fix f16 formatting inconsistency

for now, keep formatting vectors containing f16 values the old way (that is the same as what C does)

Author: folkertdev

crates/core_arch/src/macros.rs

@@ -59,7 +59,7 @@ macro_rules! types {
         $(
             $(#[$doc:meta])*
             $(stability: [$stability_already: meta])*
-            pub struct $name:ident($len:literal x $v:vis $elem_type:ty);
+            pub struct $name:ident($len:literal x $v:vis $elem_type:ident);
         )*
     ) => (types! {
         $(
@@ -78,7 +78,7 @@ macro_rules! types {
         $(
             $(#[$doc:meta])*
             $(stability: [$stability: meta])+
-            pub struct $name:ident($len:literal x $v:vis $elem_type:ty);
+            pub struct $name:ident($len:literal x $v:vis $elem_type:ident);
         )*
     ) => ($(
         $(#[$doc])*
@@ -132,12 +132,37 @@ macro_rules! types {
         impl crate::fmt::Debug for $name {
             #[inline]
             fn fmt(&self, f: &mut crate::fmt::Formatter<'_>) -> crate::fmt::Result {
-                crate::core_arch::simd::debug_simd_finish(f, stringify!($name), self.as_array())
+                let array = &$crate::core_arch::macros::format_f16_as_hex!($elem_type, self.as_array());
+                crate::core_arch::simd::debug_simd_finish(f, stringify!($name), array)
             }
         }
     )*);
 }
 
+// the `intrinsic-test` crate compares the output of C and Rust intrinsics. Currently, It uses
+// a string representation of the output value to compare. In C, f16 values are currently printed
+// as hexadecimal integers. Since https://github.com/rust-lang/rust/pull/127013, rust does print
+// them as decimal floating point values. To keep the intrinsics tests working, for now, format
+// vectors containing f16 values like C prints them.
+#[allow(unused)]
+macro_rules! format_f16_as_hex {
+    (f16, $arr:expr) => {{ $arr.map(|e| $crate::core_arch::macros::HexF16(e)) }};
+    ($elem_type:ident, $arr:expr) => {
+        *$arr
+    };
+}
+pub(crate) use format_f16_as_hex;
+
+pub(crate) struct HexF16(pub(crate) f16);
+
+impl crate::fmt::Debug for HexF16 {
+    fn fmt(&self, f: &mut crate::fmt::Formatter<'_>) -> crate::fmt::Result {
+        write!(f, "{:#06x?}", unsafe {
+            crate::mem::transmute::<f16, u16>(self.0)
+        })
+    }
+}
+
 #[allow(unused)]
 #[repr(simd)]
 pub(crate) struct SimdShuffleIdx<const LEN: usize>(pub(crate) [u32; LEN]);