Use caml_unix_get_sockaddr instead of its legacy name get_sockaddr

[kit-ty-kate]

This adds support for OCaml 5.5 to lwt due to the change of definition of caml_unix_get_sockaddr in ocaml/ocaml#14310 which triggers the following failure:

File "src/unix/dune", line 92, characters 3-18:    
92 |    unix_bytes_recv
        ^^^^^^^^^^^^^^^
In file included from lwt_unix.h:14,
                 from unix_bytes_recv.c:17:
/home/kit_ty_kate/.opam/5.5/lib/ocaml/caml/socketaddr.h:117:5: error: expected declaration specifiers or ‘...’ before ‘(’ token
  117 |     (vaddr),                                                  \
      |     ^
/home/kit_ty_kate/.opam/5.5/lib/ocaml/caml/socketaddr.h:69:22: note: in expansion of macro ‘caml_unix_get_sockaddr’
   69 | #define get_sockaddr caml_unix_get_sockaddr
      |                      ^~~~~~~~~~~~~~~~~~~~~~
unix_recv_send_utils.h:48:13: note: in expansion of macro ‘get_sockaddr’
   48 | extern void get_sockaddr(value mladdr, union sock_addr_union *addr /*out*/,
      |             ^~~~~~~~~~~~

[kit-ty-kate]

Some extra reasoning for the way i've done things in this PR: ocaml/ocaml#14516 (comment)

[raphael-proust]

There's

File "test/react/dune", line 2, characters 7-11:
2 |  (name main)
           ^^^^
(cd _build/default && /home/runner/work/lwt/lwt/_opam/bin/ocamlopt.opt -w @1..3@5..28@31..39@43@46..47@49..57@61..62@67@69-40 -strict-sequence -strict-formats -short-paths -keep-locs -g -o test/react/main.exe src/core/lwt.cmxa /home/runner/work/lwt/lwt/_opam/lib/react/react.cmxa src/react/lwt_react.cmxa /home/runner/work/lwt/lwt/_opam/lib/ocaml/unix.cmxa -I /home/runner/work/lwt/lwt/_opam/lib/ocaml /home/runner/work/lwt/lwt/_opam/lib/ocaml/bigarray.cmxa -I /home/runner/work/lwt/lwt/_opam/lib/ocaml /home/runner/work/lwt/lwt/_opam/lib/ocplib-endian/ocplib_endian.cmxa /home/runner/work/lwt/lwt/_opam/lib/ocplib-endian/bigstring/ocplib_endian_bigstring.cmxa /home/runner/work/lwt/lwt/_opam/lib/ocaml/threads/threads.cmxa -I /home/runner/work/lwt/lwt/_opam/lib/ocaml src/unix/lwt_unix.cmxa -I src/unix test/lwttester.cmxa test/react/.main.eobjs/native/dune__exe.cmx test/react/.main.eobjs/native/dune__exe__Test_lwt_event.cmx test/react/.main.eobjs/native/dune__exe__Test_lwt_signal.cmx test/react/.main.eobjs/native/dune__exe__Main.cmx)
/usr/bin/ld: src/unix/liblwt_unix_stubs.a(unix_getnameinfo_job.o): in function `lwt_unix_getnameinfo_job':
/home/runner/work/lwt/lwt/_build/default/src/unix/unix_getnameinfo_job.c:62:(.text+0x1cc): undefined reference to `caml_unix_get_sockaddr'
/usr/bin/ld: src/unix/liblwt_unix_stubs.a(unix_bind_job.o): in function `lwt_unix_bind_job':
/home/runner/work/lwt/lwt/_build/default/src/unix/unix_bind_job.c:45:(.text+0xc2): undefined reference to `caml_unix_get_sockaddr'
collect2: error: ld returned 1 exit status
File "caml_startup", line 1:
Error: Error during linking (exit code 1)

on 4.14

investigating

[raphael-proust]

fix

commit 56c1d293b7ce86e271c686a2a8908f81c4861155
Author: Raphaël Proust <code@bnwr.net>
Date:   Mon Feb 23 09:53:06 2026 +0100

    add missing macro def to some .c files

diff --git a/src/unix/unix_c/unix_bind_job.c b/src/unix/unix_c/unix_bind_job.c
index c34c24fcb..6edfcf277 100644
--- a/src/unix/unix_c/unix_bind_job.c
+++ b/src/unix/unix_c/unix_bind_job.c
@@ -14,6 +14,10 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 
+#if OCAML_VERSION_MAJOR < 5
+#define caml_unix_get_sockaddr get_sockaddr
+#endif
+
 #include "lwt_unix.h"
 
 struct job_bind {
diff --git a/src/unix/unix_c/unix_getnameinfo_job.c b/src/unix/unix_c/unix_getnameinfo_job.c
index ccc37322a..68f9eb52d 100644
--- a/src/unix/unix_c/unix_getnameinfo_job.c
+++ b/src/unix/unix_c/unix_getnameinfo_job.c
@@ -16,6 +16,10 @@
 #include <netdb.h>
 #include <sys/socket.h>
 
+#if OCAML_VERSION_MAJOR < 5
+#define caml_unix_get_sockaddr get_sockaddr
+#endif
+
 #include "lwt_unix.h"
 
 struct job_getnameinfo {

I think at some point I need to revisit all the defs and such, there might be some common patterns that would be better pulled together in a single file.