Don't use color feature for ocaml 4.02.3

src/ansi_color.ml

@@ -153,14 +153,8 @@ let strip_colors_for_stderr s =
 (* We redirect the output of all commands, so by default the compiler will disable
    colors. Since we support colors in the output of commands, we force it via OCAMLPARAM
    if stderr supports colors. *)
-let setup_env_for_ocaml_colors = lazy(
+let setup_env_for_opam_colors = lazy(
   if Lazy.force stderr_supports_colors then begin
-    let value =
-      match Sys.getenv "OCAMLPARAM" with
-      | exception Not_found -> "color=always,_"
-      | s -> "color=always," ^ s
-    in
-    Unix.putenv "OCAMLPARAM" value;
     match Sys.getenv "OPAMCOLOR" with
     | exception Not_found -> Unix.putenv "OPAMCOLOR" "always"
     | _ -> ()

src/ansi_color.mli

@@ -2,7 +2,7 @@ val colorize : key:string -> string -> string
 
 val strip : string -> string
 val stderr_supports_colors : bool Lazy.t
-val setup_env_for_ocaml_colors : unit Lazy.t
+val setup_env_for_opam_colors : unit Lazy.t
 
 (** Strip colors in [not (Lazy.force stderr_supports_colors)] *)
 val strip_colors_for_stderr : string -> string

src/context.ml

@@ -251,6 +251,23 @@ let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin ~use_findli
   let get_path var = Path.absolute (get var) in
   let stdlib_dir = get_path "standard_library" in
   let natdynlink_supported = Path.exists (Path.relative stdlib_dir "dynlink.cmxa") in
+  let version = get "version" in
+  let env,env_extra =
+    (* We redirect the output of all commands, so by default the compiler will disable
+       colors. Since we support colors in the output of commands, we force it via OCAMLPARAM
+       if stderr supports colors. *)
+    let ocaml_version = Scanf.sscanf version "%u.%u.%u" (fun a b c -> a, b, c) in
+    if Lazy.force Ansi_color.stderr_supports_colors && ocaml_version > (4, 02, 3) then
+      let value =
+        match get_env env "OCAMLPARAM" with
+        | None -> "color=always,_"
+        | Some s -> "color=always," ^ s
+      in
+      extend_env ~env ~vars:((String_map.singleton "OCAMLPARAM" value)),
+      (String_map.add ~key:"OCAMLPARAM" ~data:value env_extra)
+    else
+      env,env_extra
+  in
   return
     { name
     ; kind
@@ -280,7 +297,7 @@ let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin ~use_findli
 
     ; stdlib_dir
     ; ocamlc_config = String_map.bindings ocamlc_config
-    ; version                 = get       "version"
+    ; version
     ; ccomp_type              = get       "ccomp_type"
     ; bytecomp_c_compiler     = get       "bytecomp_c_compiler"
     ; bytecomp_c_libraries    = get       "bytecomp_c_libraries"
@@ -317,7 +334,7 @@ let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin ~use_findli
 let opam_config_var t var = opam_config_var ~env:t.env ~cache:t.opam_var_cache var
 
 let initial_env = lazy (
-  Lazy.force Ansi_color.setup_env_for_ocaml_colors;
+  Lazy.force Ansi_color.setup_env_for_opam_colors;
   Unix.environment ())
 
 let default ?(merlin=true) ?(use_findlib=true) () =

src/future.ml

@@ -502,7 +502,7 @@ module Scheduler = struct
       go_rec cwd log t
 
   let go ?(log=Log.no_log) t =
-    Lazy.force Ansi_color.setup_env_for_ocaml_colors;
+    Lazy.force Ansi_color.setup_env_for_opam_colors;
     let cwd = Sys.getcwd () in
     go_rec cwd log t
 end