Support Windows Command Processor as a shell

Support cmd as an additional option to --shell. Additionally, use
parent_putenv so that opam config env does not have to be run at the end
of opam init or after opam switch.

Windows Command Processor has no equivalent to .profile - at present,
the user must run opam env every time they launch a command
prompt.

Signed-off-by: David Allsopp <david.allsopp@metastack.com>

src/client/opamArg.ml

@@ -738,12 +738,13 @@ let installed_roots_flag =
   mk_flag ["installed-roots"] "Display only the installed roots."
 
 let shell_opt =
-  let enum = [
+  let (enum : (string * OpamTypes.shell) list) = [
       "bash",`bash;
       "sh",`sh;
       "csh",`csh;
       "zsh",`zsh;
       "fish",`fish;
+      "cmd",`cmd;
     ] in
   mk_opt ["shell"] "SHELL"
     (Printf.sprintf

src/client/opamClient.ml

@@ -599,7 +599,10 @@ let init
             else false
           in
           let advised_deps =
-            [OpamStateConfig.(Lazy.force !r.makecmd); "m4"; "cc"]
+            if OpamStd.Sys.(os () = Win32) then
+              []
+            else
+              [OpamStateConfig.(Lazy.force !r.makecmd); "m4"; "cc"]
           in
           (match List.filter (not @* check_external_dep) advised_deps with
            | [] -> ()

src/client/opamCommands.ml

@@ -859,10 +859,10 @@ let config =
       if OpamStateConfig.(!r.current_switch) = None then `Ok () else
         OpamSwitchState.with_ `Lock_none gt @@ fun st ->
         `Ok (OpamConfigCommand.env st
-               ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish) ~inplace_path)
+              ~cmd:(shell=`cmd) ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish) ~inplace_path)
     | Some `revert_env, [] ->
        `Ok (OpamConfigCommand.print_eval_env
-              ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish)
+              ~cmd:(shell=`cmd) ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish)
               (OpamEnv.add [] []))
     | Some `setup, [] ->
       let user        = all || user in
@@ -885,7 +885,7 @@ let config =
                 Main options\n\
                \    -l, --list           %s\n\
                \    -a, --all            %s\n\
-               \    --shell=<bash|sh|csh|zsh|fish>\n\
+               \    --shell=<bash|sh|csh|zsh|fish|cmd>\n\
                \                         Configure assuming the given shell.\n\
                 \n\
                 User configuration\n\
@@ -1150,10 +1150,10 @@ let env =
       if OpamStateConfig.(!r.current_switch) <> None then
         OpamSwitchState.with_ `Lock_none gt @@ fun st ->
         OpamConfigCommand.env st
-          ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish) ~inplace_path
+          ~cmd:(shell=`cmd) ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish) ~inplace_path
     | true ->
       OpamConfigCommand.print_eval_env
-        ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish)
+        ~cmd:(shell=`cmd) ~csh:(shell=`csh) ~sexp ~fish:(shell=`fish)
         (OpamEnv.add [] [])
   in
   Term.(const env $global_options $shell_opt $sexp $inplace_path $revert),

src/client/opamConfigCommand.ml

@@ -177,20 +177,31 @@ let rec print_fish_env env =
            k (OpamStd.Env.escape_single_quotes ~using_backslashes:true v));
     print_fish_env r
 
-let print_eval_env ~csh ~sexp ~fish env =
+let print_cmd_env env =
+  List.iter (fun (k, v, _) -> OpamConsole.msg "set %s=%s\n" k v) env
+
+let print_eval_env ~cmd ~csh ~sexp ~fish env =
   if sexp then
     print_sexp_env env
   else if csh then
     print_csh_env env
   else if fish then
     print_fish_env env
+  else if cmd then
+    if OpamStd.Sys.tty_out then begin
+      log "parent-putenv";
+      OpamEnv.set_cmd_env env
+    end else begin
+      log "cmd-stdout";
+      print_cmd_env env
+    end
   else
     print_env env
 
