Array.of_seq applies a circular permutation of one cell to the right on the sequence

[vicuna]

Original bug ID: 7820
Reporter: thierry.martinez
Status: resolved (set by @xavierleroy on 2018-07-11T17:17:49Z)
Resolution: fixed
Priority: normal
Severity: minor
Version: 4.07.0
Fixed in version: 4.07.1+dev/rc1
Category: standard library

Bug description

With OCaml 4.07.0 and trunk, we have

Array.of_seq (Array.to_seq [| 1; 2; 3 |]);;

• : int array = [|3; 1; 2|]

In stdlib/array.ml, line 337 (last line of of_rev_list), we have
fill (len-1) tl
whereas it should be
fill (len-2) tl
since hd, which should be assigned to the cell (len - 1), is skipped.

Steps to reproduce

Run the top-level and execute the following line

Array.of_seq (Array.to_seq [| 1; 2; 3 |]);;

[vicuna]

Comment author: @gasche

Now might be time to repeat my proposition to ask for unit tests for new stdlib functions. In my Batteries experience, this helps a lot for development (quickcheck-style tests help even more).

[vicuna]

Comment author: thierry.martinez

Even if it is sadly too late, I just proposed a regression test in #1897

[vicuna]

Comment author: @alainfrisch

Adding more test was actually discussed on #1002 , but left as future work. Perhaps I should have been stricter and waited for those tests before merging.

[vicuna]

Comment author: @xavierleroy

Thanks for the fix. Merged in trunk and in 4.07 branch.