[ruby-core:92461] [Ruby trunk Bug#15807] Range#minmax is slow and never returns for endless ranges

Issue #15807 has been updated by mame (Yusuke Endoh).


I'm never against fixing this issue but I have one concern.  Currently, `Ra=
nge#max` is not consistent with `Enumerable#minmax`.

```
p ("a".."aa").max    #=3D> "aa"
p ("a".."aa").minmax #=3D> ["a", "z"]
```

Thus, if `Range#minmax` is simply implemented, it will make it consistent. =
 This is not always good because it means that the fix brings incompatibili=
ty.

Do you have any use case?  Or, are you facing any concrete issue that is ca=
used by this inconsistency?  If so, we can believe that it would be worth f=
ixing this issue.  If not, we need to consider.

----------------------------------------
Bug #15807: Range#minmax is slow and never returns for endless ranges
https://bugs.ruby-lang.org/issues/15807#change-77810

* Author: janosch-x (Janosch M=FCller)
* Status: Open
* Priority: Normal
* Assignee: =

* Target version: =

* ruby -v: 2.6.3p62
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
current situation:

- `(1..).minmax` runs forever
- `(1..).max` raises "cannot get the maximum of endless range"
- `(1..Float::INFINITY).minmax` runs forever
- `(1..Float::INFINITY).max` returns instantly
- `(1..1_000_000_000).minmax` takes one minute
- `(1..1_000_000_000).max` returns instantly

my suggestion:

- implement `minmax` in range.c, return [`range_min`, `range_max`]
- for endless ranges, this will trigger the same error as `max` does
- delegate to enum (rb_call_super) only if called with a block (?)

i could perhaps provide a PR if you can point me to some information on how=
 to contribute.

cheers!



-- =

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