Compile for x86_32 via cross-compilation

multilib has issues, for example, in Ubunut

Signed-off-by: Kakadu <Kakadu@pm.me>

Author: Kakadu

Lama.opam

@@ -28,4 +28,8 @@ build: [
     "@doc" {with-doc}
   ]
 ]
-depexts: [ [ "gcc-14-multilib" ] {os-distribution = "ubuntu"} ]
+depexts: [
+  [ "gcc-i686-linux-gnu" "linux-libc-dev:i386"  "libc6-dev-i386-cross"] {os-distribution = "ubuntu"}
+  [ "libgcc-13-dev-i386-cross" ] {os-distribution = "ubuntu" & os-version >= "24.04" }
+  [ "libgcc-14-dev-i386-cross" ] {os-distribution = "ubuntu" & os-version >= "24.04" }
+]

Lama.opam.template

@@ -1 +1,5 @@
-depexts: [ [ "gcc-14-multilib" ] {os-distribution = "ubuntu"} ]
+depexts: [
+  [ "gcc-i686-linux-gnu" "linux-libc-dev:i386"  "libc6-dev-i386-cross"] {os-distribution = "ubuntu"}
+  [ "libgcc-13-dev-i386-cross" ] {os-distribution = "ubuntu" & os-version >= "24.04" }
+  [ "libgcc-14-dev-i386-cross" ] {os-distribution = "ubuntu" & os-version >= "24.04" }
+]

runtime32/Makefile

@@ -1,6 +1,7 @@
 RUNTIME=runtime.a
 
 .DEFAULT  := $(RUNTIME)
+CC := i686-linux-gnu-gcc
 
 $(RUNTIME): gc_runtime.o runtime.o
 	ar rc $@ gc_runtime.o runtime.o

src/X86_32.ml

@@ -833,8 +833,8 @@ let build cmd prog =
      let objs = find_objects (fst @@ fst prog) cmd#get_include_paths in
      let buf  = Buffer.create 255 in
      List.iter (fun o -> Buffer.add_string buf o; Buffer.add_string buf " ") objs;
-     let gcc_cmdline = Printf.sprintf "gcc %s -m32 %s %s.s %s %s/runtime.a" cmd#get_debug cmd#get_output_option cmd#basename (Buffer.contents buf) inc in
+     let gcc_cmdline = Printf.sprintf "i686-linux-gnu-gcc %s %s %s.s %s %s/runtime.a" cmd#get_debug cmd#get_output_option cmd#basename (Buffer.contents buf) inc in
      Sys.command gcc_cmdline
   | `Compile ->
-     Sys.command (Printf.sprintf "gcc %s -m32 -c %s.s" cmd#get_debug cmd#basename)
+     Sys.command (Printf.sprintf "i686-linux-gnu-gcc %s -c %s.s" cmd#get_debug cmd#basename)
   | _ -> invalid_arg "must not happen"