Ensure tests requiring std feature are conditionally compiled (#9)

Ensure that any test or example that requires std in order to compile and run are conditionally compiled behind the `std` crate feature.

Addresses #8.

src/lib.rs

@@ -127,6 +127,7 @@ pub use lifetime_free::LifetimeFree;
 /// Specialization in a blanket trait implementation:
 ///
 /// ```
+/// # #[cfg(feature = "std")] {
 /// use std::fmt::Display;
 /// use castaway::cast;
 ///
@@ -160,6 +161,7 @@ pub use lifetime_free::LifetimeFree;
 ///
 /// println!("specialized: {}", String::from("hello").fast_to_string());
 /// println!("default: {}", "hello".fast_to_string());
+/// # }
 /// ```
 #[macro_export]
 macro_rules! cast {
@@ -311,6 +313,7 @@ mod tests {
 
  inner2(&slice);
 
+ #[allow(clippy::needless_lifetimes)]
  fn inner3<'a>(value: &'a mut [u8]) {
  assert_eq!(cast!(value, &mut [u8]), Ok(&mut [1, 1][..]));
  }
@@ -341,6 +344,7 @@ mod tests {
  () => {};
 
  (
+ $(#[$meta:meta])*
  for $TARGET:ty as $name:ident {
  $(
  $value:expr => $matches:pat $(if $guard:expr)?,
@@ -349,6 +353,7 @@ mod tests {
  $($tail:tt)*
  ) => {
  paste::paste! {
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_ $name>]() {
@@ -364,6 +369,7 @@ mod tests {
  )*
  }
 
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_ref_ $name>]() {
@@ -379,6 +385,7 @@ mod tests {
  )*
  }
 
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_mut_ $name>]() {
@@ -401,6 +408,7 @@ mod tests {
  };
 
  (
+ $(#[$meta:meta])*
  for $TARGET:ty {
  $(
  $value:expr => $matches:pat $(if $guard:expr)?,
@@ -409,6 +417,7 @@ mod tests {
  $($tail:tt)*
  ) => {
  paste::paste! {
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_ $TARGET>]() {
@@ -424,6 +433,7 @@ mod tests {
  )*
  }
 
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_ref_ $TARGET>]() {
@@ -439,6 +449,7 @@ mod tests {
  )*
  }
 
+ $(#[$meta])*
  #[test]
  #[allow(non_snake_case)]
  fn [<cast_lifetime_free_mut_ $TARGET>]() {
@@ -478,6 +489,7 @@ mod tests {
  3.2f64 => Err(v) if v == 3.2f64,
  }
 
+ #[cfg(feature = "std")]
  for String {
  String::from("hello world") => Ok(ref v) if v.as_str() == "hello world",
  "hello world" => Err("hello world"),