Rollup merge of #42310 - scottmcm:deprecate-range-stepby, r=alexcrichton

Deprecate range-specific `step_by`

Deprecation attributes and test updates only.

Was replaced by an any-iterator version in #41439

Last follow-up (this release) to #42110 (comment)

r? @alexcrichton

Author: Mark-Simulacrum

src/libcollections/tests/lib.rs

@@ -16,12 +16,12 @@
 #![feature(collections)]
 #![feature(const_fn)]
 #![feature(exact_size_is_empty)]
+#![feature(iterator_step_by)]
 #![feature(pattern)]
 #![feature(placement_in_syntax)]
 #![feature(rand)]
 #![feature(slice_rotate)]
 #![feature(splice)]
-#![feature(step_by)]
 #![feature(str_escape)]
 #![feature(test)]
 #![feature(unboxed_closures)]

src/libcollections/tests/vec_deque.rs

@@ -510,7 +510,8 @@ fn test_from_iter() {
     let u: Vec<_> = deq.iter().cloned().collect();
     assert_eq!(u, v);
 
-    let seq = (0..).step_by(2).take(256);
+    // FIXME #27741: Remove `.skip(0)` when Range::step_by is fully removed
+    let seq = (0..).skip(0).step_by(2).take(256);
     let deq: VecDeque<_> = seq.collect();
     for (i, &x) in deq.iter().enumerate() {
         assert_eq!(2 * i, x);

src/libcore/iter/mod.rs

@@ -313,6 +313,9 @@ pub use self::iterator::Iterator;
 pub use self::range::Step;
 #[unstable(feature = "step_by", reason = "recent addition",
            issue = "27741")]
+#[rustc_deprecated(since = "1.19.0",
+                   reason = "replaced by `iter::StepBy`")]
+#[allow(deprecated)]
 pub use self::range::StepBy as DeprecatedStepBy;
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/iter/range.rs

@@ -252,6 +252,9 @@ step_impl_no_between!(u128 i128);
 #[derive(Clone, Debug)]
 #[unstable(feature = "step_by", reason = "recent addition",
            issue = "27741")]
+#[rustc_deprecated(since = "1.19.0",
+                   reason = "replaced by `iter::StepBy`")]
+#[allow(deprecated)]
 pub struct StepBy<A, R> {
     step_by: A,
     range: R,
@@ -272,6 +275,9 @@ impl<A: Step> ops::RangeFrom<A> {
     /// ```
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]
+    #[rustc_deprecated(since = "1.19.0",
+                       reason = "replaced by `Iterator::step_by`")]
+    #[allow(deprecated)]
     pub fn step_by(self, by: A) -> StepBy<A, Self> {
         StepBy {
             step_by: by,
@@ -297,6 +303,9 @@ impl<A: Step> ops::Range<A> {
     /// ```
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]
+    #[rustc_deprecated(since = "1.19.0",
+                       reason = "replaced by `Iterator::step_by`")]
+    #[allow(deprecated)]
     pub fn step_by(self, by: A) -> StepBy<A, Self> {
         StepBy {
             step_by: by,
@@ -321,6 +330,9 @@ impl<A: Step> ops::RangeInclusive<A> {
     /// ```
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]
+    #[rustc_deprecated(since = "1.19.0",
+                       reason = "replaced by `Iterator::step_by`")]
+    #[allow(deprecated)]
     pub fn step_by(self, by: A) -> StepBy<A, Self> {
         StepBy {
             step_by: by,
@@ -331,6 +343,7 @@ impl<A: Step> ops::RangeInclusive<A> {
 
 #[unstable(feature = "step_by", reason = "recent addition",
            issue = "27741")]
+#[allow(deprecated)]
 impl<A> Iterator for StepBy<A, ops::RangeFrom<A>> where
     A: Clone,
     for<'a> &'a A: Add<&'a A, Output = A>
@@ -351,11 +364,13 @@ impl<A> Iterator for StepBy<A, ops::RangeFrom<A>> where
 }
 
 #[unstable(feature = "fused", issue = "35602")]
+#[allow(deprecated)]
 impl<A> FusedIterator for StepBy<A, ops::RangeFrom<A>>
     where A: Clone, for<'a> &'a A: Add<&'a A, Output = A> {}
 
 #[unstable(feature = "step_by", reason = "recent addition",
            issue = "27741")]
+#[allow(deprecated)]
 impl<A: Step + Clone> Iterator for StepBy<A, ops::Range<A>> {
     type Item = A;
 
@@ -393,11 +408,13 @@ impl<A: Step + Clone> Iterator for StepBy<A, ops::Range<A>> {
 }
 
 #[unstable(feature = "fused", issue = "35602")]
+#[allow(deprecated)]
 impl<A: Step + Clone> FusedIterator for StepBy<A, ops::Range<A>> {}
 
 #[unstable(feature = "inclusive_range",
            reason = "recently added, follows RFC",
            issue = "28237")]
+#[allow(deprecated)]
 impl<A: Step + Clone> Iterator for StepBy<A, ops::RangeInclusive<A>> {
     type Item = A;
 
@@ -437,6 +454,7 @@ impl<A: Step + Clone> Iterator for StepBy<A, ops::RangeInclusive<A>> {
 }
 
