Fix splitting of quoted variables

Function before was incorrect on Windows and probably incorrect on Unix
- instead generalise OpamStd.Sys.split_path_variable to support
splitting with a colon-separator (and quoting).

src/core/opamStd.ml

@@ -877,15 +877,15 @@ module OpamSys = struct
   let path_sep = if Sys.win32 then ';' else ':'
 
   let split_path_variable ?(clean=true) =
-    if Sys.win32 then fun path ->
+    if Sys.win32 then fun ?(sep=path_sep) path ->
       let length = String.length path in
       let rec f acc index current last normal =
         if index = length then
           let current = current ^ String.sub path last (index - last) in
           List.rev (if current <> "" then current::acc else acc)
         else let c = path.[index]
           and next = succ index in
-          if c = ';' && normal || c = '"' then
+          if c = sep && normal || c = '"' then
             let current = current ^ String.sub path last (index - last) in
             if c = '"' then
               f acc next current next (not normal)
@@ -895,9 +895,9 @@ module OpamSys = struct
           else
             f acc next current last normal in
       f [] 0 "" 0 true
-    else fun path ->
+    else fun ?(sep=path_sep) path ->
       let split = if clean then OpamString.split else OpamString.split_delim in
-      split path path_sep
+      split path sep
 
   let with_process_in cmd args f =
     if Sys.win32 then

src/core/opamStd.mli

@@ -536,7 +536,7 @@ module Sys : sig
       it seems, because there may be quoting on Windows. By default, it returns
       the path cleaned (remove trailing, leading, contiguous delimiters).
       Optional argument [clean] permits to keep those empty strings. *)
-  val split_path_variable: ?clean:bool -> string -> string list
+  val split_path_variable: ?clean:bool -> ?sep:char -> string -> string list
 
   (** For native Windows builds, returns [`Cygwin] if the command is a Cygwin-
       compiled executable, [`Msys2] if the command is a MSYS2-compiled

src/state/opamEnv.ml

@@ -150,39 +150,10 @@ let split_var ~(sepfmt:sep_path_format) var value =
     in
     let sep = OpamTypesBase.char_of_separator separator in
     match format with
-    | Target_quoted | Host_quoted ->
-      OpamStd.String.split value sep
     | Target | Host ->
-      (* we suppose that it is in the form:
-         - "quoted":unquoted
-         - unquoted:"quoted"
-         - "quoted":unquoted:"quoted"
-         - unquoted:"quoted":unquoted
-         - "quoted"
-         - unquoted
-      *)
-      let rec aux remaining acc =
-        match String.get remaining 0 with
-        | '"' ->
-          (let remaining =
-             String.sub remaining 1 (String.length remaining - 1)
-           in
-           match OpamStd.String.cut_at remaining '"' with
-           | Some (quoted, rest) ->
-             aux rest (("\""^quoted^"\"")::acc)
-           | None -> remaining::acc)
-        | _ ->
-          let remaining =
-            if Char.equal (String.get remaining 0) sep then
-              String.sub remaining 1 (String.length remaining - 1)
-            else remaining in
-          (match OpamStd.String.cut_at remaining sep with
-           | Some (unquoted, rest) ->
-             aux rest (unquoted::acc)
-           | None -> remaining::acc)
-        | exception Invalid_argument _ -> acc
-      in
-      List.rev @@ aux value []
+      OpamStd.String.split value sep
+    | Target_quoted | Host_quoted ->
+      OpamStd.Sys.split_path_variable ~sep value
 
 let join_var ~(sepfmt:sep_path_format) var values =
   let separator =