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Fix example code for unreachable! #19360

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Nov 28, 2014
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Fix example code for unreachable! #19360

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9 changes: 4 additions & 5 deletions src/libstd/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -217,12 +217,11 @@ macro_rules! debug_assert_eq(
/// Iterators:
///
/// ```rust
/// fn divide_by_three(x: i32) -> i32 { // one of the poorest implementations of x/3
/// for i in std::iter::count(0_i32, 1) {
/// if i < 0 { panic!("i32 overflow"); }
/// if x < 3*i { return i; }
/// fn divide_by_three(x: u32) -> u32 { // one of the poorest implementations of x/3
/// for i in std::iter::count(0_u32, 1) {
/// if 3*i < i { panic!("u32 overflow"); }
/// if x < 3*i { return i-1; }
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<= 3*i should be sufficient (and more clear), no? Using checked_mul would also make more sense to me than the explicit panic guard.

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No, with <= 3*i, this gives:

0/3=0
1/3=1
2/3=1
3/3=1
4/3=2
5/3=2
6/3=2

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Derp, yes.

/// }
///
/// unreachable!();
/// }
/// ```
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