 #[unstable(feature = "fused", issue = "35602")]
+#[allow(deprecated)]
 impl<A: Step + Clone> FusedIterator for StepBy<A, ops::RangeInclusive<A>> {}
 
 macro_rules! range_exact_iter_impl {

src/libcore/tests/iter.rs

@@ -12,6 +12,15 @@ use core::iter::*;
 use core::{i8, i16, isize};
 use core::usize;
 
+// FIXME #27741: This is here to simplify calling Iterator::step_by. Remove
+// once Range::step_by is completely gone (not just deprecated).
+trait IterEx: Sized {
+    fn iter_step_by(self, n: usize) -> StepBy<Self>;
+}
+impl<I:Iterator> IterEx for I {
+    fn iter_step_by(self, n: usize) -> StepBy<Self> { self.step_by(n) }
+}
+
 #[test]
 fn test_lt() {
     let empty: [isize; 0] = [];
@@ -67,7 +76,7 @@ fn test_multi_iter() {
 
 #[test]
 fn test_counter_from_iter() {
-    let it = (0..).step_by(5).take(10);
+    let it = (0..).iter_step_by(5).take(10);
     let xs: Vec<isize> = FromIterator::from_iter(it);
     assert_eq!(xs, [0, 5, 10, 15, 20, 25, 30, 35, 40, 45]);
 }
@@ -85,7 +94,7 @@ fn test_iterator_chain() {
     }
     assert_eq!(i, expected.len());
 
-    let ys = (30..).step_by(10).take(4);
+    let ys = (30..).iter_step_by(10).take(4);
     let it = xs.iter().cloned().chain(ys);
     let mut i = 0;
     for x in it {
@@ -147,15 +156,13 @@ fn test_iterator_chain_find() {
 #[test]
 fn test_iterator_step_by() {
     // Identity
-    // Replace with (0..).step_by(1) after Range::step_by gets removed
-    let mut it = Iterator::step_by((0..), 1).take(3);
+    let mut it = (0..).iter_step_by(1).take(3);
     assert_eq!(it.next(), Some(0));
     assert_eq!(it.next(), Some(1));
     assert_eq!(it.next(), Some(2));
     assert_eq!(it.next(), None);
 
-    // Replace with (0..).step_by(3) after Range::step_by gets removed
-    let mut it = Iterator::step_by((0..), 3).take(4);
+    let mut it = (0..).iter_step_by(3).take(4);
     assert_eq!(it.next(), Some(0));
     assert_eq!(it.next(), Some(3));
     assert_eq!(it.next(), Some(6));
@@ -166,8 +173,7 @@ fn test_iterator_step_by() {
 #[test]
 #[should_panic]
 fn test_iterator_step_by_zero() {
-    // Replace with (0..).step_by(0) after Range::step_by gets removed
-    let mut it = Iterator::step_by((0..), 0);
+    let mut it = (0..).iter_step_by(0);
     it.next();
 }
 
@@ -246,7 +252,7 @@ fn test_iterator_step_by_size_hint() {
 
 #[test]
 fn test_filter_map() {
-    let it = (0..).step_by(1).take(10)
+    let it = (0..).iter_step_by(1).take(10)
         .filter_map(|x| if x % 2 == 0 { Some(x*x) } else { None });
     assert_eq!(it.collect::<Vec<usize>>(), [0*0, 2*2, 4*4, 6*6, 8*8]);
 }
@@ -648,7 +654,7 @@ fn test_iterator_scan() {
 fn test_iterator_flat_map() {
     let xs = [0, 3, 6];
     let ys = [0, 1, 2, 3, 4, 5, 6, 7, 8];
-    let it = xs.iter().flat_map(|&x| (x..).step_by(1).take(3));
+    let it = xs.iter().flat_map(|&x| (x..).iter_step_by(1).take(3));
     let mut i = 0;
     for x in it {
         assert_eq!(x, ys[i]);
@@ -674,13 +680,13 @@ fn test_inspect() {
 #[test]
 fn test_cycle() {
     let cycle_len = 3;
-    let it = (0..).step_by(1).take(cycle_len).cycle();
+    let it = (0..).iter_step_by(1).take(cycle_len).cycle();
     assert_eq!(it.size_hint(), (usize::MAX, None));
     for (i, x) in it.take(100).enumerate() {
         assert_eq!(i % cycle_len, x);
     }
 
-    let mut it = (0..).step_by(1).take(0).cycle();
+    let mut it = (0..).iter_step_by(1).take(0).cycle();
     assert_eq!(it.size_hint(), (0, Some(0)));
     assert_eq!(it.next(), None);
 }
@@ -759,7 +765,7 @@ fn test_iterator_min() {
 
 #[test]
 fn test_iterator_size_hint() {
-    let c = (0..).step_by(1);
+    let c = (0..).iter_step_by(1);
     let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
     let v2 = &[10, 11, 12];
     let vi = v.iter();
@@ -1081,6 +1087,8 @@ fn test_range() {
 
 #[test]
 fn test_range_step() {
+    #![allow(deprecated)]
+
     assert_eq!((0..20).step_by(5).collect::<Vec<isize>>(), [0, 5, 10, 15]);
     assert_eq!((20..0).step_by(-5).collect::<Vec<isize>>(), [20, 15, 10, 5]);
     assert_eq!((20..0).step_by(-6).collect::<Vec<isize>>(), [20, 14, 8, 2]);