Compilation of runtime4 on main fails with a recent gcc

[Gbury]

Compiling on main from a fresh copy (or after a git clean -dfx) fails on my machine with the following log/errors:

File "runtime4/dune", line 61, characters 0-721:
61 | (rule
62 |  (targets
63 |   libasmrun.a
....
96 |     (run make "SAK_LINK=cc -o $(1) $(2)" COMPUTE_DEPS=false sak)
97 |     (run make -sj8 %{targets} COMPUTE_DEPS=false)
98 |     (bash "rm .depend")))))
  CC prims.o
prims.c:310:14: error: conflicting types for ‘caml_get_public_method’; have ‘value(void)’ {aka ‘long int(void)’}
  310 | extern value caml_get_public_method();
      |              ^~~~~~~~~~~~~~~~~~~~~~
In file included from prims.c:2:
caml/mlvalues.h:413:18: note: previous declaration of ‘caml_get_public_method’ with type ‘value(value,  value)’ {aka ‘long int(long int,  long int)’}
  413 | CAMLextern value caml_get_public_method (value obj, value tag);
      |                  ^~~~~~~~~~~~~~~~~~~~~~
prims.c:558:14: error: conflicting types for ‘caml_set_oo_id’; have ‘value(void)’ {aka ‘long int(void)’}
  558 | extern value caml_set_oo_id();
      |              ^~~~~~~~~~~~~~
caml/mlvalues.h:602:18: note: previous declaration of ‘caml_set_oo_id’ with type ‘value(value)’ {aka ‘long int(long int)’}
  602 | CAMLextern value caml_set_oo_id(value obj);
      |                  ^~~~~~~~~~~~~~
cc1: note: unrecognized command-line option ‘-Wno-unknown-warning-option’ may have been intended to silence earlier diagnostics
make[1]: *** [../Makefile.common:174: prims.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile.common-jst:82: runtime-stdlib] Error 1

From the looks of it, it may be because I have a too recent version of gcc (i.e. gcc (GCC) 15.1.1 20250425), and downgrading to gcc 14 solves the problem, but it's still annoying.

[lthls]

Cross-ref: ocaml/ocaml#12700, which fixes the issue upstream and is already present in the default runtime (i.e. runtime5).

[lthls]

See also ocaml/ocaml#12577 which is 4.14 version of the patch, that may apply more cleanly on runtime4