Fix test for architecture used in CI environment

**Description**
 - Add `target_arch = "x86_64"` to conditional section of alignment test
 - Run `cargo fmt`

**Motivation**
This was breaking the CI tests in Github Actions because the `cfg!(...)`
condition was wrong.

**Testing Done**
 - `cargo test`
 - `cargo miri test`
 - `cargo fmt`
 - `cargo clippy`

src/tagged_pointer.rs

@@ -130,9 +130,10 @@ impl<P> TaggedPointer<P> {
  );
  let data = data & Self::DATA_MASK;
 
- let ptr_with_new_data = self.0.as_ptr().map_addr(|ptr_addr| {
- (ptr_addr & Self::POINTER_MASK) | data
- });
+ let ptr_with_new_data = self
+ .0
+ .as_ptr()
+ .map_addr(|ptr_addr| (ptr_addr & Self::POINTER_MASK) | data);
 
  // The `ptr_with_new_data` is guaranteed to be non-null because it's pointer
  // address was derived from a non-null pointer using operations that would not
@@ -431,18 +432,28 @@ mod tests {
  0b11111111_11111111_11111111_11111111_11111111_11111111_11111111_11111000usize
  );
 
- // Something weird about the representation of u128 on x86 vs aarch64 platforms:
+ // Something weird about the representation of u128 on intel architectures:
  // https://github.com/rust-lang/rust/issues/54341
- if cfg!(target_arch = "x86") {
- assert_eq!(TaggedPointer::<u128>::ALIGNMENT, 8);
+ if cfg!(any(target_arch = "x86", target_arch = "x86_64")) {
+ assert_eq!(
+ TaggedPointer::<u128>::ALIGNMENT,
+ 8,
+ "Target architecture [{}]",
+ std::env::consts::ARCH
+ );
  assert_eq!(TaggedPointer::<u128>::NUM_BITS, 3);
 
  assert_eq!(
  TaggedPointer::<u128>::POINTER_MASK,
  0b11111111_11111111_11111111_11111111_11111111_11111111_11111111_11111000usize
  );
  } else {
- assert_eq!(TaggedPointer::<u128>::ALIGNMENT, 16);
+ assert_eq!(
+ TaggedPointer::<u128>::ALIGNMENT,
+ 16,
+ "Target architecture [{}]",
+ std::env::consts::ARCH
+ );
  assert_eq!(TaggedPointer::<u128>::NUM_BITS, 4);
 
  assert_eq!(