Introduce the -without-runtime option.

Changes

@@ -39,6 +39,11 @@ Working version
   (Jules Aguillon, with help from Armaël Guéneau,
    review by Gabriel Scherer and Florian Angeletti)
 
+- #2309: New options -with-runtime and -without-runtime in ocamlopt/ocamlc
+  that control the inclusion of the runtime system in the generated program.
+  (Lucas Pluvinage, review by Daniel Bünzli, Damien Doligez, David Allsopp
+   and Florian Angeletti)
+
 - #2314: Remove support for gprof profiling.
   (Mark Shinwell, review by Xavier Clerc and Stephen Dolan)
 

asmcomp/asmlink.ml

@@ -111,7 +111,7 @@ let add_ccobjs origin l =
 let runtime_lib () =
   let libname = "libasmrun" ^ !Clflags.runtime_variant ^ ext_lib in
   try
-    if !Clflags.nopervasives then []
+    if !Clflags.nopervasives || (not !Clflags.with_runtime) then []
     else [ Load_path.find libname ]
   with Not_found ->
     raise(Error(File_not_found libname))

bytecomp/bytelink.ml

@@ -303,14 +303,16 @@ let link_bytecode ?final_name tolink exec_name standalone =
       raise (Error (Wrong_object_name exec_name));
     | _ -> ()) tolink;
   Misc.remove_file exec_name; (* avoid permission problems, cf PR#8354 *)
+  let output_permissions = if !Clflags.with_runtime then 0o777 else 0o666
+  in
   let outchan =
     open_out_gen [Open_wronly; Open_trunc; Open_creat; Open_binary]
-                 0o777 exec_name in
+                 output_permissions exec_name in
   Misc.try_finally
     ~always:(fun () -> close_out outchan)
     ~exceptionally:(fun () -> remove_file exec_name)
     (fun () ->
-       if standalone then begin
+       if standalone && !Clflags.with_runtime then begin
          (* Copy the header *)
          try
            let header =
@@ -324,7 +326,8 @@ let link_bytecode ?final_name tolink exec_name standalone =
        end;
        Bytesections.init_record outchan;
        (* The path to the bytecode interpreter (in use_runtime mode) *)
-       if String.length !Clflags.use_runtime > 0 then begin
+       if String.length !Clflags.use_runtime > 0 && !Clflags.with_runtime then
+       begin
          let runtime = make_absolute !Clflags.use_runtime in
          let runtime =
            (* shebang mustn't exceed 128 including the #! and \0 *)
@@ -538,7 +541,10 @@ let link_bytecode_as_c tolink outfile =
 (* Build a custom runtime *)
 
 let build_custom_runtime prim_name exec_name =
-  let runtime_lib = "-lcamlrun" ^ !Clflags.runtime_variant in
+  let runtime_lib =
+    if (not !Clflags.with_runtime)
+    then ""
+    else "-lcamlrun" ^ !Clflags.runtime_variant in
   let debug_prefix_map =
     if Config.c_has_debug_prefix_map && not !Clflags.keep_camlprimc_file then
       [Printf.sprintf "-fdebug-prefix-map=%s=camlprim.c" prim_name]
@@ -662,7 +668,10 @@ let link objfiles output_name =
                else Ccomp.MainDll, Config.bytecomp_c_libraries
              in
              if not (
-                 let runtime_lib = "-lcamlrun" ^ !Clflags.runtime_variant in
+                 let runtime_lib =
+                   if (not !Clflags.with_runtime)
+                   then ""
+                   else "-lcamlrun" ^ !Clflags.runtime_variant in
                  Ccomp.call_linker mode output_name
                    ([obj_file] @ List.rev !Clflags.ccobjs @ [runtime_lib])
                    c_libs

driver/compenv.ml

@@ -232,6 +232,7 @@ let read_one_param ppf position name v =
 
   | "pp" -> preprocessor := Some v
   | "runtime-variant" -> runtime_variant := v
+  | "with-runtime" -> set "with-runtime" [ with_runtime ] v
   | "open" ->
       open_modules := List.rev_append (String.split_on_char ',' v) !open_modules
   | "cc" -> c_compiler := Some v

driver/main.ml

@@ -101,6 +101,8 @@ module Options = Main_args.Make_bytecomp_options (struct
   let _rectypes = set recursive_types
   let _no_rectypes = unset recursive_types
   let _runtime_variant s = runtime_variant := s
+  let _with_runtime = set with_runtime
+  let _without_runtime = unset with_runtime
   let _safe_string = unset unsafe_string
   let _short_paths = unset real_paths
   let _strict_sequence = set strict_sequence

driver/main_args.ml

@@ -454,6 +454,16 @@ let mk_runtime_variant f =
   "<str>  Use the <str> variant of the run-time system"
 ;;
 
