Test new floating point bit casts

Author: ecstatic-morse

src/test/ui/consts/const-float-bits-conv.rs

@@ -0,0 +1,75 @@
+// run-pass
+
+#![feature(const_panic)]
+#![feature(const_if_match)]
+#![feature(const_float_bits_conv)]
+
+macro_rules! const_assert {
+    ($a:expr) => {
+        {
+            const _: () = assert!($a);
+            assert!($a);
+        }
+    };
+    ($a:expr, $b:expr) => {
+        {
+            const _: () = assert!($a == $b);
+            assert_eq!($a, $b);
+        }
+    };
+}
+
+fn f32() {
+    const_assert!((1f32).to_bits(), 0x3f800000);
+    const_assert!(u32::from_be_bytes(1f32.to_be_bytes()), 0x3f800000);
+    const_assert!((12.5f32).to_bits(), 0x41480000);
+    const_assert!(u32::from_le_bytes(12.5f32.to_le_bytes()), 0x41480000);
+    const_assert!((1337f32).to_bits(), 0x44a72000);
+    const_assert!(u32::from_ne_bytes(1337f32.to_ne_bytes()), 0x44a72000);
+    const_assert!((-14.25f32).to_bits(), 0xc1640000);
+    const_assert!(f32::from_bits(0x3f800000), 1.0);
+    const_assert!(f32::from_be_bytes(0x3f800000u32.to_be_bytes()), 1.0);
+    const_assert!(f32::from_bits(0x41480000), 12.5);
+    const_assert!(f32::from_le_bytes(0x41480000u32.to_le_bytes()), 12.5);
+    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).to_bits(), MASKED_NAN1);
+    const_assert!(f32::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
+}
+
+fn f64() {
+    const_assert!((1f64).to_bits(), 0x3ff0000000000000);
+    const_assert!(u64::from_be_bytes(1f64.to_be_bytes()), 0x3ff0000000000000);
+    const_assert!((12.5f64).to_bits(), 0x4029000000000000);
+    const_assert!(u64::from_le_bytes(12.5f64.to_le_bytes()), 0x4029000000000000);
+    const_assert!((1337f64).to_bits(), 0x4094e40000000000);
+    const_assert!(u64::from_ne_bytes(1337f64.to_ne_bytes()), 0x4094e40000000000);
+    const_assert!((-14.25f64).to_bits(), 0xc02c800000000000);
+    const_assert!(f64::from_bits(0x3ff0000000000000), 1.0);
+    const_assert!(f64::from_be_bytes(0x3ff0000000000000u64.to_be_bytes()), 1.0);
+    const_assert!(f64::from_bits(0x4029000000000000), 12.5);
+    const_assert!(f64::from_le_bytes(0x4029000000000000u64.to_le_bytes()), 12.5);
+    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).to_bits(), MASKED_NAN1);
+    const_assert!(f64::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
+}
+
+fn main() {
+    f32();
+    f64();
+}