_u64 = |rt| unsafe { mem::transmute::<f64, u64>(rt) }; + // SAFETY: We use internal implementations that either always work or fail at compile time. + unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) } } /// Raw transmutation from `u64`. @@ -936,9 +986,54 @@ impl f64 { #[must_use] #[inline] pub const fn from_bits(v: u64) -> Self { - // SAFETY: `u64` is a plain old datatype so we can always transmute from it // It turns out the safety issues with sNaN were overblown! Hooray! - unsafe { mem::transmute::<u64, f64>(v) } + // SAFETY: `u64` is a plain old datatype so we can always transmute from it + // ...sorta. + // + // It turns out that at runtime, it is possible for a floating point number + // to be subject to floating point modes that alters nonzero subnormal numbers + // to zero on reads and writes, aka "denormals are zero" and "flush to zero". + // This is not a problem usually, but at least one tier2 platform for Rust + // actually exhibits an FTZ behavior kby default: thumbv7neon + // aka "the Neon FPU in AArch32 state" + // + // Even with this, not all instructions exhibit the FTZ behaviors on thumbv7neon, + // so this should load the same bits if LLVM emits the "correct" instructions, + // but LLVM sometimes makes interesting choices about float optimization, + // and other FPUs may do similar. Thus, it is wise to indulge luxuriously in caution. + // + // In addition, on x86 targets with SSE or SSE2 disabled and the x87 FPU enabled, + // i.e. not soft-float, the way Rust does parameter passing can actually alter + // a number that is "not infinity" to have the same exponent as infinity, + // in a slightly unpredictable manner. + // + // And, of course evaluating to a NaN value is fairly nondeterministic. + // More precisely: when NaN should be returned is knowable, but which NaN? + // So far that's defined by a combination of LLVM and the CPU, not Rust. + // This function, however, allows observing the bitstring of a NaN, + // thus introspection on CTFE. + // + // In order to preserve, at least for the moment, const-to-runtime equivalence, + // reject any of these possible situations from happening. + #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")] + const fn ct_u64_to_f64(ct: u64) -> f64 { + match f64::classify_bits(ct) { + FpCategory::Subnormal => { + panic!("const-eval error: cannot use f64::from_bits on a subnormal number"); + } + FpCategory::Nan => { + panic!("const-eval error: cannot use f64::from_bits on NaN"); + } + // SAFETY: It's not a frumious number + _ => unsafe { mem::transmute::<u64, f64>(ct) }, + } + } + // SAFETY: `u64` is a plain old datatype so we can always... uh... + // ...look, just pretend you forgot what you just read. + // Stability concerns. + let rt_u64_to_f64 = |rt| unsafe { mem::transmute::<u64, f64>(rt) }; + // SAFETY: We use internal implementations that either always work or fail at compile time. + unsafe { intrinsics::const_eval_select((v,), ct_u64_to_f64, rt_u64_to_f64) } } /// Return the memory representation of this floating point number as a byte array in diff --git a/src/test/ui/consts/const-float-bits-conv.rs b/src/test/ui/consts/const-float-bits-conv.rs index c857ad6df2d..310db2174aa 100644 --- a/src/test/ui/consts/const-float-bits-conv.rs +++ b/src/test/ui/consts/const-float-bits-conv.rs @@ -37,22 +37,6 @@ fn f32() { const_assert!(f32::from_bits(0x44a72000), 1337.0); const_assert!(f32::from_ne_bytes(0x44a72000u32.to_ne_bytes()), 1337.0); const_assert!(f32::from_bits(0xc1640000), -14.25); - - // Check that NaNs roundtrip their bits regardless of signalingness - // 0xA is 0b1010; 0x5 is 0b0101 -- so these two together clobbers all the mantissa bits - const MASKED_NAN1: u32 = f32::NAN.to_bits() ^ 0x002A_AAAA; - const MASKED_NAN2: u32 = f32::NAN.to_bits() ^ 0x0055_5555; - - 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. - if !cfg!(target_arch = "x86") { - const_assert!(f32::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1); - const_assert!(f32::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2); - } } fn f64() { @@ -70,20 +54,6 @@ fn f64() { const_assert!(f64::from_bits(0x4094e40000000000), 1337.0); const_assert!(f64::from_ne_bytes(0x4094e40000000000u64.to_ne_bytes()), 1337.0); const_assert!