improve step_integer_impls macro

src/libcore/iter/range.rs

@@ -196,9 +196,6 @@ macro_rules! step_identical_methods {
  unsafe fn backward_unchecked(start: Self, n: usize) -> Self {
  start.unchecked_sub(n as Self)
  }
- };
- ( [$u:ident $i:ident] ) => {
- step_identical_methods!();
 
  #[inline]
  fn forward(start: Self, n: usize) -> Self {
@@ -207,8 +204,8 @@ macro_rules! step_identical_methods {
  if Self::forward_checked(start, n).is_none() {
  let _ = Add::add(Self::MAX, 1);
  }
- // Do wrapping math to allow e.g. `Step::forward(-128u8, 255)`.
- start.wrapping_add(n as Self) as Self
+ // Do wrapping math to allow e.g. `Step::forward(-128i8, 255)`.
+ start.wrapping_add(n as Self)
  }
 
  #[inline]
@@ -218,8 +215,8 @@ macro_rules! step_identical_methods {
  if Self::backward_checked(start, n).is_none() {
  let _ = Sub::sub(Self::MIN, 1);
  }
- // Do wrapping math to allow e.g. `Step::backward(127u8, 255)`.
- start.wrapping_sub(n as Self) as Self
+ // Do wrapping math to allow e.g. `Step::backward(127i8, 255)`.
+ start.wrapping_sub(n as Self)
  }
  };
 }
@@ -235,7 +232,7 @@ macro_rules! step_integer_impls {
  #[allow(unreachable_patterns)]
  #[unstable(feature = "step_trait", reason = "recently redesigned", issue = "42168")]
  unsafe impl Step for $u_narrower {
- step_identical_methods!( [ $u_narrower $i_narrower ] );
+ step_identical_methods!();
 
  #[inline]
  fn steps_between(start: &Self, end: &Self) -> Option<usize> {
@@ -267,7 +264,7 @@ macro_rules! step_integer_impls {
  #[allow(unreachable_patterns)]
  #[unstable(feature = "step_trait", reason = "recently redesigned", issue = "42168")]
  unsafe impl Step for $i_narrower {
- step_identical_methods!( [ $u_narrower $i_narrower ] );
+ step_identical_methods!();
 
  #[inline]
  fn steps_between(start: &Self, end: &Self) -> Option<usize> {
@@ -347,20 +344,10 @@ macro_rules! step_integer_impls {
  start.checked_add(n as Self)
  }
 
- #[inline]
- fn forward(start: Self, n: usize) -> Self {
- Add::add(start, n as Self)
- }
-
  #[inline]
  fn backward_checked(start: Self, n: usize) -> Option<Self> {
  start.checked_sub(n as Self)
  }
-
- #[inline]
- fn backward(start: Self, n: usize) -> Self {
- Sub::sub(start, n as Self)
- }
  }
 
  #[allow(unreachable_patterns)]
@@ -387,20 +374,10 @@ macro_rules! step_integer_impls {
  start.checked_add(n as Self)
  }
 
- #[inline]
- fn forward(start: Self, n: usize) -> Self {
- Add::add(start, n as Self)
- }
-
  #[inline]
  fn backward_checked(start: Self, n: usize) -> Option<Self> {
  start.checked_sub(n as Self)
  }
-
- #[inline]
- fn backward(start: Self, n: usize) -> Self {
- Sub::sub(start, n as Self)
- }
  }
  )+
  };