Dear OCaml users,

Last week, we merged an update to the compiler-libs "s= hape" API for querying

definition information from the compiler i= n the 5.2 branch of the compiler.

Unfortunately, this small change o= f API breaks compatibility with at least odoc.
Generally, we try to avoi= d this changes to the compiler library during the beta

releases o= f the compiler. However, after discussions, we concluded that it will

be easier on the long term to fix the API right now in order to avoid = multiplying

the number of supported versions of the shape API in = the various OCaml

developer tools .

We have thus released = a second beta version of OCaml 5.2.0 to give the time

to develope= r tools to update their 5.2.0 version ahead of the release

(see b= elow for the installation instructions).

Beyond this changes of API,= the new beta contains three minor bug fixes and three
documentation upd= ates, which is a good sign in term of stability.

As usual, you can f= ollow the last remaining compatibility slags on the
opam readiness for 5= .2.0 meta-issue (https://github.com/ocaml/opam-repository/issues/25182).
If you find any bugs, please report them on OCaml's issue tracker (htt= ps://github.com/ocaml/ocaml/issues).

Currently, the release is plann= ed for the beginning of May.

If you are interested in full list of f= eatures and bug fixes of the new OCaml version, the
updated change log f= or OCaml 5.2.0 is available on GitHub (https://github.com/ocaml/ocaml/blob/= 5.2/Changes).

Happy hacking,
Florian Angeletti for the OCa= ml team.

Installation Instructions
-----------------------= -----

The base compiler can be installed as an opam switch with the = following commands
on opam 2.1:

opam update
= ; opam switch create 5.2.0~beta2

The source code for the beta = is also available at these addresses:

- GitHub: https://github.com/o= caml/ocaml/archive/5.2.0-beta2.tar.gz
- OCaml archives at Inria: https:/= /caml.inria.fr/pub/distrib/ocaml-5.2/ocaml-5.2.0~beta2.tar.gz

Fine-T= uned Compiler Configuration

-------------------------------------= ----------

If you want to tweak the configuration of the compiler, y= ou can switch to the option variant with:

opam upda= te
opam switch create <switch_name> ocaml-variants.5.= 2.0~beta2+options <option_list>

where `option_list` is a space= -separated list of `ocaml-option-*` packages.

For instance, for a= `flambda` and `no-flat-float-array` switch:

= ; opam switch create 5.2.0~beta2+flambda+nffa ocaml-variants.5.2.0~be= ta2+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with `opam search ocaml-option`.
<= br>
Changes since the first beta
----------------------------

= ### Compiler-libs API Changes

- #13001(https://github.com/ocaml/ocam= l/issues/13001): do not read_back entire shapes to get aliases' uids when b= uilding the
usages index
(Ulysse G=E9rard, review by Ga= briel Scherer and Nathana=EBlle Courant)

### Bug Fixes

- #130= 58(https://github.com/ocaml/ocaml/issues/13058): Add TSan instrumentation t= o caml_call_gc(), since it may raise
exceptions.
(Fabri= ce Buoro, Olivier Nicole, Gabriel Scherer and Miod Vallat)

- #13079(= https://github.com/ocaml/ocaml/issues/13079): Save and restore frame pointe= r across Iextcall on ARM64
(Tim McGilchrist, review by KC Sivaram= akrishnan and Miod Vallat)

- #13094(https://github.com/ocaml/ocaml/i= ssues/13094): Fix undefined behavior of left-shifting a negative number. (Antonin D=E9cimo, review by Miod Vallat and Nicol=E1s Ojeda B=E4r)=

### Documentation Updates

- #13078(https://github.com/ocaml/= ocaml/issues/13078): update Format tutorial on structural boxes to mention = alignment
questions.
(Edwin T=F6r=F6k, review by Floria= n Angeletti)

- #13092(https://github.com/ocaml/ocaml/issues/13092): = document the existence of the `[@@poll error]` built-in attribute
= (Florian Angeletti, review by Gabriel Scherer)

- #13066(https://git= hub.com/ocaml/ocaml/issues/13066), update OCAMLRUNPARAM documentation for t= he stack size parameter l
(Florian Angeletti, review by Nicol=E1s= Ojeda B=E4r, Tim McGilchrist, and Miod Vallat)