+let mk_with_runtime f =
+  "-with-runtime", Arg.Unit f,
+  "Include the runtime system in the generated program (default)"
+;;
+
+let mk_without_runtime f =
+  "-without-runtime", Arg.Unit f,
+  "Don't include the runtime system in the generated program."
+;;
+
 let mk_S f =
   "-S", Arg.Unit f, " Keep intermediate assembly file"
 ;;
@@ -930,6 +940,8 @@ module type Compiler_options = sig
   val _no_principal : unit -> unit
   val _rectypes : unit -> unit
   val _runtime_variant : string -> unit
+  val _with_runtime : unit -> unit
+  val _without_runtime : unit -> unit
   val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _thread : unit -> unit
@@ -1144,6 +1156,8 @@ struct
     mk_rectypes F._rectypes;
     mk_no_rectypes F._no_rectypes;
     mk_runtime_variant F._runtime_variant;
+    mk_with_runtime F._with_runtime;
+    mk_without_runtime F._without_runtime;
     mk_safe_string F._safe_string;
     mk_short_paths F._short_paths;
     mk_strict_sequence F._strict_sequence;
@@ -1332,6 +1346,8 @@ struct
     mk_remove_unused_arguments F._remove_unused_arguments;
     mk_rounds F._rounds;
     mk_runtime_variant F._runtime_variant;
+    mk_with_runtime F._with_runtime;
+    mk_without_runtime F._without_runtime;
     mk_S F._S;
     mk_safe_string F._safe_string;
     mk_shared F._shared;

driver/main_args.mli

@@ -96,6 +96,8 @@ module type Compiler_options = sig
   val _no_principal : unit -> unit
   val _rectypes : unit -> unit
   val _runtime_variant : string -> unit
+  val _with_runtime : unit -> unit
+  val _without_runtime : unit -> unit
   val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _thread : unit -> unit

driver/optmain.ml

@@ -181,6 +181,8 @@ module Options = Main_args.Make_optcomp_options (struct
   let _no_rectypes = clear recursive_types
   let _remove_unused_arguments = set remove_unused_arguments
   let _runtime_variant s = runtime_variant := s
+  let _with_runtime = set with_runtime
+  let _without_runtime = clear with_runtime
   let _safe_string = clear unsafe_string
   let _short_paths = clear real_paths
   let _strict_sequence = set strict_sequence

man/ocamlc.m

@@ -1056,6 +1056,10 @@ Show the description of all available warning numbers.
 .B \-where
 Print the location of the standard library, then exit.
 .TP
+.B \-without-runtime
+The compiler does not include the runtime system (nor a reference to it) in the
+generated program; it must be supplied separately.
+.TP
 .BI \- \ file
 Process
 .I file

man/ocamlopt.m

@@ -684,6 +684,10 @@ Show the description of all available warning numbers.
 .B \-where
 Print the location of the standard library, then exit.
 .TP
+.B \-without-runtime
+The compiler does not include the runtime system (nor a reference to it) in the
+generated program; it must be supplied separately.
+.TP
 .BI \- \ file
 Process
 .I file

manual/manual/cmds/unified-options.etex

@@ -779,6 +779,12 @@ Show the description of all available warning numbers.
 Print the location of the standard library, then exit.
 }%notop
 
+\notop{%
+\item["-without-runtime"]
+The compiler does not include the runtime system (nor a reference to it) in the
+generated program; it must be supplied separately.
+}
+
 \item["-" \var{file}]
 \notop{Process \var{file} as a file name, even if it starts with a dash ("-")
 character.}

tools/ocamlcp.ml

@@ -87,6 +87,8 @@ module Options = Main_args.Make_bytecomp_options (struct
   let _rectypes = ignore
   let _no_rectypes = ignore
   let _runtime_variant = ignore
+  let _with_runtime = ignore
+  let _without_runtime = ignore
   let _safe_string = ignore
   let _short_paths = ignore
   let _strict_sequence = ignore

tools/ocamloptp.ml

@@ -108,6 +108,8 @@ module Options = Main_args.Make_optcomp_options (struct
   let _no_rectypes = ignore
   let _remove_unused_arguments = ignore
   let _runtime_variant = ignore
+  let _with_runtime = ignore
+  let _without_runtime = ignore
   let _S = ignore
   let _safe_string = ignore
   let _short_paths = ignore

utils/clflags.ml

@@ -163,6 +163,7 @@ let pic_code = ref (match Config.architecture with (* -fPIC *)
                      | _       -> false)
 
 let runtime_variant = ref "";;      (* -runtime-variant *)
+let with_runtime = ref true;;         (* -with-runtime *)
 
 let keep_docs = ref false              (* -keep-docs *)
 let keep_locs = ref true               (* -keep-locs *)

utils/clflags.mli

@@ -185,6 +185,7 @@ val shared : bool ref
 val dlcode : bool ref
 val pic_code : bool ref
 val runtime_variant : string ref
+val with_runtime : bool ref
 val force_slash : bool ref
 val keep_docs : bool ref
 val keep_locs : bool ref