(f64::from_bits(0xc02c800000000000), -14.25); - - // Check that NaNs roundtrip their bits regardless of signalingness - // 0xA is 0b1010; 0x5 is 0b0101 -- so these two together clobbers all the mantissa bits - const MASKED_NAN1: u64 = f64::NAN.to_bits() ^ 0x000A_AAAA_AAAA_AAAA; - const MASKED_NAN2: u64 = f64::NAN.to_bits() ^ 0x0005_5555_5555_5555; - - const_assert!(f64::from_bits(MASKED_NAN1).is_nan()); - const_assert!(f64::from_bits(MASKED_NAN1).is_nan()); - - // See comment above. - if !cfg!(target_arch = "x86") { - const_assert!(f64::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1); - const_assert!(f64::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2); - } } fn main() { diff --git a/src/test/ui/consts/const-float-bits-reject-conv.rs b/src/test/ui/consts/const-float-bits-reject-conv.rs new file mode 100644 index 00000000000..122f5b97eee --- /dev/null +++ b/src/test/ui/consts/const-float-bits-reject-conv.rs @@ -0,0 +1,62 @@ +// compile-flags: -Zmir-opt-level=0 +#![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; + const MASKED_NAN2: u32 = f32::NAN.to_bits() ^ 0x0055_5555; + + 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. + if !cfg!(target_arch = "x86") { + 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; + const MASKED_NAN2: u64 = f64::NAN.to_bits() ^ 0x0005_5555_5555_5555; + + const_assert!(f64::from_bits(MASKED_NAN1).is_nan()); + const_assert!(f64::from_bits(MASKED_NAN1).is_nan()); + + // See comment above. + if !cfg!(target_arch = "x86") { + 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(); +} diff --git a/src/test/ui/consts/const-float-bits-reject-conv.stderr b/src/test/ui/consts/const-float-bits-reject-conv.stderr new file mode 100644 index 00000000000..b39e8819701 --- /dev/null +++ b/src/test/ui/consts/const-float-bits-reject-conv.stderr @@ -0,0 +1,119 @@ +error[E0080]: evaluation of constant value failed + --> $SRC_DIR/core/src/num/f32.rs:LL:COL + | +LL | panic!("const-eval error: cannot use f32::to_bits on a NaN") + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | | + | the evaluated program panicked at 'const-eval error: cannot use f32::to_bits on a NaN', $SRC_DIR/core/src/num/f32.rs:LL:COL + | inside `core::f32::<impl f32>::to_bits::ct_f32_to_u32` at $SRC_DIR/core/src/panic.rs:LL:COL +... +LL | unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) } + | -------------------------------------------------------------------- inside `core::f32::<impl f32>::to_bits` at $SRC_DIR/core/src/num/f32.rs:LL:COL + | + ::: $SRC_DIR/core/src/ops/function.rs:LL:COL + | +LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output; + | ------------------------------------------------------------------ inside `<fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32} as FnOnce<(f32,)>>::call_once - shim(fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32})` at $SRC_DIR/core/src/ops/function.rs:LL:COL + | + ::: $SRC_DIR/core/src/intrinsics.rs:LL:COL + | +LL | called_in_const.call_once(arg) + | ------------------------------ inside `const_eval_select::<(f32,), fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32}, [closure@core::f32::<impl f32>::to_bits::{closure#0}], u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL + | + ::: $DIR/const-float-bits-reject-conv.rs:27:30 + | +LL | const MASKED_NAN1: u32 = f32::NAN.to_bits() ^ 0x002A_AAAA; + | ------------------ inside `f32::MASKED_NAN1` at $DIR/const-float-bits-reject-conv.rs:27:30 + | + = note: this error originates in the macro `$crate::panic::panic_2021` (in Nightly builds, run with -Z macro-backtrace for more info) + +error[E0080]: evaluation of constant value failed + --> $SRC_DIR/core/src/num/f32.rs:LL:COL + | +LL | panic!("const-eval error: cannot use f32::to_bits on a NaN") + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | | + | the evaluated program panicked at 'const-eval error: cannot use f32::to_bits on a NaN', $SRC_DIR/core/src/num/f32.rs:LL:COL + | inside `core::f32::<impl f32>::to_bits::ct_f32_to_u32` at $SRC_DIR/core/src/panic.rs:LL:COL +... +LL | unsafe { intrinsics::const_eval_select((self,), ct_f32_to_u32, rt_f32_to_u32) } + | -------------------------------------------------------------------- inside `core::f32::<impl f32>::to_bits` at $SRC_DIR/core/src/num/f32.rs:LL:COL + | + ::: $SRC_DIR/core/src/ops/function.rs:LL:COL + | +LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output; + | ------------------------------------------------------------------ inside `<fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32} as FnOnce<(f32,)>>::call_once - shim(fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32})` at $SRC_DIR/core/src/ops/function.rs:LL:COL + | + ::: $SRC_DIR/core/src/intrinsics.rs:LL:COL + | +LL | called_in_const.call_once(arg) + | ------------------------------ inside `const_eval_select::<(f32,), fn(f32) -> u32 {core::f32::<impl f32>::to_bits::ct_f32_to_u32}, [closure@core::f32::<impl f32>::to_bits::{closure#0}], u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL + | + ::: $DIR/const-float-bits-reject-conv.rs:28:30 + | +LL | const MASKED_NAN2: u32 = f32::NAN.to_bits() ^ 0x0055_5555; + | ------------------ inside `f32::MASKED_NAN2` at $DIR/const-float-bits-reject-conv.rs:28:30 + | + = note: this error originates in the macro `$crate::panic::panic_2021` (in Nightly builds, run with -Z macro-backtrace for more info) + +error[E0080]: evaluation of constant value failed + --> $SRC_DIR/core/src/num/f64.rs:LL:COL + | +LL | panic!("const-eval error: cannot use f64::to_bits on a NaN") + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | | + | the evaluated program panicked at 'const-eval error: cannot use f64::to_bits on a NaN', $SRC_DIR/core/src/num/f64.rs:LL:COL + | inside `core::f64::<impl f64>::to_bits::ct_f64_to_u64` at $SRC_DIR/core/src/panic.rs:LL:COL +... +LL | unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) } + | -------------------------------------------------------------------- inside `core::f64::<impl f64>::to_bits` at $SRC_DIR/core/src/num/f64.rs:LL:COL + | + ::: $SRC_DIR/core/src/ops/function.rs:LL:COL + | +LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output; + | ------------------------------------------------------------------ inside `<fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64} as FnOnce<(f64,)>>::call_once - shim(fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64})` at $SRC_DIR/core/src/ops/function.rs:LL:COL + | + ::: $SRC_DIR/core/src/intrinsics.rs:LL:COL + | +LL | called_in_const.call_once(arg) + | ------------------------------ inside `const_eval_select::<(f64,), fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64}, [closure@core::f64::<impl f64>::to_bits::{closure#0}], u64>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL + | + ::: $DIR/const-float-bits-reject-conv.rs:46:30 + | +LL | const MASKED_NAN1: u64 = f64::NAN.to_bits() ^ 0x000A_AAAA_AAAA_AAAA; + | ------------------ inside `f64::MASKED_NAN1` at $DIR/const-float-bits-reject-conv.rs:46:30 + | + = note: this error originates in the macro `$crate::panic::panic_2021` (in Nightly builds, run with -Z macro-backtrace for more info) + +error[E0080]: evaluation of constant value failed + --> $SRC_DIR/core/src/num/f64.rs:LL:COL + | +LL | panic!("const-eval error: cannot use f64::to_bits on a NaN") + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | | + | the evaluated program panicked at 'const-eval error: cannot use f64::to_bits on a NaN', $SRC_DIR/core/src/num/f64.rs:LL:COL + | inside `core::f64::<impl f64>::to_bits::ct_f64_to_u64` at $SRC_DIR/core/src/panic.rs:LL:COL +... +LL | unsafe { intrinsics::const_eval_select((self,), ct_f64_to_u64, rt_f64_to_u64) } + | -------------------------------------------------------------------- inside `core::f64::<impl f64>::to_bits` at $SRC_DIR/core/src/num/f64.rs:LL:COL + | + ::: $SRC_DIR/core/src/ops/function.rs:LL:COL + | +LL | extern "rust-call" fn call_once(self, args: Args) -> Self::Output; + | ------------------------------------------------------------------ inside `<fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64} as FnOnce<(f64,)>>::call_once - shim(fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64})` at $SRC_DIR/core/src/ops/function.rs:LL:COL + | + ::: $SRC_DIR/core/src/intrinsics.rs:LL:COL + | +LL | called_in_const.call_once(arg) + | ------------------------------ inside `const_eval_select::<(f64,), fn(f64) -> u64 {core::f64::<impl f64>::to_bits::ct_f64_to_u64}, [closure@core::f64::<impl f64>::to_bits::{closure#0}], u64>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL + | + ::: $DIR/const-float-bits-reject-conv.rs:47:30 + | +LL | const MASKED_NAN2: u64 = f64::NAN.to_bits() ^ 0x0005_5555_5555_5555; + | ------------------ inside `f64::MASKED_NAN2` at $DIR/const-float-bits-reject-conv.rs:47:30 + | + = note: this error originates in the macro `$crate::panic::panic_2021` (in Nightly builds, run with -Z macro-backtrace for more info) + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0080`. |