Issue #13420 has been updated by Eregon (Benoit Daloze).


stomar (Marcus Stollsteimer) wrote:
> Applied.
> I opened a PR for the specs: https://github.com/ruby/spec/pull/436

Thanks!
 
> Should I add a comment in `NEWS` or not?


Yes, I think the rule is to add a NEWS entry for every user-visible behavior change.

----------------------------------------
Bug #13420: Integer#{round,floor,ceil,truncate} should always return an integer, not a float
https://bugs.ruby-lang.org/issues/13420#change-64676

* Author: stomar (Marcus Stollsteimer)
* Status: Closed
* Priority: Normal
* Assignee: stomar (Marcus Stollsteimer)
* Target version: 
* ruby -v: r58307
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
The current behavior of Integer#{round,floor,ceil,truncate} produces wrong results for large integers.

In the case of a positive precision argument, these methods return the receiver converted to a float, effectively doing the same as `to_f`.

```
2.round(1)  # => 2.0
```

This leads to errors for large integers:

```
(10**25).round(2).to_i  # => 10000000000000000905969664
(10**400).round(2)      # => Infinity
```

Mathematically speaking, the value of an integer should not be changed by #round, #floor, #ceil, or #truncate, regardless of the precision (when positive). An integer rounded to e.g. 2 decimal digits is still the same (and exact) integer.

The desired behavior should be to keep precision as high as possible by not needlessly converting to Float.

The provided patch fixes these methods to return `self` for positive precision argument, similar to the behavior without a specified precision, i.e. precision 0.

---Files--------------------------------
0001-Integer-round-floor-ceil-truncate.patch (7.83 KB)


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