-let env st ~csh ~sexp ~fish ~inplace_path =
+let env st ~cmd ~csh ~sexp ~fish ~inplace_path =
   log "config-env";
   let env = OpamEnv.get_opam ~force_path:(not inplace_path) st in
-  print_eval_env ~csh ~sexp ~fish env
+  print_eval_env ~cmd ~csh ~sexp ~fish env
 
 let subst gt fs =
   log "config-substitute";

src/client/opamConfigCommand.mli

@@ -14,17 +14,18 @@
 open OpamTypes
 open OpamStateTypes
 
-(** Display the current environment. Booleans csh, sexp and fish set an alternative
-    output (unspecified if more than one is true, sh-style by default).
+(** Display the current environment. Booleans cmd, csh, sexp and fish set an
+    alternative output (unspecified if more than one is true, sh-style by
+    default).
     [inplace_path] changes how the PATH variable is updated when there is already
     an opam entry: either at the same rank, or pushed in front. *)
 val env:
-  'a switch_state -> csh:bool -> sexp:bool -> fish:bool -> inplace_path:bool ->
-  unit
+  'a switch_state -> cmd:bool -> csh:bool -> sexp:bool -> fish:bool ->
+    inplace_path:bool -> unit
 
 (** Like [env] but allows to specify the precise env to print rather than
     compute it from a switch state *)
-val print_eval_env: csh:bool -> sexp:bool -> fish:bool -> env -> unit
+val print_eval_env: cmd:bool -> csh:bool -> sexp:bool -> fish:bool -> env -> unit
 
 (** Display the content of all available variables; global summary if the list
     is empty, package name "-" is understood as global configuration *)

src/core/opamStd.ml

@@ -888,7 +888,11 @@ module OpamSys = struct
     | "zsh"  -> `zsh
     | "bash" -> `bash
     | "fish" -> `fish
-    | _      -> `sh
+    | _      ->
+        if os () = Win32 then
+          `cmd
+        else
+          `sh
 
   let executable_name =
     if os () = Win32 then
@@ -902,7 +906,11 @@ module OpamSys = struct
 
   let guess_shell_compat () =
     try shell_of_string (Filename.basename (Env.get "SHELL"))
-    with Not_found -> `sh
+    with Not_found ->
+      if os () = Win32 then
+        `cmd
+      else
+        `sh
 
   let guess_dot_profile shell =
     let home f =

src/core/opamStd.mli

@@ -497,10 +497,10 @@ module Sys : sig
   val executable_name : string -> string
 
   (** Guess the shell compat-mode *)
-  val guess_shell_compat: unit -> [`csh|`zsh|`sh|`bash|`fish]
+  val guess_shell_compat: unit -> [`csh|`zsh|`sh|`bash|`fish|`cmd]
 
   (** Guess the location of .profile *)
-  val guess_dot_profile: [`csh|`zsh|`sh|`bash|`fish] -> string
+  val guess_dot_profile: [`csh|`zsh|`sh|`bash|`fish|`cmd] -> string
 
   (** The separator character used in the PATH variable (varies depending on
       OS) *)

src/format/opamTypes.mli

@@ -299,7 +299,7 @@ type universe = {
 type pin_kind = [ `version | OpamUrl.backend ]
 
 (** Shell compatibility modes *)
-type shell = [`fish|`csh|`zsh|`sh|`bash]
+type shell = [`fish|`csh|`zsh|`sh|`bash|`cmd]
 
 (** {2 Generic command-line definitions with filters} *)
 

src/format/opamTypesBase.ml

@@ -47,6 +47,7 @@ let string_of_shell = function
   | `zsh  -> "zsh"
   | `sh   -> "sh"
   | `bash -> "bash"
+  | `cmd  -> "Windows Command Processor"
 
 let file_null = ""
 let pos_file filename = OpamFilename.to_string filename, -1, -1